1.
Air pollution
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Air pollution occurs when harmful substances including particulates and biological molecules are introduced into Earths atmosphere. It may cause diseases, allergies or death in humans, it may cause harm to other living organisms such as animals and food crops. Human activity and natural processes can both generate air pollution, indoor air pollution and poor urban air quality are listed as two of the worlds worst toxic pollution problems in the 2008 Blacksmith Institute Worlds Worst Polluted Places report. According to the 2014 WHO report, air pollution in 2012 caused the deaths of around 7 million people worldwide, an air pollutant is a substance in the air that can have adverse effects on humans and the ecosystem. The substance can be particles, liquid droplets, or gases. A pollutant can be of natural origin or man-made, pollutants are classified as primary or secondary. Primary pollutants are usually produced from a process, such as ash from a volcanic eruption, other examples include carbon monoxide gas from motor vehicle exhaust, or the sulfur dioxide released from factories. Secondary pollutants are not emitted directly, rather, they form in the air when primary pollutants react or interact. Ground level ozone is a prominent example of a secondary pollutant, some pollutants may be both primary and secondary, they are both emitted directly and formed from other primary pollutants. Substances emitted into the atmosphere by human activity include, Carbon dioxide - Debate continues over whether carbon dioxide should be classified as an atmospheric pollutant, because of its role as a greenhouse gas it has been described as the leading pollutant and the worst climate pollution. Against this it is argued that carbon dioxide is a component of the atmosphere, essential for plant life. This question of terminology has practical effects, for example as determining whether the U. S. Clean Air Act is deemed to regulate CO2 emissions, CO2 increase in earths atmosphere has been accelerating. Sulfur oxides - particularly sulfur dioxide, a compound with the formula SO2. SO2 is produced by volcanoes and in industrial processes. Coal and petroleum often contain sulfur compounds, and their combustion generates sulfur dioxide, further oxidation of SO2, usually in the presence of a catalyst such as NO2, forms H2SO4, and thus acid rain. This is one of the causes for concern over the impact of the use of these fuels as power sources. Nitrogen oxides - Nitrogen oxides, particularly nitrogen dioxide, are expelled from high temperature combustion and they can be seen as a brown haze dome above or a plume downwind of cities. Nitrogen dioxide is a compound with the formula NO2
2.
United Nations Economic Commission for Europe
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The United Nations Economic Commission for Europe was established in 1947 to encourage economic cooperation among its member States. It is one of five regional commissions under the direction of United Nations headquarters. It has 56 member States, and reports to the United Nations Economic, besides countries in Europe, it also includes Canada, the Central Asian republics, Israel and the United States of America. The UNECE secretariat headquarters is in Geneva, Switzerland, and has a budget of US$50 million. The 56 member countries are listed below,18 of the UNECEs member countries are recipients of official development assistance. CEP is the governing body of UNECE environmental activities. Participating and/or facilitating the exchange of experience in a number of activities undertaken under the leadership of UNECE. In 1947, UNECE set up a Panel on Housing Problems, the Committee is an intergovernmental body of all UNECE member States. The UNECE Transport Division has been providing services to the World Forum for Harmonization of Vehicle Regulations. The UNECE Statistical Division provides the secretariat for the Conference and its expert groups, the Statistical Division develops guidelines and training materials on statistical methodology and practices, in response to demands from member countries. The UNECE Statistical Division also provides assistance to South-East European, East European, Caucasus. 2) A biennial overview of key statistics for member countries, UNECE Countries in Figures, 3) A set of wikis to support collaboration activities and disseminate information about good practices. UNECE conducted the Fertility and Family Survey in the 1990s in 23 member States, with over 150,000 participants and this activity has hence continued in the form of the Generations and Gender Programme. From 1982 to 2007 the IOS Press published the Statistical Journal of the United Nations Economic Commission for Europe on behalf of the UNECE
3.
Multi-effect Protocol
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As of August 2014, the Protocol had been ratified by 26 parties, which includes 25 states and the European Union. The Protocol is part of the Convention on Long-Range Transboundary Air Pollution, the geographic scope of the Protocol includes Europe, North America and countries of Eastern Europe, Caucasus and Central Asia. These amendments now need to be ratified by Parties in order to make them binding, because pollutants can be carried many hundreds of kilometres by winds, pollutants emitted in one country may be deposited in other countries. Deposition of pollutants in a country can far exceed the amount of pollution produced domestically due to pollution arriving from one or more upwind countries. In 1976, the environment ministers from the Nordic countries proposed a European convention on transboundary air pollution that emphasized sulphur compounds, after negotiations,34 countries and the European Commission signed this Convention in 1979 in Geneva. The convention came into force in 1983, and has now been ratified by 47 European countries, the CLRTAP now includes eight protocols that identify specific obligations to be taken by Parties. The Gothenburg Protocol was signed on 30 November 1999 in Gothenburg, Sweden, the Gothenburg Protocol entered into force on 17 May 2005. The selection of the emission levels were based on the predicted effects of the pollutants. Emission limits are set for each participating country and those countries participating in the Protocol with significant emission levels of the most harmful pollutants and whose emissions are relatively cheap to reduce must make larger emission reductions. Annexes 4,5,6,8 and 9 list limit values for specific sources, such as for combustion plants, electricity generation. Best available techniques are required to control emissions, with the exception of Annex 9, all the emission limit values specified were also updated in 2012 by the Parties. Among the specific sources, the Protocol establishes NOx emission limits for large stationary engines. Emission limits for new stationary sources should be enforced within one year after the date of entry into force of the Protocol for the party in question. Maximum sulfur content is specified for gas oil fuels at 0. 2% effective by July 2000 and 0. 1% by January 2008, the details of the Protocol are identified in a series of Annexes that address specific pollutants and emission source sectors. The Annexes typically allow Canada and the United States to participate with different commitments than other Parties to the Protocol and this is due to the different regulatory nature of Canada and the United States versus most European countries. In the EU, the Gothenburg protocol is implemented through the National Emission Ceilings directive, of all the countries that ratified the 1999 Gothenburg Protocol, most are expected to meet their obligations. Progress towards reducing emissions was greater than the Protocol commitments due to a widespread European shift from coal to natural gas as an industrial fuel in the 1970s and 1980s. As a result, the acidification of forests and lakes was halted in large parts of Europe, reduction of NOx emissions from traffic has less than originally expected
4.
The World Factbook
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The World Factbook is a reference resource produced by the Central Intelligence Agency with almanac-style information about the countries of the world. The official print version is available from the National Technical Information Service, Other companies—such as Skyhorse Publishing—also print a paper edition. The Factbook is available in the form of a website that is updated every week. It is also available for download for use off-line, the World Factbook is prepared by the CIA for the use of U. S. Government officials, and its style, format, coverage, and content are primarily designed to meet their requirements. However, it is used as a resource for academic research papers. As a work of the U. S. Government, it is in the domain in the United States. In researching the Factbook, the CIA uses the sources listed below, Other public and private sources are also consulted. However, the CIA requests that it be cited when the Factbook is used, copying the official seal of the CIA without permission is prohibited by U. S. federal law—specifically, the Central Intelligence Agency Act of 1949. Before November 2001 The World Factbook website was updated yearly, from 2004 to 2010 it was updated every two weeks, since 2010 it has been updated weekly, generally, information currently available as of January 1 of the current year is used in preparing the Factbook. The first, classified, edition of Factbook was published in August 1962, the World Factbook was first available to the public in print in 1975. In 2008 the CIA discontinued printing the Factbook themselves, instead turning printing responsibilities over to the Government Printing Office and this happened due to a CIA decision to focus Factbook resources on the online edition. The Factbook has been on the World Wide Web since October 1994, the web version gets an average of 6 million visits per month, it can also be downloaded. The official printed version is sold by the Government Printing Office, in past years, the Factbook was available on CD-ROM, microfiche, magnetic tape, and floppy disk. Many Internet sites use information and images from the CIA World Factbook, several publishers, including Grand River Books, Potomac Books, and Skyhorse Publishing have re-published the Factbook in recent years. As of July 2011, The World Factbook consists of 267 entities and these entities can be divided into categories. They are, Independent countries This category has independent countries, which the CIA defines as people politically organized into a state with a definite territory. In this category, there are 195 entities, others The Other category is a list of other places set apart from the list of independent countries. Currently there are two, Taiwan and the European Union, dependencies and Areas of Special Sovereignty This category is a list of places affiliated with another country
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Pollution
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Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of chemical substances or energy, such as noise, pollutants, the components of pollution, can be either foreign substances/energies or naturally occurring contaminants. Pollution is often classed as point source or nonpoint source pollution, Air pollution has always accompanied civilizations. Pollution started from prehistoric times when man created the first fires, metal forging appears to be a key turning point in the creation of significant air pollution levels outside the home. The burning of coal and wood, and the presence of horses in concentrated areas made the cities the cesspools of pollution. The Industrial Revolution brought an infusion of untreated chemicals and wastes into local streams that served as the water supply, king Edward I of England banned the burning of sea-coal by proclamation in London in 1272, after its smoke became a problem. But the fuel was so common in England that this earliest of names for it was acquired because it could be carted away from some shores by the wheelbarrow and it was the industrial revolution that gave birth to environmental pollution as we know it today. London also recorded one of the extreme cases of water quality problems with the Great Stink on the Thames of 1858. Pollution issues escalated as population growth far exceeded view ability of neighborhoods to handle their waste problem, reformers began to demand sewer systems, and clean water. In 1870, the conditions in Berlin were among the worst in Europe. There were no toilets in the streets or squares. Visitors, especially women, often became desperate when nature called, in the public buildings the sanitary facilities were unbelievably primitive. As a metropolis, Berlin did not emerge from a state of barbarism into civilization until after 1870. Chicago and Cincinnati were the first two American cities to enact laws ensuring cleaner air in 1881, as historian Martin Melosi notes, The generation that first saw automobiles replacing the horses saw cars as miracles of cleanliness. By the 1940s, however, automobile-caused smog was an issue in Los Angeles. Other cities followed around the country early in the 20th century. Extreme smog events were experienced by the cities of Los Angeles and Donora, Pennsylvania in the late 1940s, Air pollution would continue to be a problem in England, especially later during the industrial revolution, and extending into the recent past with the Great Smog of 1952. Awareness of atmospheric pollution spread widely after World War II, with fears triggered by reports of fallout from atomic warfare. Then a non-nuclear event, The Great Smog of 1952 in London and this prompted some of the first major modern environmental legislation, The Clean Air Act of 1956
6.
Acid rain
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Acid rain is a rain or any other form of precipitation that is unusually acidic, meaning that it possesses elevated levels of hydrogen ions. It can have effects on plants, aquatic animals and infrastructure. Acid rain is caused by emissions of sulfur dioxide and nitrogen oxide, some governments have made efforts since the 1970s to reduce the release of sulfur dioxide and nitrogen oxide into the atmosphere with positive results. Nitrogen oxides can also be produced naturally by lightning strikes, Acid rain is a popular term referring to the deposition of a mixture from wet and dry acidic components. Distilled water, once carbon dioxide is removed, has a neutral pH of 7, liquids with a pH less than 7 are acidic, and those with a pH greater than 7 are alkaline. Clean or unpolluted rain has an acidic pH, but usually no lower than 5, a common example is nitric acid produced by electric discharge in the atmosphere such as lightning. Acid deposition as an issue would include additional acids other than H2CO3. The corrosive effect of polluted, acidic city air on limestone and marble was noted in the 17th century by John Evelyn, since the Industrial Revolution, emissions of sulfur dioxide and nitrogen oxides into the atmosphere have increased. In 1852, Robert Angus Smith was the first to show the relationship between rain and atmospheric pollution in Manchester, England. Though acidic rain was discovered in 1853, it was not until the late 1960s that scientists began widely observing and studying the phenomenon, the term acid rain was coined in 1872 by Robert Angus Smith. Canadian Harold Harvey was among the first to research a dead lake, occasional pH readings in rain and fog water of well below 2.4 have been reported in industrialized areas. Industrial acid rain is a problem in China and Russia. These areas all burn sulfur-containing coal to heat and electricity. The problem of acid rain has not only increased with population and industrial growth, the use of tall smokestacks to reduce local pollution has contributed to the spread of acid rain by releasing gases into regional atmospheric circulation. Often deposition occurs a considerable distance downwind of the emissions, with mountainous regions tending to receive the greatest deposition, an example of this effect is the low pH of rain which falls in Scandinavia. The earliest report about acid rain in the United States was from the evidence from Hubbard Brook Valley. In 1972, a group of scientists including Gene Likens discovered the rain that was deposited at White Mountains of New Hampshire was acidic, the pH of the sample was measured to be 4.03 at Hubbard Brook. The Hubbard Brook Ecosystem Study followed up with a series of research that analyzed the effects of acid rain
7.
Atmospheric dispersion modeling
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Atmospheric dispersion modeling is the mathematical simulation of how air pollutants disperse in the ambient atmosphere. It is performed with programs that solve the mathematical equations. They can also be used to predict future concentrations under specific scenarios, therefore, they are the dominant type of model used in air quality policy making. They are most useful for pollutants that are dispersed over large distances, for pollutants that have a very high spatio-temporal variability and for epidemiological studies statistical land-use regression models are also used. Dispersion models are important to governmental agencies tasked with protecting and managing the ambient air quality, the models also serve to assist in the design of effective control strategies to reduce emissions of harmful air pollutants. During the late 1960s, the Air Pollution Control Office of the U. S. EPA initiated research projects that would lead to the development of models for the use by urban and transportation planners. A major and significant application of a dispersion model that resulted from such research was applied to the Spadina Expressway of Canada in 1971. Air dispersion models are used by public safety responders and emergency management personnel for emergency planning of accidental chemical releases. Appropriate protective actions may include evacuation or shelter in place for persons in the downwind direction, at industrial facilities, this type of consequence assessment or emergency planning is required under the Clean Air Act codified in Part 68 of Title 40 of the Code of Federal Regulations. Source term and temperature of the material Emissions or release parameters such as location and height, type of source and exit velocity, exit temperature. Terrain elevations at the location and at the receptor location, such as nearby homes, schools, businesses. The location, height and width of any obstructions in the path of the emitted gaseous plume, the plots of areas impacted may also include isopleths showing areas of minimal to high concentrations that define areas of the highest health risk. The isopleths plots are useful in determining protective actions for the public, the atmospheric dispersion models are also known as atmospheric diffusion models, air dispersion models, air quality models, and air pollution dispersion models. Discussion of the layers in the Earths atmosphere is needed to understand where airborne pollutants disperse in the atmosphere, the layer closest to the Earths surface is known as the troposphere. It extends from sea-level to a height of about 18 km, the stratosphere is the next layer and extends from 18 km to about 50 km. The third layer is the mesosphere which extends from 50 km to about 80 km, there are other layers above 80 km, but they are insignificant with respect to atmospheric dispersion modeling. The lowest part of the troposphere is called the boundary layer or the planetary boundary layer. The air temperature of the boundary layer decreases with increasing altitude until it reaches what is called the inversion layer that caps the atmospheric boundary layer
8.
Chlorofluorocarbon
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A chlorofluorocarbon is an organic compound that contains only carbon, chlorine, and fluorine, produced as volatile derivative of methane, ethane, and propane. They are also known by the DuPont brand name Freon. The most common representative is dichlorodifluoromethane, many CFCs have been widely used as refrigerants, propellants, and solvents. As in simpler alkanes, carbon in the CFCs bonds with tetrahedral symmetry, because the fluorine and chlorine atoms differ greatly in size and effective charge from hydrogen and from each other, the methane-derived CFCs deviate from perfect tetrahedral symmetry. The physical properties of CFCs and HCFCs are tunable by changes in the number, in general they are volatile, but less so than their parent alkanes. The decreased volatility is attributed to the molecular polarity induced by the halides, thus, methane boils at −161 °C whereas the fluoromethanes boil between −51.7 and −128 °C. The CFCs have still higher boiling points because the chloride is even more polarizable than fluoride, because of their polarity, the CFCs are useful solvents, and their boiling points make them suitable as refrigerants. The densities of CFCs are higher than their corresponding alkanes, in general the density of these compounds correlates with the number of chlorides. CFCs and HCFCs are usually produced by halogen exchange starting from chlorinated methanes and ethanes, the chlorine atom, written often as Cl. behaves very differently from the chlorine molecule. The radical Cl. is long-lived in the atmosphere, where it catalyzes the conversion of ozone into O2. Ozone absorbs UV-B radiation, so its depletion allows more of high energy radiation to reach the Earths surface. Bromine atoms are more efficient catalysts, hence brominated CFCs are also regulated. Applications exploit the low toxicity, low reactivity, and low flammability of the CFCs and HCFCs, every permutation of fluorine, chlorine, and hydrogen based on methane and ethane has been examined and most have been commercialized. Furthermore, many examples are known for higher numbers of carbon as well as related compounds containing bromine, uses include refrigerants, blowing agents, propellants in medicinal applications, and degreasing solvents. Billions of kilograms of chlorodifluoromethane are produced annually as precursor to tetrafluoroethylene, chlorofluorocarbons, when derived from methane and ethane these compounds have the formulae CClmF4−m and C2ClmF6−m, where m is nonzero. Hydrofluorocarbons, when derived from methane, ethane, propane, and butane, these compounds have the respective formulae CFmH4−m, C2FmH6−m, C3FmH8−m, and C4FmH10−m, a numbering system is used for fluorinated alkanes, prefixed with Freon-, R-, CFC-, and HCFC-. The rightmost value indicates the number of atoms, the next value to the left is the number of hydrogen atoms plus 1. Thus, Freon-12 indicates a methane derivative containing two fluorine atoms and no hydrogen, another, easier equation that can be applied to get the correct molecular formula of the CFC/R/Freon class compounds is this to take the numbering and add 90 to it
9.
Indoor air quality
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Indoor air quality is a term which refers to the air quality within and around buildings and structures, especially as it relates to the health and comfort of building occupants. IAQ can be affected by gases, particulates, microbial contaminants, source control, filtration and the use of ventilation to dilute contaminants are the primary methods for improving indoor air quality in most buildings. Residential units can further improve air quality by routine cleaning of carpets. Determination of IAQ involves the collection of air samples, monitoring human exposure to pollutants, collection of samples on building surfaces, IAQ is part of indoor environmental quality, which includes IAQ as well as other physical and psychological aspects of life indoors. Indoor air pollution in developing nations is a health hazard. A major source of air pollution in developing countries is the burning of biomass for heating and cooking. The resulting exposure to high levels of particulate matter resulted in between 1.5 million and 2 million deaths in 2000, second-hand smoke is tobacco smoke which affects other people other than the active smoker. The only certain method to improve air quality as regards second-hand smoke is the implementation of comprehensive smoke-free laws. Radon is an invisible, radioactive gas that results from the radioactive decay of radium. Radon is probably the most pervasive serious hazard for air in the United States and Europe. There are relatively simple test kits for do-it-yourself radon gas testing, radon gas enters buildings as a soil gas and is a heavy gas and thus will tend to accumulate at the lowest level. Radon may also be introduced into a building through drinking water particularly from bathroom showers, the half life for radon is 3.8 days, indicating that once the source is removed, the hazard will be greatly reduced within a few weeks. Radon mitigation methods include sealing concrete slab floors, basement foundations, water drainage systems and they are usually cost effective and can greatly reduce or even eliminate the contamination and the associated health risks. Mold is always associated with moisture, and its growth can be inhibited by keeping humidity levels below 50%, in areas where cellulosic materials become moist and fail to dry within 48 hours, mold mildew can propagate and release allergenic spores into the air. In many cases, if materials have failed to dry out several days after the suspected water event, through a mold investigation, which may include destructive inspection, one should be able to determine the presence or absence of mold. In a situation there is visible mold and the indoor air quality may have been compromised. There are some varieties of mold that contain toxic compounds, however, exposure to hazardous levels of mycotoxin via inhalation is not possible in most cases, as toxins are produced by the fungal body and are not at significant levels in the released spores. The primary hazard of mold growth, as it relates to air quality
10.
Global dimming
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Global dimming is the gradual reduction in the amount of global direct irradiance at the Earths surface that was observed for several decades after the start of systematic measurements in the 1950s. The effect varies by location, but worldwide it has estimated to be of the order of a 4% reduction over the three decades from 1960–1990. However, after discounting an anomaly caused by the eruption of Mount Pinatubo in 1991, global dimming is thought to have been caused by an increase in particulates such as sulfate aerosols in the atmosphere due to human action. It has interfered with the cycle by reducing evaporation and may have reduced rainfall in some areas. Global dimming also creates an effect that may have partially counteracted the effect of greenhouse gases on global warming. It is thought that global dimming is probably due to the presence of aerosol particles in the atmosphere caused by human action. Aerosols and other particulates absorb solar energy and reflect back into space. The pollutants can also become nuclei for cloud droplets, water droplets in clouds coalesce around the particles. Increased pollution causes more particulates and thereby creates clouds consisting of a number of smaller droplets. The smaller droplets make clouds more reflective, so that more incoming sunlight is reflected back into space and this same effect also reflects radiation from below, trapping it in the lower atmosphere. In models, these smaller droplets also decrease rainfall, clouds intercept both heat from the sun and heat radiated from the Earth. Their effects are complex and vary in time, location, in the late-1960s, Mikhail Ivanovich Budyko worked with simple two-dimensional energy-balance climate models to investigate the reflectivity of ice. He found that the ice-albedo feedback created a feedback loop in the Earths climate system. The more snow and ice, the solar radiation is reflected back into space and hence the colder Earth grows. Other studies found that pollution or an eruption could provoke the onset of an ice age. His findings appeared to contradict global warming — the global temperature had been rising since the 70s. Less light reaching the earth seemed to mean that it should cool, ohmura published his findings Secular variation of global radiation in Europe in 1989. Dimming has also observed in sites all over the former Soviet Union
11.
Global warming
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Global warming and climate change are terms for the observed century-scale rise in the average temperature of the Earths climate system and its related effects. Multiple lines of evidence show that the climate system is warming. The largest human influence has been emission of gases such as carbon dioxide, methane. These findings have been recognized by the science academies of the major industrialized nations and are not disputed by any scientific body of national or international standing. Future climate change and associated impacts will differ from region to region around the globe, anticipated effects include warming global temperature, rising sea levels, changing precipitation, and expansion of deserts in the subtropics. Warming is expected to be greater over land than over the oceans and greatest in the Arctic, with the retreat of glaciers, permafrost. Effects significant to humans include the threat to security from decreasing crop yields. Possible societal responses to global warming include mitigation by emissions reduction, adaptation to its effects, building systems resilient to its effects, most countries are parties to the United Nations Framework Convention on Climate Change, whose ultimate objective is to prevent dangerous anthropogenic climate change. Public reactions to global warming and concern about its effects are also increasing, a global 2015 Pew Research Center report showed a median of 54% consider it a very serious problem. There are significant regional differences, with Americans and Chinese among the least concerned, the global average surface temperature shows a warming of 0.85 °C in the period 1880 to 2012, based on multiple independently produced datasets. Earths average surface temperature rose by 0. 74±0.18 °C over the period 1906–2005, the rate of warming almost doubled for the last half of that period. The rest has melted ice and warmed the continents and atmosphere, the average temperature of the lower troposphere has increased between 0.12 and 0.135 °C per decade since 1979, according to satellite temperature measurements. The warming that is evident in the temperature record is consistent with a wide range of observations. The probability that these changes could have occurred by chance is virtually zero, temperature changes vary over the globe. Since 1979, land temperatures have increased about twice as fast as ocean temperatures, ocean temperatures increase more slowly than land temperatures because of the larger effective heat capacity of the oceans and because the ocean loses more heat by evaporation. Since the beginning of industrialisation the temperature difference between the hemispheres has increased due to melting of sea ice and snow in the North. Average arctic temperatures have been increasing at almost twice the rate of the rest of the world in the past 100 years, the thermal inertia of the oceans and slow responses of other indirect effects mean that climate can take centuries or longer to adjust to changes in forcing. Some of this warming will be driven by past natural forcings which are still seeking equilibrium in the climate system
12.
Ozone depletion
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The latter phenomenon is referred to as the ozone hole. In addition to these well-known stratospheric phenomena, there are also springtime polar tropospheric ozone depletion events, the details of polar ozone hole formation differ from that of mid-latitude thinning but the most important process in both is catalytic destruction of ozone by atomic halogens. The main source of these atoms in the stratosphere is photodissociation of man-made halocarbon refrigerants, solvents, propellants. These compounds are transported into the stratosphere by winds after being emitted at the surface, both types of ozone depletion were observed to increase as emissions of halocarbons increased. CFCs and other substances are referred to as ozone-depleting substances. Three forms of oxygen are involved in the cycle, oxygen atoms, oxygen gas. Ozone is formed in the stratosphere when oxygen molecules photodissociate after intaking an ultraviolet photon whose wavelength is shorter than 240 nm and this converts a single O2 into two atomic oxygen radicals. The atomic oxygen radicals then combine with separate O2 molecules to create two O3 molecules and these ozone molecules absorb ultraviolet light between 310 and 200 nm, following which ozone splits into a molecule of O2 and an oxygen atom. The oxygen atom then joins up with a molecule to regenerate ozone. This is a process that terminates when an oxygen atom recombines with an ozone molecule to make two O2 molecules. 2 O3 →3 O2 The overall amount of ozone in the stratosphere is determined by a balance between production and recombination. Ozone can be destroyed by a number of free radical catalysts, the dot is a common notation to indicate that all of these species have an unpaired electron and are thus extremely reactive. Cl and Br atoms destroy ozone molecules through a variety of catalytic cycles, in the simplest example of such a cycle, a chlorine atom reacts with an ozone molecule, taking an oxygen atom to form chlorine monoxide and leaving an oxygen molecule. The ClO can react with a molecule of ozone, releasing the chlorine atom. More complicated mechanisms have been discovered that lead to destruction in the lower stratosphere as well. On a per atom basis, bromine is more efficient than chlorine at destroying ozone. As a result, both chlorine and bromine contribute significantly to overall ozone depletion, Laboratory studies have shown that fluorine and iodine atoms participate in analogous catalytic cycles. On average, a chlorine atom is able to react with 100,000 ozone molecules before it is removed from the catalytic cycle
13.
Particulates
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Atmospheric particulate matter – also known as particulate matter or particulates – are microscopic solid or liquid matter suspended in the Earths atmosphere. The term aerosol commonly refers to the mixture, as opposed to the particulate matter alone. Sources of particulate matter can be man-made or natural and they have impacts on climate and precipitation that adversely affect human health. The smaller PM2.5 were particularly deadly, with a 36% increase in lung cancer per 10 μg/m3 as it can penetrate deeper into the lungs, some particulates occur naturally, originating from volcanoes, dust storms, forest and grassland fires, living vegetation, and sea spray. Human activities, such as the burning of fossil fuels in vehicles, power plants and various industrial processes, coal combustion in developing countries is the primary method for heating homes and supplying energy. The composition of aerosols and particles depends on their source, wind-blown mineral dust tends to be made of mineral oxides and other material blown from the Earths crust, this particulate is light-absorbing. In addition, sea spray aerosols may contain organic compounds, which influence their chemistry, Secondary particles derive from the oxidation of primary gases such as sulfur and nitrogen oxides into sulfuric acid and nitric acid. The gases from which they originate—may have an origin and a natural biogenic origin. In the presence of ammonia, secondary aerosols often take the form of ammonium salts and this is mainly because the presence of sulfate and nitrate causes the aerosols to increase to a size that scatters light effectively. Organic matter can be primary or secondary, the latter part deriving from the oxidation of VOCs. Organic matter influences the atmospheric radiation field by both scattering and absorption, another important aerosol type is elemental carbon, this aerosol type includes strongly light-absorbing material and is thought to yield large positive radiative forcing. Organic matter and elemental carbon together constitute the carbonaceous fraction of aerosols, Secondary organic aerosols, tiny tar balls resulting from combustion products of internal combustion engines, have been identified as a danger to health. The chemical composition of the aerosol directly affects how it interacts with solar radiation, the chemical constituents within the aerosol change the overall refractive index. The refractive index will determine how light is scattered and absorbed. The particles are hygroscopic due to the presence of sulfur, and SO2 is converted to sulfate when high humidity and this causes the reduced visibility and yellow color. Aerosol particles of natural origin tend to have a larger radius than human-produced aerosols such as particle pollution, the false-color maps in the third image on this page show where there are natural aerosols, human pollution, or a mixture of both, monthly. Most of the Southern Hemisphere is covered by ocean, where the largest source of aerosols is natural sea salt from dried sea spray. Because land is concentrated in the Northern Hemisphere, the amount of small aerosols from fires, over land, patches of large-radius aerosols appear over deserts and arid regions, most prominently, the Sahara Desert in north Africa and the Arabian Peninsula, where dust storms are common
14.
Smog
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Smog is a type of air pollutant. The word smog was coined in the early 20th century as a portmanteau of the smoke and fog to refer to smoky fog, its opacity. The word was then intended to refer to what was known as pea soup fog. This kind of air pollution is composed of nitrogen oxides, sulfur oxides, ozone. Human-made smog is derived from coal emissions, vehicular emissions, industrial emissions, forest and agricultural fires, in certain other cities, such as Delhi, smog severity is often aggravated by stubble burning in neighboring agricultural areas. The atmospheric pollution levels of Los Angeles, Beijing, Delhi, Mexico City, Tehran and it is usually highly toxic to humans and can cause severe sickness, shortened life or death. Coinage of the smog is generally attributed to Dr. Henry Antoine Des Voeux in his 1905 paper, Fog. The following day the newspaper stated that Dr. Des Voeux did a service in coining a new word for the London fog. However, this is predated by a Los Angeles Times article of January 19,1893, coal fires, used to heat individual buildings or in a power-producing plant, can emit significant clouds of smoke that contributes to smog. Air pollution from this source has reported in England since the Middle Ages. London, in particular, was notorious up through the century for its coal-caused smogs. Traffic emissions – such as trucks, buses, and automobiles – also contribute. Airborne by-products from vehicle exhaust systems cause air pollution and are an ingredient in the creation of smog in some large cities. The major culprits from transportation sources are carbon monoxide, nitrogen oxides, volatile compounds, sulfur dioxide. These molecules react with sunlight, heat, ammonia, moisture, and other compounds to form the noxious vapors, ground level ozone, Photochemical smog is the chemical reaction of sunlight, nitrogen oxides and volatile organic compounds in the atmosphere, which leaves airborne particles and ground-level ozone. A secondary pollutant is not directly emitted as such, but forms when other pollutants react in the atmosphere, all of these harsh chemicals are usually highly reactive and oxidizing. Photochemical smog is therefore considered to be a problem of modern industrialization and it is present in all modern cities, but it is more common in cities with sunny, warm, dry climates and a large number of motor vehicles. Because it travels with the wind, it can affect sparsely populated areas as well, the composition and chemical reactions involved in photochemical smog were not understood until the 1950s
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Water pollution
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Water pollution is the contamination of water bodies. This form of environmental degradation occurs when pollutants are directly or indirectly discharged into water bodies without adequate treatment to remove harmful compounds, Water pollution affects the entire biosphere – plants and organisms living in these bodies of water. In almost all cases the effect is damaging not only to individual species and population, Water pollution is a major global problem which requires ongoing evaluation and revision of water resource policy at all levels. It has been suggested that pollution is the leading worldwide cause of deaths and diseases. An estimated 580 people in India die of water related illness every day. About 90 percent of the water in the cities of China is polluted, as of 2007, half a billion Chinese had no access to safe drinking water. In addition to the problems of water pollution in developing countries. The head of Chinas national development agency said in 2007 that one quarter the length of Chinas seven main rivers were so poisoned the water harmed the skin. Natural phenomena such as volcanoes, algae blooms, storms, and earthquakes also cause changes in water quality. Although interrelated, surface water and groundwater have often studied and managed as separate resources. Surface water seeps through the soil and becomes groundwater, conversely, groundwater can also feed surface water sources. Sources of surface water pollution are generally grouped into two based on their origin. Point source water pollution refers to contaminants that enter a waterway from a single, identifiable source, examples of sources in this category include discharges from a sewage treatment plant, a factory, or a city storm drain. The U. S. Clean Water Act defines point source for regulatory enforcement purposes, the CWA definition of point source was amended in 1987 to include municipal storm sewer systems, as well as industrial storm water, such as from construction sites. Nonpoint source pollution refers to contamination that does not originate from a single discrete source. NPS pollution is often the cumulative effect of small amounts of contaminants gathered from a large area, a common example is the leaching out of nitrogen compounds from fertilized agricultural lands. Nutrient runoff in storm water from sheet flow over a field or a forest are also cited as examples of NPS pollution. Contaminated storm water washed off of parking lots, roads and highways, however, because this runoff is typically channeled into storm drain systems and discharged through pipes to local surface waters, it becomes a point source
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Environmental impact of shipping
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The environmental impact of shipping includes greenhouse gas emissions, acoustic, and oil pollution. The First Intersessional Meeting of the IMO Working Group on Greenhouse Gas Emissions from Ships took place in Oslo, ballast water discharges by ships can have a negative impact on the marine environment. Ballast water discharge typically contains a variety of materials, including plants, animals, viruses. These materials often include non-native, nuisance, invasive, exotic species that can cause extensive ecological, noise pollution caused by shipping and other human enterprises has increased in recent history. The disruption of whales ability to communicate with one another is a threat and is affecting their ability to survive. Whales are starting to react to this in ways that are life-threatening, Balcomb, a whale researcher and a former U. S Navy officer, states that the day March 15,2000, is the day of infamy. As Discovery says, where him and his crew discovered whales swimming dangerously close to the shore, theyre supposed to be in deep water. So I pushed it out to sea, says Balcomb. Although sonar helps to protect us, it is destroying marine life, according to IFAW Animal Rescue Program Director Katie Moore, Theres different ways that sounds can affect animals. Theres that underlying ambient noise level thats rising, and rising, and then theres the more acute kind of traumatic impact of sound, thats causing physical damage or a really strong behavioral response. Marine mammals, such as whales and manatees, risk being struck by ships, causing injury, for example, if a ship is traveling at a speed of only 15 knots, there is a 79 percent chance of a collision being lethal to a whale. One notable example of the impact of collisions is the endangered North Atlantic right whale. The greatest danger to the North Atlantic right whale is injury sustained from ship strikes, between 1970 and 1999,35.5 percent of recorded deaths were attributed to collisions. During 1999 to 2003, incidents of mortality and serious injury attributed to ship strikes averaged one per year, in 2004 to 2006, that number increased to 2.6. Deaths from collisions has become an extinction threat, exhaust gases from ships are considered to be a significant source of air pollution, both for conventional pollutants and greenhouse gases. A difficulty is that the increasing amount shipping overwhelms gains in efficiency. The growth in tonne-kilometers of sea shipment has averaged 4 percent yearly since the 1990s, and it has grown by a factor of 5 since the 1970s. There are now over 100,000 transport ships at sea, diesel exhaust has been classified by EPA as a likely human carcinogen
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Environmental monitoring
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Environmental monitoring describes the processes and activities that need to take place to characterise and monitor the quality of the environment. All monitoring strategies and programmes have reasons and justifications which are designed to establish the current status of an environment or to establish trends in environmental parameters. In all cases the results of monitoring will be reviewed, analysed statistically, the design of a monitoring programme must therefore have regard to the final use of the data before monitoring starts. Air quality monitoring is performed using specialized equipment and analytical methods used to establish air pollutant concentrations, air monitors are operated by citizens, regulatory agencies, and researchers to investigate air quality and the effects of air pollution. Air dispersion models that combine topographic, emissions and meteorological data to predict air pollutant concentrations are often helpful in interpreting air monitoring data. If an air monitor produces concentrations of chemical compounds, a unique chemical fingerprint of a particular air pollution source may emerge from analysis of the data. Soil monitoring is the process of collection of soil and testing in laboratory by analytical methods, in laboratory, soil can be tested for pH, Chlorides, Sulphates, Phosphates and other metals. Water quality monitoring is of use without a clear and unambiguous definition of the reasons for the monitoring. Almost all monitoring is in some part invasive of the environment under study and extensive and this may be a critical consideration in wilderness areas or when monitoring very rare organisms or those that are averse to human presence. Unless individual monitoring projects fit into a strategic framework, the results are unlikely to be published. The list can be expanded or reduced based on developing knowledge, freshwater environments have been extensively studied for many years and there is a robust understanding of the interactions between chemistry and the environment across much of the world. However, as new materials are developed and new pressures come to bear, in the last 20 years acid rain, synthetic hormone analogues, halogenated hydrocarbons, greenhouse gases and many others have required changes to monitoring strategies. In ecological monitoring, the strategy and effort is directed at the plants. However, in more generalised environmental monitoring, many act as robust indicators of the quality of the environment that they are experiencing or have experienced in the recent past. The steep decline in fish populations was one of the early indications of the problem that later became known as acid rain. In recent years much more attention has been given to a holistic approach in which the ecosystem health is assessed and used as the monitoring tool itself. It is this approach that underpins the monitoring protocols of the Water Framework Directive in the European Union, the ‘measurement’ of dose often means the measurement of a dose equivalent quantity as a proxy for a dose quantity that cannot be measured directly. Also, sampling may be involved as a step to measurement of the content of radionuclides in environmental media.8
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Eutrophication
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Eutrophication, or more precisely hypertrophication, is the enrichment of a water body with nutrients, usually with an excess amount of nutrients. This process induces growth of plants and algae and due to the biomass load, one example is the bloom or great increase of phytoplankton in a water body as a response to increased levels of nutrients. Eutrophication is almost always induced by the discharge of phosphate-containing detergents, fertilizers, or sewage, Eutrophication arises from the oversupply of nutrients, which leads to overgrowth of plants and algae. After such organisms die, the degradation of their biomass consumes the oxygen in the water. According to Ullmanns Encyclopedia, the limiting factor for eutrophication is phosphate. Phosphorus is a nutrient for plants to live, and is the limiting factor for plant growth in many freshwater ecosystems. Phosphate adheres tightly to soil, so it is transported by erosion. Once translocated to lakes, the extraction of phosphate into water is slow, the sources of these excess phosphates are phosphates in detergent, industrial/domestic run-offs, and fertilizers. With the phasing out of phosphate-containing detergents in the 1970s, industrial/domestic run-off, cultural Eutrophication is the process that speeds up natural eutrophication because of human activity. Extra nutrients are supplied by treatment plants, golf courses, fertilizers, farms. When algae die, they decompose and the contained in that organic matter are converted into inorganic form by microorganisms. This decomposition process consumes oxygen, which reduces the concentration of dissolved oxygen, the depleted oxygen levels in turn may lead to fish kills and a range of other effects reducing biodiversity. Nutrients may become concentrated in a zone and may only be made available again during autumn turn-over or in conditions of turbulent flow. The water becomes cloudy, typically coloured a shade of green, yellow, brown, Eutrophication also decreases the value of rivers, lakes and aesthetic enjoyment. Health problems can occur where eutrophic conditions interfere with drinking water treatment, human activities can accelerate the rate at which nutrients enter ecosystems. Elevated levels of compounds of nitrogen can increase nitrogen availability. Phosphorus is often regarded as the culprit in cases of eutrophication in lakes subjected to point source pollution from sewage pipes. The concentration of algae and the state of lakes correspond well to phosphorus levels in water
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Freshwater environmental quality parameters
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Monitoring of environmental quality parameters is a key activity in managing the environment, restoring polluted environments and anticipating the effects of man-made changes on the environment. Freshwater environmental quality parameters are those chemical, physical or biological parameters that can be used to characterise a freshwater body, because almost all water bodies are dynamic in their composition, the relevant quality parameters are typically expressed as a range of expected concentrations. The first step in understanding the chemistry of freshwater is to establish the relevant concentrations of the parameters of interest, conventionally this is done by taking representative samples of the water for subsequent analysis in a laboratory. However, in-situ monitoring using hand-held analytical equipment or using bank-side monitoring stations are also used, freshwaters are surprisingly difficult to sample because they are rarely homogeneous and their quality varies during the day and during the year. In addition the most representative sampling locations are often at a distance from the shore or bank increasing the logistic complexity. Filling a clean bottle with water is a very simple task. Almost all natural rivers will have very significant patterns of change through the day, many rivers also have a very large flow that is unseen. Ground waters by their nature are often very difficult to access to take a sample. As a consequence the majority of data comes from samples taken from springs, wells, water supply bore-holes. Large lakes in the temperate zone often stratify in the warmer months into a warmer upper layers rich in oxygen, in the autumn, falling temperatures and occasional high winds result in the mixing of the two layers into a more homogeneous whole. Lakes also receive waters, often many different sources with varying qualities. All of these phenomena can skew the results of any environmental monitoring unless the process are well understood, where two rivers meet at a confluence there exists a mixing zone. A mixing zone may be large and extend for many miles as in the case of the Mississippi and Missouri rivers in the United States. In a mixing zone water chemistry may be variable and can be difficult to predict. The geology that underlies a river or lake has an impact on its chemistry. A river flowing across very ancient precambrian schists is likely to have dissolved very little from the rocks, conversely a river flowing through chalk hills, and especially if its source is in the chalk, will have a high concentration of carbonates and bicarbonates of Calcium and possibly Magnesium. As a river progresses along its course it may pass through a variety of geological types, oxygen is probably the most important chemical constituent of surface water chemistry, as all aerobic organisms require it for survival. It enters the water mostly via diffusion at the water-air interface, oxygen’s solubility in water decreases as water temperature increases
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Groundwater pollution
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Groundwater pollution occurs when pollutants are released to the ground and make their way down into groundwater. The pollutant creates a contaminant plume within an aquifer, movement of water and dispersion within the aquifer spreads the pollutant over a wider area. The movement of the plume, called a front, may be analyzed through a hydrological transport model or groundwater model. Analysis of groundwater pollution may focus on soil characteristics and site geology, hydrogeology, hydrology, pollution can also occur from naturally occurring contaminants, such as arsenic or fluoride. Using polluted groundwater causes hazards to health through poisoning or the spread of disease. Different mechanisms have influence on the transport of pollutants, e. g. diffusion, adsorption, precipitation, decay, the interaction of groundwater contamination with surface waters is analyzed by use of hydrology transport models. Contaminants found in cover a broad range of physical, inorganic chemical, organic chemical, bacteriological. Principally, many of the pollutants that play a role in surface water pollution may also be found in polluted groundwater. Arsenic and fluoride have been recognized by the World Health Organization as the most serious inorganic contaminants in drinking-water on a worldwide basis, the metalloid arsenic can occur naturally in groundwater, as seen most frequently in Asia, including in China, India and Bangladesh. In the Ganges Plain of northern India and Bangladesh severe contamination of groundwater by naturally occurring arsenic affects 25% of water wells in the shallower of two regional aquifers, arsenic in groundwater can also be present where there are mining operations or mine waste dumps that will leach arsenic. Natural fluoride in groundwater is of growing concern as deeper groundwater is being used, fluoride can especially be released from acidic volcanic rocks and dispersed volcanic ash when water hardness is low. Pathogens contained in feces can lead to groundwater pollution when they are given the opportunity to reach the groundwater, groundwater that is contaminated with pathogens can lead to fatal fecal-oral transmission of diseases. Nitrate is the most common contaminant in the world’s groundwater. In some low-income countries nitrate levels in groundwater are extremely high and it is also stable under high oxygen conditions. Nitrate levels above 10 mg/L in groundwater can cause blue baby syndrome, Drinking water quality standards in the European Union stipulate less than 50 mg/L for nitrate in drinking water. However, the linkages between nitrates in drinking water and blue baby syndrome have been disputed in other studies, the syndrome outbreaks might be due to other factors than elevated nitrate concentrations in drinking water. Elevated nitrate levels in groundwater can be caused by on-site sanitation and it can therefore have an urban or agricultural origin. Volatile organic compounds are a dangerous contaminant of groundwater and they are generally introduced to the environment through careless industrial practices
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Hypoxia (environmental)
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Hypoxia refers to low oxygen conditions. Normally,20. 9% of the gas in the atmosphere is oxygen, the partial pressure of oxygen in the atmosphere is 20. 9% of the total barometric pressure. In water however, oxygen levels are lower, approximately 1%. Atmospheric hypoxia occurs naturally at high altitudes, total atmospheric pressure decreases as altitude increases, causing a lower partial pressure of oxygen which is defined as hypobaric hypoxia. Oxygen remains at 20. 9% of the gas mixture, differing from hypoxic hypoxia. This is common, for example, in the burrows of some subterranean animals. Atmospheric hypoxia is also the basis of training which is a standard part of training for elite athletes. Several companies mimic hypoxia using normobaric artificial atmosphere, dissolved oxygen is typically expressed as a percentage of the oxygen that would dissolve in the water at the prevailing temperature and salinity. An aquatic system lacking dissolved oxygen is termed anaerobic, reducing, or anoxic, most fish cannot live below 30% saturation. A healthy aquatic environment should seldom experience less than 80%, the exaerobic zone is found at the boundary of anoxic and hypoxic zones. Hypoxia can occur throughout the column and also at high altitudes as well as near sediments on the bottom. It usually extends throughout 20-50% of the column, but depending on the water depth. It can occur in 10-80% of the water column, for example, in a 10-meter water column, it can reach up to 2 meters below the surface. In a 20-meter water column, it can extend up to 8 meters below the surface, while phytoplankton, through photosynthesis, will raise DO saturation during daylight hours, the dense population of a bloom reduces DO saturation during the night by respiration. When phytoplankton cells die, they sink towards the bottom and are decomposed by bacteria, if oxygen depletion progresses to hypoxia, fish kills can occur and invertebrates like worms and clams on the bottom may be killed as well. Hypoxia may also occur in the absence of pollutants, in estuaries, for example, because freshwater flowing from a river into the sea is less dense than salt water, stratification in the water column can result. Vertical mixing between the bodies is therefore reduced, restricting the supply of oxygen from the surface waters to the more saline bottom waters. The oxygen concentration in the layer may then become low enough for hypoxia to occur
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Marine debris
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Marine debris, also known as marine litter, is human-created waste that has deliberately or accidentally been released in a lake, sea, ocean or waterway. Floating oceanic debris tends to accumulate at the center of gyres and on coastlines, frequently washing aground, deliberate disposal of wastes at sea is called ocean dumping. Naturally occurring debris, such as driftwood, are also present, with the increasing use of plastic, human influence has become an issue as many types of plastics do not biodegrade. Waterborne plastic poses a threat to fish, seabirds, marine reptiles. Dumping, container spillages, litter washed into storm drains and waterways, more recent studies have found that more than half of plastic debris found on Korean shores is ocean-based. Six pack rings, in particular, are considered emblematic of the problem, the US military used ocean dumping for unused weapons and bombs, including ordinary bombs, UXO, landmines and chemical weapons from at least 1919 until 1970. Millions of pounds of ordnance were disposed of in the Gulf of Mexico and off the coasts of at least 16 states, eighty percent of marine debris is plastic. Plastics accumulate because they typically do not biodegrade as many other substances do and they photodegrade on exposure to sunlight, although they do so only under dry conditions, as water inhibits photolysis. Fishing nets left or lost in the ocean by fishermen – ghost nets – can entangle fish, dolphins, sea turtles, sharks, dugongs, crocodiles, seabirds, crabs and other creatures. These nets restrict movement, causing starvation, laceration and infection,8.8 million metric tons of plastic waste are dumped in the worlds oceans each year. Asia was the source of mismanaged plastic waste, with China alone accounting for 2.4 million metric tons. Plastic waste has reached all the worlds oceans and this plastic pollution harms an estimated 100,000 sea turtles and marine mammals and 1,000,000 sea creatures each year. Microplastics on the other hand harm smaller marine life, pelagic plastic pieces in the center of our ocean’s gyres for example outnumber live marine plankton, and are passed up the food chain to reach all marine life. A1994 study of the seabed using trawl nets in the North-Western Mediterranean around the coasts of Spain, France, plastic debris accounted for 77%, of which 93% was plastic bags. Nurdles, also known as mermaids tears, are plastic pellets, typically under five millimetres in diameter and they are a raw material in plastics manufacturing, and enter the natural environment when spilled. Research performed by MBARI found items including plastic bags below 2000m depth off the west coast of North America, an estimated 10,000 containers at sea each year are lost by container ships, usually during storms. One spillage occurred in the Pacific Ocean in 1992, when thousands of rubber ducks, the toys have since been found all over the world, providing a better understanding of ocean currents. Similar incidents have happened before, such as when Hansa Carrier dropped 21 containers, in 2007, MSC Napoli beached in the English Channel, dropping hundreds of containers, most of which washed up on the Jurassic Coast, a World Heritage Site
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Marine pollution
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Eighty percent of marine pollution comes from land. Air pollution is also a factor by carrying off pesticides or dirt into the ocean. Land and air pollution have proven to be harmful to marine life, the pollution often comes from non point sources such as agricultural runoff, wind-blown debris and dust. Nutrient pollution, a form of pollution, refers to contamination by excessive inputs of nutrients. It is a cause of eutrophication of surface waters, in which excess nutrients, usually nitrogen or phosphorus. Many potentially toxic chemicals adhere to tiny particles which are taken up by plankton and benthos animals. In this way, the toxins are concentrated upward within ocean food chains, many particles combine chemically in a manner highly depletive of oxygen, causing estuaries to become anoxic. When pesticides are incorporated into the ecosystem, they quickly become absorbed into marine food webs. Once in the webs, these pesticides can cause mutations, as well as diseases. Toxic metals can also be introduced into marine food webs and these can cause a change to tissue matter, biochemistry, behaviour, reproduction, and suppress growth in marine life. Also, many animal feeds have a fish meal or fish hydrolysate content. In this way, marine toxins can be transferred to land animals, although marine pollution has a long history, significant international laws to counter it were only enacted in the twentieth century. Marine pollution was a concern during several United Nations Conferences on the Law of the Sea beginning in the 1950s, most scientists believed that the oceans were so vast that they had unlimited ability to dilute, and thus render pollution harmless. After the Mediterranean Sea controversy, for example, Jacques Cousteau became a figure in the campaign to stop marine pollution. Marine pollution made further international headlines after the 1967 crash of the oil tanker Torrey Canyon, Marine pollution was a major area of discussion during the 1972 United Nations Conference on the Human Environment, held in Stockholm. That year also saw the signing of the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, the London Convention did not ban marine pollution, but it established black and gray lists for substances to be banned or regulated by national authorities. Cyanide and high-level radioactive waste, for example, were put on the black list, the London Convention applied only to waste dumped from ships, and thus did nothing to regulate waste discharged as liquids from pipelines. There are many different ways to categorize, and examine the inputs of pollution into our marine ecosystems, one common path of entry by contaminants to the sea are rivers
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Nutrient pollution
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Nutrient pollution, a form of water pollution, refers to contamination by excessive inputs of nutrients. It is a cause of eutrophication of surface waters, in which excess nutrients, usually nitrogen or phosphorus. Sources of nutrient pollution include surface runoff from fields and pastures, discharges from septic tanks and feedlots. TMDL reports identify pollutant levels and strategies to accomplish pollutant reduction goals, EPA has described TMDLs as establishing a pollutant budget then allocating portions of the overall budget to the pollutants sources. For many coastal water bodies, the main pollutant issue is excess nutrients, a TMDL can prescribe the minimum level of Dissolved Oxygen available in a body of water, which is directly related to nutrient levels. In 2010,18 percent of TMDLs nationwide were related to nutrient levels including organic enrichment/oxygen depletion, noxious plants, algal growth, Nutrient remediation is a form of environmental remediation, but concerns only biologically active nutrients such as nitrogen and phosphorus. “Remediation” refers to the removal of pollution or contaminants, generally for the protection of human health, in environmental remediation nutrient removal technologies include biofiltration, which uses living material to capture and biologically degrade pollutants. Examples include green belts, riparian areas, natural and constructed wetlands and these areas most commonly capture anthropogenic discharges such as wastewater, stormwater runoff, or sewage treatment, for land reclamation after mining, refinery activity, or land development. Biofiltration utilizes biological assimilation to capture, absorb, and eventually incorporate the pollutants into living tissue, another form of nutrient removal is bioremediation, which uses microrganisms to remove pollutants. Bioremediation can occur on its own as natural attenuation or intrinsic bioremediation or can be encouraged by the addition of fertilizers, Nutrient bioextraction is bioremediation involving cultured plants and animals. Nutrient bioextraction or bioharvesting is the practice of farming and harvesting shellfish and seaweed for the purpose of removing nitrogen and it has been suggested that nitrogen removal by oyster reefs could generate net benefits for sources facing nitrogen emission restrictions, similar to other nutrient trading scenarios. Several studies have shown that oysters and mussels have the capacity to dramatically impact nitrogen levels in estuaries, in 1998, a Policy for a National Nutrient Strategy was created with a focus on developing nutrient criteria. Between 2000-2010 criteria for Rivers/Streams, Lakes/Reservoirs, Estuaries, Wetlands, in 2007, EPA reiterated EPA’s expectations for numeric criteria and committed EPA to support state efforts. After the EPA had introduced watershed-based NPDES permitting in 2007, interest in nutrient removal, Nutrient trading is a type of water quality trading, a market-based policy instrument used to improve or maintain water quality. Water quality trading arose around 2005 and is based on the fact that different pollution sources in a watershed can face very different costs to control the same pollutant, the underlying principle is “polluter pays”, usually linked with a regulatory driver for participating is the trading program. As of 2013, payments were overwhelmingly initiated by public good payers like governments, part of the manure nutrient management section of the Livestock and Poultry Environmental Learning Center
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Ocean acidification
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Ocean acidification is the ongoing decrease in the pH of the Earths oceans, caused by the uptake of carbon dioxide from the atmosphere. Seawater is slightly basic, and the process in question is a shift towards pH-neutral conditions rather than a transition to acidic conditions, Ocean alkalinity is not changed by the process, or may increase over long time periods due to carbonate dissolution. An estimated 30–40% of the carbon dioxide from human activity released into the atmosphere dissolves into oceans, rivers, to achieve chemical equilibrium, some of it reacts with the water to form carbonic acid. Some of these extra carbonic acid molecules react with a molecule to give a bicarbonate ion. Between 1751 and 1996 surface ocean pH is estimated to have decreased from approximately 8.25 to 8.14, representing an increase of almost 35% in H+ ion concentration in the worlds oceans. By increasing the presence of hydrogen ions, each molecule of carbonic acid that forms in the oceans ultimately results in the conversion of two carbonate ions into bicarbonate ions. Ongoing acidification of the oceans threatens food chains connected with the oceans, while ongoing ocean acidification is anthropogenic in origin, it has occurred previously in Earths history. The most notable example is the Paleocene-Eocene Thermal Maximum, which occurred approximately 56 million years ago, for reasons that are currently uncertain, massive amounts of carbon entered the ocean and atmosphere, and led to the dissolution of carbonate sediments in all ocean basins. Ocean acidification has been called the twin of global warming. The carbon cycle describes the fluxes of carbon dioxide between the oceans, terrestrial biosphere, lithosphere, and the atmosphere, human activities such as the combustion of fossil fuels and land use changes have led to a new flux of CO2 into the atmosphere. About 45% has remained in the atmosphere, most of the rest has been taken up by the oceans, the carbon cycle involves both organic compounds such as cellulose and inorganic carbon compounds such as carbon dioxide and the carbonates. The inorganic compounds are relevant when discussing ocean acidification for it includes many forms of dissolved CO2 present in the Earths oceans. When CO2 dissolves, it reacts with water to form a balance of ionic and non-ionic chemical species, dissolved carbon dioxide, carbonic acid. The ratio of these depends on factors such as seawater temperature. These different forms of dissolved inorganic carbon are transferred from a surface to its interior by the oceans solubility pump. The resistance of an area of ocean to absorbing atmospheric CO2 is known as the Revelle factor. Since the industrial revolution began, it is estimated that surface ocean pH has dropped by more than 0.1 units on the logarithmic scale of pH. It is expected to drop by a further 0.3 to 0.5 pH units by 2100 as the oceans absorb more anthropogenic CO2, the impacts being most severe for coral reefs and the Southern Ocean
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Oil spill
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An oil spill is the release of a liquid petroleum hydrocarbon into the environment, especially marine areas, due to human activity, and is a form of pollution. The term is applied to marine oil spills, where oil is released into the ocean or coastal waters. Cleanup and recovery from an oil spill is difficult and depends upon factors, including the type of oil spilled, the temperature of the water. Spills may take weeks, months or even years to clean up, oil spills can have disastrous consequences for society, economically, environmentally, and socially. The quantity of oil spilled during accidents has ranged from a few hundred tons to several hundred thousand tons, but volume is a limited barometer of damage or impact. Oil spills at sea are generally much more damaging than those on land and these can kill seabirds, mammals, shellfish and other organisms they coat. Oil spills on land are more readily containable if an earth dam can be rapidly bulldozed around the spill site before most of the oil escapes. An oil spill represents an immediate fire hazard, the Kuwaiti oil fires produced air pollution that caused respiratory distress. The Deepwater Horizon explosion killed eleven oil rig workers, the fire resulting from the Lac-Mégantic derailment killed 47 and destroyed half of the towns centre. Spilled oil can contaminate drinking water supplies. For example, in 2013 two different oil spills contaminated water supplies for 300,000 in Miri, Malaysia,80,000 people in Coca, in 2000, springs were contaminated by an oil spill in Clark County, Kentucky. Contamination can have an impact on tourism and marine resource extraction industries. For example, the Deepwater Horizon oil spill impacted beach tourism and fishing along the Gulf Coast, in general, sрilled oil can affect animals and plants in twо ways, dirесt from the oil and from the respоnsе or cleаnup process. There is no relationship between the amount of oil in the aquatic environment and the likely impact on biodiversity. A smaller spill at the wrong time/wrong season and in an environment may prove much more harmful than a larger spill at another time of the year in another or even the same environment. Animals who rely on scent to find their babies or mothers cannot due to the scent of the oil. This causes a baby to be rejected and abandoned, leaving the babies to starve, oil can impair a birds ability to fly, preventing it from foraging or escaping from predators. As they preen, birds may ingest the oil coating their feathers, irritating the digestive tract, altering liver function, together with their diminished foraging capacity, this can rapidly result in dehydration and metabolic imbalance
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Septic tank
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Other components may include pumps, alarms, sand filters, and clarified liquid effluent disposal methods such as a septic drain field, ponds, natural stone fiber filter plants or peat moss beds. Septic systems are a type of onsite sewage facility, in North America, approximately 25 percent of the population relies on septic tanks, including some suburbs and small towns as well as rural areas. Indianapolis is one example of a city where many of the citys neighborhoods still rely on separate septic systems. In Europe, septic systems are limited to rural areas. Since septic systems require large drainfields, they are not suitable for densely built cities, the term septic refers to the anaerobic bacterial environment that develops in the tank which decomposes or mineralizes the waste discharged into the tank. Septic tanks can be coupled with other onsite wastewater treatment units such as biofilters or aerobic systems involving artificially forced aeration, periodic preventive maintenance is required to remove solids that remain and gradually fill the tank, reducing its efficiency. Maintenance requires regular pumping to remove these, according to the US Environmental Protection Agency, in the United States it is the home owners responsibility to maintain their septic systems. Anyone who disregards this requirement will eventually be faced with costly repairs when solids escape the tank and clog the clarified liquid effluent disposal system. A septic tank consists of one or more concrete or plastic tanks of between 4000 and 7500 liters, one end is connected to a wastewater pipe and the other to a septic drain field. Generally these pipe connections are made with a T pipe, allowing liquid to enter, wastewater enters the first chamber of the tank, allowing solids to settle and scum to float. The settled solids are anaerobically digested, reducing the volume of solids, the liquid component flows through the dividing wall into the second chamber, where further settlement takes place. A percolation test is required prior to installation to ensure the porosity of the soil is adequate to serve as a drain field, a piping network, often laid in a stone-filled trench, distributes the wastewater throughout the field with multiple drainage holes in the network. The size of the field is proportional to the volume of wastewater. The entire septic system can operate by gravity alone or, where topographic considerations require, certain septic tank designs include siphons or other devices to increase the volume and velocity of outflow to the drainage field. These help to fill the pipe more evenly and extend the drainage field life by preventing premature clogging or bioclogging. An Imhoff tank is a septic system where the sludge is digested in a separate tank. This avoids mixing digested sludge with incoming sewage, also, some septic tank designs have a second stage where the effluent from the anaerobic first stage is aerated before it drains into the seepage field. A properly designed and normally operating septic system is odor-free and, besides periodic inspection and emptying of the septic tank, a well designed and maintained concrete, fiberglass, or plastic tank should last about 50 years
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Surface runoff
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Surface runoff is the flow of water that occurs when excess stormwater, meltwater, or other sources flows over the Earths surface. Surface runoff is a component of the water cycle. It is the agent in soil erosion by water. Runoff that occurs on the surface before reaching a channel is also called a nonpoint source. If a nonpoint source contains man-made contaminants, or natural forms of pollution the runoff is called nonpoint source pollution, a land area which produces runoff that drains to a common point is called a drainage basin. When runoff flows along the ground, it can pick up soil contaminants including petroleum, pesticides, surface runoff can be generated either by rainfall, snowfall or by the melting of snow, or glaciers. Snow and glacier melt occur only in areas cold enough for these to form permanently, typically snowmelt will peak in the spring and glacier melt in the summer, leading to pronounced flow maxima in rivers affected by them. The determining factor of the rate of melting of snow or glaciers is both air temperature and the duration of sunlight, in high mountain regions, streams frequently rise on sunny days and fall on cloudy ones for this reason. In areas where there is no snow, runoff will come from rainfall, however, not all rainfall will produce runoff because storage from soils can absorb light showers. This occurs when the rate of rainfall on a surface exceeds the rate at which water can infiltrate the ground and this is called flooding excess overland flow, Hortonian overland flow, or unsaturated overland flow. This more commonly occurs in arid and semi-arid regions, where rainfall intensities are high and this occurs largely in city areas where pavements prevent water from flooding. When the soil is saturated and the depression storage filled, and rain continues to fall, the level of antecedent soil moisture is one factor affecting the time until soil becomes saturated. This runoff is called saturation excess overland flow or saturated overland flow, soil retains a degree of moisture after a rainfall. This residual water moisture affects the soils infiltration capacity, during the next rainfall event, the infiltration capacity will cause the soil to be saturated at a different rate. The higher the level of antecedent soil moisture, the more quickly the soil becomes saturated, once the soil is saturated, runoff occurs. After water infiltrates the soil on a portion of a hill, the water may flow laterally through the soil. This is called subsurface return flow or throughflow, any remaining surface water eventually flows into a receiving water body such as a river, lake, estuary or ocean. Urbanization increases surface runoff by creating more impervious surfaces such as pavement and it is instead forced directly into streams or storm water runoff drains, where erosion and siltation can be major problems, even when flooding is not
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Thermal pollution
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Thermal pollution is the degradation of water quality by any process that changes ambient water temperature. A common cause of pollution is the use of water as a coolant by power plants. When water used as a coolant is returned to the environment at a higher temperature. Fish and other organisms adapted to particular temperature range can be killed by a change in water temperature known as thermal shock. Urban runoff—stormwater discharged to waters from roads and parking lots—can also be a source of elevated water temperatures. Elevated temperature typically decreases the level of dissolved oxygen of water and this can harm aquatic animals such as fish, amphibians and other aquatic organisms. An increased metabolic rate may result in resources, the more adapted organisms moving in may have an advantage over organisms that are not used to the warmer temperature. As a result, food chains of the old and new environments may be compromised, some fish species will avoid stream segments or coastal areas adjacent to a thermal discharge. Biodiversity can be decreased as a result, high temperature limits oxygen dispersion into deeper waters, contributing to anaerobic conditions. This can lead to increased levels when there is ample food supply. Many aquatic species will fail to reproduce at elevated temperatures, primary producers are affected by warm water because higher water temperature increases plant growth rates, resulting in a shorter lifespan and species overpopulation. This can cause an algae bloom which reduces oxygen levels, temperature changes of even one to two degrees Celsius can cause significant changes in organism metabolism and other adverse cellular biology effects. Principal adverse changes can include rendering cell walls less permeable to necessary osmosis, coagulation of cell proteins and these cellular level effects can adversely affect mortality and reproduction. A large increase in temperature can lead to the denaturing of life-supporting enzymes by breaking down hydrogen-, decreased enzyme activity in aquatic organisms can cause problems such as the inability to break down lipids, which leads to malnutrition. In limited cases, warm water has little effect and may even lead to improved function of the receiving aquatic ecosystem. This phenomenon is especially in seasonal waters and is known as thermal enrichment. An extreme case is derived from the habits of the manatee. Projections suggest that manatee populations would decline upon the removal of these discharges, releases of unnaturally cold water from reservoirs can dramatically change the fish and macroinvertebrate fauna of rivers, and reduce river productivity
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Turbidity
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Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of water quality, fluids can contain suspended solid matter consisting of particles of many different sizes. These small solid particles cause the liquid to appear turbid, Turbidity is also applied to transparent solids such as glass or plastic. In plastic production haze is defined as the percentage of light that is deflected more than 2. 5° from the light direction. Turbidity in open water may be caused by growth of phytoplankton, human activities that disturb land, such as construction, mining and agriculture, can lead to high sediment levels entering water bodies during rain storms due to storm water runoff. Certain industries such as quarrying, mining and coal recovery can generate high levels of turbidity from colloidal rock particles. In drinking water, the higher the turbidity level, the higher the risk that people may develop gastrointestinal diseases and this is especially problematic for immunocompromised people, because contaminants like viruses or bacteria can become attached to the suspended solids. The suspended solids interfere with water disinfection with chlorine because the act as shields for the virus. Similarly, suspended solids can protect bacteria from ultraviolet sterilization of water, high turbidity levels can also affect the ability of fish gills to absorb dissolved oxygen. This phenomenon has been observed throughout the Chesapeake Bay in the eastern United States. For many mangrove areas, high turbidity is needed to support certain species, for most mangroves along the eastern coast of Australia, in particular Moreton Bay, turbidity levels as high as 600 Nephelometric Turbidity Units are needed for proper ecosystem health. The most widely used measurement unit for turbidity is the Formazin Turbidity Unit, ISO refers to its units as FNU. ISO7027 provides the method in water quality for the determination of turbidity and it is used to determine the concentration of suspended particles in a sample of water by measuring the incident light scattered at right angles from the sample. The scattered light is captured by a photodiode, which produces a signal that is converted to a turbidity. Open source hardware has been developed following the ISO7027 method to measure turbidity reliably using an Arduino microcontroller, there are several practical ways of checking water quality, the most direct being some measure of attenuation of light as it passes through a sample column of water. The alternatively used Jackson Candle method is essentially the inverse measure of the length of a column of water needed to completely obscure a candle flame viewed through it, the more water needed, the clearer the water. Of course water alone produces some attenuation, and any substances dissolved in the water that produce color can attenuate some wavelengths, modern instruments do not use candles, but this approach of attenuation of a light beam through a column of water should be calibrated and reported in JTUs. The propensity of particles to scatter a light focused on them is now considered a more meaningful measure of turbidity in water
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Urban runoff
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Urban runoff is surface runoff of rainwater created by urbanization. This runoff is a source of flooding and water pollution in urban communities worldwide. Impervious surfaces are constructed during land development, during rain storms and other precipitation events, these surfaces, along with rooftops, carry polluted stormwater to storm drains, instead of allowing the water to percolate through soil. This causes lowering of the table and flooding since the amount of water that remains on the surface is greater. Most municipal storm sewer systems discharge stormwater, untreated, to streams, rivers and this excess water can also make its way into peoples properties through basement backups and seepage through building wall and floors. Urban runoff is a cause of urban flooding, the inundation of land or property in a built-up environment caused by rainfall overwhelming the capacity of drainage systems. Where properties are built with basements, urban flooding is the cause of basement flooding. Flood flows in urban environments have been investigated relatively recently despite many centuries of flood events, some researchers mentioned the storage effect in urban areas. Several studies looked into the patterns and redistribution in streets during storm events. Some recent research considered the criteria for safe evacuation of individuals in flooded areas and these considerations ignore further the risks associated with large debris entrained by the flow motion. Roof runoff contributes high levels of organic compounds and zinc. Fertilizer use on lawns, parks and golf courses is a measurable source of nitrates. Eroding soils or poorly maintained construction sites can lead to increased sedimentation in runoff. Sedimentation often settles to the bottom of bodies and can directly affect water quality. Excessive levels of sediment in water bodies can increase the risk of infection and these high levels of nutrients can reduce oxygen and boost algae growth while limiting native vegetation growth. Limited native vegetation and excessive algae has the potential to disrupt the aquatic ecosystem due to limited light penetration, lower oxygen levels. Excessive levels of sediment and suspended solids have the potential to damage existing infrastructure as well, sedimentation can increase runoff by plugging underground injection systems, thereby increasing the amount of runoff on the surface. Increased sedimentation levels can also reduce storage behind reservoirs and this reduction of reservoir capacities can lead to increased expenses for public land agencies while also impacting the quality of water recreational areas
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Wastewater
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Wastewater, also written as waste water, is any water that has been adversely affected in quality by anthropogenic influence. Wastewater can originate from a combination of domestic, industrial, commercial or agricultural activities, surface runoff or stormwater, municipal wastewater is usually conveyed in a combined sewer or sanitary sewer, and treated at a wastewater treatment plant. Treated wastewater is discharged into receiving water via an effluent pipe, wastewaters generated in areas without access to centralized sewer systems rely on on-site wastewater systems. These typically comprise a septic tank, drain field, and optionally an on-site treatment unit, the management of wastewater belongs to the overarching term sanitation, just like the management of human excreta, solid waste and stormwater. Sewerage is the infrastructure, including pipes, pumps, screens. Soluble organic material such as urea, fruit sugars, soluble proteins, drugs, pharmaceuticals, inorganic particles such as sand, grit, metal particles, ceramics, etc. Soluble inorganic material such as ammonia, road-salt, sea-salt, cyanide, hydrogen sulfide, thiocyanates, thiosulfates, animals such as protozoa, insects, arthropods, small fish, etc. Macro-solids such as napkins, nappies/diapers, condoms, needles, childrens toys, dead animals or plants. Gases such as sulfide, carbon dioxide, methane, etc. Emulsions such as paints, adhesives, mayonnaise, hair colorants, emulsified oils, toxins such as pesticides, poisons, herbicides, etc. The result is that the content of the water will be decreased. Those biochemical reactions create what is measured in the laboratory as the oxygen demand. Such chemicals are also liable to be broken down using strong oxidizing agents, both the BOD and COD tests are a measure of the relative oxygen-depletion effect of a waste contaminant. Both have been adopted as a measure of pollution effect. The BOD test measures the demand of biodegradable pollutants whereas the COD test measures the oxygen demand of oxidizable pollutants. The so-called 5-day BOD measures the amount of oxygen consumed by oxidation of waste contaminants in a 5-day period. The total amount of consumed when the biochemical reaction is allowed to proceed to completion is called the Ultimate BOD. Because the Ultimate BOD is so time consuming, the 5-day BOD has been almost universally adopted as a measure of pollution effect
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Water quality
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Water quality refers to the chemical, physical, biological, and radiological characteristics of water. It is a measure of the condition of water relative to the requirements of one or more biotic species and it is most frequently used by reference to a set of standards against which compliance can be assessed. The most common used to assess water quality relate to health of ecosystems, safety of human contact. In the setting of standards, agencies make political and technical/scientific decisions about how the water will be used, in the case of natural water bodies, they also make some reasonable estimate of pristine conditions. Natural water bodies will vary in response to environmental conditions, Environmental scientists work to understand how these systems function, which in turn helps to identify the sources and fates of contaminants. Environmental lawyers and policymakers work to define legislation with the intention that water is maintained at a quality for its identified use. The vast majority of water on the Earth is neither potable nor toxic. This remains true when seawater in the oceans is not counted, another general perception of water quality is that of a simple property that tells whether water is polluted or not. In fact, water quality is a subject, in part because water is a complex medium intrinsically tied to the ecology of the Earth. Industrial and commercial activities are a cause of water pollution as are runoff from agricultural areas, urban runoff. The parameters for water quality are determined by the intended use, work in the area of water quality tends to be focused on water that is treated for human consumption, industrial use, or in the environment. Water quality depends on the geology and ecosystem, as well as human uses such as sewage dispersion, industrial pollution, use of water bodies as a heat sink. The United States Environmental Protection Agency limits the amounts of contaminants in tap water provided by US public water systems. The U. S. Food and Drug Administration regulations establish limits for contaminants in bottled water that must provide the protection for public health. Drinking water, including bottled water, may reasonably be expected to contain at least small amounts of some contaminants, the presence of these contaminants does not necessarily indicate that the water poses a health risk. Water drawn directly from a stream, lake, or aquifer, dissolved minerals may affect suitability of water for a range of industrial and domestic purposes. Hard water may be softened to remove these ions, the softening process often substitutes sodium cations. Hard water may be preferable to soft water for consumption, since health problems have been associated with excess sodium
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Water stagnation
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Water stagnation occurs when water stops flowing. Stagnant water can be an environmental hazard. Malaria and dengue are among the dangers of stagnant water. Stagnant water can be dangerous for drinking because it provides a better incubator than running water for many kinds of bacteria, stagnant water is often contaminated with human and animal feces, particularly in deserts or other areas of low rain. Stagnant water may be classified into the basic, although overlapping, types, Water body stagnation Surface. The water may be trapped in human artifacts, as well as in natural containers, such as tree trunks. To avoid ground and surface water stagnation, drainage of surface, areas with a shallow water table are more susceptible to ground water stagnation due to the lower availability of natural soil drainage. Some plants prefer flowing water, while others, such as lotuses, various anaerobic bacteria are commonly found in stagnant water. For this reason, pools of stagnant water have historically used in processing hemp and some other fiber crops. Several weeks of soaking makes bast fibers easily separable due to bacterial, dragonfly nymphs Fly maggots Mosquito larvae Nepidae Algae Biofilm A number of species of frogs prefer stagnant water. Some species of turtles Mata mata Wetland Residence time distribution Water pollution
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Soil contamination
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Soil contamination or soil pollution as part of land degradation is caused by the presence of xenobiotic chemicals or other alteration in the natural soil environment. It is typically caused by activity, agricultural chemicals, or improper disposal of waste. The most common chemicals involved are petroleum hydrocarbons, polynuclear aromatic hydrocarbons, solvents, pesticides, lead, Contamination is correlated with the degree of industrialization and intensity of chemical usage. In North America and Western Europe the extent of contaminated land is best known, with many of countries in areas having a legal framework to identify. Developing countries tend to be tightly regulated despite some of them having undergone significant industrialization. Soil pollution can be caused by the following Oil drilling Mining and activities by other heavy industries Accidental spills as may happen during activities, in a wider sense, genetically modified plants can count as a risk factor for soils, because of their potential to affect the soil fauna. Any activity that leads to other forms of soil degradation may indirectly worsen the effects in that soil remediation becomes more tedious. Coal naturally concentrates lead and zinc during its formation, as well as heavy metals to a lesser degree. When the coal is burned, most of these metals become concentrated in the ash, coal ash and slag may contain sufficient lead to qualify as a characteristic hazardous waste, defined in the USA as containing more than 5 mg/l of extractable lead using the TCLP procedure. In addition to lead, coal ash typically contains variable but significant concentrations of polynuclear aromatic hydrocarbons and these PAHs are known human carcinogens and the acceptable concentrations of them in soil are typically around 1 mg/kg. Coal ash and slag can be recognised by the presence of off-white grains in soil, gray heterogeneous soil, or bubbly, treated sewage sludge, known in the industry as biosolids, has become controversial as a fertilizer. As it is the byproduct of sewage treatment, it contains more contaminants such as organisms, pesticides. In the European Union, the Urban Waste Water Treatment Directive allows sewage sludge to be sprayed onto land, the volume is expected to double to 185,000 tons of dry solids in 2005. This has good agricultural properties due to the nitrogen and phosphate content. In 1990/1991, 13% wet weight was sprayed onto 0. 13% of the land, however, this is expected to rise 15 fold by 2005. Advocates say there is a need to control this so that microorganisms do not get into water courses. A pesticide is a substance or mixture of substances used to kill a pest, a pesticide may be a chemical substance, biological agent, antimicrobial, disinfectant or device used against any pest. Although there are benefits to the use of pesticides, there are drawbacks, such as potential toxicity to humans
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Bioremediation
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Bioremediation is a waste management technique that involves the use of organisms to remove or neutralize pollutants from a contaminated site. According to the United States EPA, bioremediation is a treatment that uses naturally occurring organisms to break down hazardous substances into less toxic or non toxic substances, technologies can be generally classified as in situ or ex situ. In situ bioremediation involves treating the material at the site. Some examples of related technologies are phytoremediation, bioventing, bioleaching, landfarming, bioreactor, composting, bioaugmentation, rhizofiltration. For example, the US Army Corps of Engineers demonstrated that windrowing, recent advancements have also proven successful via the addition of matched microbe strains to the medium to enhance the resident microbe populations ability to break down contaminants. Microorganisms used to perform the function of bioremediation are known as bioremediators, however, not all contaminants are easily treated by bioremediation using microorganisms. For example, heavy metals such as cadmium and lead are not readily absorbed or captured by microorganisms, a recent experiment, however, suggests that fish bones have some success absorbing lead from contaminated soil. Bone char has been shown to bioremediate small amounts of cadmium, copper, a recent experiment suggests that the removals of pollutants from tannery wastewater were studied in batch experiments using marine microalgae. The assimilation of metals such as mercury into the chain may worsen matters. Phytoremediation is useful in these circumstances because natural plants or transgenic plants are able to bioaccumulate these toxins in their above-ground parts, the heavy metals in the harvested biomass may be further concentrated by incineration or even recycled for industrial use. Some damaged artifacts at museums contain microbes which could be specified as bio remediating agents, the use of genetic engineering to create organisms specifically designed for bioremediation has great potential. The bacterium Deinococcus radiodurans has been modified to consume and digest toluene, releasing genetically augmented organisms into the environment may be problematic as tracking them can be difficult, bioluminescence genes from other species may be inserted to make this easier. Mycoremediation is a form of bioremediation in which fungi are used to decontaminate the area, one of the primary roles of fungi in the ecosystem is decomposition, which is performed by the mycelium. The mycelium secretes extracellular enzymes and acids that break down lignin and cellulose and these are organic compounds composed of long chains of carbon and hydrogen, structurally similar to many organic pollutants. The key to mycoremediation is determining the right fungal species to target a specific pollutant, certain strains have been reported to successfully degrade the nerve gases VX and sarin. In one conducted experiment, a plot of soil contaminated with oil was inoculated with mycelia of oyster mushrooms. After four weeks, more than 95% of many of the PAH had been reduced to components in the mycelial-inoculated plots. It appears that the natural microbial community participates with the fungi to break down contaminants, eventually into carbon dioxide, wood-degrading fungi are particularly effective in breaking down aromatic pollutants, as well as chlorinated compounds
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Herbicide
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Herbicide, also commonly known as weedkillers, are chemical substances used to control unwanted plants. Apart from selective/non-selective, other important distinctions include persistence, means of uptake, Herbicides have also been used in warfare and conflict. Modern herbicides are often mimics of natural plant hormones which interfere with growth of the target plants. The term organic herbicide has come to mean herbicides intended for organic farming, due to herbicide resistance - a major concern in agriculture - a number of products also combine herbicides with different means of action. In the US in 2007, about 83% of all herbicide usage, in 2007, world pesticide expenditures totaled about $39.4 billion, herbicides were about 40% of those sales and constituted the biggest portion, followed by insecticides, fungicides, and other types. Smaller quantities are used in forestry, pasture systems, and management of areas set aside as wildlife habitat, prior to the widespread use of chemical herbicides, cultural controls, such as altering soil pH, salinity, or fertility levels, were used to control weeds. Mechanical control was used to control weeds. The first modern herbicide,2, 4-D, was first discovered and synthesized by W. G. Templeman at Imperial Chemical Industries, in 1940, he showed that Growth substances applied appropriately would kill certain broad-leaved weeds in cereals without harming the crops. By 1941, his team succeeded in synthesizing the chemical, in the same year, Pokorny in the US achieved this as well. Independently, a team under Juda Hirsch Quastel, working at the Rothamsted Experimental Station made the same discovery, Quastel was tasked by the Agricultural Research Council to discover methods for improving crop yield. By analyzing soil as a system, rather than an inert substance. Quastel was able to quantify the influence of plant hormones, inhibitors and other chemicals on the activity of microorganisms in the soil. While the full work of the unit remained secret, certain discoveries were developed for use after the war, including the 2. When it was released in 1946, it triggered a worldwide revolution in agricultural output. It allowed for greatly enhanced weed control in wheat, maize, rice, and similar cereal crops, because it kills dicots. The low cost of 2, 4-D has led to continued usage today, like other acid herbicides, current formulations use either an amine salt or one of many esters of the parent compound. These are easier to handle than the acid, atrazine does not break down readily after being applied to soils of above neutral pH. Under alkaline soil conditions, atrazine may be carried into the profile as far as the water table by soil water following rainfall causing the aforementioned contamination
