A fertilizer or fertiliser is any material of natural or synthetic origin, applied to soils or to plant tissues to supply one or more plant nutrients essential to the growth of plants. Many sources of fertilizer exist, both natural and industrially produced. Fertilizers enhance the growth of plants; this goal is met in the traditional one being additives that provide nutrients. The second mode by which some fertilizers act is to enhance the effectiveness of the soil by modifying its water retention and aeration; this article, like many on fertilizers, emphasises the nutritional aspect. Fertilizers provide, in varying proportions: three main macronutrients: Nitrogen: leaf growth Phosphorus: Development of roots, seeds, fruit. Of occasional significance are silicon and vanadium; the nutrients required for healthy plant life are classified according to the elements, but the elements are not used as fertilizers. Instead compounds containing these elements are the basis of fertilizers; the macro-nutrients are consumed in larger quantities and are present in plant tissue in quantities from 0.15% to 6.0% on a dry matter basis.
Plants are made up of four main elements: hydrogen, oxygen and nitrogen. Carbon and oxygen are available as water and carbon dioxide. Although nitrogen makes up most of the atmosphere, it is in a form, unavailable to plants. Nitrogen is the most important fertilizer since nitrogen is present in proteins, DNA and other components. To be nutritious to plants, nitrogen must be made available in a "fixed" form. Only some bacteria and their host plants can fix atmospheric nitrogen by converting it to ammonia. Phosphate is required for the production of DNA and ATP, the main energy carrier in cells, as well as certain lipids. Micronutrients are consumed in smaller quantities and are present in plant tissue on the order of parts-per-million, ranging from 0.15 to 400 ppm DM, or less than 0.04% DM. These elements are present at the active sites of enzymes that carry out the plant's metabolism; because these elements enable catalysts their impact far exceeds their weight percentage. Fertilizers are classified in several ways.
They are classified according to whether they provide a single nutrient, in which case they are classified as "straight fertilizers." "Multinutrient fertilizers" provide two or more nutrients, for example N and P. Fertilizers are sometimes classified as inorganic versus organic. Inorganic fertilizers exclude carbon-containing materials except ureas. Organic fertilizers are plant- or animal-derived matter. Inorganic are sometimes called synthetic fertilizers since various chemical treatments are required for their manufacture; the main nitrogen-based straight fertilizer is its solutions. Ammonium nitrate is widely used. Urea is another popular source of nitrogen, having the advantage that it is solid and non-explosive, unlike ammonia and ammonium nitrate, respectively. A few percent of the nitrogen fertilizer market has been met by calcium ammonium nitrate; the main straight phosphate fertilizers are the superphosphates. "Single superphosphate" consists of 14–18% P2O5, again in the form of Ca2, but phosphogypsum.
Triple superphosphate consists of 44-48% of P2O5 and no gypsum. A mixture of single superphosphate and triple superphosphate is called double superphosphate. More than 90% of a typical superphosphate fertilizer is water-soluble; the main potassium-based straight fertilizer is Muriate of Potash. Muriate of Potash consists of 95-99% KCl, is available as 0-0-60 or 0-0-62 fertilizer; these fertilizers are common. They consist of two or more nutrient components. Major two-component fertilizers provide both phosphorus to the plants; these are called NP fertilizers. The main NP fertilizers are diammonium phosphate; the active ingredient in MAP is NH4H2PO4. The active ingredient in DAP is 2HPO4. About 85% of MAP and DAP fertilizers are soluble in water. NPK fertilizers are three-component fertilizers providing nitrogen and potassium. NPK rating is a rating system describing the amount of nitrogen and potassium in a fertilizer. NPK ratings consist of three numbers separated by dashes describing the chemical content of fertilizers.
The first number represents the percentage of nitrogen in the product. Fertilizers do not contain P2O5 or K2O, but the system is a conventional shorthand for the amount of the phosphorus or potassium in a fertilizer. A 50-pound bag of fertilizer labeled 16-4-8 contains 8 lb of nitrogen, an amount of phosphorus equivalent to that in 2 pounds of P2O5, 4 pounds of K2O. Most fertilizers are labeled according to this N-P-K convention, although Australian convention, following an N-P-K-S system, adds a fourth number for sulfur, uses elemental values for all values including P and K; the main micronutrients are molybdenum, zinc and copper. These elements are provided as water-soluble salts
Water quality refers to the chemical, physical 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 or to any human need or purpose, it is most used by reference to a set of standards against which compliance achieved through treatment of the water, can be assessed. The most common standards used to assess water quality relate to health of ecosystems, safety of human contact, drinking water. 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 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 an appropriate quality for its identified use.
The vast majority of surface water on the Earth is neither toxic. This remains true. 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 complex subject, in part because water is a complex medium intrinsically tied to the ecology of the Earth. Industrial and commercial activities are a major cause of water pollution as are runoff from agricultural areas, urban runoff and discharge of treated and untreated sewage; the parameters for water quality are determined by the intended use. Work in the area of water quality tends to be focused on water, treated for human consumption, industrial use, or in the environment. Contaminants that may be in untreated water include microorganisms such as viruses and bacteria. Water quality depends on the local geology and ecosystem, as well as human uses such as sewage dispersion, industrial pollution, use of water bodies as a heat sink, overuse; the United States Environmental Protection Agency limits the amounts of certain contaminants in tap water provided by US public water systems.
The Safe Drinking Water Act authorizes EPA to issue two types of standards: primary standards regulate substances that affect human health. The U. S. Food and Drug Administration regulations establish limits for contaminants in bottled water that must provide the same 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 indicate that the water poses a health risk. In urbanized areas around the world, water purification technology is used in municipal water systems to remove contaminants from the source water before it is distributed to homes, businesses and other recipients. Water drawn directly from a stream, lake, or aquifer and that has no treatment will be of uncertain quality. Dissolved minerals may affect suitability of water for a range of domestic purposes; the most familiar of these is the presence of ions of calcium and magnesium which interfere with the cleaning action of soap, can form hard sulfate and soft carbonate deposits in water heaters or boilers.
Hard water may be softened to remove these ions. The softening process substitutes sodium cations. Hard water may be preferable to soft water for human consumption, since health problems have been associated with excess sodium and with calcium and magnesium deficiencies. Softening may increase cleaning effectiveness. Various industries' wastes and effluents can pollute the water quality in receiving bodies of water. Environmental water quality called ambient water quality, relates to water bodies such as lakes and oceans. Water quality standards for surface waters vary due to different environmental conditions and intended human uses. Toxic substances and high populations of certain microorganisms can present a health hazard for non-drinking purposes such as irrigation, fishing, rafting and industrial uses; these conditions may affect wildlife, which use the water for drinking or as a habitat. Modern water quality laws specify protection of fisheries and recreational use and require, as a minimum, retention of current quality standards.
There is some desire among the public to return water bodies to pristine, or pre-industrial conditions. Most current environmental laws focus on the designation of particular uses of a water body. In some countries these designations allow for some water contamination as long as the particular type of contamination is not harmful to the designated uses. Given the landscape changes in the watersheds of many freshwater bodies, returning to pristine conditions would be a significant challenge. In these cases, environmental scientists focus on achieving goals for maintaining healthy ecosystems and may concentrate on the protection of populations of endangered species and protecting human health; the complexity of water quality as a subject is reflected in the many types of measu
Climate change occurs when changes in Earth's climate system result in new weather patterns that last for at least a few decades, maybe for millions of years. The climate system is comprised of five interacting parts, the atmosphere, cryosphere and lithosphere; the climate system receives nearly all of its energy from the sun, with a tiny amount from earth's interior. The climate system gives off energy to outer space; the balance of incoming and outgoing energy, the passage of the energy through the climate system, determines Earth's energy budget. When the incoming energy is greater than the outgoing energy, earth's energy budget is positive and the climate system is warming. If more energy goes out, the energy budget is negative and earth experiences cooling; as this energy moves through Earth's climate system, it creates Earth's weather and long-term averages of weather are called "climate". Changes in the long term average are called "climate change"; such changes can be the result of "internal variability", when natural processes inherent to the various parts of the climate system alter Earth's energy budget.
Examples include cyclical ocean patterns such as the well-known El Nino Southern Oscillation and less familiar Pacific decadal oscillation and Atlantic multidecadal oscillation. Climate change can result from "external forcing", when events outside of the climate system's five parts nonetheless produce changes within the system. Examples include changes in solar volcanism. Human activities can change earth's climate, are presently driving climate change through global warming. There is no general agreement in scientific, media or policy documents as to the precise term to be used to refer to anthropogenic forced change; the field of climatology incorporates many disparate fields of research. For ancient periods of climate change, researchers rely on evidence preserved in climate proxies, such as ice cores, ancient tree rings, geologic records of changes in sea level, glacial geology. Physical evidence of current climate change covers many independent lines of evidence, a few of which are temperature records, the disappearance of ice, extreme weather events.
The most general definition of climate change is a change in the statistical properties of the climate system when considered over long periods of time, regardless of cause. Accordingly, fluctuations over periods shorter than a few decades, such as El Niño, do not represent climate change; the term "climate change" is used to refer to anthropogenic climate change. Anthropogenic climate change is caused by human activity, as opposed to changes in climate that may have resulted as part of Earth's natural processes. In this sense in the context of environmental policy, the term climate change has become synonymous with anthropogenic global warming. Within scientific journals, global warming refers to surface temperature increases while climate change includes global warming and everything else that increasing greenhouse gas levels affect. A related term, "climatic change", was proposed by the World Meteorological Organization in 1966 to encompass all forms of climatic variability on time-scales longer than 10 years, but regardless of cause.
During the 1970s, the term climate change replaced climatic change to focus on anthropogenic causes, as it became clear that human activities had a potential to drastically alter the climate. Climate change was incorporated in the title of the Intergovernmental Panel on Climate Change and the UN Framework Convention on Climate Change. Climate change is now used as both a technical description of the process, as well as a noun used to describe the problem. Prior to the 18th century, scientists had not suspected that prehistoric climates were different from the modern period. By the late 18th century, geologists found evidence of a succession of geological ages with changes in climate. In the years since, a great deal of scientific progress has been made understanding the workings of the climate system. On the broadest scale, the rate at which energy is received from the Sun and the rate at which it is lost to space determine the equilibrium temperature and climate of Earth; this energy is distributed around the globe by winds, ocean currents, other mechanisms to affect the climates of different regions.
Factors that can shape climate are called climate forcings or "forcing mechanisms". These include processes such as variations in solar radiation, variations in the Earth's orbit, variations in the albedo or reflectivity of the continents and oceans, mountain-building and continental drift and changes in greenhouse gas concentrations. There are a variety of climate change feedbacks that can either amplify or diminish the initial forcing; some parts of the climate system, such as the oceans and ice caps, respond more in reaction to climate forcings, while others respond more quickly. There are key threshold factors which when exceeded can produce rapid change. Forcing mechanisms can be either "internal" or "external". Internal forcing mechanisms are natural processes within the climate system itself. External forcing mechanisms can be either natural. Whether the initial forcing mechanism is internal or external, the response of the climate system might be fast, slow (e.g. thermal exp
Aquatic plants are plants that have adapted to living in aquatic environments. They are referred to as hydrophytes or macrophytes. A macrophyte is an aquatic plant that grows in or near water and is either emergent, submergent, or floating, includes helophytes. In lakes and rivers macrophytes provide cover for fish and substrate for aquatic invertebrates, produce oxygen, act as food for some fish and wildlife. Aquatic plants require special adaptations for living submerged at the water's surface; the most common adaptation is aerenchyma, but floating leaves and finely dissected leaves are common. Aquatic plants can only grow in water or in soil, permanently saturated with water, they are therefore a common component of wetlands. Fringing stands of tall vegetation by water basins and rivers may include helophytes. Examples include stands of Equisetum fluviatile, Glyceria maxima, Hippuris vulgaris, Carex, Sparganium, yellow flag and Phragmites australis; the principal factor controlling the distribution of aquatic plants is the depth and duration of flooding.
However, other factors may control their distribution and growth form, including nutrients, disturbance from waves and salinity. Aquatic vascular plants have originated on multiple occasions in different plant families. Seaweeds are not vascular plants. A few aquatic plants are able to survive in brackish and salt water; the only angiosperms capable of growing submerged in seawater are the seagrasses. Examples are found in genera such as Zostera. Although most aquatic plants can reproduce by flowering and setting seed, many have extensive asexual reproduction by means of rhizomes and fragments in general. One of the largest aquatic plants in the world is the Amazon water lily. Many small aquatic animals use plants like duckweed for a home, or for protection from predators, but areas with more vegetation are to have more predators; some other familiar examples of aquatic plants might include floating heart, water lily and water hyacinth. Based on growth form, macrophytes can be classified as: Emergent macrophytes Floating-leaved macrophytes Submerged macrophytes Free floating macrophytes An emergent plant is one which grows in water but which pierces the surface so that it is in air.
Collectively, such plants are emergent vegetation. This habit may have developed because the leaves can photosynthesize more efficiently above the shade of cloudy water and competition from submerged plants but the main aerial feature is the flower and the related reproductive process; the emergent habit permits pollination by flying insects. There are many species of emergent plants, among them, the reed, Cyperus papyrus, Typha species, flowering rush and wild rice species; these may be found growing in fens but less well owing to competition from other plants. Some species, such as purple loosestrife, may grow in water as emergent plants but they are capable of flourishing in fens or in damp ground. Floating-leaved macrophytes have root systems attached to the substrate or bottom of the body of water and with leaves that float on the water surface. Common floating leaves macrophytes are pondweeds. Submerged macrophytes grow under water with root attached to the substrate or without any root system.
Free-floating macrophytes are aquatic plants that are found suspended on water surface with their root not attached to substrate or sediment or bottom of water body. They are blown by air and provide breeding ground for mosquito. Example include Pistia spp called water lettuce, water cabbage or Nile cabbage The many possible classifications of aquatic plants are based upon morphology. One example has six groups as follows: Amphiphytes: plants that are adapted to live either submerged or on land Elodeids: stem plants that complete their entire lifecycle submerged, or with only their flowers above the waterline Isoetids: rosette plants that complete their entire lifecycle submerged Helophytes: plants rooted in the bottom, but with leaves above the waterline Nymphaeids: plants rooted in the bottom, but with leaves floating on the water surface Pleuston: vascular plants that float in the water Macrophytes perform many ecosystem functions in aquatic ecosystems and provide services to human society.
One of the important functions performed by macrophyte is uptake of dissolve nutrients from water. Macrophytes are used in constructed wetlands around the world to remove excess N and P from polluted water. Beside direct nutrient uptake, macrophytes indirectly influence nutrient cycling N cycling through influencing the denitrifying bacterial functional groups that are inhabiting on roots and shoots of macrophytes. Macrophytes promote the sedimentation of suspended solids by reducing the current velocities, impede erosion by stabilising soil surfaces. Macrophytes provide spatial heterogeneity in otherwise unstructured water column. Habitat complexity provided by macrophytes like to increase the richness of taxonomy and density of both fish and invertebrates; some aquatic plants are used by humans as a food source. Examples include wild rice, water caltrop, Chinese wa
Biodiversity action plan
A biodiversity action plan is an internationally recognized program addressing threatened species and habitats and is designed to protect and restore biological systems. The original impetus for these plans derives from the 1992 Convention on Biological Diversity; as of 2009, 191 countries have ratified the CBD, but only a fraction of these have developed substantive BAP documents. The principal elements of a BAP include: preparing inventories of biological information for selected species or habitats. A fundamental method of engagement to a BAP is thorough documentation regarding individual species, with emphasis upon the population distribution and conservation status; this task, while fundamental, is daunting, since only an estimated ten percent of the world’s species are believed to have been characterized as of 2006, most of these unknowns being fungi, invertebrate animals, micro-organisms and plants. For many bird and reptile species, information is available in published literature, it is useful to compile time trends of population estimates in order to understand the dynamics of population variability and vulnerability.
In some parts of the world complete species inventories are not realistic. A species plan component of a country’s BAP should ideally entail a thorough description of the range, behaviour and interaction with other species. Once a determination has been made of conservation status, a plan can be created to conserve and restore the species population to target levels. Examples of programmatic protection elements are: habitat restoration; the plan should articulate which public and private agencies should implement the protection strategy and indicate budgets available to execute this strategy. Where a number of threatened species depend upon a specific habitat, it may be appropriate to prepare a habitat protection element of the Biodiversity Action Plan. Examples of such special habitats are: raised acidic bogs of Scotland. In this case careful inventories of species and the geographic extent and quality of the habitat must be documented; as with species plans, a program can be created to protect, enhance and/or restore habitat using similar strategies as discussed above under the species plans.
Some examples of individual countries which have produced substantive Biodiversity Action Plans follow. In every example the plans concentrate on plants and vertebrate animals, with little attention to neglected groups such as fungi, invertebrate animals and micro-organisms though these are part of biodiversity. Preparation of a country BAP may cost up to 100 million pounds sterling, with annual maintenance costs ten percent of the initial cost. If plans took into account neglected groups, the cost would be higher. Costs for countries with small geographical area or simplified ecosystems have a much lesser cost. For example, the St. Lucia BAP has been costed in the area of several million pounds sterling. Australia has developed rigorous Biodiversity Action Plan; this document estimates that the total number of indigenous species may be 560,000, many of which are endemic. A key element of the BAP is protection of the Great Barrier Reef, in a much higher state of health than most of the world’s reefs, Australia having one of the highest percentages of treated wastewater.
There is, however,serious ongoing concerns in regards to the ongoing negative impact on water quality from land use practices. Climate change impact is feared to be significant. Considerable analysis has been conducted on the sustainable yield of firewood production, a major threat to deforestation in most tropical countries. Biological inventory work. Extensive research has been conducted on the relation of brush clearance to biodiversity decline and impact on water tables. New Zealand has ratified the Convention on Biological Diversity and as part of The New Zealand Biodiversity Strategy and Biodiversity Action Plans are implemented on ten separate themes. Local government and some companies have their own Biodiversity Action Plan; the St. Lucia BAP recognizes impacts of large numbers of tourists to the marine and coastal diversity of the Soufrière area of the country; the BAP acknowledges that the carrying capacity for human use and water pollution discharge of sensitive reef areas was exceeded by the year 1990.
The plan addresses conservation of the historic island fishing industry. In 1992, several institutions in
Urbanization refers to the population shift from rural areas to urban areas, the gradual increase in the proportion of people living in urban areas, the ways in which each society adapts to this change. It is predominantly the process by which towns and cities are formed and become larger as more people begin living and working in central areas. Although the two concepts are sometimes used interchangeably, urbanization should be distinguished from urban growth: urbanization is "the proportion of the total national population living in areas classed as urban", while urban growth refers to "the absolute number of people living in areas classed as urban"; the United Nations projected that half of the world's population would live in urban areas at the end of 2008. It is predicted that by 2050 about 64% of the developing world and 86% of the developed world will be urbanized; that is equivalent to 3 billion urbanites by 2050, much of which will occur in Africa and Asia. Notably, the United Nations has recently projected that nearly all global population growth from 2017 to 2030 will be by cities, about 1.1 billion new urbanites over the next 13 years.
Urbanization is relevant to a range of disciplines, including urban planning, sociology, architecture and public health. The phenomenon has been linked to modernization, industrialization, the sociological process of rationalization. Urbanization can be seen as a specific condition at a set time, or as an increase in that condition over time. So urbanization can be quantified either in terms of, the level of urban development relative to the overall population, or as the rate at which the urban proportion of the population is increasing. Urbanization creates enormous social and environmental changes, which provide an opportunity for sustainability with the “potential to use resources more efficiently, to create more sustainable land use and to protect the biodiversity of natural ecosystems.”Urbanization is not a modern phenomenon, but a rapid and historic transformation of human social roots on a global scale, whereby predominantly rural culture is being replaced by predominantly urban culture.
The first major change in settlement patterns was the accumulation of hunter-gatherers into villages many thousand years ago. Village culture is characterized by common bloodlines, intimate relationships, communal behavior, whereas urban culture is characterized by distant bloodlines, unfamiliar relations, competitive behavior; this unprecedented movement of people is forecast to continue and intensify during the next few decades, mushrooming cities to sizes unthinkable only a century ago. As a result, the world urban population growth curve has up till followed a quadratic-hyperbolic pattern. Today, in Asia the urban agglomerations of Osaka, Jakarta, Shanghai, Manila and Beijing are each home to over 20 million people, while Delhi and Tokyo are forecast to approach or exceed 40 million people. Cities such as Tehran, Mexico City, São Paulo, New York City and Cairo are, or soon will be, home to over 10 million people each. From the development of the earliest cities in Mesopotamia and Egypt until the 18th century, an equilibrium existed between the vast majority of the population who engaged in subsistence agriculture in a rural context, small centres of populations in the towns where economic activity consisted of trade at markets and manufactures on a small scale.
Due to the primitive and stagnant state of agriculture throughout this period, the ratio of rural to urban population remained at a fixed equilibrium. However, a significant increase in the percentage of the global urban population can be traced in the 1st millennium BCE. Another significant increase can be traced to Mughal India, where 15% of its population lived in urban centers during the 16th–17th centuries, higher than in Europe at the time. In comparison, the percentage of the European population living in cities was 8–13% in 1800. With the onset of the British agricultural and industrial revolution in the late 18th century, this relationship was broken and an unprecedented growth in urban population took place over the course of the 19th century, both through continued migration from the countryside and due to the tremendous demographic expansion that occurred at that time. In England and Wales, the proportion of the population living in cities with more than 20,000 people jumped from 17% in 1801 to 54% in 1891.
Moreover, adopting a broader definition of urbanization, we can say that while the urbanized population in England and Wales represented 72% of the total in 1891, for other countries the figure was 37% in France, 41% in Prussia and 28% in the United States. As labourers were freed up from working the land due to higher agricultural productivity they converged on the new industrial cities like Manchester and Birmingham which were experiencing a boom in commerce and industry. Growing trade around the world allowed cereals to be imported from North America and refrigerated meat from Australasia and South America. Spatially, cities expanded due to the development of public transport systems, which facilitated commutes of longer distances to the city centre for the working class. Urbanization spread across the Western world and, since the 1950s, it has begun to take hold in the developing world as well. At the turn of the 20th century, just 15% of the world population lived in cities. According to the UN, the year 2007 witnessed the turning point when more than 50% of the world population were living in cities, for the first time in human history.
Yale University in June 2016 published urbanization