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
Conservation biology is the management of nature and of Earth's biodiversity with the aim of protecting species, their habitats, ecosystems from excessive rates of extinction and the erosion of biotic interactions. It is an interdisciplinary subject drawing on natural and social sciences, the practice of natural resource management; the conservation ethic is based on the findings of conservation biology. The term conservation biology and its conception as a new field originated with the convening of "The First International Conference on Research in Conservation Biology" held at the University of California, San Diego in La Jolla, California in 1978 led by American biologists Bruce A. Wilcox and Michael E. Soulé with a group of leading university and zoo researchers and conservationists including Kurt Benirschke, Sir Otto Frankel, Thomas Lovejoy, Jared Diamond; the meeting was prompted by the concern over tropical deforestation, disappearing species, eroding genetic diversity within species.
The conference and proceedings that resulted sought to initiate the bridging of a gap between theory in ecology and evolutionary genetics on the one hand and conservation policy and practice on the other. Conservation biology and the concept of biological diversity emerged together, helping crystallize the modern era of conservation science and policy; the inherent multidisciplinary basis for conservation biology has led to new subdisciplines including conservation social science, conservation behavior and conservation physiology. It stimulated further development of conservation genetics which Otto Frankel had originated first but is now considered a subdiscipline as well; the rapid decline of established biological systems around the world means that conservation biology is referred to as a "Discipline with a deadline". Conservation biology is tied to ecology in researching the population ecology of rare or endangered species. Conservation biology is concerned with phenomena that affect the maintenance and restoration of biodiversity and the science of sustaining evolutionary processes that engender genetic, population and ecosystem diversity.
The concern stems from estimates suggesting that up to 50% of all species on the planet will disappear within the next 50 years, which has contributed to poverty and will reset the course of evolution on this planet. Conservation biologists research and educate on the trends and process of biodiversity loss, species extinctions, the negative effect these are having on our capabilities to sustain the well-being of human society. Conservation biologists work in the field and office, in government, non-profit organizations and industry; the topics of their research are diverse, because this is an interdisciplinary network with professional alliances in the biological as well as social sciences. Those dedicated to the cause and profession advocate for a global response to the current biodiversity crisis based on morals and scientific reason. Organizations and citizens are responding to the biodiversity crisis through conservation action plans that direct research and education programs that engage concerns at local through global scales.
Conscious efforts to conserve and protect global biodiversity are a recent phenomenon. Natural resource conservation, has a history that extends prior to the age of conservation. Resource ethics grew out of necessity through direct relations with nature. Regulation or communal restraint became necessary to prevent selfish motives from taking more than could be locally sustained, therefore compromising the long-term supply for the rest of the community; this social dilemma with respect to natural resource management is called the "Tragedy of the Commons". From this principle, conservation biologists can trace communal resource based ethics throughout cultures as a solution to communal resource conflict. For example, the Alaskan Tlingit peoples and the Haida of the Pacific Northwest had resource boundaries and restrictions among clans with respect to the fishing of sockeye salmon; these rules were guided by clan elders who knew lifelong details of each river and stream they managed. There are numerous examples in history where cultures have followed rules and organized practice with respect to communal natural resource management.
The Mauryan emperor Ashoka around 250 B. C. issued edicts restricting the slaughter of animals and certain kinds of birds, as well as opened veterinary clinics. Conservation ethics are found in early religious and philosophical writings. There are examples in the Tao, Hindu and Buddhist traditions. In Greek philosophy, Plato lamented about pasture land degradation: "What is left now is, so to say, the skeleton of a body wasted by disease. In the bible, through Moses, God commanded to let the land rest from cultivation every seventh year. Before the 18th century, much of European culture considered it a pagan view to admire nature. Wilderness was denigrated. However, as early as AD 680 a wildlife sanctuary was founded on the Farne Islands by St Cuthbert in response to his religious beliefs. Natural history was a major preoccupation in the 18th century, with grand expeditions and the opening of popular public displays in Europe and North America. By 1900 there were 150 natural history museums in Germany, 250 in Great Britain, 250 in the United States, 300 in France.
Preservationist or conservationist sentiments are a development of the late 18th to early 20th centuries. Before C
A road is a thoroughfare, route, or way on land between two places, paved or otherwise improved to allow travel by foot or some form of conveyance, including a motor vehicle, bicycle, or horse. Roads consist of one or two roadways, each with one or more lanes and any associated sidewalks and road verges. There is sometimes a bike path. Other names for roads include parkways, freeways, interstates, highways, or primary and tertiary local roads. Many roads were recognizable routes without any formal construction or maintenance; the Organisation for Economic Co-operation and Development defines a road as "a line of communication using a stabilized base other than rails or air strips open to public traffic for the use of road motor vehicles running on their own wheels", which includes "bridges, supporting structures, crossings and toll roads, but not cycle paths". The Eurostat, ITF and UNECE Glossary for Transport Statistics Illustrated defines a road as a "Line of communication open to public traffic for the use of road motor vehicles, using a stabilized base other than rails or air strips.
Included are paved other roads with a stabilized base, e.g. gravel roads. Roads cover streets, tunnels, supporting structures, junctions and interchanges. Toll roads are included. Excluded are dedicated cycle lanes."The 1968 Vienna Convention on Road Traffic defines a road as the entire surface of any way or street open to public traffic. In urban areas roads may diverge through a city or village and be named as streets, serving a dual function as urban space easement and route. Modern roads are smoothed, paved, or otherwise prepared to allow easy travel. In the United Kingdom The Highway Code details rules for "road users", but there is some ambiguity between the terms highway and road. For the purposes of the English law, Highways Act 1980, which covers England and Wales but not Scotland or Northern Ireland, road is "any length of highway or of any other road to which the public has access, includes bridges over which a road passes"; this includes footpaths and cycle tracks, road and driveways on private land and many car parks.
Vehicle Excise Duty, a road use tax, is payable on some vehicles used on the public road. The definition of a road depends on the definition of a highway. A 1984 ruling said. Another legal view is that while a highway included footpaths, driftways, etc. it can now be used to mean those ways that allow the movement of motor-vehicles, the term rights of way can be used to cover the wider usage. In the United States, laws distinguish between public roads, which are open to public use, private roads, which are controlled. Maintenance is becoming an increasing problem in the United States. Between 1997 and 2018, the number of existing roads too bumpy to drive on compared to roads with decent surfaces has increased by 11% due to potholes that are not being properly addressed; the assertion that the first pathways were the trails made by animals has not been universally accepted. Some believe; the Icknield Way may examplify this type of road origination, where human and animal both selected the same natural line.
By about 10,000 BC human travelers used rough roads/pathways. The world's oldest known paved road was constructed in Egypt some time between 2600 and 2200 BC. Stone- paved streets appear in the city of Ur in the Middle East dating back to 4000 BC. Corduroy roads are found dating to 4000 BC in England; the Sweet Track, a timber track causeway in England, is one of the oldest engineered roads discovered and the oldest timber trackway discovered in Northern Europe. Built in winter 3807 BC or spring 3806 BC, it was claimed to be the oldest road in the world until the 2009 discovery of a 6,000-year-old trackway in Plumstead, London. Brick-paved streets appeared in India as early as 3000 BC. c. 1995 BC: an early subdividing of roadways evidenced with sidewalks built in Anatolia. In 500 BC, Darius I the Great started an extensive road system for the Achaemenid Empire, including the Royal Road, one of the finest highways of its time, connecting Sardis to Susa; the road remained in use after Roman times.
These road systems reached as far east as India. In ancient times, transport by river was far easier and faster than transport by road considering the cost of road construction and the difference in carrying capacity between carts and river barges. A hybrid of road transport and ship transport beginning in about 1740 is the horse-drawn boat in which the horse follows a cleared path along the river bank. From about 312 BC, the Roman Empire built straight strong stone Roman roads throughout Europe and North Africa, in support of its military campaigns. At its peak the Roman Empire was connected by 29 major roads moving out from Rome and covering 78,000 kilometers or 52,964 Roman miles of paved roads. In the 8th century AD, many roads were built throughout the Arab Empire; the most sophisticated roads were those in Baghdad, which were paved wit
Sustainability is the process of maintaining change in a balanced environment, in which the exploitation of resources, the direction of investments, the orientation of technological development and institutional change are all in harmony and enhance both current and future potential to meet human needs and aspirations. For many in the field, sustainability is defined through the following interconnected domains or pillars: environment and social, which according to Fritjof Capra is based on the principles of Systems Thinking. Sub-domains of sustainable development have been considered also: cultural and political. While sustainable development may be the organizing principle for sustainability for some, for others, the two terms are paradoxical. Sustainable development is the development that meets the needs of the present without compromising the ability of future generations to meet their own needs. Brundtland Report for the World Commission on Environment and Development introduced the term of sustainable development.
Sustainability can be defined as a socio-ecological process characterized by the pursuit of a common ideal. An ideal is by definition unattainable in space. However, by persistently and dynamically approaching it, the process results in a sustainable system. Healthy ecosystems and environments are necessary to the survival of other organisms. Ways of reducing negative human impact are environmentally-friendly chemical engineering, environmental resources management and environmental protection. Information is gained from green computing, green chemistry, earth science, environmental science and conservation biology. Ecological economics studies the fields of academic research that aim to address human economies and natural ecosystems. Moving towards sustainability is a social challenge that entails international and national law, urban planning and transport, supply chain management and individual lifestyles and ethical consumerism. Ways of living more sustainably can take many forms from reorganizing living conditions, reappraising economic sectors, or work practices, using science to develop new technologies, or designing systems in a flexible and reversible manner, adjusting individual lifestyles that conserve natural resources."The term'sustainability' should be viewed as humanity's target goal of human-ecosystem equilibrium, while'sustainable development' refers to the holistic approach and temporal processes that lead us to the end point of sustainability."
Despite the increased popularity of the use of the term "sustainability", the possibility that human societies will achieve environmental sustainability has been, continues to be, questioned—in light of environmental degradation, climate change, population growth and societies' pursuit of unlimited economic growth in a closed system. The name sustainability is derived from the Latin sustinere. Sustain can mean "maintain", "support", or "endure". Since the 1980s sustainability has been used more in the sense of human sustainability on planet Earth and this has resulted in the most quoted definition of sustainability as a part of the concept sustainable development, that of the Brundtland Commission of the United Nations on March 20, 1987: "sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs"; the 2005 World Summit on Social Development identified sustainable development goals, such as economic development, social development and environmental protection.
This view has been expressed as an illustration using three overlapping ellipses indicating that the three pillars of sustainability are not mutually exclusive and can be mutually reinforcing. In fact, the three pillars are interdependent, in the long run none can exist without the others; the three pillars have served as a common ground for numerous sustainability standards and certification systems in recent years, in particular in the food industry. Standards which today explicitly refer to the triple bottom line include Rainforest Alliance, Fairtrade and UTZ Certified; some sustainability experts and practitioners have illustrated four pillars of sustainability, or a quadruple bottom line. One such pillar is future generations, which emphasizes the long-term thinking associated with sustainability. There is an opinion that considers resource use and financial sustainability as two additional pillars of sustainability. Sustainable development consists of balancing local and global efforts to meet basic human needs without destroying or degrading the natural environment.
The question becomes how to represent the relationship between those needs and the environment. A study from 2005 pointed out. Ecological economist Herman Daly asked, "what use is a sawmill without a forest?" From this perspective, the economy is a subsystem of human society, itself a subsystem of the biosphere, a gain in one sector is a loss from another. This perspective led to the nested circles figure of'economics' inside'society' inside the'environment'; the simple definition that sustainability is something that improves "the quality of human life while living within the carrying capacity of supporting eco-systems", though vague, conveys the idea of sustainability having quantifiable limits. But sustainability is a call to action, a task in progress or "journe
In forest ecology, a snag refers to a standing, dead or dying tree missing a top or most of the smaller branches. In freshwater ecology it refers to trees and other pieces of occurring wood found sunken in rivers and streams; when used in manufacturing in Scandinavia, they are called "dead wood" and in Finland "kelo wood". Snags are an important structural component in forest communities, making up 10–20% of all trees present in old-growth tropical and boreal forests. Snags and downed coarse woody debris represent a large portion of the woody biomass in a healthy forest. In temperate forests, snags provide critical habitat for more than 100 species of bird and mammal, snags are called'wildlife trees' by foresters. Dead, decaying wood supports a rich community of decomposers like bacteria and fungi and other invertebrates; these organisms and their consumers, along with the structural complexity of cavities and broken tops make snags important habitat for birds and small mammals, which in turn feed larger mammalian predators.
Snags are optimal habitat for primary cavity nesters such as woodpeckers which create the majority of cavities used by secondary cavity users in forest ecosystems. Woodpeckers excavate cavities for more than 80 other species and the health of their populations relies on snags. Most snag-dependent birds and mammals are insectivorous and represent a major portion of the insectivorous forest fauna, are important factors in controlling forest insect populations. There are many instances in which birds reduced outbreak populations of forest insects, such as woodpeckers affecting outbreaks of southern hardwood borers and Engelmann spruce beetles. Snag creation occurs as trees die due to old age, drought, or wildfire. A snag undergoes a series of changes from the time the tree dies until final collapse, each stage in the decay process has particular value to certain wildlife species. Snag persistence depends on two factors, the size of the stem, the durability of the wood of the species concerned; the snags of some large conifers, such as Giant Sequoia and Coast Redwood on the Pacific Coast of North America, the Alerce of Patagonia, can remain intact for 100 years or more, becoming progressively shorter with age, while other snags with decaying wood, such as aspen and birch, break up and collapse in 2–10 years.
Snag Forests, or Complex Early Seral Forests, are ecosystems that occupy forested sites after a stand-replacement disturbance and before re-establishment of a closed-forest canopy. They are generated by natural disturbances such as wildfire or insect outbreaks that reset ecological succession processes and follow a pathway, influenced by biological legacies that were not removed during the initial disturbance. Water hunting birds like the osprey or kingfishers can be found near water, perched in a snag tree, or feeding upon their fish catch. In freshwater ecology in Australia and the United States, the term snag is used to refer to the trees and other pieces of occurring wood found in a sunken form in rivers and streams; such snags have been identified as being critical for shelter and as spawning sites for fish, are one of the few hard substrates available for biofilm growth supporting aquatic invertebrates in lowland rivers flowing through alluvial flood plains. Snags are important as sites for biofilm growth and for shelter and feeding of aquatic invertebrates in both lowland and upland rivers and streams.
In Australia, the role of freshwater snags has been ignored until and more than one million snags have been removed from the Murray-Darling basin. Large tracts of the lowland reaches of the Murray-Darling system are now devoid of the snags that native fish like Murray cod require for shelter and breeding; the damage such wholesale snag removal has caused is enormous but difficult to quantify, however some quantification attempts have been made.. Most snags in these systems are river red gum snags; as the dense wood of river red gum is impervious to rot it is thought that some of the river red gum snags removed in past decades may have been several thousand years old. Known as deadheads submerged snags posed hazards to early riverboat navigation and commerce. If hit, snags punctured the wooden hulls used in early 20th century. Snags were, in fact, the most encountered hazard in the early years of steamboat travel. In the United States, the U. S. Army Corps of Engineers operated "snagboats" such as the W. T.
Preston in the Puget Sound of Washington State and the Montgomery in the rivers of Alabama to pull out and clear snags. Starting in 1824, there were successful efforts to remove snags from the Mississippi and its tributaries. By 1835, a lieutenant reported to the Chief of Engineers that steamboat travel had become much safer, but by the mid-1840s the appropriations for snag removal dried up and snags re-accumulated until after the Civil War. In Scandinavia and Finland snags, invariably pine trees, known in Finnish as kelo and in Swedish as torraka, are collected for the production of different objects, from furniture to entire log houses. Commercial enterprises market them abroad as "dead wood" or in Finland as "kelo wood", they have been prized for their silver-grey weathered surface in the manufacture of vernacular or national romantic products. The suppliers of "dead wood" emphasise its age: the wood has developed with dehydration in the dry coldness of the subarctic zones, the tree having stopped growing after some 300–400 years, a
In ecology, primary production is the synthesis of organic compounds from atmospheric or aqueous carbon dioxide. It principally occurs through the process of photosynthesis, which uses light as its source of energy, but it occurs through chemosynthesis, which uses the oxidation or reduction of inorganic chemical compounds as its source of energy. All life on Earth relies directly or indirectly on primary production; the organisms responsible for primary production are known as primary producers or autotrophs, form the base of the food chain. In terrestrial ecoregions, these are plants, while in aquatic ecoregions algae predominate in this role. Ecologists distinguish primary production as either net or gross, the former accounting for losses to processes such as cellular respiration, the latter not. Primary production is the production of chemical energy in organic compounds by living organisms; the main source of this energy is sunlight but a minute fraction of primary production is driven by lithotrophic organisms using the chemical energy of inorganic molecules.
Regardless of its source, this energy is used to synthesize complex organic molecules from simpler inorganic compounds such as carbon dioxide and water. The following two equations are simplified representations of photosynthesis and chemosynthesis: CO2 + H2O + light → CH2O + O2 CO2 + O2 + 4 H2S → CH2O + 4 S + 3 H2OIn both cases, the end point is a polymer of reduced carbohydrate, n molecules such as glucose or other sugars; these simple molecules may be used to further synthesise more complicated molecules, including proteins, complex carbohydrates and nucleic acids, or be respired to perform work. Consumption of primary producers by heterotrophic organisms, such as animals transfers these organic molecules up the food web, fueling all of the Earth's living systems. Gross primary production is the amount of chemical energy as biomass that primary producers create in a given length of time; some fraction of this fixed energy is used by primary producers for cellular respiration and maintenance of existing tissues.
The remaining fixed energy is referred to as net primary production. NPP = GPP - respiration Net primary production is the rate at which all the plants in an ecosystem produce net useful chemical energy; some net primary production goes toward growth and reproduction of primary producers, while some is consumed by herbivores. Both gross and net primary production are in units of mass per unit area per unit time interval. In terrestrial ecosystems, mass of carbon per unit area per year is most used as the unit of measurement. On the land all primary production is now performed by vascular plants, with a small fraction coming from algae and non-vascular plants such as mosses and liverworts. Before the evolution of vascular plants, non-vascular plants played a more significant role. Primary production on land is a function of many factors, but principally local hydrology and temperature. While plants cover much of the Earth's surface, they are curtailed wherever temperatures are too extreme or where necessary plant resources are limiting, such as deserts or polar regions.
Water is "consumed" in plants by the processes of transpiration. The latter process is driven by the evaporation of water from the leaves of plants. Transpiration allows plants to transport water and mineral nutrients from the soil to growth regions, cools the plant. Diffusion of water vapour out of a leaf, the force that drives transpiration, is regulated by structures known as stomata; these structure regulate the diffusion of carbon dioxide from the atmosphere into the leaf, such that decreasing water loss decreases carbon dioxide gain. Certain plants use alternative forms of photosynthesis, called Crassulacean acid metabolism and C4; these employ physiological and anatomical adaptations to increase water-use efficiency and allow increased primary production to take place under conditions that would limit carbon fixation by C3 plants. In a reversal of the pattern on land, in the oceans all photosynthesis is performed by algae, with a small fraction contributed by vascular plants and other groups.
Algae encompass a diverse range of organisms, ranging from single floating cells to attached seaweeds. They include photoautotrophs from a variety of groups. Eubacteria are important photosynthetizers in both oceanic and terrestrial ecosystems, while some archaea are phototrophic, none are known to utilise oxygen-evolving photosynthesis. A number of eukaryotes are significant contributors to primary production in the ocean, including green algae, brown algae and red algae, a diverse group of unicellular groups. Vascular plants are represented in the ocean by groups such as the seagrasses. Unlike terrestrial ecosystems, the majority of primary production in the ocean is performed by free-living microscopic organisms called phytoplankton. Larger autotrophs, such as th