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Area Source
Area sources are sources of pollution which emit a substance or radiation from a specified area. Air pollution For example, area sources of air pollution are air pollutant emission sources which operate within a certain locale. The U.S. Environmental Protection Agency has categorized 70 different categories of air pollution area source. Locomotives operating on certain linear tracks are examples of a line source, whereas locomotives operating within a railyard are an example of an area source of pollution. Other area sources of air pollution are: * Multiple flue gas stacks within a single industrial plant * Open burning and forest fires * Evaporation losses from large spills of volatile liquids Water pollution Water pollution manifestations of an area source—often called nonpoint source pollution—include: * Surface runoff of fertilizer or pesticides from rainfall or irrigation water * Widespread failure of a septic drain field * Dispersal of an oil spill in a water body ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air Pollution
Air pollution is the contamination of air due to the presence of substances in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials. There are many different types of air pollutants, such as gases (including ammonia, carbon monoxide, sulfur dioxide, nitrous oxides, methane, carbon dioxide and chlorofluorocarbons), particulates (both organic and inorganic), and biological molecules. Air pollution can cause diseases, allergies, and even death to humans; it can also cause harm to other living organisms such as animals and food crops, and may damage the natural environment (for example, climate change, ozone depletion or habitat degradation) or built environment (for example, acid rain). Air pollution can be caused by both human activities and natural phenomena. Air pollution is a significant risk factor for a number of pollution-related diseases, including respiratory infections, heart disease, COPD ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Measures Of Pollutant Concentration
Measures of pollutant concentration are used to determine risk assessment in public health. Industry is continually synthesizing new chemicals, the regulation of which requires evaluation of the potential danger for human health and the environment. Risk assessment is nowadays considered essential for making these decisions on a scientifically sound basis. Measures or defined limits include: * ''no-observed-adverse-effect level'' (NOAEL), also called ''no-effect concentration'' (NEC), ''no-observed-effect concentration'' (NOEC) or similarly * ''lowest-observed-adverse-effect level'' (LOAEL) * ''acceptable operator exposure level'' (AOEL) * ECx (in percentage). No-effect concentration ''No-effect concentration'' (NEC) is a risk assessment parameter that represents the concentration of a pollutant that will not harm the species involved, with respect to the effect that is studied. It is often the starting point for environmental policy. There is not much debate on the existence o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Model
Computer simulation is the process of mathematical modelling, performed on a computer, which is designed to predict the behaviour of, or the outcome of, a real-world or physical system. The reliability of some mathematical models can be determined by comparing their results to the real-world outcomes they aim to predict. Computer simulations have become a useful tool for the mathematical modeling of many natural systems in physics (computational physics), astrophysics, climatology, chemistry, biology and manufacturing, as well as human systems in economics, psychology, social science, health care and engineering. Simulation of a system is represented as the running of the system's model. It can be used to explore and gain new insights into new technology and to estimate the performance of systems too complex for analytical solutions. Computer simulations are realized by running computer programs that can be either small, running almost instantly on small devices, or large-sca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volume Source (pollution)
A volume source of pollution is a three-dimensional source of pollutant emissions. Essentially, it is an area source with a third dimension. Examples of a volume source of pollution are: * Dust emissions from the wind erosion of uncovered gravel piles, sand piles, limestone piles, coal piles, etc. * Fugitive gaseous emissions from pipe flanges, packed valve seals, gas compressor seals, control valve seals, piping and vessel seals within industrial facilities such as oil refineries and petrochemical plants. * Buildings, containing air pollutant emission sources, with no singular emission vent (i.e., buildings with multiple roof vents or multiple open windows). See also * Air pollution dispersion terminology * Area source * Atmospheric dispersion modeling * List of atmospheric dispersion models * Line source * Point source (pollution) * Roadway air dispersion modeling Roadway air dispersion modeling is the study of air pollutant transport from a roadway or other linear emitter. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Roadway Air Dispersion Modeling
Roadway air dispersion modeling is the study of air pollutant transport from a roadway or other linear emitter. Computer models are required to conduct this analysis, because of the complex variables involved, including vehicle emissions, vehicle speed, meteorology, and terrain geometry. Line source dispersion has been studied since at least the 1960s, when the regulatory framework in the United States began requiring quantitative analysis of the air pollution consequences of major roadway and airport projects. By the early 1970s this subset of atmospheric dispersion models was being applied to real-world cases of highway planning, even including some controversial court cases. How the model works The basic concept of the roadway air dispersion model is to calculate air pollutant levels in the vicinity of a highway or arterial roadway by considering them as line sources. The model takes into account source characteristics such as traffic volume, vehicle speeds, truck mix, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Point Source (pollution)
A point source of pollution is a single identifiable source of air, water, thermal, noise or light pollution. A point source has negligible extent, distinguishing it from other pollution source geometries (such as nonpoint source or area source). The sources are called ''point sources'' because in mathematical modeling, they can be approximated as a mathematical point to simplify analysis. Pollution point sources are identical to other physics, engineering, optics, and chemistry point sources and include: * Air pollution from an industrial source (rather than an airport or a road, considered a line source, or a forest fire, which is considered an area source, or volume source) *Water pollution from factories, power plants, municipal sewage treatment plants and some farms (''see'' concentrated animal feeding operation). The U.S. Clean Water Act also defines municipal separate storm sewer systems and industrial stormwater discharges (such as construction sites) as point sources. * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Line Source
A line source, as opposed to a point source, area source, or volume source, is a source of air, noise, water contamination or electromagnetic radiation that emanates from a linear (one-dimensional) geometry. The most prominent linear sources are roadway air pollution, aircraft air emissions, roadway noise, certain types of water pollution sources that emanate over a range of river extent rather than from a discrete point, elongated light tubes, certain dose models in medical physics and electromagnetic antennas. While point sources of pollution were studied since the late nineteenth century, linear sources did not receive much attention from scientists until the late 1960s, when environmental regulations for highways and airports began to emerge. At the same time, computers with the processing power to accommodate the data processing needs of the computer models required to tackle these one-dimensional sources became more available. In addition, this era of the 1960s saw the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Atmospheric Dispersion Models
Atmospheric dispersion models are computer programs that use mathematical algorithms to simulate how pollutants in the ambient atmosphere disperse and, in some cases, how they react in the atmosphere. US Environmental Protection Agency models Many of the dispersion models developed by or accepted for use by the U.S. Environmental Protection Agency (U.S. EPA) are accepted for use in many other countries as well. Those EPA models are grouped below into four categories. Preferred and recommended models * AERMOD – An atmospheric dispersion model based on atmospheric boundary layer turbulence structure and scaling concepts, including treatment of multiple ground-level and elevated point, area and volume sources. It handles flat or complex, rural or urban terrain and includes algorithms for building effects and plume penetration of inversions aloft. It uses Gaussian dispersion for stable atmospheric conditions (i.e., low turbulence) and non-Gaussian dispersion for unstable condit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atmospheric Dispersion Modeling
Atmospheric dispersion modeling is the mathematical simulation of how air pollutants disperse in the ambient atmosphere. It is performed with computer programs that include algorithms to solve the mathematical equations that govern the pollutant dispersion. The dispersion models are used to estimate the downwind ambient concentration of air pollutants or toxins emitted from sources such as industrial plants, vehicular traffic or accidental chemical releases. They can also be used to predict future concentrations under specific scenarios (i.e. changes in emission sources). 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 and that may react in the atmosphere. For pollutants that have a very high spatio-temporal variability (i.e. have very steep distance to source decay such as black carbon) and for epidemiological studies statistical land-use regression models are also used. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air Pollution Dispersion Terminology
In environmental science, air pollution dispersion is the distribution of air pollution into the atmosphere. ''Air pollution'' is the introduction of particulates, biological molecules, or other harmful materials into Earth's atmosphere, causing disease, death to humans, damage to other living organisms such as food crops, and the natural or built environment. Air pollution may come from anthropogenic or natural sources. ''Dispersion'' refers to what happens to the pollution during and after its introduction; understanding this may help in identifying and controlling it. Air pollution dispersion has become the focus of environmental conservationists and governmental environmental protection agencies (local, state, province and national) of many countries (which have adopted and used much of the terminology of this field in their laws and regulations) regarding air pollution control. Air pollution emission plumes Air pollution emission plume – flow of pollutant in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Land Use
Land use involves the management and modification of natural environment or wilderness into built environment such as settlements and semi-natural habitats such as arable fields, pastures, and managed woods. Land use by humans has a long history, first emerging more than 10,000 years ago. It has been defined as "the purposes and activities through which people interact with land and terrestrial ecosystems" and as "the total of arrangements, activities, and inputs that people undertake in a certain land type." Land use is one of the most important drivers of global environmental change. History Human tribes since prehistory have segregated land into territories to control the use of land. Today, the total arable land is 10.7% of the land surface, with 1.3% being permanent cropland. Regulation Land use practices vary considerably across the world. The United Nations' Food and Agriculture Organization Water Development Division explains that "Land use concerns the produ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Model
Computer simulation is the process of mathematical modelling, performed on a computer, which is designed to predict the behaviour of, or the outcome of, a real-world or physical system. The reliability of some mathematical models can be determined by comparing their results to the real-world outcomes they aim to predict. Computer simulations have become a useful tool for the mathematical modeling of many natural systems in physics (computational physics), astrophysics, climatology, chemistry, biology and manufacturing, as well as human systems in economics, psychology, social science, health care and engineering. Simulation of a system is represented as the running of the system's model. It can be used to explore and gain new insights into new technology and to estimate the performance of systems too complex for analytical solutions. Computer simulations are realized by running computer programs that can be either small, running almost instantly on small devices, or large-sca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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