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Three factors determine the severity of a pollutant: its chemical nature, its concentration and its persistence. Some pollutants are biodegradable and therefore will not persist in the environment in the long term. However the degradation products of some pollutants are themselves polluting such as the products DDE and DDD produced from degradation of DDT
Types of pollutants
Pollutants that the environment has little or no absorptive capacity are called stock pollutants (e.g. persistent synthetic chemicals, non-biodegradable plastics, and heavy metals). Stock pollutants accumulate in the environment over time. The damage they cause increases as more pollutant is emitted, and persists as the pollutant accumulates. Stock pollutants can create a burden for future generations by passing on damage that persists well after the benefits received from incurring that damage have been forgotten.
Fund pollutants are those for which the environment has some absorptive capacity. Fund pollutants do not cause damage to the environment unless the emission rate exceeds the receiving environment's absorptive capacity (e.g. carbon dioxide, which is absorbed by plants and oceans). Fund pollutants are not destroyed, but rather converted into less harmful substances, or diluted/dispersed to non-harmful concentrations.
Notable pollutants include the following groups:
- Heavy metals
- Persistent organic pollutants
- Polycyclic aromatic hydrocarbons
- Volatile organic compounds
- Environmental xenobiotics
Zones of influence
Pollutants can also be defined by their zones of influence, both horizontally and vertically.
The vertical zone is referred to whether the damage is ground-level or atmospheric. Surface pollutants cause damage by concentrations of the pollutant accumulating near the Earth's surface Global pollutants cause damage by concentrations in the atmosphere
Pollutants can cross international borders and therefore international regulations are needed for their control. The Stockholm Convention on Persistent Organic Pollutants, which entered into force in 2004, is an international legally binding agreement for the control of persistent organic pollutants. Pollutant Release and Transfer Registers (PRTR) are systems to collect and disseminate information on environmental releases and transfers of toxic chemicals from industrial and other facilities.
The European Pollutant Emission Register is a type of PRTR providing access to information on the annual emissions of industrial facilities in the Member States of the European Union, as well as Norway.
Clean Air Act standards. Under the Clean Air Act, the National Ambient Air Quality Standards (NAAQS) are standards developed for outdoor air quality. The National Emissions Standards for Hazardous Air Pollutants are emission standards that are set by the Environmental Protection Agency (EPA) which are not covered by the NAAQS.
Clean Water Act standards. Under the Clean Water Act, EPA promulgated national standards for municipal sewage treatment plants, also called publicly owned treatment works, in the Secondary Treatment Regulation. National standards for industrial dischargers are calledEffluent guidelines(for existing sources) andNew Source Performance Standards, and currently cover over 50 industrial categories. In addition, the Act requires states to publish water quality standards for individual water bodies to provide additional protection where the national standards are insufficient.
soil surface layer of the earth, composed of fine rock material disintegrated by geological processes; and humus , the organic remains of decomposed vegetation. In agriculture , soil is the medium that supports crop plants, both physically and biologically. Soil may be from a few inches to several feet thick. Components and Structure The inorganic fraction of soil may include various sizes and shapes of rocks and minerals; in order of increasing size these are termed clay , silt , sand , gravel , and stone. Coarser soils have lower capacity to retain organic plant nutrients, gases, and water, which are essential for plants. Soils with higher clay content, which tend to retain these substances, are therefore usually better suited for agriculture. In most soils, clay and organic particles aggregate into plates, blocks, prisms, or granules. The arrangement of particles, known as soil structure, largely determines the soil's pore space and density, which translates into its capacity to hold air and water. Organic matter consists of decomposed plant and animal material and living plant roots. Microorganisms, living in the organic portion of soil, perform the essential function of decomposing plant and animal matter, releasing nutrients to be used by growing plants. Besides organic matter, soil is largely composed of elements and compounds of silicon, aluminum, iron, oxygen, and, in smaller quantities, calcium, magnesium, sodium, and potassium. Factors determining the nature of soil are vegetation type, climate, and parent rock material; geographic relief and the geological age of the developing soil are also factors. Acidic soils occur in humid regions because alkaline minerals are leached downward: alkaline soils occur in dry regions because alkaline salts remain concentrated near the surface. Geologically young soils resemble their parent material more than older soils, which have been altered over time by climate and vegetation. For advice and information on soils, consult state agricultural experiment stations and their publications. Undisturbed soils tend to form layers, called horizons, roughly parallel to the surface. The Russian system of soil classification, from which most others derive, is based on the distinctive horizons of the soil profile. The A horizon, the surface layer, contains most of the humus. The B horizon contains inorganic compounds formed by decomposition of organic material, a process known as mineralization; the material is brought to the B layer by the downward leaching action of water. The lowest soil layer, the C horizon, represents the weathered mineral parent substance. Soil Fertility and Conservation Soil fertilityâ€”the ability to support plant growthâ€”depends on various factors, including the soil's structure or texture; its chemical composition, esp. its content of plant nutrients; its supply of water; and its temperature. Agriculture necessarily lowers soil fertility by removing soil nutrients incorporated in the harvested crops. Cultivation, especially with heavy machinery, can degrade soil structure. Agricultural soils are also vulnerable to mismanagement. Exposure of soils to wind and rain during cultivation encourages erosion of the fertile surface. Excessive cropping or grazing can depress soil-nutrient levels and degrade soil structure. Soil conservation techniques have been developed to address the range of soil management issues. Various methods of cultivation conserve soil fertility (see cover crop ; rotation of crops ). Minimum-tillage systems, often entailing herbicide use, avoid erosion and maintain soil structure. Soil fertility and agricultural productivity can also be improved, restored, and maintained by the correct use of fertilizer , either organic, such as manure , or inorganic, and other soil amendments. Organic matter can be added to improve soil structure. Soil acidity can be decreased by addition of calcium carbonate or increased by addition of sulfuric acid. Bibliography See F. R. Steiner, Soil Conservation in the United States (1990); M. Alexander, Introduction to Soil Microbiology (2d ed. 1991); E. J. Plaster, Soil Science and Management (2d ed. 1991); publications of the U.S. Soil Conservation Service.
The moment that pollutants in soils become dissolved in natural waters, their potential for transport is greatly magnified, as is the likelihood that people will ingest them. The primary health risk from many hazardous waste sites, dumps, septic tanks, factory outflows, and other pollution sources is the possibility that pollutants will be dissolved into groundwaters or surface waters, then ultimately reach drinking water. Pollutants of concern include industrial solvents such as perchlorethlyene (PCE); trichlorethylene (TCE); motor fuel components such as benzene, toluene, ethylbenzene, and xylene, (collectively termed BTEX); and inorganic contaminants such as lead, chromate, arsenic, and nitrate. Just as each contaminant tends to affect specific organs in the human body depending on its chemistry, the behavior of contaminants in groundwaters and surface waters likewise varies from contaminant to contaminant. Rarely do chemicals behave identically in natural waters; typically there is at least one natural reaction that causes the bioavailability of a given contaminant to decrease, or attenuate, over time. These attenuation reactions include the following. Contaminant attenuation can be split into two components. Organic contaminants are made up of electron-rich molecules containing linked carbon atoms. Soil microorganisms can derive energy by using oxygen, sulfate, nitrate, or ferrous iron to oxidize and break these chains down into carbon dioxide plus water. Often this breakdown is more rapid than engineered remediation. Rapid microbial attenuation is often observed for fuel hydrocarbons such as are found beneath leaking underground fuel tanks. Attenuation tends to be most rapid under oxidizing (aerobic ) conditions that often prevail in loose soils. In oxygen-poor (anaerobic ) waters, attenuation tends to be slower. PCE and TCE are two of the most common contaminants at hazardous waste sites. They are quite toxic and also tend to resist chemical attenuation. Microorganisms are only able to rapidly attenuate them by first reducing them under anaerobic conditions, and then oxidizing them under aerobic conditions. Obviously the potential for PCE or TCE attenuation hinges upon the chemical condition of the aquifer or soil. Chemical attenuation of inorganic contaminants such as lead, chromate, nitrate, and arsenic often involves sorption onto mineral surfaces. Microorganisms generally cannot break down such contaminants into less toxic compounds except in a few cases. Most notably, microorganisms are able to reduce oxidized (and toxic) chromate to insoluble and less toxic trivalent chromium. Likewise, microorganisms can convert nitrate to ammonia and/or nitrogen gas. Most other inorganic contaminants must be sorbed to mineral surfaces to be attenuated. Soil and aquifer solids tend to be negatively charged because of broken or unsatisfied bonds that exist at their surfaces. This negative charge that exists at mineral surfaces pulls oppositely charged cations from solution. Many dissolved metals exist as positively charged cations in natural waters and are hence attracted to, and attenuated at, mineral surfaces. This is particularly true for such industrial metals as lead, cadmium, zinc, and nickel. It is also true for such important radionuclides that are present in radioactive waste as 90Sr, 137Cs, and isotopes of Pu (plutonium) and U (uranium). Chromate and arsenate sorb appreciably to many soil minerals despite the overall negative charge of both partners. Inorganic contaminants that initially sorb onto mineral surfaces from a contaminant-rich solution might in theory "desorb" back into contaminantpoor waters recharging a contaminated aquifer after the contaminant source has been removed. In fact, numerous field observations suggest that many sorbed contaminants become permanently sequestered after prolonged interaction with mineral surfaces. In other words, sorbed contaminants are taken up into mineral lattices (structures) where they are no longer bioavailable. Mineral uptake also makes the complete engineered removal of contaminants from soils and aquifers nearly impossible. In effect, the crystal lattices must be destroyed to remove the bound contaminants. Pollutant attenuation is most commonly taken advantage of in the treatment of sewage; that is, oxidation of organic matter is hastened by mixing on-site or by discharging into surface waters that have sufficient capacity to rapidly attenuate the imposed pollutant load. Increasingly, pollutant attenuation, or equivalently "monitored natural attenuation" or MNA, is being used as a component of hazardous waste site cleanups. Specifically, MNA is relied upon to remove contaminants from groundwaters, in parallel to and, after active remediation has ceased. Bioremediation of contaminated sites typically involves the engineered acceleration of natural organic activity that leads to the breakdown of organic contaminantsâ€”most commonly spilled fuels and solventsâ€”ultimately to carbon dioxide. Less common is the introduction of new organisms, themselves, to contaminated sites. Natural soil organic activity tends to be sufficiently pervasive that, given the appropriate nutrients, breakdown of contaminants can be achieved by native populations of microorganisms. Nutrient additions may include oxygen, a carbon substrate such as molasses, and/or hydrogen. It must be noted that not all contaminants attenuate rapidly enough to prevent potential impacts on human health. Instead, knowledge of attenuation rates and capacities is critical to the successful implementation of pollutant attenuation in either realm. Each area remains the subject of intense investigation by chemists, biologists, geochemists, engineers, and other scientists. see also Fresh Water, Natural Composition of; Fresh Water, Physics and Chemistry of; Groundwater; Modeling Groundwater Flow and Transport; Modeling Stream Flow and Quality; Pollution of Groundwater; Pollution of Lakes and Streams; Radioactive Chemicals; Septic System Impacts; Wastewater Treatment and Management. Patrick V. Brady Brady, Patrick V., Michael V. Brady, and David J. Borns. Natural Attenuation: CERCLA, RBCAs, and the Future of Environmental Remediation. Boca Raton, FL: Lewis Publishers, 1997. Rice, David W. et al. "Recommendations to Improve the Cleanup Process for California's Leaking Underground Fuel Tanks." In Lawrence Livermore National Laboratory Report. Lawrence Livermore National Laboratory, CA: 1995.
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Answers:This question I have already answered . You need an essay on '' soil pollution"?? For free essays on '' soil pollution'' see the following web pages. It is in English , please convert to Hindi. http://www.oppapers.com/essays/Soil-Poll http://www.allfreeessays.com/topics/soil
Answers:My friend did a science fair on what is the worst form of pollution for fishes.. She used 2 fish tanks filled with gold fish and she put one tank on the mouth of her gas pipe behind the car every morning when she warms up her car. She threw all sorts of trash she could find to the second tank. Maybe this can make u think of some ideas..
Answers:soil erosion is a non-point source of pollution. contaminated soil can be transported from one location and deposited in another. the contaminants within can be then leached into different soil horizons hence, possibly contaminating unconfined groundwater bodies. of course this is based on the assumption that substantial amounts are eroded that are sufficient to cause such pollution. similarly, soil erosion can be a non-point source of pollution to surface water bodies as well possibly cause eutrophication. topics you can include in your paper would be mostly addressing the sources and causes of soil pollution (for ex: agriculture and industry - agriculture: fertilizers (you can also talk about the filler material), pesticides. industry - inappropriate disposal of hazardous wastes or accidental spills, there are also industrial emissions into the air that can be deposited onto the soil either wet or dry deposition). how soil pollution affects the environment and residents (humans/animals/plants) you can also add how each sector addressed the above: agriculture - precision farming, IPM (Integrated Pest Management (or Integrated Crop Management - ICM) the establishment of GAP (Good Agricultural Practices) industry - legislations that state maximum allowable levels and state the appropriate means to handle chemicals as well as response in emergency situations such as spills etc. hope i helped :)
Answers:Pollution in soil has important effects on living things so yes, it should fall under life sciences. It will likely also fall under chemistry and others like the social sciences. I don't know if environmental science is considered a life science but one could make the argument that the core values in environmental science are about life. I'd say it's a connection between life sciences and others like chemistry and social science.