Pollutants, environmental media

EPA. Each environmental statute has its own particular focus, whether it is controlling the levels of pollutants introduced into a single environmental medium (i.e., air, soil, or water) or addressing a specific area of concern, such as pesticides or waste cleanup. 

An unforeseen consequence of recent regulation is that pollutants are often shuffled from one environmental medium to another, with little net environmental improvement. In other cases, regulation has caused industry to substitute materials, which in turn may become subject to regulation. While the current regulatory system has reduced risk and improved the environment, it has in some cases been inefficient and unnecessarily costly in achieving environmental goals. 

An example of a concentration limit is a cleanup level, which is a type of an action level used in remediation projects. Pollutant concentrations in an environmental medium that are greater than the cleanup levels warrant a remedial action. Cleanup levels are often developed based on site conditions, such as future land use exposure pathways the presence of groundwater and the likelihood of its beneficial use the presence of specific ecological receptors background concentrations. 

Actions shifting hazardous waste from one environmental medium to another. Many of the waste management, treatment and control practices used to date have simply collected pollutants and moved them from one environmental medium to another, as follows (a) collection of pollutants from air and water via pollution control devices, which are then legally disposed of in land disposal sites, and (b) transfer of volatile pollutants from surface impoundments, landfills, water treatment units, groundwater air stripping operations, to the air through evaporation. 

Total human exposure Accounts for all exposures a person has to a specific contaminant, regardless of environmental medium or route of entry (inhalation, ingestion and dermal absorption). Sometimes, total exposure is used incorrectly to refer to exposure to all pollutants in an environment. Total exposure to more than one pollutant should be stated explicitly as such (NRC, 1991). 

Regulation is still largely based on media interests, e.g. water pollution, air pollution, etc. Because of this it is quite conceivable that over-regulation for one environmental medium may cause a transfer of pollution potential to another environmental medium. To some extent this has been addressed under the principle of Integrated Pollution Control, but this form of... 

Lead is a multimedia pollutant, i.e., it provides exposures through diverse environmental media. The specific characteristics of each environmental contributor, such as Pb concentrations and intake amounts of some environmental medium, help determine the extent to which different individuals and populations sustain actual exposures. This also means that while some Pb sources can be characterized on a national, international, or other macroscale as being significant, the actual sources and pathways in specific cases for substances such as lead or other elements require specific evaluation. Some segments of human populations may sustain exposures from Pb in more than one environmental medium, in which case one employs methods to sort out potential contributions or the relative total contributions to total exposures. 

Pollution of the environment - means pollution of the environment due to the release (into any environmental medium) from any process of substances which are capable of causing harm to man or any other living organisms supported by the environment. 

Supercritical fluids also find application in the areas of pollution prevention and remediation, and supercritical carbon dioxide is used as a replacement solvent for many hazardous solvents in both extraction and separation processes and also as a reaction medium and in materials processing. Although carbon dioxide is considered as a greenhouse gas , there is actually no net increase in the amount of the gas if it is removed from the environment, used as the solvent instead of a hazardous substance, and returned to the environment. In this way, most of the uses of supercritical carbon dioxide may be considered as environmentally friendly. Because the solubilities of oils and greases in carbon dioxide are high, it is particularly suited to the cleaning of machinery 47 and, as discussed in the literature 48, it is used as a solvent in textile dyeing operations where it is used to treat any dye-laden... 

The contamination of groundwater by leakage of hydrocarbons or other pollutants from underground storage tanks, distribution systems and various industrial operations is a major environmental problem. Conventional treatment techniques suffer from serious shortcomings which limit their applicability and efficiency. These include high cost and maintenance requirements, the need to transfer the contamination from one medium to another, and the extended duration of the operation, since decades may be necessary to prevent continued growth of contaminant plumes (Yerushalmi et al., 1999). An alternative to these treatments lies in in situ remediation. 

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