Organic contaminants, environmental chlorinated hydrocarbons

The purpose of this chapter is to provide the reader with robust, easily applied methods for estimating diffusivities within the dominant natural phases (air, water, solid matrix, oil, etc.) for a range of environmentally and geochemically relevant compounds. The types of compounds considered include atomic (Hg) and diatomic (O2, CI2) elements, simple molecules (H2S, CO2, NO), organic contaminants (polynuclear aromatic hydrocarbons, polychlorinated biphenyls, chlorinated solvents), as well as dissolved cationic (Pb +, Cr +) and anionic (Br , SO ) species. Examples showing the application of estimation methods are provided and the results of different methods are compared to measured values from the literature. When available, estimates regarding the accuracy of theoretical and empirical methods are included. Experimental methods for determining diffusivities in air, water, porous... 

CRMs for Contaminants in Environmental Matrices For nearly two decades NIST has been involved in the development of SRMs for the determination of organic contaminants such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and chlorinated pesticides in natural environmental matrices such as fossil fuels (Hertz et al.1980 Kline et al. 1985), air and diesel particulate material (May and Wise 1984 Wise et al. 2000), coal tar (Wise et al. 1988a), sediment (Schantz et al. 1990, 1995a Wise et al. 1995), mussel tissue (Wise et al. 1991 Schantz et al. 1997a), fish oil, and whale blubber (Schantz et al. 1995b). Several papers have reviewed and summarized the development of these environmental matrix SRMs (Wise et al. 1988b Wise 1993 Wise and Schantz 1997 Wise et al. 2000). Seventeen natural matrix SRMs for the determination of organic contaminants are currently available from NIST with certified and reference concentrations primarily for PAHs, PCBs, chlorinated pesticides, polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofiirans (PCDFs) see Table 3.11. 

Widespread substantial contamination of the environment has arisen primarily from the massive use of the persistent chlorinated hydrocarbon pesticides. The extent and significance of this contamination is only partly known. Our limited knowledge is most apparent in two areas. First, there is no organized environmental monitoring and human surveillance system to provide comprehensive and representative data about the locations, amounts, and trends of this contamination second, we are technically unprepared to predict the significant long term effects of this contamination on animal and human life. 

The increasing production and use of fossil fuels have substantially increased the probability of soil and water resource contamination by them, particularly groundwater and aquifers. Indeed, aquifers and groundwater contamination by fuels and other NAPL compounds (e.g., chlorinated hydrocarbons) associated with industrial, commercial, and military activities already constitute an environmental issue of major concern worldwide [1,5]. In fact, nearly one quarter of the organic chemicals listed as priority pollutants by the U.S. Environmental Protection Agency (EPA) are... 

Many persistent organic pollutants (POPs) and other environmental contaminants have been associated with immunotoxic effects, but, in most instances, it remains difficult to assign the effects to pure compounds. For example, immunotoxic effects of PCBs in free-ranging harbor seals have been associated with increasing blubber concentrations of PCBsJ34 yet the waters inhabited by these animals are also contaminated with other POPs, including chlorinated pesticides and chlorinated polynuclear aromatic hydrocarbons. Indeed, the PCBs themselves are mixtures of different moieties with varying immunotoxic properties. 

The estimated world production in the period 1930 to 1974 is about 1.2 X 10 tons," of this about one third has been released into the environment without any precautions regarding toxic effects on biota and any care to prevent environmental pollution. This has led to the widespread occurrence of PCBs aU over the world, even in remote areas. The U.S. Environmental Protection Agency (EPA), under the provisions of the Toxic Substances Control Act, specifically banned most of the uses of PCBs in 1997. Current releases of PCBs are mainly as a result of the cycle of these persistent contaminants from soil to air and back to soil again. Other possible sources of contamination, such as leaching, occurs. Moreover, PCBs can be unintentionally produced as by-products in a wide variety of chemical processes which contain chlorine and hydrocarbon sources, during water chlorination, and by thermal degradation of other chlorinated organics. ... 

Chlorinated organic compounds (COCs) refer to the substitution of one or more hydrogen in aliphatic and aromatic hydrocarbons and their derivatives by chlorine. COCs are widely used in the fields of chemistry, medicine, electronics, pesticides, etc. Many COCs are endocrine disturbance substances, show carcinogenic effects, and have been listed as priority pollutants by the US Environmental Protection Agency (USEPA). When released into the environment, COCs are transported in both air and water. However, COCs are chemically stable and difficult to destroy, and they are eventually deposited in soils and sediments due to their hydrophobic-ity. Soils and sediments contaminated with COCs are long-term sources of pollutants and pose great threats to human health and ecosystems. Therefore, remediation of these contaminated soils and sediments is of great importance. 

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