Widespread Contamination

Surface-active substances (SAS) are the most widespread contaminants of sewage and natural waters. They translate in small dispertion condition liquid and firm polluting substances - chlororganic, mineral oils, pesticides. Therefore, the SAS contents determination in water solutions is now one of actual tasks of analytical chemistry. 

Phthalate esters are widespread contaminants and the dialkyl phthalates are hydrolyzed before degradation of the resulting phthalate (Eaton and Ribbons 1982), which is discussed in Chapter 8, Part 3. For dimethyl phthalate, dimethyl terephthalate, and dimethyl isophthalate only partial hydrolysis may take place (Li et al. 2005). Cocaine is hydrolyzed to benzoate and ecgonine methyl ester by a strain of Pseudomonas maltophilia (Britt et al. 1992). 

Enrichment factors have been used in stndies with methyl tert-butyl ether (MTBE) that is a fuel additive and is a widespread contaminant in snbsnrface aquatic systems. 

Polychlorinated biphenyls (PCBs) were manufactured by catalytic chlorination of biphenyl to produce complex mixtures, each containing 60-90 different PCB molecular species or congeners (see Chaps. 1 and 4). In the United States, PCB mixtures were manufactured by Monsanto under the trade name Aroclor and were widely used as dielectric fluids in capacitors and transformers from 1929 to 1978. PCBs are widespread contaminants of aquatic sediments and continue to be a focus of environmental concern because they tend to accumulate in biota and are potentially toxic. The following sections show the most effective bioremediation techniques applied to various PCB contaminated environments ... 

An application well-suited for IMS is the decommissioning and cleanup of sites where extensive manufacturing of explosives has taken place in the last century and where widespread contamination of soils and waters has occurred [74]. Decontamination of model metal scrap artificially contaminated with TNT and of decommissioned mortar rounds stiU containing explosives residue was followed by sampling surfaces with analysis by a portable mobility spectrometer. Mixed anaerobic microbial populations of bioslurries were employed in decontamination of scrap and the mortar rounds, and the IMS analyzer was seen as a sensitive field... 

Not all of the evidence was sound because the early analytical methods for DDT using gas chromatography could confuse PCBs (polychlorinated biphenols) and DDT breakdown products, ffowever, these analyses alerted scientist and the public to the widespread contamination of the environment with PCBs (widely used in electrical transformers and other industrial equipments at that time but subsequently banned), which became a new concern. 

Exhibit 9 shows that many of the vegetable products contain banned pesticides. These data show that 33 vegetable products are contaminated with banned pesticides, whereas 21 or 47 percent of the vegetable products are contaminated with multiple banned pesticides. This widespread contamination transcends the five recommended vegetable groups that are included in a balanced diet. For example ... 

Nitroaromatic compounds (NACs) are one of the widespread contaminants in the environments. Sources of NACs are numerous they originate from insecticides, herbicides, explosives, pharmaceuticals, feedstock, and chemicals for dyes (Agrawal and Tratnyek, 1996). Under anaerobic conditions, the dominant action is nitro reduction by zero-valent iron to the amine. Other pathways do exist, such as the formation of azo and azoxy compounds, which is followed by the reduction of azo compounds to form amines. Also, in addition to the possibility of azo and azoxy compounds, phenylhydrox-ylamine may be an additional intermediate (Agrawal and Tratnyek, 1996). Nitrobenzene reduction forms the amine aniline. Known for its corrosion inhibition properties, aniline cannot be further reduced by iron. Additionally, it interferes with the mass transport of the contaminant to the surface of the iron. The overall reaction is as follows ... 

Abstract The widespread contamination of waters by halogenated and unsaturated... 

DDT and PCBs remain the most widespread contaminants in human milk around the world. Other common contaminants of mother s milk include flame retardants, pesticides, wood preservatives, toilet deodorizers, and dry-cleaning fluids. 

Despite the fact that the average consumption of pesticides are still low in India, (05kg ha-1) against 6.6 and 12kg ha-1 in Korea and Japan, respectively, there has been widespread contamination of food commodities with pesticide residues, basically due to their non-judicious use. In a recent review Gupta (2004) has stated that in India, 51% of food commodities are contaminated with pesticide residues and out of these, 20% have residues above the maximum permissible residue levels on a worldwide basis. 

Minh, T.B., Watanabe, M., Tanabe, S., Miyazaki, N., Jefferson, T.A., Prudente, M.S., Subramanian, A., Karuppiah, S., 2000a. Widespread contamination by tris (4-chloro-phenyl) methan and tris (4-chlorophenyl) methanol in cetaceans from the North Pacific and Asian coastal waters. Environ. Pollut. 110, 459-468. 

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