Organic contaminants, environmental aromatic hydrocarbons

The growth of industrialization and the use of chemical confounds have resulted in serious environmental poUutioiL Various organic contaminants, including aromatic hydrocarbons, nitroaromatic compounds and chloroaromatics persist in the environment. It is technically difficult to decontaminate these chemicals and traditional physiochemical treatments are e ensive. 

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. 

Biopract provides technological products and processes for industry, agriculture, and environment. They not only produce technical enzyme preparations but also develop enzymes for applications in agriculture, food, and textile industry as well as in environmental technologies. On the later, bioremediation has been an area of service delivery from Biopract. Their activities regards microbial preparations for the bioremediation of organic contaminants (mineral oil (MKW), polycyclic aromatic hydrocarbons (PAH), benzene, toluene, ethylbenzene, xylene (BTEX), methyl-tert-butyl ether (MTBE), volatile organic hydrocarbons (VOC), and dimethyl sulfoxide (DMSO)). 

The NO + 03 chemiluminescent reaction [Reactions (1-3)] is utilized in two commercially available GC detectors, the TEA detector, manufactured by Thermal Electric Corporation (Saddle Brook, NJ), and two nitrogen-selective detectors, manufactured by Thermal Electric Corporation and Antek Instruments, respectively. The TEA detector provides a highly sensitive and selective means of analyzing samples for A-nitrosamines, many of which are known carcinogens. These compounds can be found in such diverse matrices as foods, cosmetics, tobacco products, and environmental samples of soil and water. The TEA detector can also be used to quantify nitroaromatics. This class of compounds includes many explosives and various reactive intermediates used in the chemical industry [121]. Several nitroaromatics are known carcinogens, and are found as environmental contaminants. They have been repeatedly identified in organic aerosol particles, formed from the reaction of polycyclic aromatic hydrocarbons with atmospheric nitric acid at the particle surface [122-124], The TEA detector is extremely selective, which aids analyses in complex matrices, but also severely limits the number of potential applications for the detector [125-127],... 

Polycyclic aromatic hydrocarbons (PAHs) represent a heterogeneous class of environmental contaminants formed by incomplete combustion or pyrolysis of organic matter. They comprise compounds with 2-6 fused benzene rings, most of which (4-6 ring compounds) are known human mutagens and carcinogens. 

Wild, S. R., Jones, K. C., Waterhouse, K. S. McGrath, S. P. (1990a). Organic contaminants in an agricultural soil with a history of sewage sludge amendments Polynuclear aromatic hydrocarbons. Environmental Science Technology, 24, 1706—11. 

Organic chemicals that are susceptible to oxidation and are of concern from the perspective of contamination and environmental degradation include aliphatic and aromatic hydrocarbons, alcohols, aldehydes, and ketones phenols, polyphenols, and hydroquinones sulfides (thiols) and sulfoxides nitriles, amines, and diamines nitrogen and sulfur heterocyclic compounds mono- and di-halogenated aliphatics linear alkybenzene-sulfonate and nonylphenol polyethoxylate surfactants and thiophosphate esters. Table... 

Polycyclic aromatic hydrocarbons (PAHs) are a class of persistent organic pollutants (POPs) and widespread environmental contaminants, some of which may exhibit toxic, carcinogenic and mutagenic effects Because of their low water solubility and hydrophobic nature, PAHs are partitioned... 

In some cases, the effects of complex environmental mixtures could be accounted for in terms of concentration-additive effects of a few chemicals. In sediments of the German river Spittelwasser, which were contaminated by chemical industries in its vicinity, around 10 chemicals of a cocktail of several hundred compounds were found to explain the toxicity of the complex mixture to different aquatic organisms (Brack et al. 1999). The complex mixture of chemicals contained in motorway runoff proved toxic to a crustacean species (Gammarus pulex). Boxall and Maltby (1997) identified 3 polycyclic aromatic hydrocarbons (PAHs) as the cause of this toxicity. Subsequent laboratory experiments with reconstituted mixtures revealed that the toxicity of motorway runoff could indeed be traced to the combined concentration-additive effects of the 3 PAHs. Svenson et al. (2000) identified 4 fatty acids and 2 monoterpenes to be responsible for the inhibitory effects on the nitrification activity of the bacteria Nitrobacter in wastewater from a plant for drying wood-derived fuel. The toxicity of the synthetic mixture composed of 6 dominant toxicants agreed well with the toxicity of the original sample. 

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. 

Organic contaminants that present a concern to environmental protection include pesticides (used in agriculture), polycyclic aromatic hydrocarbons (PAHs, a by-product of incomplete combustion), polychlorinated biphenyls (PCBs, components of coolants and lubricants), phenols (used in the production of plastics and pesticides), dioxins (unwanted by-products of many industrial processes including incineration and chemical manufacturing of phenols, PCBs, and herbicides) and alkyphenols (surfactants in agrochemicals and household cleaning products). 

Monocrotaline, a pyrrolizidine alkaloid of chemotherapeutic interest, has been extracted from the seeds of Crotalaria spectabilis using supercritical carbon dioxide and carbon dioxide-ethanol mixtures (29). Other alkaloids that have been extracted using SFE include nicotine and caffeine. Environmental applications of supercritical fluids include regeneration of activated carbon, extraction of organic contaminants like polynuclear aromatic hydrocarbons and polychlorinated biphenyls from water and soils, and the newly emerging field of supercritical water oxidation. 

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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