Chlorinated compounds aromatic

G. S. Sayler, Microbial Decomposition of Chlorinated Aromatic Compounds, USEPA 600/2-86/090, Washington, D.C., 1986. 

Ref. 14 contains a more general and simplistic order of decreasing biodegradabihty straight-chain compounds, aromatic compounds, chlorinated straight-chain compounds, and chlorinated aromatic compounds. 

As recently as 1970, only about 30 naturally occurring organohalogen compounds were known. It was simply assumed that chloroform, halogenated phenols, chlorinated aromatic compounds called PCBs, and other such substances found in the environment were industrial pollutants. Now, only a third of a century later, the situation js quite different. More than 5000 organohalogen compounds have been found to occur naturally, and tens of thousands more surely exist. From a simple compound like chloromethane to an extremely complex one like vancomycin, a remarkably diverse range of organohalogen compounds exists in plants, bacteria, and animals. Many even have valuable physiological activity. Vancomycin, for instance, is a powerful antibiotic produced by the bacterium Amycolatopsis orientalis and used clinically to treat methicillin-resistant Staphylococcus aureus (MRSA). 

The photolysis of chlorinated aromatic compounds occurs by several processes which follow predictable routes 13). They frequently undergo photochemical loss of chlorine by dissociation of the excited molecule to free radicals or, alternatively, through a nucleophilic displacement reaction with a solvent or substrate molecule. Either mechanism is plausible, and the operation of one or the other may be influenced by the reaction medium and the presence of other reagents. 

The pyrolysis of vinylidene chloride produced a range of chlorinated aromatic compounds including polychlorinated benzenes, styrenes, and naphthalenes (Yasahura and Morita 1988), and a series of chlorinated acids including chlorobenzoic acids has been identified in emissions from a municipal incinerator (Mowrer and Nordin 1987). 

The signiflcance of toxic metabolites is important in diverse metabolic situations (a) when a pathway results in the synthesis of a toxic or inhibitory metabolite, and (b) when pathways for the metabolism of two (or more) analogous substrates supplied simultaneously are incompatible due to the production of a toxic metabolite by one of the substrates. A number of examples are provided to illustrate these possibilities that have achieved considerable attention in the context of the biodegradation of chlorinated aromatic compounds (further discussion is given in Chapter 9, Part 1) ... 

Klecka GM, WJ Maier (1988) Kinetics of microbial growth on mixtures of pentachlorophenol and chlorinated aromatic compounds. Biotechnol Bioeng 31 328-335. 

Application of NMR has been made to a restricted range of chlorinated aromatic compounds (Kolehmainen et al. 1992), and has been used to establish the source of oxygen in the metabolites produced from acetate and 02 by Aspergillus melleus (Staunton and Sutkowski 1991). 

There is an additional problem that has important implications for the bioremediation of contaminated sites when two substrates such as a chlorinated and an alkylated aromatic compound are present. The extradiol fission pathway is generally preferred for the degradation of alkylbenzenes (Figure 9.17), although this may be incompatible with the degradation of chlorinated aromatic compounds since the 3-chlorocatechol produced inhibits the activity of the catechol-2,3-oxygenase (Klecka and Gibson 1981 Bartels et al. 1984). 

Shimizu et al. 2002). It was therefore shown that it is possible to produce transgenic plants with the capability of degrading chlorinated aromatic compounds, which are degraded with the formation of 3-chlorocatechol. 

Feidieker D, P Kampfer, W Dott (1994) Microbiological and chemical evaluation of a site contaminated with chlorinated aromatic compounds and hexachlorocyclohexanes. EEMS Microbiol Ecol 15 265-278. 

Lang E, H Viedt, J Egestorff, HH Hanert (1992) Reaction of the soil microflora after contamination with chlorinated aromatic compounds and HCH. EEMS Microbiol Ecol 86 275-282. 

Bioconcentration factors of dioxins in fishes are relatively low compared to other chlorinated aromatic compounds because of the low metabolic conversion of dioxins, their low available concentrations in test systems, and their highly variable uptake rates (de Voogt et al. 1990). In general, bioconcentration factors for persistent superlipophilic chemicals, such as OCDD, derived for freshwater fishes from supersaturated solutions may seriously underestimate the true BCF (Geyer... 

Zitko [20] has described a confirmatory method in which the chloroparaffins in sediments are reduced to normal hydrocarbons which are then analysed by gas chromatography. This method lacks sufficient sensitivity for trace (sub-ppm) analysis and the confirmatory method may be difficult to apply. Friedman and Lombardo [21] have described a gas chromatographic method applicable to chloroparaffins that are slightly volatile the method is based on microcoulometric detection and photochemical elimination of chlorinated aromatic compounds that otherwise interfere. 

Albro PW, Parker CE. 1972. General approach to the fractionation and class determination of complex mixtures of chlorinated aromatic compounds. J Chromatogr 197(2) 155-169. 

Dichlorobenzene is a chlorinated aromatic compound. It is used as a deodorant for restrooms (Howard 1990), for moth control (Merck 1989), and as an insecticide (Farm Chemicals 1983). Information regarding the chemical identity of 1,4-dichlorobenzene is located in Table 3-1. 

Figure 2. Glass capillary gas chromatogram of chlorinated aromatic compounds in a magnesium plant effluent...

Armenante, P. M., Kafkewitz, D., Lewandowski, G. Kung, C-M. (1992). Integrated anaerobic-aerobic process for the biodegradation of chlorinated aromatic compounds. Environmental Progress, 11, 113—22. 

Chatterjee, D. K., Kellogg, S. T., Watkins, D. R. Chakrabarty, A. M. (1981). Plasmids in the biodegradation of chlorinated aromatic compounds. In Molecular Biology, Pathogenicity, and Ecology of Bacterial Plasmids, ed. S. B. Levy, R. C. Clowes E. L. Koenig, pp. 519-28. New York Plenum Press. 

Rochkind-Dubinsky, M. L., Sayler, G. S. Blackburn, J. W. (1987). Microbiological Decomposition of Chlorinated Aromatic Compounds. New York Marcel Dekker. 

UNIFAC Approach Jensen et al. [16] have employed the UNIFAC group contribution approach to develop an estimation method for pure-component vapor pressures. The model developed applies to hydrocarbons, alcohols, ketones, acids, and chloroalkanes of less than 500 molecular mass and in the vapor pressure region between 10 and 2000 mmHg. Burkhard et al. [8] extended this model to chlorinated aromatic compounds such as chlorobenzenes and PCBs. 

Chlorine Number-KRelationships For chlorinated aromatic compounds, linear correlations between Kow and Nq have been reported [32] ... 

Pfefferle W, Anke H, Bross M, Steglich W (1990) Inhibition of Solubilized Chitin Synthase by Chlorinated Aromatic Compounds Isolated from Mushroom Cultures. Agric Biol Chem 54 1381... 

Lauritsen FR, Lunding A (1998) A Study of the Bioconversion Potential of the Fungus Bjerkandera adusta with Respect to a Production of Chlorinated Aromatic Compounds. Enzyme Microbial Technol 22 459... 

Chlorinated aromatic compounds are hazardous compounds that result from various industrial and agricultural activities. Water disinfection, waste incineration, and uncontrolled use of biocides are the major sources of chlorinated aromatics in the environment. Chlorinated compounds are also formed as subproducts of the biochemical reactions of herbicides containing chlorophe-noxy compounds. Treatment of chlorinated compounds has been studied using biological treatment, adsorption, air stripping, and incineration. Biodegradation of chlorinated compounds is a slow process that is ineffective for extremely low concentrations. Air stripping and adsorption simply trans-... 

Chlorinated aromatic compounds are commonly found as contaminants in environmental soil samples. For example, chlorobenzenes have been listed as priority pollutants and can be found in various matrixes such as water, soils, sediments and sewage sludges. Polychlorinated biphenyls are probable human carcinogens but have been applied in large doses in various industrial products. Analysis of these compounds in solid matrixes, such as soils and sediments, requires several steps. 

Much of the effort on environmental chemicals that contaminate food has concentrated on a small range of chlorinated chemicals. In addition to the chlorinated PCDDs, PCDFs and PCBs already mentioned, other chlorinated compounds can be separated into two groups chlorinated aromatic compounds and chlorinated aliphatic compounds. Although there is a number of organochlorine pesticides that are persistent in the environment, these will not be considered here, as they comprise an extensive field of study in their own right. 

Chlorinated aromatic compounds and polyaromatic compounds, organophosphates... 

The photocatalytic degradation of chlorophenols on ZnO has also been demonstrated [127]. The photocatalytic degradation of other chlorinated aromatic compounds [127], phenol [128-134], fluorinated aromatic compounds [135], and other substituted phenols and aromatic compounds [Izumi 1981, 738 Matthews 1984, 2386 Abdullah 1990, 2099 [136-141] have been demonstrated. The degradation of halogenated aromatic pollutants such as polychlorinated biphenyls (PCBs) [142] and polybrominated dibenzofiirans [143] has also been attempted. 

In the literature, the wildlife ecotoxicology of CACs has not been dealt with to the extent of agrochemicals.18 The purpose of this chapter is to review eco-toxicological aspects of chlorinated aromatic compounds, with emphasis on polychlorinated biphenyls, dibenzo-p-dioxins and dibenzofurans. Rather than being complete we will try to review recent information on bioaccumulation, biotransformation and effects of CACs. The focus will be on avian and mammalian... 

Similar hndings have been reported on a more incidental base from other areas in the world. From these, the common estuaries of the rivers Rhine/Meuse/Scheldt in Northwest Europe are relatively well studied with regard to chlorinated aromatic compounds. Breeding success of several birds species in this area (cormorant and common tern) has been shown to be related to contamination levels.106,107 Other species, however, do not show signihcantly reduced breeding success and do not seem to be at risk.108... 

The knowledge of ecotoxicology of chlorinated aromatic compounds has increased substantially over the last 10 years. In particular, observations in wildlife have shown that, contrary to what is believed now for humans, certain PCBs, PCDDs and PCDFs are causing harmful effects to individuals and populations, despite the fact that their concentrations in both the abiotic and the biotic environment have been declining continuously since the 1970s. 

Chlorinated aromatic compounds are dispersed globally because of their... 

Despite their persistency, chlorinated aromatic compounds can be transformed by microflora and fauna as well as higher organisms. The products of these processes are different. Metabolism is an important process for vertebrates to regulate or detoxify their body burden of these compounds. Some products of the biotransformation process, however, may elicit toxic effects or accumulate themselves, thereby acting opposite to the goals of biotransformation. 

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