Biotic transformation

Brodsky J, Andersson JT, Ballschmiter K. 1986. Chemical degradation of xenobiotics II. Simulation of the biotic transformation of bis(2-ethylhexyl) phthalate and dioctylphthalate by abiotic means. Chemosphere 15 139-147. 

Andersson, J.T., Haussler, R., and Ballschmiter, K. Chemical degradation of xenobiotics. III. Simulation of the biotic transformation of 2-nitrophenol and 3-nitrophenol, Chemosphere, 15(2) 149-152,1986. 

No published data were located referencing biotic transformation of thorium in soil. Abiotic transformation processes that can convert immobile thorium in soil into mobile forms through the formation of complexes were discussed in Section 5.3.13. 

The pollutants discharged into the environment, may, in the best case, undergo abiotic or biotic transformations, resulting in innocuous compounds that may not represent an immediate health hazard. However, many of the xenobiotic compounds are toxic and may undergo partial transformations that result in even more toxic derivatives. This process is known as activation. 

An example in which a biotic transformation of a man-made pollutant generates a nontoxic product is the metabolic biotic transformation of the dodecylsulfate detergent into acetoacetic acid. On the other hand, an example of the generation of a toxic substance due to human chemical treatment is the generation of chloroform (or other organo-chlorine compounds or trihalomethanes) in treated... 

Vogel TM, McCarty PL. 1987. Abiotic and biotic transformations of 1,1,1-trichloroethane under methanogenic conditions. Environ Sci Technol 21 1208-1213. 

Alterations may include transformation, degradation, and changes in speciation or ionization. Transformation occurs when a contaminant is chemically altered by the addition of oxygen, hydrogen, or nitrogen, or is combined with or bound to another chemical. Abiotic transformations may include chemical oxidations or reductions in aerobic or anaerobic environments, respectively. Biotic transformations may be carried out by bacteria and fungi in the environment, or may take place within the bodies of plants and animals. Transformations may either make the chemical more or less toxic, depending on the reaction involved. If the chemical is broken down... 

In addition organo-mercuiy compounds are of environmental interest in aquatic systems not only since the Minamata disaster (Takizawa 2000). Especially methylated mercuiy species were detected and monitored in riverine systems as the result of biotic transformation of inorganic mercury... 

Qualitative and quantitative as well as stable carbon isotope analyses were performed and discussed in terms of environmental stability of the groundwater residues described. Anaerobic microbial degradation of the main pollutant 1-chloronaphthalene was evident from identification of 1-chloro-4-naphthol and 1-chloronaphthoic acid as biotic transformation products. While this observation indicates microbial involvement in degradation of chloronaphthalenes, several aspects of our analysis are inconsistent with an extensive degree of microbial degradation ... 

No accumulation of the biotic transformation products was detected in parallel to decreasing concentrations of the educt as the result of ongoing microbial activities. 

Biotic transformation or microbial metabolism is generally the most effective in degrading toxic compounds in wetlands. 

The second case refers to hormones, pharmaceuticals, and other compounds that are ingested, metabolized, and excreted by mammals (Table 1). Usually a hormone or pharmaceutical is extensively metabohzed in the body and is excreted by mammals as a mixture of different metabolites. Although the general belief is that metabolism renders a drug more water soluble and consequently less hazardous for the aquatic environment, there are exceptions for pro-drugs and specifically acting metabolites. The third case refers to environmental transformation products of pesticides and other environmental pollutants (Table 1), which are formed both by abiotic and biotic transformation processes. 

Reactions affecting the environmental fate of halogenated one- and two-carbon compounds can be broadly classified as substitutions, dehydrohalogenatdons, oxidations, and reductions [4]. These reactions can be either abiotic or biotic. Dehydrohalogenations are typically abiotic, while oxidations in dark environments are mostly biotic. Substitutions and reductions can be either biotic or abiotic. With some notable exceptions, abiotic transformations tend to be slow. Biotic transformations can be rapid when the microorganisms, that nthesize reactive enzymes or cofactors, are present in suffident numbers. 

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