Degradation of pesticides

Winterlin W, Seiber JN, Craigmill A, et al. 1989. Degradation of pesticide waste taken from a highly contaminated soil evaporation pit in California. Arch Environ Contam Toxicol 18 734-747. 

Brooks, G.T. (1972). Pathways of enzymatic degradation of pesticides. Environmental Quality and Safety 1, 106-163. 

Dick WA, RO Ankumah, G McClung, N Abou-Assaf (1990) Enhanced degradation of S-ethyl A, A -dipropyl-carbamothioate in soil and by an isolated soil microorganism. In Enhanced Bio degradation of Pesticides in the Environment (Eds KD Racke and JR Coats), pp 98-112. American Chemical Society Symposium Series 426, American Chemical Society, Washington, DC. 

Linn DM, Carski TH, Brusseau ML, Chang FH, eds. Sorption and Degradation of Pesticides and Organic Chemicals in Soil. Madison, WI Soil Science Society of America and American Agronomy Society of Agronomy 1993. 

Hydrolysis reactions occur by nucleophilic attack at a carbon single bond, involving either the water molecule directly or the hydronium or hydroxyl ion. The most favorable conditions for hydrolysis, e.g. acidic or alkaline solutions, depend on the nature of the bond which is to be cleaved. Mineral surfaces that have Bronsted acidity have been shown to catalyze hydrolysis reactions. Examples of hydrolysis reactions which may be catalyzed by the surfaces of minerals in soils include peptide bond formation by amino acids which are adsorbed on clay mineral surfaces and the degradation of pesticides (see Chapter 22). 

Rao PSC, Beilin CA, BrusseauML (1993) In Linn DM (ed) Sorption and degradation of pesticides and organic chemicals in soil. Soil Science Society of America, Madison, WI,... 

Schoen, S.R. and Winterlin, W.E. The effects of various soil factors and amendments on the degradation of pesticide mixtures,... 

Surface-catalyzed degradation of pesticides has been examined in the context of research on contaminant-clay interactions. Such interactions were observed initially when clay minerals were used as carriers and diluents in the crop protection industry (Fowker et al. 1960). Later specific studies on the persistence of potential organic contaminants in the subsurface defined the mechanism of clay-induced transformation of organophosphate insecticides (Saltzman et al. 1974 Mingelgrin and Saltzman 1977) and s-triazine herbicides (Brown and White 1969). In both cases, contaminant degradation was attributed to the surface acidity of clay minerals, controlled by the hydration status of the system. 

Degradation of Pesticides in Controlled Water-Soil Systems... 

The hydrolysis of pesticides which are sorbed to sterilized natural sediments has been investigated in aqueous systems at acid, neutral and alkaline pH s. The results show that the rate constants of pH independent ("neutral") hydrolyses are the same within experimental uncertainties as the corresponding rate constants for dissolved aqueous phase pesticides. Base-catalyzed rates, on the other hand, are substantially retarded by sorption and acid-catalyzed rates are substantially enhanced. A large body of evidence will be presented which substantiates these conclusions for a variety of pesticide types sorbed to several well-characterized sediments. The significance of our results for the evaluation of the effects of sorption on the degradation of pesticides in waste treatment systems and natural water bodies will also be discussed. 

Whether such disposal is intentional or incidental, significant quantities of pesticides and pesticide wastes end up in natural and artificial aquatic systems. Thus, any consideration of the disposal of this broad category of anthropogenic chemicals must include an understanding of the reaction mechanisms and principal pathways for degradation of pesticides in aquatic systems. Of the degradative pathways relevant to such systems, hydrolysis reactions are perhaps the most important type of chemical decomposition process ( 1 7 ). 

Based on this model, the following rate equations relating the hydrolytic degradation of pesticides from sediment water suspensions can be written dC... 

The limited acid-hydrolysis results, if substantiated, have broader implications. They suggest that rapid hydrolysis of pesticide wastes in acidified artificial sediment/water slurries may be an attractive method for the intentional disposal and degradation of pesticide wastes. 

Chakrabarty has extensively reviewed the biodegradation of pesticides (J ). Table I shows the results of several studies on the enzymatic activity of microbial cell-free extracts for pesticide degradation. Clearly, there is substantial evidence to suggest that enzymes might be used in the development of biotechnology for use in degradation of pesticides. 

Roles of Iron—Sulfur Proteins in Degradation of Pesticidal Chemicals by Microorganisms... 

Somasundaram L, Coats JR, Racke KD. 1989. Degradation of pesticides in soil as influenced by the presence of hydrolysis metabolites. J Environ Sci Health B24 457-478. 

Ainsworth, C. C., Frederickson, J. K. Smith, S. C. (1993). Effect of sorption on the degradation of aromatic acids and bases. In Sorption and Degradation of Pesticides and Organic Chemicals in Soil, ed. D. M. Linn, T. H. Carski, M. L. Brusseau F-H. Chang, pp. 125-44. Madison, WI Soil Science Society of America, American Society of Agronomy. 

Nitrophenols are persistent pollutants and commonly found in industrial wastewaters. Degradation of nitrophenols to less dangerous materials or mineralization is difficult by natural process involving biodegradation or oxidation. Nitrophenols are commonly found in degradation of pesticides such as parathion and nitrofen. Kiwi et al. (1994) showed efficient photo-and dark oxidation via Fenton-like reactions on 2 and 4-nitrophenols. Photolysis of acidic solutions of H2Oz give OH radicals as primary photoproducts (Baxendale and Wilson, 1957) as follows ... 

Research has previously shown that bacteria are not uniformly distributed in soil, reflecting soil structure and available nutrients (Richaume et al., 1993). The distribution of microorganisms throughout the soil can also be considered from the applied ecological perspective of patch dynamics, where patch formation is a reflection of intrinsic and extrinsic forces (Rao et al., 1986). The same authors also showed spatial variability in the degradation of pesticides applied to a soil system. 

Fomsgaard, I.S. (1995). Degradation of pesticides in subsurface soils, unsaturated zone A review of methods and results. Ini. J. Environ. Anal. Chem., 58 231-245. 

Matsumura, F. (1982). Degradation of pesticides in the environment by microorganisms and sunlight. In F. Matsumura and C.R. Murti Krishna, eds., Biodegradation of Pesticides. New York Plenium Press, pp. 67-87. 

Mansour, M. (1996). Abiotic degradation of pesticides and other organic chemicals in aquatic systems. Pestic. Outlook, 7 9-10. Mansour, M., A. Mamouni, and P. Meallier (1988). Factors determining the behavior and transformation of selected pesticides in water, soil suspension and soils. In Proceedings of Methodological Aspects of the Study of Pesticide Behaviour in Soil. Versailles, France, INRA, June 16-17, pp. 87-100. 

Rtidel, H., Schmidt, S., Kordel, W., Klein, W. (1993) Degradation of pesticides in soil comparison of laboratory experiments in a biometer system and outdoor lysimeter experiments. Sci. Total Environ. 132, 181-200. 

Schwartz, H.J. (1967) Microbial degradation of pesticides in aqueous solutions. J. Water Pollut. Control Fed. 39, 1701. 

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