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1B+C Abiotic Transformations + Biodegradation (MOP/42) Anaerobic biodegradation of benzidine in Lake Macatawa sediment/water system. Nyman, Marianne1, Harden, Joel1, 1 Rensselaer Polytechnic Institute, Troy, New York, USA ABSTRACT- The release of 3,3′-dichlorobenzidine (DCB), an intermediate in dye manufacturing, into Lake Macatawa (MI, USA) is an environmental and health concern due to its carcinogenic nature. Laboratory and field studies have shown that DCB degrades to form a short lived intermediate (e.g., 3-monochlorobenzidine), and benzidine (Nyman et al., 1997) another known carcinogen. Sediment and water samples were collected from four locations in Lake Macatawa in May, 2001. Organic carbon content and particle size distribution analysis were performed on each sediment sample studied. The samples varied in composition from silty-clay to sandy sediments, with total organic carbon compositions of 13.0 to 17.3%. To elucidate the fate of benzidine, bottles containing a lake sediment/water mixture were spiked with benzidine and incubated under anaerobic conditions for twelve months at three temperatures (e.g., 5, 15, and 23°C). Autoclaved bottles containing sediment and deionized water were also spiked with benzidine and used as controls. Analysis of bottle slurry samples revealed time dependant reduction in benzidine concentrations with a corresponding increase in unknown product peak areas. Further analysis has suggested the biologically mediated production of 2-ethyl-1-hexanol and other yet to be identified products. Sorption isotherms, using lake water, were also determined for benzidine to ascertain the sorption properties for these sediments. All isotherms investigated demonstrated non-linearity. The Freunlich sorption coefficient, Kf, seemed to be correlated with the particle size distribution (e.g., <75 Key words: benzidine, biodegradation, 3,3′-dichlorobenzidine |
m fraction).