| Abstract: | Indigenous mixed populations of anaerobic microorganisms from an irrigation tailwater drain and submerged agricultural chemical waste pit readily biodegraded the major isomer of endosulfan (endosulfan I). Endosulfan I was biodegraded to endosulfan diol, a low toxicity degradation product, in the presence of organic carbon sources under anaerobic, methanogenic conditions. While there was extensive degradation (>85%) over the 30 days, there was no significant enhancement of degradation from enriched inocula. This study demonstrates that endosulfan I has the potential to be biodegraded in sediments, in the absence of enriched microorganisms. This is of particular importance since such sediments are prevalent in cotton-growing areas and are typically contaminated with endosulfan residues. The importance of minimizing non-biological losses has also been highlighted as a critical issue in determining anaerobic biodegradation potential. Seals for such incubation vessels must be both oxygen and pollutant impermeable. Teflon-lined butyl rubber provides such a seal because of its resistance to the absorption of volatiles and in preventing volatilization. Moreover, including a 100 mM phosphate buffer in the anaerobic media has reduced non-biological losses from chemical hydrolysis, allowing biodegradation to be assessed. |
