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Biodegradation of DIMP, Dieldrin, Isodrin, DBCP, and PCPMSO in Rocky Mountain Arsenal Soils. Installation Restoration Program, Environmental Technology Development

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Final rept., Jan 1987-Jan 1989

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The role of biodegradation in the environmental fate of DIMP, dieldrin, isodrin, DBCP, and PCPMSO in Rocky Mountain Arsenal soils was evaluated. Surface soil borings were collected from contaminated and uncontaminated regions at RMA. The extent of heterotrophic microbial activity in the soil samples was determined by monitoring 14-CO2 production from soils spiked with a mixture of 14C-glucose, 14C-acetate, and 14C-amino acids. Soil extracts were plated on nutrient agar to enumerate total heterotrophs. Two of six soil samples exhibited little or no heterotrophic activity. The lack of metabolic activity in these two samples was attributed to microbially inhibitive soil contaminants. Inactive soils were not utilized in subsequent mineralization studies. The mineralization of radiolabeled DIMP, dieldrin, isodrin, DBCP, and PCPMSO in contaminated and uncontaminated RMA soils was determined. Soil samples were spiked with test compound and incubated at 22 deg C. Headspace in the test flasks was periodically sampled and analyzed for 14C-organics and 14-CO2. Mineralization studies were conducted for a period of 26 weeks. All five test compounds were poorly degraded under aerobic conditions. Low, but statistically significant compared to sterile controls levels of 14-CO2 were produced from 14C-isodrin and 14C-dieldrin. Previous research by other investigators indicated that the five test compounds are resistant to aerobic degradation. Data from the present study support these findings. The mineralization of 14C-isodrin was also evaluated in a laboratory-scale composting system maintained at 55 deg C. Less than 0.1 percent of 14C-isodrin was evolved as 14-CO2 during a 39 day test period.

Subject Categories:

  • Biochemistry
  • Soil Mechanics
  • Environmental Health and Safety

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