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Environmental fate & pathways

Biodegradation in soil

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Description of key information

Dichloromethane degradation was observed under aerobic and anaerobic conditions in a variety of soils

Key value for chemical safety assessment

Half-life in soil:
14.2 d
at the temperature of:
25 °C

Additional information

The aerobic degradation of dichloromethane was observed in a variety of (sub)surface soils (a sand, a sandy loam, a sandy clay loam and a clay soil). Degradation was also observed in the sandy loam soil under anaerobic conditions. The rate of degradation was dependent on the soil type, substrate concentration, organic carbon availability and redox condition of the particular soil studied.

Degradation was found to occur over concentrations ranging from appr. 0.1 to 50 ppm. No products other than carbon dioxide were detected in the biologically active microcosms. The time required for 50% disappearance of the parent compound ranged from 1.3 to 191.4 days. Dichloromethane degradation was observed under anaerobic conditions in sandy loam soil (Davis and Madsen 1991). The removal of dichloromethane from aerobic soil was significantly increased following exposure to methane (Henson et al., 1988). The median value for primary biodegradation rate constant in soil of dichloromethane from the study of Davis and Madsen (1991) is 0.0488/day; this value corresponding to a half-life of 14.2 days is used in the assessment.