Dechlorination activity (cross‐acclimation) of freshwater sediments adapted to whom it may concern: It may concern: Mono‐ and di‐chlorophenols

Abstract

The reductive dechlorination of chlorophenols (CPs) in sediment slurries (10% solids) adapted to dechlorinate mono‐ and di‐CPs (DCP) was investigated to define the regiospecificity of the dechlorination reaction. Unadapted sediment slurries amended with various ortho‐substituted CPs exhibited lag periods ranging from 8 to 12 days before the onset of dechlorination. In contrast, 2‐ and 3‐CP as well as 2,3‐ and 2,4‐DCP were dechlorinated without a lag period by sediments adapted to transform 2‐CP. Dechlorination of 4‐CP was not observed after incubation for 35 days. Adaptation to 2‐CP, therefore, enhanced the onset of dechlorination of 3‐CP and all ortho‐substituted CPs tested. Dechlorination of 2‐CP, 3‐CP, 2,3‐DCP, and 3,4‐DCP was also effected without a lag period by sediments adapted to transform 3‐CP.

Sediments adapted to dechlorinate individual DCPs (2,3‐, 2,4‐, and 3,4‐DCP) exhibited dechlorination of 2‐CP, 2,3‐, 2,4‐, and 3,4‐DCP without a lag phase. The preference for dechlorination by 2,3‐ and 2,4‐DCP adapted sediments was at the ortho chlorine. 3,4‐DCP adapted sediments, which preferentially dechlorinate at the para position of 3,4‐DCP, exhibited rapid dechlorination of the ortho and meta chlorines of all mono‐ and di‐CPs tested. Interestingly, dechlorination at the para position was not detected when 4‐CP was incubated with 3,4‐DCP adapted sediment.

Key words:

• Reductive dechlorination
• dichlorophenol (DCP)
• regiospecificity
• anoxic sediments

Notes

Current address: Dept. of Environmental Engineering Science, Univ. of Florida, Gainesville, Fla, 32611

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