TABLE 1.
Dehalogenation of chlorinated and brominated biphenyls in microcosms of Woods Pond sedimenta
| Chlorinated biphenyls
|
Brominated biphenyls
|
|||||
|---|---|---|---|---|---|---|
| Congener | Product(s) | Acclimation timeb (weeks) | Reference | Congener | Product(s)g | Acclimation time (weeks) |
| 2-CBc | None | (27) | 24, 28 | 2-BB | BP | 2 |
| 4-CBc | None | (27) | 24, 26, 28 | 4-BB | BP | 1 |
| 24-CBd | 2-CB, 4-CB | 8 | 26, 28 | 24-BB | 2-BB, 4-BB, BP | 1 |
| 25-CBd | None | (17) | 24, 26 | 25-BB | 2-BB, BP | 1 |
| 26-CBd | None | (43) | 6, 23, 26, 28 | 26-BB | 2-BB, BP | 1 |
| 2-2-CB | None | (8) | 24 | 2-2-BB | 2-BB, BP | 14 |
| 4-4-CB | None | (8) | 24 | 4-4-BB | 4-BB, BP | 2 |
| 245-CB | 25-CB, (24-CB)e | 3 | 24, 26 | 245-BB | 24-BB, 25-BB, 2-BB, BP | <2 |
| 246-CBf | 24-CB, 2-CB, 4-CB | 8 | 26, 28 | 246-BB | 24-BB, 26-BB, 2-BB, 4-BB, BP | 7 |
| 246-CBf | 26-CB | 8 | 6, 28 | 246-BB | 24-BB, 26-BB, 2-BB, 4-BB, BP | 7 |
| 345-CB | 35-CB | 3 | 26 | 345-BB | 34-BB, 35-BB, 3-BB, 4-BB, BP | <2 |
| 25-3-CBd | None | (8) | 3 | 25-3-BB | 25-BB, 2-3-BB, 2-BB, 3-BB, BP | <1 |
Dehalogenation of four PCB congeners, 2-CB, 4-CB, 2-2-CB, and 4-4-CB, was tested in the same batch of sediment used to test dehalogenation of the brominated biphenyls. Results for dehalogenation of the remaining chlorinated biphenyls are from previous experiments with different batches of sediment. Except for small differences in acclimation time, the results of dehalogenation of chlorinated biphenyls were the same in studies by several different investigators.
The time given is the shortest time observed before any dehalogenation products were observed. For cases in which dechlorination did not occur, the time in parentheses is the time at which the experiment was terminated.
When incubated separately, this congener persisted until the experiments were terminated at 8 weeks (24). When produced as a dehalogenation intermediate of 24-CB, this congener persisted for >27 weeks.
This congener was produced as the dehalogenation product of another congener. The acclimation time was counted only after the congener had accumulated to high levels.
24-CB was a minor product (<1% of the total).
The time given is for incubations in which 246-CB was a product of 2346-CB (28). When the congener was incubated separately, the observed acclimation time was 24 weeks (26).
BP, biphenyl.