Toxaphene degradation in estuarine sediments

Williams, R. R.; Bidleman, Terry F.

doi:10.1021/jf60215a034

Cited by 31 publications

(15 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Because of its various fields of application, several environmental compartments were contaminated with toxaphene. Despite evidence of extensive transformation under reducing conditions (sediment, soil, and sewage sludge), several primarily lower-chlorinated compounds persist in artificially and naturally contaminated environments [3][4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Anaerobic transformation of compounds of technical toxaphene. 2. Fate of compounds lacking geminal chlorine atoms

Ruppe

Neumann

Braekevelt

et al. 2004

Enviro Toxic and Chemistry

View full text Add to dashboard Cite

The major toxaphene metabolites in sediment and soils (2-exo,3-endo,6-exo,8,9,10-hexachlorobornane [B6-923] and 2-endo,3-exo,5-endo,6-exo,8,9,10-heptachlorobornane [B7-1001]) were incubated with the isolated gram-negative bacterium Dehalospirillum multivorans. Within 14 d, biotransformation of B7-1001 was nearly quantitative, resulting in two penta- and six hexachlorobornanes, as well as one unsaturated hexachloro compound of technical toxaphene. The major transformation product (approximately 50% of all metabolites) was identified as 2-exo,3-endo,5-exo,8,9,10-hexachlorobornane (B6-903). Abiotic dehydrochlorination of B7-1001 with methanolic KOH resulted in the formation and subsequent identification of the lone unsaturated compound as 2,5-endo,6-exo,8,9,10-hexachloroborn-2-ene. Thus, dehydrochlorination was found to be a minor process of the anaerobic transformation of toxaphene. Biotransformation of 70% of amended B6-923 within 14 d demonstrated that reductive dechlorination was not exclusively associated with geminal Cl atoms, as previously suggested. Three pentachlorobornanes were identified as transformation products, one of which was identical with a transformation product of B7-1001. This commonality unequivocally proves this metabolite to be 2-exo,3-endo,8,9,10-pentachlorobornane. Fifteen previously unknown metabolites of B6-923, B7-1001, and other toxaphene compounds identified in this study were detected in sediment from Lake Ontario (Canada), underscoring the importance of microbial toxaphene transformation in natural, aquatic environments.

show abstract

Section: Introductionmentioning

confidence: 99%

Anaerobic transformation of compounds of technical toxaphene. 2. Fate of compounds lacking geminal chlorine atoms

Ruppe

Neumann

Braekevelt

et al. 2004

Enviro Toxic and Chemistry

View full text Add to dashboard Cite

show abstract

“…In the environment, the multicomponent mixture is significantly changed, and only some persistent CTTs resist transformation. The toxaphene residue pattern in marine mammals is usually dominated by the 2‐ endo , 3‐ exo , 5‐ endo , 6‐ endo , 8,8,10,10‐octachlorobornane (B8‐1413) and 2‐ endo , 3‐ endo , 5‐ endo , 6‐ exo , 8,8,9,10,10‐nonochlorobornane (B9‐1679) [5,6], whereas in soil and sediment, it is dominated by 2‐ exo , 3‐ endo , 6‐ exo , 8,9,10‐hexachlorobornane (B6‐923), 2‐ endo , 3‐ exo , 5‐ endo , 6‐ exo , 8,9,10‐heptachlorobornane (B7‐1001), and other penta‐ to heptachloro‐CTTs [7–10].…”

Section: Introductionmentioning

confidence: 99%

Anaerobic transformation of compounds of technical toxaphene. I. Regiospecific reaction of chlorobornanes with geminal chlorine atoms

Ruppe

Neumann

Vetter

2003

Enviro Toxic and Chemistry

View full text Add to dashboard Cite

Technical toxaphene (Melipax) and the single compounds of technical toxaphene (CTTs) 2,2,5-endo,6-exo,8,8,9,10-octachlorobornane (B8-806), 2,2,5-endo,6-exo, 8,9,9,10-octachlorobornane (B8-809), 2,2,5,5,8,9,9,10,10-nonachlorobornane (B9-1025), 2-endo,3-exo,5-endo,6-exo,8,8,9,10,10-nonochlorobornane (B9-1679), 2-endo,3-exo,5-endo,6-exo,8,9,10,10-octachlorobornane (B8-1414), 2-endo,3-exo,5-endo,6-exo,8,8,9,10-octachlorobornane (B8-1412), and 2-exo,3-endo,5-exo,9,9,10,10-heptachlorobornane (B7-1453) were treated with suspensions of the anaerobic bacterium Dehalospirillum multivorans. After 7 d, more than 50% of technical toxaphene was transformed, and the relative amount of early eluting CTTs increased. After 16 d, only 2-exo,3-endo,6-exo, 8,9,10-hexachlorobornane (B6-923), 2-endo,3-exo,5-endo,6-exo, 8,9,10-heptachlorobornane (B7-1001), and a few minor penta- and hexachloro-CTTs were detected in the samples. The result of the transformation was comparable with observations in naturally contaminated sediments and soil. However, the performance with D. multivorans was more simple and reproducible, as well as faster, than use of soil, sediment, or anaerobic sewage sludge. In agreement with reports in the literature, reductive dechlorination at geminal chlorine atoms (gem-C1s) was found to be the major CTT transformation pathway. Experiments conducted with CTTs and gem-C1s at both primary and secondary carbons clarified that the initial C1 --> H substitution takes place at the secondary carbon C2. Furthermore, the 2-endo-C1 position was preferably substituted with hydrogen. In the case of B8-806, the dechlorination at the secondary carbon C2 was approximately 20-fold faster than the subsequent, slow reduction at the primary carbon C8. The three different formerly unknown heptachloro-CTTs, 2-exo,3-endo,6-exo,8,9,9,10-heptachlorobornane (B7-1473), 2-exo, 3-endo,6-endo,8,9,9,10-hepatchlorobornane (B7-1461), and 2-exo, 3-endo,6-exo,8,8,9,10-heptachlorobornane (B7-1470) were found as intermediates of the B8-806/809 transformation. Treatment of B9-1679 with D. multivorans indicated that gem-C1s on the bridge (C8 and C9) are dechlorinated faster than gem-C1s on the bridgehead (C10).

show abstract

“…Reductive dehalogenation appears to be the main pathway and converts DDT to DDD (Glass, 1972;Zoro et al, 1974), DTE to DDE (Beland et al, 1974), and lindane to benzene (Beland et al, 1976) under reducing conditions. Anaerobic degradation of toxaphene mixtures has also been reported in anaerobic soils (Parr and Smith, 1976) and in salt marsh sediments (Williams and Bidleman, 1978). These and other papers dispute the role of biological processes in this mechanism.…”

Section: Oa Bmentioning

confidence: 96%

The role of colloidal organic matter in the marine geochemistry of PCBs

Brownawell¹

1986

View full text Add to dashboard Cite

WITHDRAWN AD -sT~i~Bñ~c i~tZ4-2-ABSTRACT Polychlorinated biphenyls (PCBs) were used as model hydrophobic organic compounds (HOC) to study physical-chemical processes which affect the speciation and fate of HOC in coastal environments. The focus of this study is on the sorption of PCBs with colloidal organic matter in seawater, and the influence of this process on the distribution of PCBs in coastal sediments. Laboratory and field experiments were used to make quantitative estimates of PCB-organic matter sorption, and to test predictions of three-phase equilibrium models.A static headspace partitioning method was developed to measure the sorption of several individual chlorobiphenyls with colloidal organic matter enriched from coastal seawater by hollow fiber ultrafiltration. This technique directly measured the dissolved phase fugacity of PCBs in experimental bottles, and avoided uncertain separation techniques often used in isolating various chemical phases. Colloidal organic carbon normalized partition coefficients (Koc) were determined from linear sorption isotherms, and increased from 1.9 x 10' (L/Kg) for 2,4'-dichlorobiphenyl to 3.5 x 10 s for 2,2',3,4,5'-pentachlorobiphenyl. Sorption tended to increase with increasing octanol-water partition coefficients (Kow) of the sorbate, and values of Koc were within a range of those reported in other experimental sorption studies with sediments and dissolved humic substances. Experimental partitioning results support the hypothesis that HOC-organic colloid sorption is similar to HOC sorption by sediment organic matter.PCBs were measured in the interstitial waters and sediments of three box cores obtained from New Bedford Harbor and Buzzards Bay, Massachusetts. The three sites studied had a wide range of sediment PCB concentrations, and reducing conditions provided environments containing high concentrations of colloidal organic matter. Dissolved organic carbon (DOC) and total sediment organic carbon (TOC) were measured in two cores to test the role of organic matter on the observed partitioning of PCBs. PCB concentrations, particularly those of less soluble chlorobiphenyls, were highly elevated in interstitial waters compared to water column concentrations at all three sites. The measured apparent distribution coefficients (K'd) of individual chlorobiphenyls did not increase with hydrophobicity (Kow) and indicate that a large fraction of PCBs in interstitial waters must be sorbed to organic colloids. A three-phase equilibrium sorption model, in which dissolved PCBs are in a dynamic equilibrium with colloidal and sediment organic matter, accounts for many aspects of the field data. There is good agreement of observed partitioning at New Bedford Station 67 and Buzzards Bay Station M with model calculations based on predictions derived from laboratory experiments of HOC sorption with sediments and organic colloids, but model calculations underpredict K'd at Station 84 in New Bedford Harbor.-3-The sediment-interstitial water results were contrasted with a study of PCB pa...

show abstract

Toxaphene degradation in estuarine sediments

Cited by 31 publications

References 8 publications

Anaerobic transformation of compounds of technical toxaphene. 2. Fate of compounds lacking geminal chlorine atoms

Anaerobic transformation of compounds of technical toxaphene. 2. Fate of compounds lacking geminal chlorine atoms

Anaerobic transformation of compounds of technical toxaphene. I. Regiospecific reaction of chlorobornanes with geminal chlorine atoms

The role of colloidal organic matter in the marine geochemistry of PCBs

Contact Info

Product

Resources

About