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Field Validation of Anaerobic Degradation Pathways for Dichlorodiphenyltrichloroethane (DDT) and 13 Metabolites in Marine Sediment Cores from China

State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
Environmental Science & Technology (Impact Factor: 5.48). 06/2011; 45(12):5245-52. DOI: 10.1021/es2006397
Source: PubMed

ABSTRACT Although the production and use of dichlorodiphenyltrichloroethane (DDT), a legacy component of persistent organic pollutants, have been highly restricted worldwide, the environmental fate of DDT has remained a great concern as it is not only ubiquitous and bioaccumulative but can also be degraded to a series of metabolites that may be more hazardous ecologically. The present study, taking advantage of the abundant levels of DDT and its metabolites in a subtropical coastal region of China, investigated into the degradation pathways of DDT in natural coastal sediment. Sediment profiles indicated that degradation of 1,1,1-trichloro-2,2-bis-(p-chlorophenyl)ethane (p,p'-DDT) to 1,1-dichloro-2,2-bis-(p-chlorophenyl)ethane (p,p'-DDD) mainly occurred in sediment of the top 20 cm layer. 1,1-dichloro-2,2-bis-(p-chlorophenyl)ethylene (p,p'-DDE), aerobically transformed from p,p'-DDT prior to sedimentation, was likely to degrade to 1-chloro-2,2-bis-(p-chlorophenyl)ethylene (p,p'-DDMU) which was further converted to 2,2-bis(p-chlorophenyl)ethylene (p,p'-DDNU). In addition, p,p'-DDNU could be transformed to 2,2-bis(p-chlorophenyl)ethane (p,p'-DDNS) and other high-order metabolites. On the other hand, the conversions of p,p'-DDD to p,p'-DDMU and 1-chloro-2,2-bis-(p-chlorophenyl)ethane (p,p'-DDMS) to p,p'-DDNU were deemed slow in anaerobic sediment. Therefore, the present study confirmed all the degradation pathways involving reductive dechlorination and p,p'-DDE being a more important precursor for p,p'-DDMU than p,p'-DDD in anaerobic sediment, as proposed previously. On the other hand, the present study suggested that p,p'-DDMU instead of p,p'-DDMS was more likely the precursor for formation of high-order metabolites. Based on the current assessments, use of (DDD+DDE)/DDTs to indicate whether there is fresh DDT input may lead to large uncertainties if the concentrations of high-order metabolites are not negligible. Similarly, ecological risk assessment associated with DDT should be conducted with consideration of high-order DDT metabolites.

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Available from: Huan-Yun Yu, Jun 08, 2014
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    • "RM and TB contained significantly higher abundances of p,p 0 -DDT than those of p,p 0 -DDE. If the ratios of (DDE + DDD)/DDTs were higher than 0.5, DDT can be regarded as historical residue instead of fresh input (Yu et al., 2011). As shown in Fig. 6, the ratios of (DDE + DDD)/DDTs in marine fish from the Natuna Island ranged from 0.01 to 1.0, with a mean value of 0.64. "
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    ABSTRACT: Five marine fish species were collected from the Natuna Island, South China Sea to investigate the occurrence of polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs). Concentrations of PBDEs, PCBs, and DDTs in marine fish ranged from 2.85 to 7.82, 14.3 to 48.1, and 7.99 to 40.3ng/g lipid weight, respectively. Higher concentrations of PBDEs, PCBs, and DDTs were observed in Snakefish (Trachinocephalus myops), which might be attributed to their different feeding and living habits. PCBs were the predominant POPs in all marine fish, followed by DDTs and PBDEs. BDE 47 and PCB 153 were the predominant congener of PBDEs and PCBs, respectively. Compositional distribution of DDTs indicated the possible presence of fresh input sources around the Natuna Island. The ratios of o,p'-DDT/p,p'-DDT being less than 1 in fish samples suggested that DDT contributions from dicofol seemed considerably low. New input sources of DDT in South China Sea are worth further research.
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    • "Similar results have previously reported that p,p ′-DDE contributed more than 85% to DDTs in eggs of great tit and blue tit from different European countries (Van den Steen et al., 2009, 2010a,2010b), and starling from Europe, North America and Australia (Eens et al., 2013). The ratios of (DDE + DDD)/DDTs have been used to indicate whether fresh input of DDT is prevailing and (DDE + DDD)/DDTs N 0.5 can be thought that DDTs come from historical use instead of fresh input (Yu et al., 2011). In this study, the ratios of (DDE + DDD)/DDTs ranged from 0.85 to 1.0, with an average value of 0.95 (Table 1), indicating that historical residue is likely the main source of DDT in birds from Guangdong Province. "
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    ABSTRACT: Thirty-two light-vented bulbuls (Pycnonotus sinensis) were collected from six sampling sites in Guangdong Province, South China to investigate the geographical variation on the occurrence of polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs). Concentrations of PCBs and DDTs in the pectoral muscle of light-vented bulbul ranged from 140 to 73,000ng/g lipid weight (lw) and 12 to 4600ng/g lw, respectively. PCB concentrations were significantly higher in birds from e-waste site compared to other sampling sites (mean, 18,000 vs 290ng/g lw, p<0.0001), implying that PCBs mainly came from e-waste recycling activities. No significant differences for DDT levels were observed among the sampling sites (p=0.092). Differences in PCB homologue profiles among the sampling sites were found and can be probably ascribed to different local contamination sources. p,p'-DDE (>80%) was the most abundant component of DDTs in birds. Compositional pattern of DDTs suggested that historical residue was the main source of DDT. The toxic equivalent (TEQ) concentrations had significant positive correlations with PCB concentrations, indicating that elevated PCB levels may have adverse effects on light-vented bulbuls.
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    • "The ratio of (DDE + DDD)/DDTs are often used to indicate whether new input of DDT is prevailing. (DDE + DDD)/DDTs > 0.5 can be thought that DDTs are derived from historical use instead of new input (Yu et al., 2011b). In the present study, the ratios of (DDE + DDD)/DDTs in fish species from Yongxing Island were in the range of 0.15–1.0 with a mean value of 0.75 (Table 1), indicating that historical residues remained the main source of DDTs in Yongxing Island. "
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