Persistent halogenated compounds in two typical marine aquaculture zones of South China

Liang

et al. 2011

Environ. Sci. Technol.

Self Cite

100

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.

Section: Articlementioning

confidence: 79%

“…Detailed descriptions of the sediment sample preparation procedures have been given previously. 16,21 Instrumental Analysis. Concentrations of DDXs excluding p,p 0 -DDA were determined with a Shimadzu model 2010 GC coupled with a Model QP2010 mass spectrometer (MS) (Shimadzu, Japan).…”

Section: Articlementioning

confidence: 99%

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

Liang

et al. 2011

Environ. Sci. Technol.

Self Cite

100

“…A large set of data on the relative abundances of BDE-209 in 23 environmental matrices sampled from the PRD was compiled from the literature [24][25][26][27][28][29][30][31][32][33][34][35][36][37] and is graphically displayed in Figure 3. An independent samples t test for equality of means indicates that there is a significant difference ( p < 0.001) in the relative abundances of BDE-209 between the abiotic (n ¼ 79 from 11 matrices) and biotic (n ¼ 73 from 12 matrices) samples, i.e., the average relative abundances of BDE-209 were 74 AE 29% and 35 AE 30% in abiotic and biotic samples, respectively.…”

Section: Field-measured Relative Abundances Of Bde-209mentioning

confidence: 99%

Sorption of PBDE in low‐density polyethylene film: Implications for bioavailability of BDE‐209

Enviro Toxic and Chemistry

You

Zeng

2011

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Abstract-The coefficients of partitioning (K pew ) between low-density polyethylene (LDPE) film (50-mm thickness) and water for 23 polybrominated diphenyl ether (PBDE) congeners were determined based on a regression analysis of sorption kinetics over an extended exposure period (up to 365 d). A curvilinear relationship between log K pew and log K OW (octanol-water partition coefficient) was obtained for the target BDE congeners with the turning point at log K OW approximately 8. Previously obtained dietary uptake efficiencies of BDE congeners in common carp (Cyprinus carpio) were also found to relate curvilinearly to log K OW . In addition, fieldmeasured relative abundances of BDE-209 compiled from previous investigations conducted in the Pearl River Delta of South China were significantly ( p < 0.001) higher in abiotic samples (n ¼ 79 from 11 matrices) than in biotic samples (n ¼ 73 from 12 matrices), suggesting the likelihood for reduced bioavailability of BDE-209 in certain biota. Finally, a molecular-scale analysis indicated that the curvilinear relationship between log K pew and log K OW can be attributed to the energy barrier that a molecule has to overcome as it attempts to diffuse into the LDPE structure, which can become significant for larger molecules. Similarly, the reduced bioavailability of BDE-209 in many biological species can be regarded as a reflection of the magnitude of molecular interactions between cell membranes and

“…Apparently, the source profiles are quite different for snubnose pompano and saddletail snapper. Local fishermen indicated that snubnose pomano mainly feeds on composite food, whereas saddletail snapper largely consumes trash fish (Yu et al 2011b). The inconsistency between the source profiles and feeding inhabits may suggest the occurrence of different biotransformation mechanisms in these two fish species.…”

Section: Modeling Resultsmentioning

confidence: 99%

“…The total number of samples for air, water, surface sediment, snubnose pompano, saddletail snapper, and algae in Haling Bay and Daya Bay was 33, 13, 46, 41, 36, and 8, respectively. In addition, the average concentrations of DDTs in seawater farmed fish food, including 14 trash fish samples and 21 composite feeds of 13 brands, were collected from mariculturing (Yu et al 2011a). Data of DDTs are also available for seven antifouling paint products, purchased from a local shop at the coast of Hailing Bay in November 2010 (Yu et al 2011b). Apart from antifouling paint samples, all other samples were collected between July 2007 and April 2008.…”

Section: Methodology Data Collection and Evaluationmentioning

confidence: 99%

Source apportionment of DDTs in maricultured fish: a modeling study in South China

Fang

Yiruhan

et al. 2015

Environ Sci Pollut Res

Self Cite

Fish is one of the most important nutrition sources for humanity. Contaminant exposure risk in fish farming will eventually deliver to the crowd through diet. China is the largest fish producing as well as exporting country, where mariculture plays an important role in fish production, especially in South China. Previous investigations indicated that a variety of compartments in farming areas of South China Sea were polluted by persistent organic pollutants, including DDT (dichlorodiphenyltrichloroethane) and its derivatives, some of which is designated as DDTs. In the present study, Hailing Bay and Daya Bay of Guangdong Province, China, were selected as the study sites and DDTs as the target compounds. A fish enrichment model was developed to assess the relative contributions of various pathways to the mass loadings of DDTs in the fish. Average concentrations (and concentration ranges) of DDTs in various environmental compartments of Hailing Bay and Daya Bay were included in modeling and analysis. Modeling results indicated that fish food and seawater contributed approximately the same proportions for the DDTs in maricultured fish. Antifouling paint was supposed to be the primary source of water DDTs in mariculture zone of Hailing Bay and Daya Bay, which contributed 69 % of the total DDTs to the mariculture water. We suggest that in order to protect people from consuming highly contaminated maricuture zone fish, the most effective and feasible methods are using environment-friendly antifouling paint and applying less polluted fish food in the fish reproduction process.