Ecological fate, effects and prospects for the elimination of environmental polychlorinated biphenyls (PCBs)
ABSTRACT Polychlorinated biphenyls (PCBs) present an environmental health hazard of global scale and man-made origin. Their impact on nearly every member of the biota results in a wide range of interacting negative effects. Due to their chemical nature, these recalcitrant toxicants are poised to enter and bioaccumulate in the food web. Recent advances in biodegradation research and molecular biology have shown that natural microorganisms and genetically modified bacterial strains could be used to decontaminate PCB-containing sites. The aim of this review is to summarize the chemistry, environmental fate and toxicological effects of PCBs and to evaluate the currently available technologies for nondisruptive elimination of PCBs from the environment.
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ABSTRACT: An on-going study in the Houston Ship Channel (HSC) characterized polychlorinated biphenyl (PCB) levels in sediment, water, and tissue in 2002-2003 and 2008. The observed PCB concentration ranges in all media were higher than those measured in other PCB-impacted water bodies in the world, with the highest concentrations occurring within the industrialized segments. Contrary to polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/PCDF) observations, the PCB concentrations in the dissolved phase were greater than the suspended phase. Possible explanations include passage of colloids, competition for adsorption sites from other hydrophobic contaminants, and continuing current sources. The PCB homologue distributions were similar for suspended water, sediment and tissue with the profile normalized around penta-chlorobiphenyls, while the dissolved phase profile normalized around tri-chlorobiphenyls. PCB-209 was detected in the suspended water phase and in sediment (10%) prompting interest into its sources to the HSC since PCB-209 was present only in rare commercial mixtures and is a byproduct in very few manufacturing processes. Inter-media analyses showed a significant correlation and transfer of PCBs. Dioxin-like PCBs contributed significant toxicity to total equivalent in tissue (33%), while they were insignificant in water (<10%) and sediment (<5%). The PCB concentrations over time showed a significant decrease in suspended water, sediment and tissue, while dissolved water concentrations showed insignificant change. The homolog distribution, however, showed a significant change in dissolved water and fish, a minor change in sediment and insignificant change in suspended water. Furthermore, an analysis for six representative congeners showed that they were accurate in predicting the total PCB concentrations and could be thus used as indicator PCBs.Chemosphere 06/2010; 80(2):100-12. · 3.14 Impact Factor
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ABSTRACT: A bacterium was screened from the sediment of the southern Yellow Sea, which could degrade PCBs as the sole carbon source and was named strain Q. The identification and degradation characteristics of strain Q were studied. The effect and influencing factors of application of strain Q to remedy PCBs-contaminated soil through simulated experiments were also studied in lab. The results showed that the strain was initially identified as the Streptomyces. With the increase of PCBs concentration, the growth of strain Q was inhibited and the removal rate of the PCBs also decreased. The measures such as adding organic nitrogen source, one disturbance every two days, intermediate temperate and high salinity were all conducive to the bioremediation of PCBs-contaminated soil by strain Q. The removal rate of PCBs was higher than forty percent after twenty days. The strain Q was also proved to be halophilic bacterium, which was more suitable for the remediation of PCBs-contaminated soil with high salinity.01/2011;
- Clinical Neurophysiology - CLIN NEUROPHYSIOL. 01/2010; 121.