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: It has been proposed that the accumulation of PCBs by aquatic organisms is a physicochemical process that is governed by the equilibrium partitioning of PCBs between the organisms and the ambient water. This approach focuses primarily on the hydrophobicity of PCBs, while neglecting the biological impacts of PCB accumulation and possible differences in species-specific response. Furthermore, it does not reflect the complex mechanistic aspects of PCB accumulation. Current modeling, while focusing on accumulation via contaminated food, has been for large lake systems and is not appropriate for lower trophic organism interactions. The objective of this research was to evaluate the ecotoxicological fate of PCBs in a laboratory stream system and to determine if species-specific differences in the accumulation and toxic effects of PCBs existed. Bench scale experiments were conducted to determine kinetic and equilibrium parameters measuring algal uptake of PCB, and these results were used to explain the periphytic response to low level PCB exposure in the laboratory stream system. The results revealed that the accumulation rate, accumulation capacity and toxicity of PCBs differed for the species tested. The observation of PCB fate in the laboratory stream system indicated that PCB volatilization, sediment adsorption and periphyton bioaccumulation were the major pathways of PCB fate. The periphytic biolayer was the significant sink for PCB concentration. The accumulation capacity of periphytic biolayer to PCBs was one order of magnitude greater than that of sediments on a TOC basis. Comparison of the experimental data with model predictions illustrates that equilibrium partitioning models are not very accurate for predicting the accumulation of hydrophobic chemicals by low trophic biota.Water Research 01/1999; · 4.66 Impact Factor
- Bulletin of Environmental Contamination and Toxicology 12/1993; 51(5):651-6. · 1.11 Impact Factor
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ABSTRACT: The effect of yeast extract and its less complex substituents on the rate of aerobic dechlorination of 2-chlorobenzoic acid (2-ClBZOH) and 2,5-dichlorobenzoic acid (2,5-Cl2BZOH) by Pseudomonas sp. CPE2 strain, and of 3-chlorobenzoic acid (3-ClBZOH), 4-chlorobenzoic acid (4-ClBZOH) and 3,4-dichlorobenzoic acid (3,4-Cl2BZOH) by Alcaligenes sp. CPE3 strain were investigated. Yeast extract at 50 mg/l increased the average dechlorination rate of 200 mg/l of 4-ClBZOH, 2,5-Cl2BZOH, 3,4-Cl2BZOH, 3-ClBZOH and 2-ClBZOH by about 75%, 70%, 55%, 7%, and 1%, respectively. However, in the presence of yeast extract the specific dechlorination activity of CPE2 and CPE3 cells (per unit biomass) was always lower than without yeast extract, although it increased significantly during the exponential growth phase. When a mixed vitamin solution or a mixed trace element solution was used instead of yeast extract the rate of 4-ClBZOH dechlorination increased by 30%-35%, whereas the rate of 2,5-Cl2BZOH and 3,4-Cl2BZOH dechlorination increased by only 2%-10%. The presence of vitamins or trace elements also resulted in a specific dechlorination activity that was generally higher than that observed for the same cells grown solely on chlorobenzoic acid. The results of this work indicate that yeast extract, a complex mixture of readily oxidizable carbon sources, vitamins, and trace elements, enhances the growth and the dechlorination activity of CPE2 and CPE3 cells, thus resulting in an overall increase in the rate of chlorobenzoic acid utilization and dechlorination.Applied Microbiology and Biotechnology 05/1995; 43(1):171-7. · 3.81 Impact Factor