Extractability of polychlorinated biphenyls from complex organic matrices and assessing their fate in simulated ultraviolet environment

PCBs are synthetic polychlorinated biphenyl compounds that have found numerous industrial applications. Some of the properties that provide stability to the compounds during usage are the properties responsible for the persistence of the chemicals in the environment. Accidental spills and discharge of industrial effluent have resulted in wide contamination of marine sediments. PCBs available by or from marine sediment can be accessed by marine organisms and passed into human beings. These compounds have been shown to evoke toxic responses in a number of animal species.;There is a need for studying availability of hydrophobic contaminants from organic matrices because of the contaminant strong sorptive nature. The Accelerated Solvent Extraction (ASE), Soxhlet Extraction (SE) and Thermal Extraction (TE) results showed that PCB recovery from spiked organic matrix depends on the type and molecular weight of congener as well as the nature of matrix. The PCB extractability from a spiked matrix is highly sensitive to carbon content and layered structure of the matrix. For some selected PCB congeners, ortho-substituted chlorine did influence the PCB recovery from graphite matrix. TE results of PCB sorbed organic matrix suggests the existence of deep energy traps that play a vital role in the complete recovery of the contaminant.;The fate of PCB congeners in natural environment was studied by simulated UV conditions. Photodegradation of selected PCB congeners was shown to follow dechlorination pathway. Photodegradation of PCBs obeyed pseudofirst-order kinetics in simulated UV light. The rate of photodechlorination of lower chlorinated PCBs was found to be faster in di-ortho-chloro substituted than mono-ortho-chloro substituted than no ortho-chloro substituted PCB congener. The rate of photodechlorination of higher chlorinated PCBs was found to depend on the number and position of chlorine substituents in the PCB congener.