Gas chromatographic analysis of polychlorinated biphenyls in compost samples from different origin.

Depending on the origin, the compost produced may contain not only nutrients but also pollutants, such as heavy metals and persistent organic pollutants. It is very important to determine them in soil-improving substances, because persistent organic pollutants show environmental toxic, cancerogenic, mutagenic effects and do not decompose for a long time. The aim of this study was to determine seven polychlorinated biphenyls concentrations in different kinds of composts produced in Lithuania and to evaluate the appliance of these composts in agricultural land. First, before routine analysis was done a gas chromatography with electron-capture detector method was developed. In this study 145 samples of green waste, sewage sludge, cattle manure, food waste, mixed municipal waste, digestate and composts made from mixed municipal waste after mechanical-biological treatment were analysed. Obtained results show that 28% of investigated cattle manure composts (CMCs) and 10.5% of food waste composts (FWCs) were free from polychlorinated biphenyls. Other kinds of composts investigated in this study (green waste compost (GWC), sewage sludge compost (SSC), mixed municipal waste compost (MMWC), mixed municipal waste compost after mechanical biological treatment (MMWCABMT) and digestate (DIG)) were contaminated 100% with polychlorinated biphenyls. Despite the fact that polychlorinated biphenyls were forbidden 25 years ago, their concentration varied from 2.70 to 163.7 µg kg-1 in different kinds of composts produced in Lithuania. According to get an increasing average amount of Σ7 polychlorinated biphenyls, Lithuanian composts were distributed as follows CMC > GWC > DIG > FWC > SSC > MMWCABMT > MMWC.