Levels and source of non-ortho coplanar polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in pond sediments and paddy field soil

Non-ortho chlorine substituted coplanar polychlorinated biphenyl (Co-PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in the sediment samples from reservoir and irrigation ponds, and in a soil from paddy field were analyzed isomer specifically using 13C-labeled their respective internal standards and a selected ion monitoring method of high resolution gas chromatograph mass spectrometry (GC/MS). These compounds were found in all samples analyzed. The average concentrations of the total Co-PCBs, PCDDs and PCDFs in the 10 sediment samples taken from reservoir ponds were 83, 3900 and 360 pg/g of dry weight, respectively, those in 7 sediments from irrigation ponds were 96, 3200, and 96 pg/g, those in 10 sediments from an irrigation pond near an incineration facility were 260, 10,000, and 290 pg/g, respectively, and those in the soil from a paddy field near an incineration facility were 120, 96,000, and 4700 pg/g, respectively. The concentrations of Co-PCBs, PCDDs and PCDFs in the sediments of the irrigation pond were higher than those in the sediments of any other ponds. On the other hand, the concentrations of PCDDs in the paddy field soil were much higher than those in any other sediment samples, but the Co-PCB concentration was about one-half of those in the sediments of an irrigation pond near the facility. These findings suggest that one of pollution sources of Co-PCBs as well as PCDDs and PCDFs, was municipal waste incineration, but that Co-PCB pollution was not caused by herbicides applied in the past.