Polychlorinated biphenyls in the atmosphere of an urban city: levels, distribution, and emissions.

Polychlorinated biphenyl (PCB) concentrations, profiles, and possible sources were determined in the atmosphere of Guangzhou, the largest city in south China. summation operator PCB concentrations ranged from 160 to 2720 pg/m(3), which is comparable with values found by similar studies in North America, Europe, and Asia. The highest PCB concentrations were found in the old industrial district, suggesting it to be the principal emission source. The most important PCB homologue group was tetra-PCB, followed by tri- and penta-PCB. The PCBs' homologue composition differs from that found in Chinese transformer oils: Chinese PCB products (no. 1 PCB and no. 2 PCB), Aroclor1242, and Aroclor1254. However, it is similar in composition to that found in sediments and soils subjected to arbitrary disposal of used electronic appliances in this region. Our results suggest that volatilization from PCB-contaminated soils in the old urban center may be the major source of PCBs in the atmosphere of Guangzhou. Additional studies will be required to characterize the geochemical cycles of PCBs from the contaminated environmental "hot spots" during the typical subtropical climate conditions in the study regions.