Levels and distribution of organochlorine pesticides in various media in a mega-city, China.

As one of China's great metropolises, Taiyuan is generally recognized to be one of the most polluted cities in the world. It is affected by pollution from heavy industries, and from organochlorine pesticides (OCPs). In this study, we measured the concentrations of OCPs in various environmental media in Taiyuan. We measured the levels of OCPs in 15 soil samples and 34 samples of respirable particulate matter (PM) (17 of PM(2.5) and 17 of PM(10)) from urban areas of Taiyuan. Analysis of the composition ratios of OCP residues revealed that dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) were the predominant compounds in soil, PM(2.5) and PM(10). The total DDT concentrations were 1.8-1.0x10(2)ngg(-1) in soil, 6.5-1.0x10(3)pgm(-3) in PM(2.5), and 8.5-1.5x10(3)pgm(-3) in PM(10). The total HCH concentrations were 1.4-45ngg(-1) in soil, 5.2-8.0x10(2)pgm(-3) in PM(2.5), and 9.6-8.7x10(2)pgm(-3) in PM(10). Furthermore, source analysis indicated that there was new input of OCPs at some sites. Finally, analysis of the individual OCPs revealed that new OCP contamination was the major problem in Taiyuan. This study suggests that measures should be taken to reduce the levels of OCP residues in order to improve the environmental quality in Taiyuan.