Sources of γ-HCH in Chinese air at near-surface level and deposited to Chinese soil

CanMETOP model was employed to assess the contributions to γ-HCH in Chinese air and soil from four major γ-HCH residual regions, including India, the former Soviet Union (FSU), Europe (excluding the FSU), and China itself in 2005. Modeled annual average air concentrations of γ-HCH at 1.5 m height above ground surface ranged for 10~100 pg/m³ in eastern region, and 1~10 pg/m³ in western region of China. The former was mainly due to Chinese source (30% 80%), while the major of the later was attributable to Indian source (> 50%). The European and FSU sources both mostly contributed to the Chinese northwestern region (10%). The contributions of deposition in China were also different in different area. Chinese source dominated the deposition of γ-HCH in the northeastern area (75%), while Indian source made the largest contribution in northwestern (63%) and southern (67%) areas of China. For whole China, annual total deposition of γ-HCH in 2005 was 691 t, among which, 55.1% was from India, 31.6% was from China, 3.6% was from Europe, and 2.5% was from the FSU.