Cyclic organosilicon compounds in ambient air in Guangzhou, Macau and Nanhai, Pearl River Delta

Silicon is present in the Earthʹs atmosphere as a consequence of several processes including the release of Si compounds from anthropogenic sources, but little information is available on airborne Si compounds of anthropogenic origins. In this study ambient air samples from Guangzhou, Macau and Nanhai in the Pearl River Delta, South China were collected by sorbent tubes for the determination of concentrations of volatile organosilicon compounds. Samples were analysed by thermal desorption followed by a GC–MSD technique for compound identification and quantitative analysis. Hexamethylcyclotrisiloxane (D3) and octamethylcyclotetrasilo-xane (D4) were found to be the two dominant organosilicon compounds in the air. In Guangzhou, higher total D3 and D4 concentrations were observed in the industrial area, landfill and waste water treatment plant, while the lowest levels occurred in suburb forest. Two types of linear correlation between D3 and D4 were found in Guangzhou samples, indicating different sources of these organosilicon compounds. Samples in Macau and Nanhai showed different D3 and D4 relationships from the samples in Guangzhou.