Scavenging of carbonyl sulfide precursor in the atmosphere by precipitation

Abstract

Twenty-eight precipitation samples were collected in Beijing during the whole year of 2006-2007 and analyzed for the initial dissolved carbonyl sulfide (COS) (9.4-40.3 ng L -1) and the photochemical production of COS (13.7-146.5 ng L -1) by UV radiation around 365 nm. The concentration of COS precursors) in this study was designated as the COS concentration produced by the UV irradiation (16 fluorescent lamps, 30 W for each) for 2.5 hours. The seasonal variation of COS precursor(s) concentration in the collected precipitation samples showed that the maximum values appeared during the winter and the lowest during the summer. The decrease in the concentration of COS precursors) during a sequential rain event implied that precipitation might scavenge COS precursors) in the atmosphere. The high negative correlation (r = -0.75, p = 0.05) between rainfall intensity and the concentration of COS precursor(s) also revealed that precipitation might act as a sink for atmospheric COS precursor(s). Significant amount of COS preeursor(s) in the atmosphere was also first observed, with high values at night and early morning and the minimum at noon. Copyright 2009 by the American Geophysical Union.