Ion Composition of Fog Water and Its Relation to A

Authors: Jun Yang YuJing Xie ChunE Shi DuanYang Liu ShengJie Niu ZiHua Li

Publish Date: 2011/06/07

Volume: 169, Issue: 5-6, Pages: 1037-1052

PDF Link

Abstract

Intensive field experiments focused on fog chemistry were carried out in the northern suburb of Nanjing during the winters of 2006 and 2007 Thirtyseven fog water samples were collected in nine fog events Based on the chemical analysis results of those samples and the simultaneous measurements of air pollution gases and atmospheric aerosols the chemical characteristics of fog water and their relations with air pollutants during fog evolution were investigated The results revealed an average total inorganic ionic concentration TIC = 2118 meq/L and the top three ion concentrations were those of SO4 2− NH4 + and Ca2+ average concentrations 699 595 377 meq/L respectively However the average pH value of fog water was 585 which is attributable to neutralization by basic ions NH4 + and Ca2+ The average TIC value of fog water measured in advection–radiation fog was around 22 times that in radiation fog and the most abundant cation was NH4 + in advection–radiation fog and Ca2+ in radiation fog In dense fog episodes the concentration variations of primary inorganic pollution gases showed a “V”shaped pattern while those of volatile organic compounds VOCs displayed a “Λ”shaped pattern The dense fog acted as both the source and sink of atmospheric aerosol particles fog processes enhanced particle formation leading to the phenomenon that the aerosol concentration after fog dissipation was higher than that before the fog and at the same time mass concentration of PM10 reached the lowest value in the late stage of extremely dense fog episodes because of the progressive accumulated effect of wet deposition of large fog droplets Both air pollution gases and aerosols loading controlled the ion compositions of fog water The Ca2+ in fog water originated from airborne particles while SO4 2− and NH4 + were from both heterogeneous production and soluble particulate speciesWe wish to thank Bin Zhu GuoZheng Zhang ShuXian Fan JunLin An LiLi Tang WeiWei Wang Jing Wang and JiaDe Yan for their help in the field observations and chemical analyses of fog water and aerosol samples This material is based on work supported jointly by the Key Project of Natural Science Foundation of Jiangsu Province under Grant No BK2007727 the Special Fund of Industrial Meteorology Research for Public Welfare of China under Grant No GYHYQX200906012 and GYHYQX200706026 the National Natural Science Foundation of China under Grant No40775010 and the Key Basic Research Project of Natural Science of Jiangsu Provincial Colleges and Universities under Grant No 06KJA17021

Keywords: