Influence of gaseous and particulate species on neutralization processes of polar aerosol and snow——A case study from Ny-?lesund  

作　　者：Roseline C.Thakur Meloth Thamban 

机构地区：[1]ESSO-National Centre for Antarctic and Ocean Research [2]Institute of Atmospheric and Earth System Research,University of Helsinki

出　　处：《Journal of Environmental Sciences》2019年第2期12-25,共14页环境科学学报（英文版）

基　　金：National Centre for Antarctic and Ocean Research,Goa,for encouragement and the Ministry of Earth Sciences,Government of India for financial support on the project (Mo ES/P.O.(Seismo) 3(44)/2013)

摘　　要：The inter-conversion of nitrogen and sulfur species between the gas and particulate phases and their interaction with alkaline species influences the acidity of the aerosols and surface snow. To better understand these processes, a short field campaign was undertaken in Ny-?lesund,Svalbard, during 13th April 2012 to 24th April 2012. Air measurements were carried out through a particulate sampler equipped with denuders and filter packs for simultaneous collection of trace gases(HNO_3, NO_2, SO_2 and reactive nitrogen compounds) and aerosols, with daily collection of snow samples. Ionic composition of the samples was analyzed using ion chromatography technique. The results suggested that nitrate-rich aerosols are formed when PAN(peroxy acetyl nitrate) disassociates to form NO_2 and HNO_3 which further hydrolyzes to form pNO_3^-(particulate nitrate). This resulted in a high contribution of pNO_3^-(62%) to the total nitrogen budget over the study area. The acidity of the aerosols and snow evaluated through cation/anion ratio(C/A)indicated alkaline conditions with C/A > 2. The bicarbonates/carbonates of Mg^(2+) played an important role in neutralization processes of surface snow while the role of NH_3 was dominant in aerosol neutralization processes. Such neutralization processes can increase the aerosol hygroscopicity causing warming. Chloride depletion in the snow was significant as compared to the aerosols, indicating two important processes, scavenging of coarse sea salt by the snow and gaseous adsorption of SO_2 on the snow surface. However, a more systematic and long term study is required for a better understanding of the neutralization processes and chemical interconversions.The inter-conversion of nitrogen and sulfur species between the gas and particulate phases and their interaction with alkaline species influences the acidity of the aerosols and surface snow. To better understand these processes, a short field campaign was undertaken in Ny-?lesund,Svalbard, during 13th April 2012 to 24th April 2012. Air measurements were carried out through a particulate sampler equipped with denuders and filter packs for simultaneous collection of trace gases(HNO_3, NO_2, SO_2 and reactive nitrogen compounds) and aerosols, with daily collection of snow samples. Ionic composition of the samples was analyzed using ion chromatography technique. The results suggested that nitrate-rich aerosols are formed when PAN(peroxy acetyl nitrate) disassociates to form NO_2 and HNO_3 which further hydrolyzes to form pNO_3^-(particulate nitrate). This resulted in a high contribution of pNO_3^-(62%) to the total nitrogen budget over the study area. The acidity of the aerosols and snow evaluated through cation/anion ratio(C/A)indicated alkaline conditions with C/A > 2. The bicarbonates/carbonates of Mg^(2+) played an important role in neutralization processes of surface snow while the role of NH_3 was dominant in aerosol neutralization processes. Such neutralization processes can increase the aerosol hygroscopicity causing warming. Chloride depletion in the snow was significant as compared to the aerosols, indicating two important processes, scavenging of coarse sea salt by the snow and gaseous adsorption of SO_2 on the snow surface. However, a more systematic and long term study is required for a better understanding of the neutralization processes and chemical interconversions.

关 键 词：PARTICULATE AEROSOL SCAVENGING NEUTRALIZATION ARCTIC 

分 类 号：X[环境科学与工程]