不同酸性气体及相对湿度对海盐氯损耗过程的影响

使用在广州南村站、深圳竹子林站及西涌站的MARGA仪器实测资料,分析了不同酸性气体及相对湿度对海盐氯损耗过程的影响.在分析深圳竹子林站、西涌站的海盐氯损耗中发现,竹子林站氯损耗平均为48.0％,西涌站海盐氯损耗平均为56.9％,氯损耗的峰值一般出现于下午14时.西涌站、竹子林站和广州南村站酸性气体和碱性气体均以HNO2、SO2、NH3为主,但各站点的比例分布不同,西涌站以HNO2最多(42％),SO2(32％)次之；竹子林站以NH3与SO2为主,百分比分别为36％和34％；广州南村站以SO2为主(58％),NH3次之(20％)；而三站HNO3所占比例很小,均为7％.另外,分析了HCl的来源,主要关注了海盐粒子中的NaCl与HNO3反应、NH4Cl的挥发及H2SO4与NaCl的反应这3个来源,发现西涌站与竹子林站HCl和HNO3之间的线性关系较好(R2西涌=0.689,R2竹子林=0.594),说明西涌站与竹子林站的HCl主要来源于NaCl与HNO3反应过程中Cl被HNO3置换而成；而广州南村站二者线性关系较差(R2南村=0.295),说明还存在其他的损耗机制.在研究相对湿度对氯损耗的影响中发现,相对湿度低时氯损耗更容易发生.

Influence of different acidic gases and relative humidity on the chlorine loss of marine aerosols

In this work, we investigated the influence of various acidic gases and relative humidity on depletion of chloride on sea salt aerosols at three locations in the Pearl River Delta Region using online chemical composition data obtained by MARGA. The three locations include Nancun (NC) in Guangzhou, Xichong (XC) and Zhuzilin (ZZL) in Shenzhen. Chloride depletion reached an average of 48.0% at ZZL and 56.9% at XC, typically peaking around 14:00. The major acidic gases were HNO₂ and SO₂ and the major alkaline gas was NH₃ at all three stations, but their proportions differed among the stations. At XC, HNO₂ was the most abundant (42%), followed by SO₂ (32%). At ZZL, NH₃ and SO₂ accounted for 36% and 34%, respectively. At NC, SO₂ dominated (58%), followed by NH₃ (20%), while HNO₂ only accounted for 7%. We further explored the sources of HCl, including the reactions with HNO₃ and H₂SO₄ and the volatilization of NH₄Cl. At XC and ZZL, HCl and HNO₃ showed very good correlation (R²_XC=0.689,R²_ZZL=0.594), suggesting that HCl was primarily from the reaction of HNO₃ with NaCl. At NC in Guangzhou, the two species had a weak correlation (R²_NC=0.295), likely suggesting the presence of other chloride depletion pathways. In addition, we found that the extent of chloride loss was larger under lower relative humidity conditions.