Du Wenjiao, Hong Zhenyu, Chen Yanting, Deng Junjun, Chen Jinsheng, Xu Lingling, Hong Youwei, Xiao Hang
Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, People's Republic of China.
Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen, 361021, People's Republic of China.
Environ Sci Pollut Res Int. 2017 Mar;24(9):8399-8410. doi: 10.1007/s11356-017-8498-3. Epub 2017 Feb 9.
To investigate the characteristics and sources of low molecular weight (LMW) organic acids in wet precipitation at a coastal city, Xiamen, a total of 313 rainwater samples were collected at seven different functional areas from September 2012 to August 2013. Spatiotemporal characteristics of LMW organic acids as well as pH and electrical conductivity were analyzed. Meanwhile, air mass clusters in different seasons and the positive matrix factorization (PMF) source apportion model were comprehensively used to identify the sources of organic acids. In conclusion, the volume-weighted mean (VWM) concentration of formic (3.20 μmol/L), acetic (1.84 μmol/L), lactic (0.44 μmol/L), and oxalic acid (0.53 μmol/L) were obtained, which jointly contributed to 4.33% of the total free acidity (TFA). At the same time, the highest wet deposition flux of LMW organic acids and contribution of that to TFA were achieved at the forest protection area during growing season in Xiamen. In addition, biogenic emissions (77.12%), sea salts (13.77%), regional agriculture activities (3.92%), soil emissions (2.56%), biomass burning (1.47%), and secondary aerosols (1.15%) were determined as the source of LMW organic acids. Besides, the dominancy of biomass burning via long-range transport in non-growing season (NGS) and the contribution of biogenic emission in growing season (GS) were recognized. Finally, the considerable influence of sea salts on the LMW organic acids (13.77%) in Xiamen was quantified, especially for oxalic acid.
为研究沿海城市厦门湿沉降中低分子量（LMW）有机酸的特征和来源，于2012年9月至2013年8月在七个不同功能区共采集了313个雨水样本。分析了LMW有机酸的时空特征以及pH值和电导率。同时，综合利用不同季节的气团聚类和正定矩阵因子分解（PMF）源解析模型来识别有机酸的来源。结果表明，甲酸（3.20 μmol/L）、乙酸（1.84 μmol/L）、乳酸（0.44 μmol/L）和草酸（0.53 μmol/L）的体积加权平均（VWM）浓度，它们共同占总游离酸度（TFA）的4.33%。同时，厦门生长季森林保护区的LMW有机酸湿沉降通量最高，对TFA的贡献也最大。此外，确定生物源排放（77.12%）、海盐（13.77%）、区域农业活动（3.92%）、土壤排放（2.56%）、生物质燃烧（1.47%）和二次气溶胶（1.15%）为LMW有机酸的来源。此外，认识到非生长季（NGS）生物质燃烧通过长距离传输的主导作用以及生长季（GS）生物源排放的贡献。最后，量化了海盐对厦门LMW有机酸（13.77%）的显著影响，尤其是对草酸的影响。
