Low-molecular-weight organic acids in the Tibetan Plateau: Results from one-year of precipitation samples at the SET station
Low-molecular-weight organic acids in the Tibetan Plateau: Results from one-year of precipitation samples at the SET station
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DOI：
10.1016/j.atmosenv.2013.12.028
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发表时间：
2014-04
影响因子：
5
通讯作者：
B. Liu;Shi-chang Kang;Jimin Sun;Xin Wan;Yongjie Wang;Shao-peng Gao;Z. Cong
中科院分区：
文献类型：
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作者：
B. Liu;Shi-chang Kang;Jimin Sun;Xin Wan;Yongjie Wang;Shao-peng Gao;Z. Cong
青藏高原南部 (TP) 的背景大气有机酸：甲酸 (F)、乙酸 (A)、草酸 (O) 和甲磺酸 (MSA，缩写为 M)，是通过在偏远高山站进行的一年降水测量来确定的。这些有机酸以草酸（体积加权平均值为 0.51 μmol l−1）/甲酸（0.38 μmol l−1）为主，其次是乙酸（0.20 μmol l−1）和 MSA（0.10 μmol l−1）。它们的水平与其他偏远地区的水平相当，但低于人口稠密地区的水平。南亚季风是造成有机酸浓度季节性变化的原因：季风季节MSA相对丰富，其他有机酸浓度较低（通过稀释效应），而非季风季节则相反。通过主成分分析结合相应的示踪剂确定了不同的来源。这些是人为干扰（解释了 41% 的差异）、海洋排放（24%）和生物排放（16%）。此外，季风与非季风样本中F/A、M/(F+A)和O/(F+A)的方差与来源的变化有关。此外，这些化学指标表明，青藏高原上的活跃光化学对于有机酸的产生具有重要意义，从而提高了季风降雨中 M/(F + A) 和 O/(F + A) 的比率。上升的热带湿气中有机化合物的升高意味着对高海拔有机酸的二次形成和亚洲季风的变化具有潜在的意义。
Background atmospheric organic acids: formic (F), acetic (A), oxalic (O), and methanesulfonic (MSA, abbreviated to M) acids in the southern Tibetan Plateau (TP), were determined in one-year of precipitation measurements at a remote alpine station. These organic acids were dominated by oxalic (volume-weighted mean of 0.51 μmol l−1)/formic acid (0.38 μmol l−1), followed by acetic acid (0.20 μmol l−1) and MSA (0.10 μmol l−1). Their levels were comparable with those from other remote sites, while they were lower than those found in populated areas. The South Asian monsoon is responsible for the seasonal variation of organic acid concentration: a relative abundance of MSA and lower concentrations of other organic acids (by the dilution effect) in the monsoon season, while opposite in the non-monsoon season. Diverse sources were identified by principal component analysis combined with the corresponding tracers. These were anthropogenic disturbances (which explain 41% of the variance), marine emission (24%), and biogenic emission (16%). Moreover, the variances of F/A, M/(F + A), and O/(F + A) in monsoonal versus non-monsoonal samples, were involved with the changes of sources. Furthermore, these chemical indexes suggest that active photochemistry over the TP was significant for the production of organic acids and consequently enhanced the ratios of M/(F + A) and O/(F + A) in monsoonal rainfalls. The elevated organic compounds within the ascending tropical moisture imply potential significances for the secondary formation of organic acids in the high-altitude and the changes of the Asian monsoon.