| 中国南海大气降水化学特征 |
| 摘要点击 2537 全文点击 1267 投稿时间：2013-06-19 修订日期：2013-08-30 |
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| 中文关键词 南海 化学组成 大气降水 来源 后向轨迹 |
| 英文关键词 South China Sea chemical composition precipitation source backward trajectory |
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| 中文摘要 |
| 利用中国科学院南海海洋研究所“实验3”号船南海海洋断面科学考察2012年夏季航次进行大气降水采样，测定样品pH值和主要阴阳离子浓度，结合TrajStat 软件模拟后向气团轨迹，分析南海夏季大气降水离子化学特征及来源. 结果表明，夏季降水pH平均值为6.3，最小值为5.6. 阴阳离子浓度顺序均分别表现为Cl- > SO42- >NO3-和Na+ >Mg2+ >Ca2+ >K+，Cl-和Na+是主要的阴离子和阳离子，浓度平均值分别为2637.5 μeq·L-1和2095.5 μeq·L-1，表现出了海洋性大气降水的特征. 7种离子间均表现出良好的线性相关关系，相关系数在0.9以上，说明它们可能具有统一来源；NO3-与其他离子的相关系数相对较低，可能NO3-具有相对复杂的来源；Ca2+和K+还可能跟南海珊瑚环境有关. 本研究的6个站位后向轨迹显示，水汽气团来源于正南或西南方向，未经过大陆上空，因此本研究中南海夏季大气降水的离子来源受人为影响可以忽略. |
| 英文摘要 |
| Rainwater samples were collected in the summer on "Shiyan 3" during the 2012 South China Sea Sectional Scientific Survey. The concentrations of anion and cation, and pH in precipitation were determined and backward trajectories of air mass were simulated to analyze the chemical characteristics of ions and examine the source of ions. The results indicated that the mean pH value of precipitation was 6.3, with 5.6 of minimal value in summer in South China Sea. The order of anion and cation abundance was Cl- >SO42->NO3- and Na+ >Mg2+>Ca2+ >K+. Cl- was the major anion and Na+ was the major cation, with concentrations of 2637.5 μeq·L-1 and 2095.5 μeq·L-1, respectively, showing that they were the characteristics of marine atmospheric precipitation. There was a good linear relationship between each pair of 7 ions, with correlation coefficient above 0.9, suggesting that they may have a common source. However, the correlation coefficients were lower between NO3- and other ions than the others, suggesting that NO3- had more complex sources. The concentrations of Ca2+ and K+ in precipitation may be related to coral environment in South China Sea. The backward trajectories in 6 stations showed that the air mass was from south and southwest of South China Sea, without passing through above the continent. These results suggested that precipitation affected by human ion source can be ignored in summer in South China Sea. |
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