| 祁连山东段降水的水化学特征及离子来源研究 |
| 摘要点击 3099 全文点击 1412 投稿时间：2016-01-28 修订日期：2016-04-25 |
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| 中文关键词 降水 离子浓度 离子来源 水汽运输 祁连山 |
| 英文关键词 precipitation ion concentration ion source water vapor transportation Qilian Mountains |
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| 中文摘要 |
| 我国西北地区深处内陆，水汽经过长距离输送才可以到达，降水量少且变率大，与季风区降水有很大不同.运用因子分析法、富集因子法、后向轨迹分析法，对2013-05-01～2014-07-11连续收集的降水主要离子进行分析，研究了祁连山东段降水的水化学特征及离子来源.结果表明，祁连山东段降水电导率值的变化范围在29.20～892.00 μS·cm-1之间，pH值在7.02～8.89之间，降水电导率受碱性元素控制，为弱碱性水；降水中阳离子浓度大小排序为Ca2+ >Mg2+ >Na+ >NH4+ >K+，阴离子浓度大小排序为SO42- >Cl- >NO3-，降水为SO42--Ca2+型；降水中K+、Mg2+、Ca2+、NH4+、Cl-、NO3-、SO42-浓度在秋季最高，Na+浓度在冬季最高；降水中的Na+和Cl-主要是海源贡献，但Na+在冬季也有陆源贡献，Cl-在秋季有人为源的影响，K+、Mg2+、Ca2+主要是陆源贡献，Mg2+在冬季有人为源的影响，NO3- 和SO42-主要是人为源的贡献；降水中离子来源的水汽输送有西北、北方、北方+东南、西北+东南、西北+西南、西北+北方+东南路径，其中西北路径是最主要来源.祁连山降水中海源离子通过西风环流和季风环流长距离输送，陆源离子主要由中亚、新疆、蒙古高原的沙漠和戈壁提供，人为源离子主要与各路径上的城市污染和绿洲工、农业生产有关，而降水中离子含量多少受各天气系统的强弱变化影响. |
| 英文摘要 |
| Precipitation of the northwest China is different from that in other regions of China. The vapor reaches this region after long distance transportation with little precipitation, and the ratio of precipitation variation is large. Wushaoling at the east Qilian Mountains is an important divided line of climate in China. The east region of it is affected by South Asia and East Asia monsoon, while the west region of it is influenced by Westerly circulation. So ion combinations in precipitation are complex for the trajectories of water vapor transportation, the natural environments and the development levels of social and economy in different regions. Precipitation samples were collected at Heisongyi located at the east Qilian Mountains. Hydrochemical characteristics and sources of ions were analyzed by factor analysis, Enrichment factor analysis and back trajectory analysis. EC values in precipitation ranged from 29.20 to 892.00 μS·cm-1, which were controlled by alkaline element. The precipitation was weak alkaline with pH values ranging from 7.02 to 8.89. EC values in precipitation were higher in autumn and winter than in spring and summer, opposite to pH values. The type of precipitation was SO42--Ca2+ for the cation concentrations following the order of Ca2+ >Mg2+ >Na+ >NH4+ >K+ and the anion concentrations following the order of SO42- >Cl- >NO3-. The concentrations of K+, Mg2+, Ca2+, NH4+, Cl-, NO3- and SO42- were the highest in autumn, but the peak value of Na+ concentration appeared in winter. As a whole, ion concentrations were higher in autumn and winter than in spring and summer. Enrichment factor indicated that Na+and Cl- mainly came from marine source but Na+ partly originated from crust source in winter and Cl- partly originated from anthropogenic source in winter, and that K+, Mg2+ and Ca2+ mainly came from crust source except that Mg2+ partly originated from anthropogenic source in winter, and that NO3- and SO42- mainly came from anthropogenic source. The trajectories of water vapor transportation from directions of northwest, north, north with southeast, northwest with southeast, northwest with southwest, northwest with north and southeast were ion original sources in precipitation, and the major trajectory came from northwest direction. Among these trajectories of water vapor transportation, that from northwest, north and north with southeast appeared in each season, but that from northwest with southeast appeared in spring and summer, that from northwest with southwest and northwest and north with southeast appeared in summer. Though ions originated from marine transport by Westerly and monsoon, from crust provided by desert and Gobi in central Asia, Xingjiang and Mongolian plateau, and from humanity activity related to cities pollution and industrial and agriculture production of oasis at all trajectories, the concentrations of ions in precipitation were effected by the strong and weak variations of different weather systems. |
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