西安市黑河上游水源地大气降水离子特征及来源分析

摘要

于2014年9月-2015年8月期间,对西安黑河上游水源地云龙沟站点大气降水样品进行采集,采用相关性分析和富集因子法对样品的离子特征及来源进行分析.黑河上游地区大气降水中主要阳离子为Ca2+和NH4+,主要阴离子为SO42-和NO3-,与国内大多数城市地区降水的离子特征相似.除NH4+和F-外,其他离子浓度的季节变化特征为冬季>春季>夏季>秋季,表明离子浓度除了与发生源有关外,降雨量也是重要影响因素.离子间的相关性分析及离子来源的计算表明,SO42-与NO3-相关性很强,且均主要受人为因素的影响;Na+与Cl-相关性很强且均来自海洋源;地壳元素Ca2+、Mg2+和K+两两间相关性也较高.所有离子的来源贡献结果显示:人为活动贡献率为52.90%,地壳来源和海洋来源贡献率分别为38.43%和8.67%.%Samples of atmospheric precipitation were collected during the period from September 2014 to August 2015 at the Yunlonggou Station in the water source region of the upper reaches of the Heihe River in Xi′an for analysis of ions the samples contained.Then characteristics and sources of the ions were explored through correlation analysis and with the enrichment factor method.The main cations contained in the samples were Ca2+ and NH4+ and the main anions SO42-and NO3-, which was similar to the characteristics of the precipitations in most urban areas of China.All the ions, except for NH4+ and F-, varied in concentration with the season, in an order of winter > spring > summer > autumn, which indicates that concentrations of the ions were related to their origins and amount of the precipitation as well.Correlation analysis of the ions and their origins indicates the correlation between SO42-and NO3-was very high and both were affected by human factors;the correlation between Na+ and Cl-was very high, too, because they are from the same source, i.e.sea;and so were the correlations between Ca2+, Mg2+ and K+ for they are all earth crust elements.Source analysis of the ions shows that human activities contribute 52.90%, more than half, of the ions in the precipitation, the earth crust does 38.43% and the oceans do 8.67%.