大气沉降对川东北喀斯特河水中Mg、Ca、Sr和Ba的贡献

在受大气粉尘活动强烈影响的岩溶地区,大气输入对岩溶地表河水中的金属元素尤其是溶解态元素的影响还较少评估。选择位于秦岭山地、受大气粉尘活动强烈影响的川东北岩溶地区的诺水河,通过2011年7月至2014年6月河水中Mg、Ca、Sr和Ba等元素含量及其变化,结合当地大气沉降观测结果,分析了河水中这些元素的季节变化与影响因素,特别是大气输入对河水中这些金属元素的贡献。结果显示:(1)河水中Mg、Ca、Sr和Ba四种元素显示出明显的季节变化,大气降水稀释作用导致夏季河水中元素浓度值偏低,冬季稀释作用的减弱和粉尘活动加强可能导致河水中元素浓度值偏高;(2)河水中Mg、Ca、Sr和Ba四种元素来源于大气沉降的比例分别是3.1%、7.2%、21.3%和34.8%。这表明在川东北地区,大气沉降对喀斯特河水中部分金属元素如Sr和Ba存在显著影响。

Contribution and Significance of Atmospheric Deposition to Mg, Ca, Sr and Ba in Karst River Water in Northeast Sichuan Province

In karst areas where it was strongly affected by atmospheric dust activity, the impact of atmospheric inputs on metal elements, especially those in dissolved phase in surface river water has seldom been evaluated. The Nuoshui River located in the Qinling Mountains in Northeastern Sichuan runs through a karst area was intensively affected by the atmospheric dust activity and therefore was selected to investigate the elements Mg, Ca, Sr, and Ba in river water, and in particular, their inputs from atmospheric deposition during the period from July 2011 to June 2014. The results show that: (1) The four elements Mg, Ca, Sr and Ba in river water illustrated notable seasonal variations with higher values occurring in winters and lower values in summers. Heavy rainfall in summers is inferred to be responsible for the lower concentrations of these metals in the river water. Relatively less dilution by precipitation and strengthening of atmospheric dust activity in winters may have contributed to the higher concentrations in river water. (2) The proportions of Mg, Ca, Sr, and Ba derived from atmospheric deposition were 3.1%, 7.2%, 21.3%, and 34.8%, respectively. This indicates that in Northeast Sichuan, an area intensively influenced by atmospheric dust activity, atmospheric deposition has a significant influence on some metal elements such as Sr and Ba in karst river water.