喜马拉雅东段错那地区雪中主要离子年际变化及来源分析

雪中阴阳离子化学记录可以提供关于大气环流、气候和环境变化的信息,喜马拉雅山因其独特的位置和丰富的冰川资源成为研究雪化学的重要地区。本论文基于两个年度(2018年2～3月和2018年12月～2019年1月)在喜马拉雅东段错那地区采集的新雪样品,对雪中主要离子的组成和浓度特征的年际变化进行分析,并结合相关分析法、海盐示踪法和气团后向轨迹法对其来源进行研究。结果表明,错那地区两年度雪中主要阳离子均为Ca²⁺,主要阴离子均为SO^2-₄。受2019年强降雪清除作用的影响,2019年度各离子的浓度明显低于2018年度。错那地区雪中Ca²⁺的含量明显高于喜马拉雅山其他研究区域,可能是由于其海拔较低,受近源陆地粉尘影响较大。离子来源分析结果表明,错那地区雪中离子以局地陆源物质输入为主,部分来源于海洋源(Cl^-、Na⁺)、盐湖矿物风化(Cl^-、Na⁺、K⁺和SO^2-₄)以及人为源(NH⁺₄、NO^-₃、SO^2-₄)。本文可为错那地区生态建设管理及喜马拉雅地区的雪化学和大气环流特征研究提供参考。

Interannual Variations and Source Analysis of Major Ions in Snow from Cona Region, Eastern Himalayas

Major ions in snow can reflect the influence of both atmospheric circulation patterns and the local and regional environment. The Himalayas provides a unique site for understanding atmospheric chemistry and processes. Therefore, to understand the snow chemistry characteristics in the eastern Himalayas, fresh snow samples were collected in Cona region from 2018 to 2019, and major ions, pH and electric conductivity (EC) in fresh snow samples were analyzed to evaluate chemical characteristics and interannual variations. It was found that Ca²⁺ and SO^2-₄ dominated in cations and anions in both 2018 and 2019, respectively. The scavenging effect by heavy snowfall in 2019 led to much lower concentrations of all the ions in 2019 than that in 2018. The concentration of Ca²⁺ in snow was significantly higher in Cona region than that in other areas of Himalayas, indicating the chemistry of snow is greatly influenced by local crustal sources. The correlation analysis, sea-salt tracing methods and air mass backward trajectory clustering analysis demonstrated that the sources of major ions were dominated by local mineral dust, partly from sea-salt aerosol (Cl^- and Na⁺), the weather of mineral salts (Cl^-, Na⁺, K⁺ and SO^2-₄) and anthropogenic sources (NH⁺₄, NO^-₃ and SO^2-₄). The research has certain reference value for the ecological construction of Cona region, and further provides data support for the study of snow chemistry and atmospheric circulation characteristics in the Himalayas.