北疆积雪中溶解性砷和汞的空间分布特征及来源分析

为了解北疆积雪中砷（As）和汞（Hg）的空间分布特征及来源，基于2018年1月在北疆地区58个采样点采集的积雪样品，采用原子荧光光谱法测定积雪中溶解性砷和汞的含量，用反距离加权插值法分析空间分布特征，并利用后向轨迹模型探讨了其来源。结果表明：积雪中溶解性砷和汞的浓度分别在0.21~2.69 μg?L^-1和5.32~64.09 ng?L^-1，均低于地表水I类水质标准限值，说明积雪中砷和汞元素污染较轻。反距离加权插值法分析表明，积雪中砷和汞污染物的空间分布存在差异性，其中准噶尔盆地和天山北坡地区的浓度分布较高。结合后向轨迹聚类分析结果，推断积雪中砷和汞污染物主要来自局地活动，周边国家气团远距离传输所产生的影响较小。研究结果可为评估北疆生态环境质量及区域污染防治提供科学支持。

Spatial distribution characteristics and possible sources of dissolved arsenic and mercury in the snow pack of northern Xinjiang

Snow is an important environmental medium and can be used to reflect regional characteristics and to trace sources of air pollution. To understand the spatial distribution and possible sources of arsenic （As） and mercury （Hg） in snow pack， snow pack samples were collected in 58 sample sites from the northern Xinjiang， and dissolved As and Hg concentrations were analyzed using an atomic fluorescence spectroscopy. The spatial distribution pattern was investigated by inverse distance weighted interpolation algorithm， and the possible sources of snow pack As and Hg were tracked by using backward trajectory model. The results indicate that the concentrations of As and Hg were within a range of 0.21 to 2.69 μg?L^-1 and 5.32 to 64.09 ng?L^-1， respectively. The average concentrations of the dissolved As and Hg in the snow samples were （0.70±0.46） μg?L^-1 and （15.94±10.49） ng?L^-1， respectively. The average concentrations of the dissolved As and Hg are lower than the standard limit of Chinese surface water quality I， indicating that snow pack As and Hg were less polluted. The inverse distance weight analysis shows that snow pack As and Hg had differences patterns in spatial distribution， and the snow pack As and Hg were mainly influenced by the industrial coal combustion and winter heating. Moreover， the higher concentrations of snow pack As and Hg were observed in the Junggar Basin and northern Tianshan slope， due to the domination of heavy industries in the area. The backward trajectory model analysis shows that the regional/local anthropogenic activities and desert sand transport are likely the sources of As and Hg in the snow pack. However， these pollutants in surface snow were less affected by the long-range transport of air pollution. Our study can provide important scientific insights for assessing the quality of remote ecosystems and implementing air pollution control in northern Xinjiang.