我国新疆北部积雪中痕量元素的时空分布及污染评估

Spatial and temporal distribution of trace elements in the snow cover and pollution assessment in northern Xinjiang

积雪中记录的痕量元素含量,能很好地评估当地大气污染状况。利用电感耦合等离子体质谱仪(ICP-MS),对2018年1月和3月采自新疆北部的天山北坡、伊犁河谷、塔城地区和阿勒泰地区的积雪样品进行了16种痕量元素测试。结果表明:北疆地区积雪中痕量元素含量的平均值在0.06 ng·g^(-1)(Cd)~1481.1 ng·g^(-1)(Al)之间。时间分布上,消融期多数痕量元素浓度低于积累期、稳定期;Pb、Cr等元素消融期含量高于其他时期,可能与外源输入有关。空间分布上,塔城地区和天山北坡的多数痕量元素含量高出伊犁河谷和阿勒泰地区1~3倍。与其他地区雪冰中痕量元素含量对比,发现新疆北部高出青藏高原北部1~3倍,与受人类活动影响较大的天山乌鲁木齐河源1号冰川相应痕量元素浓度接近,揭示了新疆北部积雪中痕量元素较高的浓度特征。元素富集系数表明,Fe、Be等元素主要来自地壳粉尘,Pb、Cd、Zn、As等元素呈显著富集(EFc>10),受人类排放活动主导。结合后向气团轨迹分析,塔城地区的痕量元素可能受到哈萨克斯坦的影响,阿勒泰地区的痕量元素可能受到中亚、阿尔泰山南缘等地的影响,天山北坡与伊犁河谷主要受新疆本地气团的影响。

Trace elements recorded in snow cover can be a good assessment of local air pollution.Using inductively coupled plasma mass spectrometer(ICP-MS),16 trace elements were detected in snow cover samples collected in January and March 2018 from the northern slope of Tianshan Mountain,Yili River valley,Tacheng region and Altai region in northern Xinjiang.It is shown that the average of trace elements in the snow cover in northern Xinjiang is between 0.06 ng·g^(-1)(Cd)~1481.1 ng·g^(-1)(Al).In terms of time distribution,most trace element concentration during the ablation period is lower than the accumulation period and stable period;and the ablation period content of some elements of Pb,Cr is higher than other periods,which may be related to external input.In terms of spatial distribution,most trace elements in the Tacheng area and the northern slope of Tian⁃shan Mountain are 1~3 times higher than that in the Yili River Valley and Altai region.Compared with the content of trace elements in the snow ice in other regions,it was found that northern Xinjiang is 1~3 times higher than the northern Tibetan Plateau,and the corresponding trace elements concentration is close to the No.1 Glacier of Urumqi River of Tianshan Mountain,which is greatly affected by human activity,revealing the high concentration characteristics of trace elements in the snow in northern Xinjiang.Elemental enrichment coefficient indicates that elements like Fe,Be are mainly from crust dust,and elements like Pb,Cd,Zn,As are significantly enriched(EFc>10),dominated by human emission activity.The backward air mass trajectory shows that trace elements in Tacheng area may be affected by Kazakhstan,and trace elements in Altai area may be affected by Central Asia,the southern edge of Altai Mountains and other places,and the northern slope of Tianshan Mountain and Yili valley are mainly dominated by the local gas mass in Xinjiang.