寒旱区草原湖泊沉积物重金属地球化学基线构建——以达里诺尔湖为例

为了科学识别寒旱区典型草原湖泊——达里诺尔湖的沉积物重金属累积状况，在调查表层及柱状沉积物重金属含量的基础上，采用多种统计学方法构建了沉积物重金属地球化学基线，并针对构建结果进行了多方面比较分析.结果表明，Cr、Ni、Cu、Zn、As、Cd、Hg、Pb在表层及柱状沉积物中均呈正态分布或对数正态分布，其中，柱状沉积物中的重金属分布较表层更为集中，且As、Cd、Hg在近表层呈现较明显的增长趋势，表明存在一定的表层富集；使用参考元素法、相对累积频率法和迭代2倍标准差法构建的表层、柱状沉积物重金属基线值之间无显著差异（P<0.05），综合考虑科学性，适用性，简便性，人为误差性等方面，可优先选取迭代2倍标准差法进行元素基线构建；研究构建的达里诺尔湖沉积物重金属基线值与所在区域的大尺度土壤背景值相比存在差异，且表层与柱状沉积物基线值也存在差异，考虑到达里诺尔湖流域人为干扰极小，使用研究区域的表层沉积物开展基线值构建，可为识别湖泊当前重金属富集状况和生态风险提供更为科学和准确的参考依据.研究结果可为类似的寒旱区草原湖泊沉积物重金属基线值构建提供理论依据.

Geochemical baseline establishment in grassland-type lake sediments in cold-arid regions: A case study in Dalinuoer Lake,China

In order to scientifically identify the accumulation of heavy metals in the sediments of Dalinuoer Lake, a typical grassland-type lake in cold-arid regions, the content of heavy metals in surface and core sediments were investigated, the geochemical baselines of heavy metals in the sediments were constructed by various statistical methods, and different baseline results were comparatively analyzed from many aspects. The results showed that: the 8 metals including Cr, Ni, Cu, Zn, As, Cd, Hg, and Pb were distributed normally or log-normally in the surface and core sediments of Dalinuoer Lake, and the metal distributions in the core sediments were more concentrated than those in the surface sediments. The vertical distributions of As, Cd, Hg showed obvious increasing trends in the near surface layer, indicating a certain degree of enrichment. Three statistical methods including the reference element method, the relative cumulative frequency method and the iterative 2times standard deviation method were used to calculated the heavy metal baselines and there were no significant differences (P<0.05) among the baselines obtained by the above methods both in surface sediment and in core sediment. Considering scientificity,applicability, simplicity, and personal error, the iterative 2 times standard deviation method could be preferred to construct element baselines. The constructed geochemical baselines of heavy metals in Dalinuoer Lake sediments were different from the soil background values of heavy metals in large-scale regions, and the heavy metal baselines in surface sediment were also different from those in core sediment. Considering few human interference in Dalinuoer Lake Basin, the metal baselines of surface sediment were more useful for scientific and accurate identification in the current accumulation and ecological risks of heavy metals in the lake. The results could provide the important theoretical basis in constructing the metal baselines in similar grassland-type lake sediments in cold-arid regions.