Heavy metal geochemistry characteristics of cryoconite in glaciers in Western China
Heavy metal geochemistry characteristics of cryoconite in glaciers in Western China
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发表时间：
2015
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通讯作者：
LI Quan-lia
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作者：
LI Quan-lia
本文测定了中国西部四条典型冰川中冷石的粒度、总有机碳含量和十种重金属元素(Sc、V、Cr、Ni、Cu、Co、As、Pb、Cd、Zn)的含量。分析了重金属在冻石中的分布和富集规律，以及重金属与冻石粒度、粘粒含量和总有机碳的相关性。结果表明，冻石的粒度范围为0.69~995.6μm，平均为20μm，其中七一冰川重金属总量最高(507.61±22.53)mg/kg，木扎特冰川重金属总量最低(40.06±12.42)mg/kg。结果表明，冷石中重金属含量与晶粒度呈负相关，说明晶粒度越小，其重金属含量越高。总有机碳含量与粘土含量呈正相关，但相关性不显著，表明有限数量的粘土对有机碳和重金属的吸附较弱。以Sc为参照元素，以青藏高原表土为参比水平，计算了冰川中冷石对重金属的富集度。除MUZART冰川冻石中Cd的富集率为~10外，其他重金属的富集率一般在1左右，基本在3以下，表明冻石中的重金属主要来源于岩石风化残留物和土壤粉尘。
In this study, the grain size, total organic carbon content and ten heavy metals(Sc, V, Cr, Ni, Cu, Co, As, Pb, Cd and Zn) contents of cryoconite in four typical glaciers in western China were measured. Distribution and enrichment pattern of heavy metals in the cryoconite as well as correlation among heavy metals and cryoconite grain size, clay content and total organic carbon were analyzed. We found that the cryoconite grain size ranges between 0.69–995.6 μm with an average of 20 μm. The Qiyi glacier shows the highest total heavy metal content(507.61±22.53) mg/kg and the Muzart glacier shows the lowest total heavy metal of content(40.06±12.42) mg/kg. The heavy metal content in the cryoconite was found to be negatively correlated with the grain size, indicating that the heavy metal content is higher at smaller cryoconite grain size. The total organic carbon is positively but not significantly related with clay content, indicating that the limited amount of clay in the cryoconite shows weak adsorption towards organic carbon and heavy metals. The heavy metal enrichment factors for cryoconite in glaciers were calculated by using Sc as the reference element and by considering the Tibetan plateau topsoil as the reference level. Except for Cd in the Muzart glacier cryoconite, which shows an enrichment factor of ~10, the enrichment factors for all other heavy metals in cryoconite from these glaciers were found to be generally around 1 and basically below 3, indicating that the heavy metals in cryoconite mainly originate from rock weathering residue and soil dust.