西宁市夏季周边表层土壤中汞形态的空间分布特征

Spatial Distribution of Mercury Species in the Topsoils of Ambient Areas Surrounding Xining Urban in Summer

利用修正的Tessier连续化学浸提法对青海省西宁市周边地区的土壤中汞形态分布进行了研究。结果表明，西宁市周边地区表层土壤中汞含龄在0．013～0．308mg／kg之间，各采样点间差异较大，表层土壤中汞含量在四部区域较高，东部较低。根据采样点土地利用类型分类，土壤中汞含量呈现出工业园区内土壤汞含量明显高于其他土地利用类型，并且土壤中汞含量由农耕地向道路旁、撂荒地、林地依次递减。土壤中汞的形态以残渣态为主，碳酸盐结合念和溶解态与可交换态含量极低，且各种土地利用类型下的土壤形态汞占总汞的百分比存在差异。土壤总汞、有机质与硫化物结合态汞和残渣态都与TOC含量显著相关，总汞及各形态汞与pH没有明显的相关性。

Hg species in soil were analyzed by modified Tessier sequential extraction method to study their spatial distributions in ambient areas surrounding Xining, Qinghai Province. Results indicated that Hg content in the topsoils surrounding Xining ranged from 0.013 to 0.308 mg/kg with large differences among different sampling sites, which was higher in the western areas and lower in the eastern areas. Based on the functional land type of sampling sites, it was found that the mercury content in the soil of industrial area was significantly higher than those of other areas, and Hg content descended as the descending order of agricultural land, highways, abandoned land and forested land. Hg speciation was dominated by residual form, while the carbonate traction and exchangeable fraction were much lower. The percentage of mercury species in different land types was different between each others. Total mercury, organic and sulfide-bounded fraction and residual fraction were found to have a significant correlation with TOC, but no strong correlation was found between total mercury as well as mercury species and pH value.