【摘要】 选取位于西北内陆的吉兰泰盐湖盆地为研究对象,按照表层(0—10 cm)、50 cm层(50—60 cm)和100 cm层(100—110 cm)分层土壤取样,系统采集了120个样品,测定了重金属Cr、Hg和As,以及主要化学成分的含量,以地统计学插值绘图揭示了吉兰泰盐湖盆地Cr、Hg和As的空间分布特征,以单因子指数法、内梅罗指数法和潜在生态风险指数法评价解析了盐湖盆地Cr、Hg和As的污染及生态风险状况,以统计相关检验和主成分分析法进行了盐湖盆地Cr、Hg和As的源分析。结果表明:1)盐湖盆地土壤中Cr、Hg、As总体具有相似的空间分布特征,Cr在西北部的巴音乌拉山、乌兰布和沙漠地区和西南台地地区的含量较高,Hg仅在西南低山台地地区、以及东北局部区域的含量较高,As在盐湖附近、东南贺兰山、巴音乌拉山西北部和乌兰布和沙漠地区含量较高;2)基于内蒙古土壤质量背景值,土壤污染分布次序为As>Hg>Cr,其中Hg和As中度污染以上累计比重达到为45%,而Cr仅有7.5%的轻微污染;研究区无清洁土壤,仅有尚清洁土壤占2.5%,开始受到污染和中度污染以上土壤比重为50%和42.5%;土壤潜在风险次序为Hg>As>Cr,Hg整体处于很强生态风险水平;轻微生态风险占到40%,由中度、强度到极强在20%以内,很强生态风险程度略超20%,大部地区处于轻微生态风险状况;3)基于国家土壤环境质量二级标准值,土壤中Cr、Hg、As无论是单因子污染、综合污染,还是潜在生态风险指数均未出现超标区域,不存在Cr、Hg、As污染或潜在生态风险,但相对内蒙古整个地区来说,盐湖盆地Cr、Hg、As含量较高;4)研究区土壤中Cr主要来源于土壤母质形成过程中的自然来源,Hg和As主要来源于工业排放、交通污染源等人类活动,均受到人类活动和自然环境变化的综合影响。更多还原

【Abstract】 The Jilantai Salt Lake Basin in the northwest inland area of China was selected as the study area. A total 120 soil samples from soil surface, 50 and 100 cm depth were collected to test for Cr, Hg, As, and the concentration of the main chemicals. The spatial distribution characteristics of Cr, Hg, and As were identified through geo-statistical interpolation. The pollution degree, pollution distribution, and ecological risk of Cr, Hg, and As were analyzed by a single factor index method, Nemero index method, and a potential ecological risk index. A source analysis of Cr, Hg, and As was performed by a statistical correlation test and a principal component analysis. There were similar spatial distribution characteristics for the concentrations of Cr, Hg, and As in the soils of the Salt Lake Basin. Cr was higher in the Bayinwula mountain area, the Wulanbuhe desert area, and the hilly area of the southwest study area; Hg was higher only in the northeast local area and the hilly area of the southwest study area; and As was higher in near the lake, the Helan mountain area, the Bayinwula mountain area, and the Wulanbuhe desert area than in the other areas. Based on the background value of soil quality for inner Mongolia, the order of soil pollution is As > Hg > Cr, in which Hg and As was at a moderate level of pollution above the cumulative proportion of 45%, but Cr was only at a slight level of pollution at 7.5%. There was no clean soil in the study area; cleaner soil only accounted for 2.5%. The beginning stages of contamination to moderate pollution in the soil are above 50% and 42.5%, respectively. The soil risk order is Hg > As > Cr. Broadly for the study area, Hg was at a very strong ecological risk level. A slight ecological risk accounted for 40%. Moderate to strong risk were within 20%. Most areas were in a slight ecological risk situation. Based on the Chinese national standard value of soil environmental quality and the assessment results from the single factor pollution, comprehensive pollution, and the potential ecological risk index, Cr, Hg, and As in the soil do not appear in a polluted area. Although there is no Cr, Hg, and As pollution or potential ecological risk, the concentration of Cr, Hg, and As in the study area soil from inner Mongolia was higher than that in the other areas. In the study area, Cr may be mainly derived from a natural source of soil parental formation, where Hg and As may be mainly derived from industrial emissions, traffic pollution, and other human-related activities. All the heavy metals are subject to integrated impacts from human activities and changes to the natural environment.更多还原