贵州锁黄仓沼泽土壤重金属含量分布特征及污染评价

贵州锁黄仓湿地公园位于草海湖下游,而草海湖是典型的高原天然淡水湖泊,研究湿地公园沼泽土壤重金属分布特征对该区域的生态环境保护具有重要意义。采集锁黄仓湿地公园中沼泽表层土壤（0-20 cm）,分析其重金属Cr、Ni、Zn、As、Pb的含量、空间分布特征,并采用地质累积指数法和综合污染指数法进行污染评价。结果表明,锁黄仓湿地公园沼泽表层土壤中,Cr、Ni、Zn、As、Pb的含量分别为105. 68 mg·kg-1、70. 97 mg·kg-1、148. 80 mg·kg-1、26. 57 mg·kg-1、53. 69 mg·kg-1,其含量均高于贵州土壤重金属元素背景值。5种土壤重金属含量空间分布,都呈现由锁黄仓湿地南部进水口,向北部出水口整体递增的趋势,Ni和As的含量在湖泊西岸高于东岸,在S20采样点、五孔桥附近形成明显的聚集点;Cr和Pb为东岸高于西岸,在S25~S33采样点、靠近铁路的东岸形成聚集;Zn整体分布相对均匀,没有形成明显聚集点。污染评价结果显示,Ni处于“中度偏重”污染水平,Zn、As、Pb都处于“中度偏轻”污染水平,Cr处于“轻微”污染水平。综上,锁黄仓湿地土壤重金属污染主要是由人为活动所引起,尤其是在北部出水口污染较为严重,由此应加强采矿冶炼污染排放和农药化肥使用的管控措施。

Pollution assessment and distribution characteristics of heavy metal contents in swamp soils in Suohuangcang in Guizhou

Guizhou Suohuangcang Wetland Park is located in the lower reaches of Caohai lake, which Caohai lake in Guizhou province is a typical natural freshwater lake in the plateau, so the study of heavy metals in swamp lands plays an important role for the ecological and environmental protection of the area. A total of 48 samples of surface soil (0-20 cm) of swamp land in Suohuangcang Wetland Park were collected, contents, spatial distribution characteristics, pollution assessment results of heavy metals Cr, Ni, Zn, As and Pb in soil were analyzed, and heavy metal contamination in soil was assessed by geological accumulation index and comprehensive pollution index. The results show that, in the surface soil of swamp land in Suohuangcang Wetland Park, the contents of Cr, Ni, Zn, As and Pb were 105. 68 mg·kg-1, 70. 97 mg·kg-1, 148. 80 mg·kg-1, 26. 57 mg·kg-1, 53. 69 mg·kg-1, which are higher than the background values of heavy metals in Guizhou soil. The distribution of all measured elements showed an overall increasing trend from the southern Caohai wetland inlet to the northern Suohuangcang wetland outlet. The distribution pattern of Ni and AS is similar, showing that the west bank of the lake is higher than the east bank, and there are obvious aggregation points near S20 sampling point and Five-hole Bridge. The distribution pattern of Cr and Pb is similar, showing that the east bank of the lake is higher than the west bank, and there are aggregation points near S25~S33 sampling point and railway. The overall distribution of Zn is relatively uniform, and no obvious aggregation point is formed. According to the results of pollution assessment, Ni is at "moderate to heavy" pollution level, Zn, As and Pb are all at the "moderate to light" pollution level and Cr is at "slight" pollution level. To sum up, the heavy metal pollution in the soils of Suohuangcang wetland is mainly caused by human activities, especially in the northern outlet. Therefore, it is necessary to strengthen the control measures on the discharge of mining and smelting pollution and the use of pesticides and fertilizers.