江苏海岸带土壤重金属来源解析及空间分布

以江苏省响水如东段海岸带为研究区,系统采集了239个表层土壤样品,分析测试了Cd、Cr、Cu、Hg、Ni、Pb和Zn等7种重金属元素,综合运用多元统计和地统计方法,探讨了研究区土壤重金属的主要来源,绘制了重金属的空间分布图.结果表明:(1)江苏响水如东段海岸带土壤Cd、Cr、Cu、Hg、Ni、Pb和Zn的平均含量分别为0.14、64.23、24.15、0.026、29.16、22.24和77.94 mg·kg~(-1),Cd、Cu、Hg、Pb和Zn存在较为明显的富集,Cr和Ni的平均值低于江苏滨海土壤背景值.(2)Cd、Cr、Cu、Ni、Pb和Zn在海积物母质发育土壤中的含量显著低于河流冲积物、潟湖相沉积物和三角洲沉积物母质;Cd、Cu、Hg、Pb和Zn在城镇建设用地的平均含量显著高于其他地类.(3)Cr和Ni为自然来源元素,受到成土母质的控制;Cd、Cu、Pb和Zn受到成土母质和人类活动的共同影响,人为源主要包括工业、交通排放和农业活动;Hg为人为来源,受到人为排放的大气沉降的影响.(4)Cd、Cu、Pb和Zn的高值区分布在研究区的北部、南部和西部,Hg的高值区分布在研究区的西部和南部的城镇密集区.

Identifying the Origins and Spatial Distributions of Heavy Metals in the Soils of the Jiangsu Coast

A total of 239 samples of surface soils were collected along the Xiangshui to Rudong coast, in Jiangsu Province, and analyzed for Cd, Cr, Cu, Hg, Ni, Pb, and Zn. A multivariate analysis was applied to identify the sources of heavy metals, and ordinary kriging was used to map the spatial distributions of the heavy metal concentration. The mean contents of Cd, Cu, Hg, Pb, and Zn in the surface soils of the Jiangsu Coastal Zone were higher than the background values of the Jiangsu Coastal Plain, which indicated that there were obvious accumulations of these heavy metals in surface soils; while the mean contents of Cr and Ni were lower than the background values. The contents of Cd, Cr, Cu, Pb, Ni, and Zn in soils that originated from marine deposition were significantly lower than those from alluvium and lagoon facies deposition, including the Yangtze River Delta deposition. Urban areas exhibited higher Cd, Cu, Hg, Pb, and Zn contents than other land covers. Cr and Ni were controlled by the parent material and seemed to originate from a natural source. Cd, Cu, Pb, and Zn were associated with the combination of parent material and anthropogenic inputs. Hg was dominated by atmospheric deposition related to various human activities. The high values of Cd, Cu, Pb, and Zn were distributed in the northern, western, and southern parts of the study area, and Hg exhibited high values around the urban areas in the western and southern parts.