北京市延庆区土壤重金属元素地球化学特征及其来源分析

北京市延庆区是首都生态涵养区,开展土壤重金属分布特征及来源解析研究对保障土地安全利用、防控生态环境风险具有重要意义。采集延庆区2 354件表层土样及44件深层土样,测试分析了重金属元素As、Cd、Cr、Hg、Ni、Pb、V、Zn及Sc等含量。采用空间分布分析、多元统计分析与受体模型相结合的方法,阐明了土壤重金属元素分布特征,解析了土壤重金属潜在来源,并计算了不同来源对土壤重金属的相对贡献率。结果表明,表层土壤中V、Cr、Ni、As元素主要来源于成土母质,Cd、Zn、Pb含量高值区集中分布于人口密集区域,人为活动对该3种元素影响较大,而Hg主要受大气干湿沉降的影响。深层土壤中Hg元素在居民区含量较高,而其余元素均未受到人为活动的影响。

Geochemistry and Source Identification of Heavy Metals in the Top and Subsoil of Yanqing District in Beijing

As Yanqing District in Beijing is the ecological conservation of the capital, the study on the distribution and the source identification of heavy metals in the soil is of great significance to ensure the safe use of land and to prevent the risk of their ecological environment. In this study, 2 354 topsoil samples and 44 subsoil samples were collected from Yanqing District, and the concentrations of As, Cd, Cr, Hg, Ni, Pb, V, Zn and Sc were respectively analyzed. Based on the methods of the spatial analysis, multivariate statistics analysis and positive matrix factorization, the spatial distribution characteristics of these metals in the soil were illustrated, and the potential sources were identified, and the relative contribution of the different sources was also calculated. Conclusively, elements of V, Cr, Ni and As in the topsoil are mainly originated from soil parent materials. On the other hand, the relatively high level of Cd, Pb and Zn in the topsoil were observed in areas with high density of population, and human activities greatly affected their distribution. In addition, the distribution of Hg in topsoil was mainly affected by the atmospheric deposition. In the subsoil, the element of Hg showed high level in the residential area, and the left elements were almost not affected by human activities.