黄浦江中上游地区农用土壤重金属含量特征分析

以黄浦江中上游地区农用土壤为研究区域,在获取区域内729个农用表层土壤样品重金属含量数据的基础上,运用多元统计和地统计相结合的方法,对黄浦江中上游地区农用土壤重金属的含量水平、分布特征和来源进行系统分析.结果表明,黄浦江中上游地区农用土壤中Cd、Hg、As、Cr、Pb、Cu 、Zn 的平均值分别为0.163,0.144,7.54,86.3,24.9,31.4,98.8mg/kg,均低于国家土壤环境质量二级标准,但Hg、Cd、Cr、Cu 、Zn平均含量均超过上海市土壤中相应重金属元素含量背景值,其中尤以Hg显著,是对应背景值的1.44倍;以上海市土壤背景值为标准,农田土壤中Cd、Hg、As、Cr、Pb、Cu 、Zn 超标率分别为59.7%,68.2%,19.3%,67.1%,44.9%,58.4%,76.7%,表现为Zn> Hg> Cr> Cd> Cu > Pb> As.从空间分布来看,青浦、松江远郊区域农用土壤中Cd、Hg、As含量明显高于奉贤、闵行区,靠近市区的闵行Zn、Cr、Cu含量最高,各区域Pb含量差异不大;重金属来源分析表明,As、Cd、Hg元素来源主要与成土母质、农业生产活动等结构性因素有关,而Cu、Cr、Zn、Pb累积受工业生产、人民生活以及交通活动等随机性因素影响较大;Cd含量在不同农用土地利用类型间差异较大,其余元素差异不明显.

Heavy metal concentration in agricultural soils around the upper-middle reaches of Huangpu River

Based on 729 topsoil samples collected from the agricultural lands around the area of upper-middle reaches of Huangpu River, the content, distribution and sources of the heavy metals in the agricultural soil were analyzed with the methods of combining multivariate statistics and geo-statistical. The results showed that the average concentrations of the Cd, Hg, As, Cr, Pb, Cu and Zn in agricultural soil of the upper-middle reaches of Huangpu River were, respectively, 0.163, 0.144, 7.54, 86.3, 24.9, 31.4, 98.8mg/kg, they were lower than the secondary criterion of the state soil environment; but the average concentrations of the Hg, Cd, Cr, Cu and Zn were higher than background values of Shanghai physical soil, especially the Hg, which was 1.44 times higher than the background values. If taking Shanghai physical soil background value as an evaluating indicator, the over-limit ratios of the Cd, Hg, As, Cr, Pb, Cu, Zn in agricultural soil were, respectively, 59.7%, 68.2%, 19.3%, 67.1%, 44.9%, 58.4%, 76.7%, with the scale order: Zn> Hg> Cr> Cd> Cu > Pb> As. The spatial distribution of the metallic elements showed that the concentrations of Cd, Hg, As in the agricultural soil in the Qingpu and Songjiang districts were higher than that in Fengxian and Minhang districts, and the concentrations of Zn, Cr, Cu were highest in the Minhang district, which is near the urban areas. Differences of the concentrations of Pb in all areas were not obvious. Source Analysis of Heavy Metals showed that the sources of As, Cd, Hg were mainly influenced by the structural factors, such as soil parent materials, agricultural production activities; but the accumulation of Cu, Cr, Zn, Pb were mainly affected by random factors, like as industrial production, people's living and transport activities. The content of Cd was quite different in each type of agricultural lands, and the remaining elements were not significantly different.