摘要
以南京沿江典型蔬菜生产系统为研究对象,通过测定并分析表层土壤、剖面土壤、肥料及大气降尘中重金属含量,揭示了土壤重金属异常的空间变异特征以及土壤重金属的来源。结果表明,(1)研究区表层土壤镉(Cd)、砷(As)、汞(Hg)、铅(Pb)、铜(Cu)、锌(Zn)和铬(Cr)平均含量均高于南京市土壤背景值,部分样点土壤Cd含量超过了国家土壤环境质量标准的二级标准,在土壤中呈现较高的累积;(2)除Cr以外,其他表层土壤重金属均呈现东南偏高西北偏低的空间分布特征,与土壤有机质的空间分布规律一致;(3)土壤重金属累积和分布状况与研究区的地形、周边工农业布局以及风向有关;(4)除土壤重金属累积的自然背景原因以外,农业施肥和大气沉降对土壤重金属的累积具有非常重要的贡献。
A vegetable production base, typical of the area along the Yangtze River in Nanjing, was selected as a case for study. Concentrations of heavy metals in topsoil, soil profiles, fertilizers and atmospheric deposition were measured for analysis of spatial variation of soil heavy metal anomaly and sources of the heavy metals in the soils. Results show that （1） the average content of cadmium （Cd）, arsenic （As）, mercury （Hg）, lead （Pb）, copper （Cu）, zinc （Zn） and chromium （Cr） in topsoil was 0.33, 11.2, 0.09, 36.2, 45.4, 120 and 98.7 mg kg-1, respectively, all higher than their respective soil background value in Nanjing; Concentrations of Cd in 49% of the soil samples were found to be above the criteria of GradeⅡof the Standard for Soil Environmental Quality of China, implying higher Cd accumulations in the soils. （2） The concentrations of heavy metals in the topsoils were closely related to soil pH, soil organic matter and soil textures of the area; Spatial distribution of the heavy metals in topsoil, except Cr, was characterized by a trend of tending to be higher in the southeast and lower in the northwest, which was consistent with the spatial distribution of soil organic matter and opposite to the spatial distribution of soil pH; Concentrations of the heavy metals were higher in silty clay soils than in silty clay loam and silty loam soils. （3） Accumulation and distribution of the heavy metals in the soils was also related to the terrain, the layout of agriculture and industry, and the perennial dominant wind direction in the study area. The maximum values of Cd, Cu and Zn contents were found in the southeast of the study area and the maximum values of As in the centre. Concentrations of Hg tended to be high in areas with intensive agriculture and peaked in the northeast of the study area, while the highest concentration of Pb was found in the northwest and southeast of the study area. （4） In addition to the natural geological background, agricultural fertilization and atmospheric deposition were also important contributors to heavy metals accumulation in the soils of the area. In terms of concentrations of Cd in fertilizers, a decreasing order was found of commodity chemical fertilizer 〉 organic fertilizer 〉 manure 〉 rapeseed cake. Contents of Cd, As and Hg were higher in chemical fertilizer, while contents of Pb and Cr higher in organic fertilizer. The contents of Cu and Zn in organic fertilizer were much higher than those in the other fertilizers, which were mainly related to the higher concentrations of Cu and Zn in the feed of livestock. As heavy metals in the soil has the feature of long-term accumulation, long-term intensive application of fertilizers high in heavy metals would lead to heavy metal accumulation in the soil, with a risk of gradually exceeding the standard for soil environmental quality or environmental capacity. The content of Cr in the atmospheric deposition was approximate to the background value of the soil in Nanjing. Compared with other researches on atmospheric deposition in Nanjing, this study found higher contents of Cu and Zn, which is probably because some of the sampling sites were quite close to industry parks in the vicinity and hence affected by chemical activities of the plants. Atmospheric deposition flux varied sharply from month to month, and contents of heavy metals increased obviously in winter, especially in the northwest industrial area. Contents of Pb and Cu in the atmospheric deposition varied in a similar way. Thus, it could be inferred that they have similar sources in the study area.
出处
《土壤学报》
CAS
CSCD
北大核心
2014年第6期1251-1261,共11页
Acta Pedologica Sinica
基金
国家自然科学基金项目(41101491)
环保公益性行业科研专项项目(201409044)资助
关键词
蔬菜基地
重金属
累积特征
空间变异
来源分析
Vegetable fields
Heavy metals
Accumulation characteristics
Spatial variability
Source analysis
