摘要
采用地统计软件GS+和地理信息系统(geographic information system,GIS)相结合的方法,研究浙江省北部某电池厂(污染场地F1)和火电厂(污染场地F2)周边农田表层土壤(0～20cm)和亚表层土壤(20～40cm)汞(Hg)、镉(Cd)、铅(Pb)、锌(Zn)、铜(Cu)、镍(Ni)6种重金属的含量及其空间变异特征;通过反距离权重(inversedistance weighting,IDW)空间插值分析方法对未测点土壤重金属含量进行最优估计,并对这些重金属的来源进行初步识别。结果表明:对于污染场地F1,土壤Cd污染比较突出,有91%表层土壤样点Cd质量分数超过国家《土壤环境质量标准》(GB15618—1995)的2级标准值(Cd>0.3mg/kg);而且F1表层土壤Cd和Pb质量分数具有相似的空间分布特征,随着与污染场地距离的增加重金属含量逐渐降低;同时F1表层土壤Cd和Pb的质量分数均极显著大于亚表层土壤,说明污染场地F1周边农田表层土壤重金属Cd和Pb污染主要来自外源污染,且污染源可能是污染场地F1;对于污染场地F2,土壤Cd和Hg污染比较突出,分别有63%和11%表层土壤样点Cd和Hg质量分数超过国家《土壤环境质量标准》(GB15618—1995)的2级标准值(Hg、Cd>0.3mg/kg),F2表层土壤Hg质量分数极显著大于亚表层土壤,说明污染场地F2周边农田表层土壤重金属Hg超标主要来自外源污染。综上可见,污染场地周边农田土壤重金属污染与污染场地的影响密切相关,应该引起高度重视。
Summary The pollution of heavy metal is increasingly concerned, especially the soil heavy metals pollution around the contaminated sites. Many researchers have reported a significant increase of heavy metal in the surface soil. However, few reports have been found in the literature about soil heavy metal spatial distribution and source identification around contaminated sites. Therefore, this study has the aim of elucidating the spatial distribution and source identification of soil heavy metals in croplands near two contaminated sites. Our specific objectives were to examine the spatial dependency and the variation mechanism of heavy metals in soils, to map the spatial distribution and risk assessment of soil heavy metals,and to identify the main sources of soil heavy metal pollution. The surface soil （0-20 cm） and subsurface soil （20 - 40 cm） were collected from nearby fields of a battery plant （F1） and a thermal power plant （F2） in the north of Zhejiang Province. The concentrations of soil mercury （Hg）, cadmium （Cd）, lead （Pb）, zinc （Zn）, copper （Cu）, and nickel （Ni） in these two typical contaminated sites were determined and the spatial distribution patterns and pollution source of the heavy metals were analyzed using Geographic Information System （GIS） and geostatistical methods, Based on the type II limit of ＂Environmental Quality Standard for Soils＂ （GB15618-1995）, the single factor method and Nemerow index method were used to assess the comprehensive pollution risks of the soil heavy metals around the contaminated sites. Inverse distance weighted interpolation （IDW） was used to simulate the pollution risk and spatial distribution and the source identification of these heavy metal pollution. Results showed there was a serious soil heavy metal pollution problem around contaminated sites, with Cd concentrations in 80.77% of the surface soil samples exceeded the type II limit （Cd -0.3 mg/kg） of GB15618-1995. Hg concentrations in 3.85% of the surface soil samples exceeded the type II limit. Nemerow index method assessment results showed that there were 25 soil samples exceeded the standard, with overproof rate of 48.08%. Based on the Technical Specification for Soil Environmental Monitoring, the maximum index value was 3. la, which exhibited heavy pollution. Particularly in nearby contaminated site F1, soil Cd and Pb pollution were serious problems in the soils, with Cd concentration in 91% of the surface soil samples exceeded the type II limit （Cd 2〉 0.3 mg/kg） of GB15618-1995, and the maximum surface soil Cd concentration was 3.3 mg/kg. The soil Pb pollution was also the potential problem even then its concentration was not exceeded the type II limit. The maximum surface soil Pb concentration was 123.67 mg/kg, and the mean surface soil Pb concentration was 58.69 mg/kg. While the surface soil Cd and Pb concentrations were significantly higher than the subsurface soil. At the nearby contaminated site F2, soil Cd and Hg pollution were serious problems in the soils. Cd concentrations in 63 % of the surface soil samples, and Hg concentrations in 11% of the surface soil samples were higher than the type II limit （Cd -0.3 mg/kg, Hg -0.3 mg/kg） of GB15618-1995. The maximum surface soil Cd concentration was 0.71 mg/kg. The mean surface soil Hg concentration was 0. 214 mg/kg. Cd and Pb concentrations in the surface soil samples from F1 had similar spatial distribution patterns and the concentrations reduced with farther distance away from F1, and they were significantly higher than those in the corresponding subsurface soils. These results indicated that pollution of soil heavy metals （Cd and Pb） was mainly caused by external pollution, and F1 was the most probable pollution source. The battery plant can discharge Cd and Pb into environment. At the contaminated site F2, the heavy metal concentrations in some soil samples were higher than the type II limit （Cd - 0.3 mg/kg） of GB15618-1995. The mean surface soil Hg concentration was significantly （P = 0.01） higher than that of the subsurface soil. These results indicated that soil heavy metal Hg pollution at site F2 was mainly caused by external pollution from the thermal power plant and the contaminated site F2 was one of the pollution sources. In conclusion, soil heavy metal pollution is a serious problem in the study area around the .contaminated sites. The pollution of surface soil by Cd and Pb at the nearby site F1 and the pollution of surface soil by Hg and Cd at the nearby site F2 mainly comes from external pollution sources, the increase of surface soil Cd and Pb concentrations around site F1 is most likely caused by the contaminated site F1. Soil pollution by Cd, Pb and Hg of nearby fields is closely related with the contaminated sites F1 and F2, thus much more attention should be given to the prevention of the heavy metal pollution.
出处
《浙江大学学报（农业与生命科学版）》
CAS
CSCD
北大核心
2013年第3期325-334,共10页
Journal of Zhejiang University:Agriculture and Life Sciences
基金
国家自然科学基金资助项目(41071144)
浙江省“农产品安全标准与检测控制技术”重点科技创新团队资助项目(2010R50028)
关键词
土壤重金属
污染场地
空间变异
地统计学
污染源识别
soil heavy metal
contaminated site
spatial variability
geostatistics
pollution source identification
