Abstract: Heavy metal pollution has been observed in part of the farmland in Hunan province, threatening not only crops growth, but also human health. In order to better understand the distribution characteristics of soil heavy metals and quantitatively analyzing the pollution sources, this paper collected 107 soil samples, 13 fertilizer samples and 31 irrigation water samples in potential contaminated areas in Hunan province, tested the contents of Cd, Pb, Cu, Zn, and analyzed the pollution resources of heavy metles by UNMIX model. Results indicated that the average Cd, Pb, Cu and Zn contents in soil surface of the studying areas were 5.22, 4.58, 1.10 and 1.49 times of their background values, respectively. Among them, the Cd and Pb enrichments were obvious. Comparing to the National Standard GradeⅡ, their points exceeding rate were 69.16%, 5.61%, 3.73% and 6.54%, respectively. Visibly the Cd pollution was extremely severe. However, the Cd content in fertilizer and irrigation water was not in excess of relative limit of National Standard. UNMIX analysis revealed that the soil surface Cd contaminations in Chenzhou and Hengyang regions were mostly derived from industrial activities (the contribution rate were 66.15% and 64.88%, respectively), and the soil Pb pollution was jointly caused by industrial activities (49.10% and 54.28%) and transportation and natural pollution (43.24% and 50.23%). In Changsha region, its soil Cd pollution was mostly caused by agricultural activities (61.50%), while the Pb contamination was on accounts of transportation and natural pollution (94.29%). Generally, the soil surface Zn and Cu pollutions were mainly derived from fertilization and irrigation, etc. agricultural activities. These results provided theoretical basis for preventing and controlling soil heavy metal pollution in typical paddy-upland rotation regions of Hunan Province.

Key words: soil, heavy metal pollution, UNMIX Model, source apportionment, Hunan province

摘要： 湖南省部分农田存在重金属污染现象，不仅影响农作物生长，而且威胁人体健康。为进一步明确土壤重金属分布特征，定量解析污染来源，采集了湖南省重金属潜在风险区内典型水旱轮作区107个土壤样品、13个肥料样品和31个灌溉水样品，测定了其中Cd、Pb、Zn、Cu 4种元素含量，并利用UNMIX模型对农田重金属污染源进行了解析。结果表明：研究区域内表层土壤Cd、Pb、Zn、Cu平均含量分别为背景值的5.22倍、4.58倍、1.10倍、1.49倍，其中Cd、Pb富集明显；对比国家土壤重金属二级标准，点位超标率分别为69.16%、5.61%、3.73%和6.54%，可见Cd污染尤为严重。肥料和灌溉水中Cd含量未超过我国有关限量标准。UNMIX解析结果表明，在郴州和衡阳区域，土壤表层Cd污染主要由工业活动（贡献率分别为66.15%和64.88%）引起，Pb污染同时受工业活动（贡献率分别为49.10%和54.28%）和交通运输及自然污染（贡献率分别为43.24%和50.23%）共同影响；在长沙区域，土壤表层Cd污染受农业源影响最大（61.50%），而Pb污染主要与交通运输及自然污染综合源（94.29%）有关。综合3个研究区域，土壤表层Zn、Cu污染物主要来源于施肥和灌溉等农事活动。本研究结论可为湖南省典型水旱轮作区重金属污染防控和治理提供理论基础。

关键词: 土壤, 重金属污染, UNMIX模型, 源解析, 湖南省