山东省小清河沿岸土壤重金属污染分布及迁移规律

通过对山东省小清河流域土壤重金属污染现状的调查研究,查明土壤重金属污染状况,元素来源和分布迁移规律,从而为该区土壤重金属污染的科学治理提供有效依据。研究发现,小清河沿岸地区的重金属污染主要表现为As、Cd、Cr、Ni等元素的污染;依据内梅罗污染指数评价方法发现研究区存在重金属污染的土壤总面积为880.5 km2,未受到重金属污染的土壤面积为1 822.1 km2,分别占全区总土壤面积的32.58%和67.42%,其中上游的济南市城区北园镇至华山镇区域的小清河两岸是重污染区。对小清河流域土壤重金属来源的探析表明,大气干湿沉降是土壤重金属污染的主要来源;土壤重金属的生物有效性评价显示重金属元素Cd的活动态比例高达56.17%,活化迁移能力强,是该区对生态环境危害性最大的污染因子。此外,As、Cd、Cr、Pb等重金属元素的活动态含量明显受pH值和Corg含量的制约,在低pH值、高Corg含量的土壤区应高度重视As和Cd的污染问题。

Distribution and migration regularity of soil heavy metal pollution along the Xiaoqing watershed, Shandong Province

This paper aims to clarify the degree,pollution sources and the plant availability of the soil heavy metal pollution along the Xiaoqing River so as to provide the basis for the scientific management of the heavy metal pollution in this area.It is found that along the basin of the Xiaoqing River,the main heavy metal pollutants are As,Cd,Cr and Ni.According to the Nemerow pollution index evaluation,the area without heavy metal pollution in the study area is 1822.1 km2,while the soil area contaminated by heavy metals has reached 880.5 km2,accounting for 67.42% and 32.58% of the total area,respectively.The both sides of the Xiaoqing River from Beiyuan Town to Huashan Town of the Jinan City are heavily polluted areas.An analysis of sources of heavy metals in soil shows that that the dry and wet atmospheric deposition obviously from irrigation and fertilization are the main sources of heavy metal pollution.The bioavailability evaluation of the heavy metals was carried out by the method of sequential extraction,and the result shows that the active state of the heavy metal Cd is as high as 56.17%,with a strong capability of mobilization and migration,which constitutes the most harmful pollution factor affecting the ecological environment in this area.In addition,the contents of active state of As,Cd,Cr,Pb and other heavy metals are significantly constrained by pH and Corg content,and in areas with low pH and high Corg content,great importance should be attached to the pollution problem of As and Cd.