南四湖及主要入湖河流表层沉积物重金属形态组成及污染研究

采用BCR（SM&T）方法对南四湖及主要入湖河流丰水季节表层沉积物中Cr、Cu、Mn、Ni、Pb、Zn 6种重金属元素的酸提取态、可还原态、可氧化态及残渣态进行了连续提取,分析了各水体单元表层沉积物重金属元素的形态组合特征、人为污染状况及潜在生态风险.研究结果表明,泗河、京杭运河、洙赵新河、府河上游、上级湖南部湖区及下级湖区表层沉积物中Cr、Cu、Ni、Zn以残渣态为主,其含量可占到该元素总量的80%～90％,人为污染程度较弱;老运河、府河入湖口、白马河表层沉积物中Cr、Cu、Ni、Zn的残渣态含量明显降低,而可提取态（酸提取态、可还原态、可氧化态）含量可增至80％以上,其中以可氧化态、酸提取态为主,人为污染程度较重;各水体单元表层沉积物中Pb、Mn以残渣态和可氧化态为主,其含量占Pb、Mn含量的95％、70％左右,基本未受人为污染.随着表层沉积物中有机物的矿化分解及环境条件的改变,老运河、府河入湖口、白马河等重金属人为污染较重的沉积物中Cr、Cu、Ni、Zn的可氧化态、酸提取态及可还原态可发生活化,具有较高的潜在生态风险.

Chemical Fractionation and Pollution Characteristics of Heavy Metals in the Sediment of Nansihu Lake and Its Main Inflow Rivers, China

Chemical forms of Cr, Cu, Mn, Ni, Pb and Zn in the surface sediments of Nansihu Lake and its main inflow rivers are determined by the BCR sequential extraction method. The chemical fractionation composition characteristics, pollution state and potential ecological effects of the heavy metals are discussed. Cr, Cu, Ni and Zn in the sediments of Sihe River, Jinghang Canal, Zhuzhaoxin River, Guangfu River, south area of the Upper Lakes, and Down Lakes mainly exist in residual fraction, which account for 80% - 90% of their content, mainly reflecting the natural characteristics of the heavy metals ; but for the sediment of Old Canal, Guangfu River estuary, Baima River, nearly 80 % of Cr, Cu, Ni and Zn exist in extractable fractions due to human pollution, especially with high oxidizable and acid extractable fractions content. Pb and Mn mainly exist in residual fraction and oxidizable fraction in the sediment of Nansihu Lake and its main inflow rivers, which account for 95 % and 70% of the content of Pb and Mn, similar to other unpolluted sediments. With the mineralization and decomposition of organic matter and change of environment condition of the surface sediment, the extractable fractions of Cr, Cu, Ni,Zn in the polluted sediment can be reactivated, bringing on ecological harm to the water ecological system.