滇池沉积物中重金属污染特征及其生态风险评估

采集了滇池北部和中心区域2根柱状沉积物样品，分析其常量元素（Fe、Mn、Al、Ti、Ca、K）、微量元素（Ba、Sr、Cu、Pb、Zn、V、Cd）剖面分布特征，并采用H？kanson潜在生态危害指数法对典型重金属（Cd、Cu、Zn、Pb）进行了污染潜在生态风险评估。结果表明：沉积物中常量元素以Fe2O3、CaO及Al2O3为主，MnO、K2O及TiO2含量较少，变化范围是Fe2O3为8.0～14.9%、MnO为0.1～0.2%、Al2O3为9.0～20.1%、TiO2为1.5%～2.8%、CaO为0.4～21.7%、K2O为1.5～2.0%；微量元素Pb, Cd, Zn, Ba, Cu, Sr 及V含量均较高，变化范围是Pb为73.8～105.3 mg·kg^-1、Cd为1.0～3.4 mg·kg^-1、Zn为123.4～210.6 mg·kg^-1、Ba为264.8～435.7 mg·kg^-1、Cu为77.5～133.5 mg·kg^-1、Sr为34.9～137.5 mg·kg^-1以及V为177.7～284.7 mg·kg^-1。尤其表层0～12 cm内（1950 s以后），各元素含量值均明显高于12 cm以下各值，20世纪50年代后滇池流域内工农业发展及污染物输入是造成金属元素含量累积的主要因素。沉积物中典型重金属Cu、Zn、Pb、Cd污染潜在生态风险评估结果：Cu、Zn和Pb处于中度污染，且C if 值越接近表层（0～12 cm）其值越高，这表明自1950S后污染程度不断加重，其中 Cd 累积与污染比较严重，分析多种元素的多因子污染参数之和C d表明滇池沉积物中多种元素污染整体处于“较高”污染程度，分析多种元素的潜在生态风险指数RI表明滇池沉积物中重金属潜在生态风险处于“很高”水平。同时，滇池北部沉积物中重金属潜在危害较严重且近年来污染有加重趋势。

Pollution Characteristics and Ecological Risk Assessment of Heavy Metals in Sediments of Dianchi Lake

Two sediment profiles were collected from the northern and central parts of Dianchi Lake. Distribution characteristics of major elements （Fe, Mn, Al, Ti, Ca and K） and trace elements （Ba, Sr, Cu, Pb, Zn, V and Cd） were investigated. And then the potential ecological risk of heavy metals （Cd, Cu, Zn and Pb） was analyzed by the method of H？kanson. The contents of Fe2O3, CaO, and Al2O3 were high and contributed mainly to the major elements, while the contents of MnO, K2O and TiO2 were low in the sediments from Dianchi Lake. The contents of Fe2O3, CaO, Al2O3, MnO, K2O and TiO2 were 8.0～14.9%, 0.4～21.7%, 9.0～20.1%, 0.1～0.2%, 1.5～2.0%, and 1.5%～2.8%, respectively. For the trace elements, contents of Pb, Cd, Zn, Ba, Cu, Sr and V were relatively high, which were 73.8～105.3 mg·kg^-1, 1.0～3.4 mg·kg^-1, 123.4～210.6 mg·kg^-1, 264.8～435.7 mg·kg^-1, 77.5～133.5 mg·kg^-1, 34.9～137.5 mg·kg^-1 and 177.7～^284.7 mg·kg^-1, respectively. The contents of these elements were greater in the top 12 cm of sediments, which were due to industrial and agricultural development after 1950s. The ecological risk assessment on 4 typical heavy metals including Cu, Zn, Pb, and Cd showed that the value of ifC was greater in the top 12 cm, which indicated the pollution status of heavy metals were serious after 1950 s. The Cu, Zn, and Pb were in the status of moderate pollution. The Cd was accumulated in the sediments, which was in the serious pollution status. The multiple factor pollution index, such as the value of dC , showed that heavy metal pollution was at the level of“high”. The index of RI for ecological risk assessment also showed that the potential ecological risk was at a“very high”level. Further more, ecological risk of heavy metals from sediments was greater in northern part of Dianchi Lake, and the pollution becomes more serious in recent years.