洪湖沉积柱中重金属的历史分布特征及来源

Historical records, distribution characteristics and sources of heavy metals from sediment core in Honghu Lake,China

为了解历史上洪湖重金属的含量水平及来源,于2014年12月在洪湖中心位置采集了沉积柱,分析了沉积柱中4种重金属(Cu、Cd、Zn、Pb)的含量,并结合^(137)Cs和^(210)Pb定年技术得到沉积物中重金属高分辨率年代沉积序列.结果表明:洪湖沉积柱中4种重金属总量介于67.86~189.57mg/kg之间,4种重金属含量的高低为Pb>Zn>Cu>Cd.地累计指数表明Cu和Zn未达到污染级别,而Pb为无污染到中度污染级别,Cd为中度污染到强污染级别.沉积物中重金属含量受洪水和围湖造田的共同影响,新滩水闸建成前,洪水会导致沉积物中重金属含量先降低,随后升高.水闸建成后,洪水会导致洪湖出现内涝致使沉积物中重金属含量升高;围湖造田导致沉积物中重金属含量升高.源解析研究表明,沉积物重金属来源于非点源农业污染、交通活动以及工业废水和生活废水排放.

In order to understand the historical level of heavy metals concentrations of Honghu Lake, a sediment core was collected in December 2014. The concentrations of 4 heavy metals （Cu, Cd, Zn, Pb） were determined and the chronology was dated by 137Cs and 210Pb. The total concentrations of 4heavy metals ranged from 67.86mg/kg to 189.57mg/kg and the concentrations of individual heavy metals ranked as Pb〉Zn〉Cu〉Cd. The geoaccumulation index indicated that the concentrations of Cu and Zn were uncontaminated, while level of Pb was uncontaminated to moderately contaminated and Cd was moderately contaminated to strongly contaminated. The concentrations of heavy metals in sediments were affected by the flood events and reclamations. Before the construction of Xintan sluice, the tendency of heavy metal concentrations caused by floods decreased at first, then increased. However, the concentrations increased due to the waterlogging caused by floods after the sluice’s built. Reclamations contributed to increasing of heavy metals concentrations in sediments. Source diagnosis results suggested that heavy metals in sediment were from non-point agriculture source, transportation activities and industrial and domestic wastewater.