南京玄武湖富营养化及重金属污染现状

摘要

In order to investigate the distribution of nutrient and heavy metal pollution after silt dredging in Xuanwu Lake in Nanjing City, water and sediment samples were collected at six stations in three different lake zones of Xuanwu Lake. Physicochemical parameters including pH, total nitrogen (TN), total phosphorus (IP), and organic matter were measured according to standard methods. The concentrations of five heavy metals, including Cr, Pb, Cu, Zn, and Ni, were analyzed with inductively coupled plasma atomic emission spectroscopy. In combination with the geo-accumulation index method, the pollution status of the heavy metals in the sediments was evaluated. The results show that the north lake zone was in moderate or severe eutrophication status, the southeast lake zone was in severe eutrophication status, and the southwest lake zone was in slight eutrophication status with a relatively high concentration of TN. The concentration of Cr collected in the water of the southeast lake zone exceeded the standards of surface water in China. The concentrations of Cr and Pb in the lake sediments decreased after silt dredging, and the pollution of the lake was alleviated. The sediments at two sampling stations were slightly polluted by Zn and not polluted by other heavy metals.%针对南京玄武湖清淤后营养盐及重金属污染物的分布问题,在其3个湖区中设置6个采样点,采集水体和沉积物样品,分析pH、总氮、总磷和有机质等理化参数并采用电感耦合等离子体原子发射光谱法分析Cr,Pb,Cu,Zn,Ni 5种重金属质量分数,并结合地累积指数法对沉积物中重金属的污染程度进行评价.结果表明:玄武湖北湖湖区水体处于中度富营养化到严重富营养化状态,东南湖区则处于严重富营养化状态,而西南湖区水质相对较好,处于轻度富营养化状态,只是总氮质量浓度稍微偏高；重金属污染方面,东南湖水体中的Cr质量浓度存在超标现象；清淤之后,玄武湖沉积物中Cr和Pb的质量分数有所降低,污染状况有所缓解；2个采样点沉积物中的Zn处于轻度污染程度,其余金属污染程度均为清洁.