珠湖沉积物污染物空间分布特征及污染评价

Spatial Distribution Characteristics and Assessment of Pollutants in the Profile Sediments of Zhuhu Lake

珠湖是鄱阳湖唯一具有重要饮用水水源供水功能的大型子湖和国家水质良好湖泊,但长期以来对其沉积物中累积性污染缺乏了解。为研究珠湖沉积物污染物积累情况和主要污染物的来源,采集内珠湖、外珠湖7个不同湖区的深层柱状沉积物,研究其营养盐(总氮(TN)、总磷(TP)、氨氮(NH_(4)^(+)-N)和总有机碳(TOC))和重金属(Cr、As、Cu、Zn、Cd和Pb)的水平与垂直空间分布特征。结果表明:湖泊沉积物TOC和TN含量从底层到表层总体呈增加趋势,而TP和NH_(4)^(+)-N与沉积深度的相关性不显著,TOC和TN的最高含量出现在闸口区(DS1),TP和NH_(4)^(+)-N的最高含量则出现在外珠湖白沙洲湖区(DS2)。沉积物中营养盐与6种重金属整体呈现外珠湖高,通道区域次之,内珠湖最低的规律,而在部分湖区表层沉积物Cd、Cr和Pb含量较深层区呈增加的趋势,表明部分湖区表层沉积物中的重金属呈现积累风险。主成分分析和相关性分析表明,珠湖6种重金属受到外源输入影响明显,内珠湖沉积物中Cu和Cr可能来源于农业种植活动,外珠湖沉积物中Pb、As、Zn和Cu中可能来源于水产养殖活动。珠湖沉积物6种重金属污染水平为外珠湖白沙洲湖区>闸口区>外珠湖大塘村湖区>通道区>外珠湖双港湖区>内珠湖腰里湖区>内珠湖团林湖区。在外珠湖白沙洲湖区Cr、Pb累积效应明显,珠湖沉积物中重金属Cr、Pb潜在风险应引起重视。

Zhuhu Lake is not only the sole large sublake that has the function of important drinking water supplyment in Poyang Lake but also one of national good-quality lakes.However,it's not well-documented on the accumulative pollution in sediment of Zhuhu Lake.Our study examined the variation patterns and main sources of target pollutants in its sediments.Field sampling was conducted in the inner and outer Zhuhu Lake,and core sediments sampled to examine the vertical distributions of nutrients(total phosphorus(TP),total nitrogen(TN)ammonia(NH_(4)^(+))&total organic carbon(TOC)),and heavy metals(Cr,As,Cu,Zn,Cd&Pb)in seven different lake areas.We found that TOC and TN contents decreased with the depth of core sediment,and both of TP&NH_(4)^(+)contents were not related with the depth of core sediment.The maximum of TOC and TN concentrations in sediments were both found in the water-gate area(DS1),and the maximum of TP and NH_(4)^(+)contents both appeared in the Baishazhou area of outer Zhuhu Lake(DS2).The contents of pollutants in sediments were spatially different,with the greatest in the outer Zhuhu Lake,then in the channel area,and the lowest in the inner Zhuhu Lake.Compared to the contents in the deep layers,Cd,Cr and Pb concentrations were gradually increasing in the surface layers of some profile sediments,which meant an increased risk of heavy metal pollution in these lake areas.Results of principal component analysis and correlation analysis showed that accumulation of heavy metal in sediment was affected by exogenous pollutants.The sources of Cu and Cr in the sediment at the inner Zhuhu Lake might come from agricultural planting activities,and the source of Pb,As,Zn and Cu in the sediment at outer Zhuhu Lake might come from aquaculture activities.The pollution level of heavy metals in the sediments was ranked in the following order:the Baishazhou area of outer Zhuhu Lake>the water-gate area>the Datang area of outer Zhuhu Lake>the channel area>the Shuanggang area of outer Zhuhu Lake>the Yaoli area of inner Zhuhu Lake>the Tuanlin area of inner Zhuhu Lake.In the Baishazhou lake area of outer Zhuhu Lake,the accumulation effect of Cr and Pb was marked,Attention should be paid to the potential risks of Cr and Pb in the sediments of Zhuhu Lake.