基于137Cs计年法估算滇池沉积物重金属负荷

根据滇池流域地貌、湖盆形态、物源供给等,用GIS方法将滇池外海分作7个区域,以137Cs计年法确定各区域上部沉积物3个沉积时段为1954～1963、1963～1986、1986～2003年,测算不同时段各区域的泥沙年均沉积通量和年均蓄积量,与当地实情及他人用其它方法研究对照,结果可以吻合.在此基础上,结合实验室测量,估算各区域的Cu、Cr、Cd、Pb、Hg、Zn在各时段的年均沉积通量,得到1963～2003年期间滇池沉积物几种重金属负荷分别达到1 040.8、1 054.0、11.2、824.7、2.5、2 465.6 t.故应十分重视滇池沉积物中重金属,采用减少重金属和泥沙入湖量并举的措施控制沉积物重金属负荷的进一步增长.

Heavy Metals Loads in Sediment of Dianchi Lake Based on 137Cs Dating

According to the shape of Dianchi Lake,the land forms of the lake basin and the sources of sediment and heavy metals,Dianchi Lake was divided into seven zones by using Geographic Information System(GIS).The sediments in the upper part of each zone,which were identified by 137Cs dating at different depths,correlate to special periods,such as 1954-1963,1963-1986,1986-2003.The mean sedimentation flux and annual total amounts of sediment accumulations of seven zones were evaluated.The results agree with the events occurred in Dianchi basin in lately 50 years obtained by different methods.Based on the sedimentation fluxes and the concentrations of heavy metals in the sediments measured in laboratory,the mean sedimentation fluxes and mean annual accumulation amounts of heavy metals,such as Cu,Cr,Cd,Pb,Hg,Zn,of each zone in three periods were calculated.The heavy metals loads from 1963 to 2003 in the sediments of Lake Dianchi were 1 040.8,1 054.0,11.2,824.7,2.5,2 465.6 t,individually.In order to control the increases of heavy metal loads,it is necessary to reduce the amounts of both heavy metals and materials entering Dianchi Lake.