| Popis: |
Effects of river (Yangtze River)-lake (Poyang Lake) relation on the distribution and potential ecological risk of Cu, Pb, Zn, Cr and Cd were investigated in surface sediment of Poyang Lake under different waterregimens. The results indicated: (1) the sediments of Poyang Lake were polluted by various concentrations of heavy metals mainly originated from particulates of Yangtze River, and Cu and Pb were the main pollution factors. The pollution level of determined heavy metals followed the order of CuPbZnCrCd. The concentration ranges of Cu, Pb, Zn, Cr and Cd in the sediment of Poyang Lake were 13.1-108.1 mg.kg-1 , 37-119.1 mg.kg-1, 29.9-129.9 mgkg-1, 13.3-98.6 mgkg-1 and 0. 19-2.77 mg.kg-1 during the wet period, and 3.05-69.7 mg.kg-1, 27.5-105 mgkg-1, 18.8-95.4 mg.kg-1, 7.34-70 mg.kg- and 0.033-0.406 mg.kg-1 during the dry period respectively. The region with the highest heavy metal concentrations was located in water input area of the " Five River" and water output area of " Hukou" ; (2)The regions with high risk of heavy metals in sediment were mainly located in the area of the trail of "Five Rivers" during the wet period; while during the dry period, the area with high risk of heavy metals in sediment enlarged, which was not only limited in the area of the trail of "Five Rivers", but also enlarged northwards. The potential ecological risk of "Hukou" was relatively high, however, the potential ecological risk of the sediment in the whole lake during the dry period was lower than that during the wet period. (3) With the change of river-lake relation, water level rose, the maintaining time was shortened during the wet period, the dry season appeared ahead of schedule, the transformation course of Poyang Lake from "Lake morphology" to " River morphology" increased, and the typical river properties were enhanced, which resulted in the decreased potential ecological risk of heavy metals in sediment of the whole lake, however, the area of high risk-region was enlarged northwards. |
