大明湖水系统中重金属元素的分布特征

Distribution Characteristics of Heavy Metal Elements in Water System of Daming Lake

[目的]湖泊水生态系统（表层水、上覆水和孔隙水）重金属元素的研究对于评价重金属元素对水体的影响具有重要意义。[方法]用ICP-MS仪,测定了大明湖水系统中Fe、Mn、Ni和Cr浓度。[结果]同一采样点重金属元素的浓度由高到低的顺序为Fe〉Mn〉Ni〉Cr,且孔隙水中重金属元素浓度高于表层水和上覆水。Fe和Mn元素在孔隙水中的浓度峰值出现在界面较深处,Cr和Ni元素的迁移较为复杂,在孔隙水中的浓度随深度的变化趋势基本一致,在6～8 cm深度处达到最大值。[结论]大明湖水系统中活泼重金属元素的含量高于稳定态重金属,且人为活动对水系统重金属元素的分布产生重要影响。大明湖沉积物中Fe是重要的有机质分解氧化剂,湖水溶氧较强使得铁锰氧化边界下移。

[Objectine] It was significant to evaluate the effect of the heavy metals on the water quality by the study on heavy metal elements in the surface water,the overlying water and the pore water of urban lake ecological system.[Method] The concentration of Fe,Mn,Ni and Cr in Daming Lake was determined using ICP-MS.[Result] The order for the concentration of heavy metals in identical sampling point was Fe 〉Mn〉Ni 〉Cr,and the concentration of heavy metal in the pore water was higher than that in the surface water and the overlying water.The peak concentration value of Fe and Mn in the pore water was in the deep place of interface.The migration of Cr and Ni was complex,and the variation tendency of their concentration in pore water was consistent along with depth and the maximum value was in the place of 6-8 cm.[Conclusion] In the water system of Daming Lake,the concentration of active heavy metals was higher than that of stable heavy metals.Meanwhile,human activities had great impacts on the distribution of heav y metals in the lake. The fraction of Fe in the sediments of Daming Lake was important organic resolvent oxidant and the high concentration of dissolved oxygen made the redox boundary of Fe and Mn move down.