湖泊沉积物-水界面微量重金属扩散作用及其水质影响研究

Study on Trace Heavy Metal Diffusion at Sediment water Interface and Its Effects on Overlying Lake Water Quality *

通过对云南泸沽湖、洱海沉积物孔隙水微量重金属剖面特征及界面扩散通量的研究，定量评估了微量重金属界面扩散作用对上覆湖水水质的影响，并探讨了其季节性变化规律．结果表明，孔隙水微量重金属浓度剖面均呈典型的峰形分布，界面氧化还原状况的变化是影响这种分布的主要因素；微量重金属界面扩散通量在夏季明显大于冬季，深水区大于浅水区；这种扩散作用对湖水中微量重金属含量的变化影响较大，尤其对深度较小、水体寄宿时间长、重金属含量低的湖泊，界面扩散作用更是控制水质的关键因素．

Based on the research of the vertical profiles of Fe,Mn,Cu,Ni,Cd and Pb in pore water and calculation of their diffusive fluxes from the sediment to its overlying water in Lugu and Erhai Lake in Yunnan Province,the author quantitatively evaluated the influence of trace heavy metal diffusion on the overlying water,and discussed the seasonal changes of the diffusion.The results showed that the concentration profiles of trace heavy metals in pore water are typical peakshape,whick is mainly controlled by the changes of redox state near the interface,and their diffusive fluxes are significantly higher in summer than in winter,at deeper stations than at shallower ones,and the diffusion near the interface significantly affects the concentration of trace heavy metals in overlying water,and is one of the most important factors controlling the water quality for the lakes which have less depth,longer resident time and lower concentration of heavy metals.