南四湖表层沉积物重金属的赋存形态及底部界面扩散通量的估算  

CHEMICAL FORMS OF THE HEAVY METALS IN SURFACE SEDIMENT FROM NANSIHU LAKE AND THEIR DIFFUSION FLUX AT THE SEDIMENT-WATER INTERFACE

作　　者：刘恩峰[1] 沈吉[1] 王建军[1] 袁和忠[1] 

机构地区：[1]中国科学院南京地理与湖泊研究所,湖泊与环境国家重点实验室,南京210008

出　　处：《环境化学》2010年第5期870-874,共5页Environmental Chemistry

基　　金：国家自然科学基金(40702058);中国科学院南京地理与湖泊研究所所长基金项目资助

摘　　要：采用"SOFIE"模拟装置,研究了南四湖污染程度不同的两个湖区(南阳湖及独山湖区)表层沉积物中重金属元素的形态组成,间隙水及界面上覆水中重金属浓度的变化特征.结果表明,南阳湖区沉积物间隙水及界面上覆水中Cr,Cu,Ni,Zn和Pb的浓度均高于独山湖区,这与沉积物中重金属元素的有效结合态含量变化一致,主要与人为污染有关.南阳湖及独山湖区沉积物-水界面±0.5 cm范围内重金属元素具有较高的浓度梯度,间隙水中Fe与Mn浓度明显高于界面上覆水;Cu,Ni,Zn,Pb的浓度均低于界面上覆水;独山湖区沉积物间隙水中Cr浓度与界面上覆水相似,而南阳湖区沉积物间隙水中Cr浓度略高于界面上覆水.采用Fick第一定律,计算得到南阳湖及独山湖区沉积物-水界面附近Cu,Ni,Zn,Pb的扩散通量,分别为-0.23,-1.47,-2.57,-0.04 mmol.m-.2d-1和-0.34,-0.67,-0.48,-0.01 mmol.m-.2d-1,沉积物表现为重金属元素的"汇";而Cr的扩散通量分别为0.03 mmol.m-.2d-1和-0.02 mmol.m-.2d-1,说明污染较重的南阳湖区沉积物中Cr已表现出向上覆水体扩散的特征.The chemical forms of Fe,Mn,Cr,Cu,Ni,Zn and Pb in the surface sediments from the Nanyang lake area and Dushan lake area of Nansihu lake were determined.The variation characteristics for the heavy metals at the sediment-water interface were presented by the SOFIE device.The heavy metal concentrations in the porewater and overlying water of Nanyang lake were higher than that in the Dushan lake,and it is consistent with the content of extractable fractions of the heavy metals,which should be influenced by the human contamination.Concentration gradient for the metals was high at the ±0.5cm of the sediment-water interface.High concentrations of Fe and Mn was found in the porewater,and that of Cu,Ni,Zn,Pb was found in the overlying water.The concentration gradient for Cr in the porewater and overlying water in Dushan lake was low,and it was generally higher in Nanyang lake.The diffusion fluxes for Cu,Ni,Zn,Pb calculated by the Fick′s First Law of Diffusion were-0.23,-1.47,-2.57,-0.04 mmol·m^-2·d^-1 and-0.34,-0.67,-0.48,-0.01 mmol·m^-2·d^-1 respectively,indicating that the sediment acted as the sink of the metals.The diffusion flux was-0.02 mmol·m^-2·d^-1 for Cr in Dushan lake,and it was 0.03 mmol·m^-2·d^-1 in Nanyang lake,suggesting that the sediment worked as the source of Cr.

关 键 词：重金属 沉积物-水界面 扩散通量 南四湖 

分 类 号：X524[环境科学与工程—环境工程]