再悬浮扰动对巢湖沉积物重金属元素释放的影响

Effect of resuspension disturbance on the release of heavy metal from sediments in Chaohu Lake

文章使用Y型再悬浮装置探究在不同扰动强度和持续时间条件下,巢湖底泥沉积物再悬浮对上覆水体理化性质及重金属元素释放的影响。研究发现:沉积物再悬浮过程中,南淝河入湖区与西湖心的悬浮颗粒物质量浓度、pH值和溶解氧(dissolved oxygen, DO)均与物理扰动的强度、时间有关;南淝河入湖区上覆水体中Cr、Cu、Ni、Zn、Pb、Hg、As的质量浓度整体随水体流速和颗粒物悬浮时间的增加逐渐增大,Hg、Pb和Cu水溶态质量浓度在垂向分布上随水体深度增加而逐渐增大;西湖心上覆水体中Zn、Ni、Hg、As、Pb和Cr的质量浓度在扰动实验的初期迅猛上升至峰值,但后期逐渐下降并趋于稳定,且在垂向上分布均匀。通过分析释放通量发现,南淝河入湖区与西湖心上覆水体表层、中层和深层的溶解态重金属元素释放量并不是持续增长的,但可推断由于再悬浮进入上层水体的沉积物颗粒中重金属元素污染物含量比底泥中更高。

The Y-type resuspension device was used to explore the effect of sediments resuspension on the physical and chemical properties of the overlying water and the release of heavy metals in Chaohu Lake under different disturbance intensity and duration conditions. In the process of resuspension, the content of suspended particulate matter, pH, and dissolved oxygen(DO) at the inlet area of the Nanfei River and the center of the western lake were all related to the intensity and duration of physical disturbance. The content of heavy metals(Cr, Cu, Ni, Zn, Pb, Hg, As) in the overlying water at the inlet area of the Nanfei River increased gradually with the increase of the disturbance time and frequency, and the concentration of Hg, Pb and Cu increased with the depth of the water in the vertical distribution. The content of Zn, Ni, Hg, As, Pb and Cr in the overlying water at the center of the western lake rose rapidly to the peak at the initial stage of disturbance experiment, and then gradually decreased and stabilized, showing a uniform distribution in the vertical direction. Results of resuspension fluxes showed that the release of dissolved heavy metals in the surface, middle and deep layers of the overlying water at the inlet area of the Nanfei River and the center of the western lake did not increase continuously. However, it can be inferred that the sediment resuspended into the overlying water may contain more heavy metal pollutants than the bottom sediment.