Liu Xiaozhu, Sheng Yanqing, Liu Qunqun, Jiang Ming
Key Laboratory of Coastal Zone Environmental Processes, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.
University of Chinese Academy of Sciences, Beijing, China.
Environ Monit Assess. 2022 Mar 25;194(4):297. doi: 10.1007/s10661-022-09975-w.
In this study, the impacts of dissolved oxygen (DO) on dynamics concentrations of heavy metals (Cu, Cd, Cr, and Pb) from estuary sediments were investigated in a 49-day laboratory simulation. The exchange flux method, Bureau Communautaire de Référence (BCR) sequential extraction procedure, and risk assessment code (RAC) were used to analyze the behavior of heavy metals. The results indicated that oxic environments promoted the concentrations of Cu and Cd in overlying water compared to the anoxic environments. The exchange fluxes showed that the diffusion of Cu, Cd, Cr, and Pb from sediments was the predominant process in the first 9 days, and a metastable equilibrium state was gradually reached in the later period under anoxic conditions. However, oxic conditions extended the time required to reach metastable equilibrium for Cu over the sediment-water (overlying water) interface (SWI). Although the reducible fractions of Cu, Cd, and Pb accounted for a large proportion of their total levels, the release ability of Cu, Cd, and Pb was limited by the high content of sulfide under anoxic conditions. The RAC values indicated that anoxic environments increased the proportion of acid-soluble fraction. The information obtained from this study highlights the potential risk for re-release of heavy metal from sediments under different redox conditions.
在本研究中，通过为期49天的实验室模拟，研究了溶解氧（DO）对河口沉积物中重金属（铜、镉、铬和铅）动态浓度的影响。采用交换通量法、欧盟标准物质与测量研究所（BCR）连续提取程序和风险评估代码（RAC）来分析重金属的行为。结果表明，与缺氧环境相比，有氧环境促进了上覆水中铜和镉的浓度。交换通量表明，在最初的9天里，沉积物中铜、镉、铬和铅的扩散是主要过程，在缺氧条件下后期逐渐达到亚稳态平衡。然而，有氧条件延长了铜在沉积物-水（上覆水）界面（SWI）达到亚稳态平衡所需的时间。尽管铜、镉和铅的可还原部分占其总量的很大比例，但在缺氧条件下，铜、镉和铅的释放能力受到高含量硫化物的限制。RAC值表明，缺氧环境增加了酸溶部分的比例。本研究获得的信息突出了在不同氧化还原条件下沉积物中重金属再次释放的潜在风险。
