CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China; University of Chinese Academy of Sciences, Beijing, China.
CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.
Environ Res. 2023 Dec 1;238(Pt 1):117135. doi: 10.1016/j.envres.2023.117135. Epub 2023 Sep 14.
Excessive nutrients in aquatic ecosystems are the main driving factors for eutrophication and water quality deterioration. However, the influence of nutrients in overlying water on sediment heavy metals is not well understood. In this study, the effects of nitrate nitrogen (NO-N) addition and phosphate addition in the overlying water on the environmental behaviors of chromium (Cr), copper (Cu), and cadmium (Cd) in coastal river sediments were investigated. Fresh estuary sediments and synthetic saltwater were used in microcosm studies conducted for 13 d. To determine the biological effect, unsterilized and sterilized treatments were considered. The results showed that the diffusion of Cr and Cu was inhibited in the unsterilized treatments with increased NO-N. However, under the NO-N sterilized treatments, Cr and Cu concentrations in the overlying water increased. This was mostly related to changes in the microbial regulation of dissolved organic carbon and pH in the unsterilized treatments. Further, in the unsterilized treatments, NO-N addition considerably increased the concentrations of the acid-soluble (Cr, Cu, and Cd increased by 5%-8%, 29%-41%, and 31%-42%, respectively) and oxidizable (Cr, Cu, and Cd increased by 10%, 5%, and 14%, respectively) fractions. Additionally, compared with that in the unsterilized treatments, Cu and Cd concentrations in P-3 treatments decreased by 7% and 63%, respectively. By producing stable metal ions, microorganisms reduced the amount of unstable heavy metals in the sediment and heavy metal concentration in the overlying water, by considerably enhancing the binding ability of phosphate and heavy metal ions. This study provides a theoretical basis for investigating the coupling mechanisms between heavy metals and nutrients.
水生态系统中过量的营养物质是富营养化和水质恶化的主要驱动因素。然而，上覆水中的营养物质对沉积物重金属的影响还不太清楚。在这项研究中，研究了上覆水中硝酸盐氮（NO-N）和磷酸盐的添加对沿海河流沉积物中铬（Cr）、铜（Cu）和镉（Cd）环境行为的影响。采用新鲜河口沉积物和合成盐水进行了为期 13 天的微宇宙研究。为了确定生物效应，考虑了未灭菌和灭菌处理。结果表明，在未灭菌处理中，随着 NO-N 的增加，Cr 和 Cu 的扩散受到抑制。然而，在 NO-N 灭菌处理下，上覆水中 Cr 和 Cu 的浓度增加。这主要与未灭菌处理中溶解有机碳和 pH 值的微生物调节变化有关。此外，在未灭菌处理中，NO-N 的添加大大增加了酸溶态（Cr、Cu 和 Cd 分别增加了 5%-8%、29%-41%和 31%-42%）和可氧化态（Cr、Cu 和 Cd 分别增加了 10%、5%和 14%）的浓度。此外，与未灭菌处理相比，P-3 处理中 Cu 和 Cd 的浓度分别降低了 7%和 63%。微生物通过产生稳定的金属离子，降低了沉积物中不稳定重金属的数量和上覆水中重金属的浓度，从而显著增强了磷酸盐和重金属离子的结合能力。这项研究为研究重金属和营养物质之间的耦合机制提供了理论依据。
