University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water- and Waste-Management, Laboratory of Soil- and Groundwater-Management, Pauluskirchstraße 7, 42285, Wuppertal, Germany; King Abdulaziz University, Faculty of Meteorology, Environment, and Arid Land Agriculture, Department of Arid Land Agriculture, 21589, Jeddah, Saudi Arabia; University of Kafrelsheikh, Faculty of Agriculture, Department of Soil and Water Sciences, 33516, Kafr El-Sheikh, Egypt.
State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, 311300, China; Department of Soil Sciences, Faculty of Agriculture, Ain Shams University, Cairo, 11241, Egypt.
J Environ Manage. 2020 Feb 1;255:109778. doi: 10.1016/j.jenvman.2019.109778. Epub 2019 Dec 26.
Waterlogged soils and sediments contaminated with potentially toxic elements (PTEs) constitute a complicated case of degraded areas; their management requires understanding of the dynamic redox-driven PTE mobilization. Such studies about PTE redox-induced dynamics in fishpond sediments are still scarce, but of great importance concerning environmental and human health risk. We studied the redox potential (E)-induced impacts on the solubility of As, Co, Cu, Mo, Ni, Se, V, and Zn in the sediments of a fish farm in the Nile Delta, Egypt, using an automated apparatus of biogeochemical microcosm. We assessed the fate of elements as affected by the E-induced changes in pH, Fe, Mn, SO, Cl, and the dissolved aliphatic (DOC) and aromatic (DAC) organic carbon. Sediment redox ranged from -480 mV to +264 mV. Flooding the sediments caused a significant decrease in pH from 8.2 to 5.7. Dissolved concentrations of As, Co, Ni, Se, and Zn, as well as DOC, Fe, and Mn increased under the reducing acidic conditions. The release of As, Co, Ni, Se, and Zn could be attributed to the decrease of E and the subsequent decrease of pH, as well as to the increase of DOC, and/or the dissolution of Fe-Mn oxides caused by redox reactions. Dissolved concentrations of Cu, Mo, and V increased under oxic conditions and were significantly positive correlated with E, pH, DAC, and SO. This enhancement might be caused by the E-dependent increase of pH under oxic conditions (particularly for Mo and V), which also led to DAC increase. Sulfide oxidation and the release of the associated elements may have also had a contribution, particularly in the release of Cu. Therefore, the release dynamics of dissolved Cu, Mo, and V in the sediments were controlled, to a certain extent, by the changes of E/pH, DAC, and sulfur chemistry. We conclude that the biogeochemical differences in the behaviour of the studied elements under variable redox regimes substantially affected the fishponds via possible enhancement of PTE mobilization. Our work shows that the potential environmental risks related to PTE mobilization and fish food security should be taken into consideration for the management of degraded aquaculture systems and waterlogged soils and sediments.
受污染的水淹土壤和沉积物中含有潜在毒性元素 (PTE)，这构成了退化区域的一个复杂案例；其管理需要了解动态氧化还原驱动的 PTE 迁移。关于鱼塘沉积物中 PTE 氧化还原诱导动态的此类研究仍然很少，但对于环境和人类健康风险非常重要。我们使用生物地球化学微宇宙的自动仪器研究了埃及尼罗河三角洲一个养鱼场沉积物中氧化还原电位 (E) 对 As、Co、Cu、Mo、Ni、Se、V 和 Zn 溶解度的影响。我们评估了元素的命运，因为 E 引起的 pH 值、Fe、Mn、SO、Cl 和溶解的脂肪族 (DOC) 和芳香族 (DAC) 有机碳的变化会影响元素的命运。沉积物的氧化还原范围从-480 mV 到+264 mV。淹没沉积物会导致 pH 值从 8.2 显著下降到 5.7。在还原酸性条件下，As、Co、Ni、Se 和 Zn 的溶解浓度以及 DOC、Fe 和 Mn 增加。As、Co、Ni、Se 和 Zn 的释放可归因于 E 的降低和随后 pH 值的降低，以及由于氧化还原反应，DOC 的增加和/或 Fe-Mn 氧化物的溶解。在氧化条件下，Cu、Mo 和 V 的溶解浓度增加，与 E、pH、DAC 和 SO 呈显著正相关。这种增强可能是由于氧化条件下 E 依赖性 pH 值的增加（特别是对于 Mo 和 V），这也导致 DAC 增加。硫化物氧化和相关元素的释放也可能有贡献，特别是在 Cu 的释放方面。因此，沉积物中溶解 Cu、Mo 和 V 的释放动力学在一定程度上受到 E/pH、DAC 和硫化学变化的控制。我们得出结论，在可变氧化还原条件下，研究元素的生物地球化学差异极大地影响了鱼塘，可能增强了 PTE 的迁移。我们的工作表明，应考虑与 PTE 迁移和鱼类食品安全相关的潜在环境风险，以管理退化的水产养殖系统和水淹土壤和沉积物。
