Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China; College of Engineering, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
Key Laboratory of Integrated Regulation and Resources Development of Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China.
Sci Total Environ. 2020 Jul 1;724:138204. doi: 10.1016/j.scitotenv.2020.138204. Epub 2020 Mar 28.
The deterioration of reservoirs in southern China due to the kinetics of Iron (Fe), Phosphorus (P) and sulphide (S) at the sediment-water interface (SWI) is a major problem that needs urgent attention. Studies on the biogeochemistry of Fe, P, and S using high-resolution profile techniques in reservoirs in this region are limited. The diffusive gradient in thin films (DGT) technique, high-resolution dialysis, DGT-computer imaging densitometry (CID), DGT-induced fluxes in sediments (DIFS) and planar optode (PO) device were used to describe the dynamics Fe-P-S in SWI during hypoxia. The results showed the release of Fe-P-S in SWI was due to sulfate reduction and iron reduction influenced greatly by hypoxia. Positive apparent fluxes were recorded indicating that the sediments release Fe-P-S to the overlying water. High positive correlations (r > 0.7) for DGT-labile Fe and DGT-labile P in sediments revealed that iron-bound P controlled the release of P at SWI during reductive dissolution. The low correlation between DGT-labile Fe and DGT-labile S (r < 0.4) disclosed the combative nature between sulfate reduction and iron reduction process. The low correlation occurred because of the co-precipitation between Fe and S, forming black materials such as monosulfide (FeS) and pyrite (FeS) in a hypoxic environment. The DIFS model showed the resupply ability (R-values) of P in sediments belonged to the partially sustained case with a steady state case of resupply at TB3 (Tc = 1088s, Kd = 1005.61 cm/g R = 0.72, K = 0.19 day) and TB4 (Tc = 712 s, Kd = 712.53 cm/g, R = 0.78, K = 0.46 day). The resupply rate belonged to the non-steady state case at TB1 (Tc = 10,990 s, Kd = 396.3 cm/g, R = 0.35, K = 0.07 day) and TB2 (Tc = 6097 s, Kd = 578.5 cm/g, R = 0.45, K = 0.10 day). The DGT-CID-PO-DIFS provided a deep insight on the mechanism of Fe-P-S and remobilization of P at SWI leading to Blackwater events and eutrophication.
中国南方水库中由于铁（Fe）、磷（P）和硫化物（S）在沉积物-水界面（SWI）处的动力学而导致的恶化是一个需要紧急关注的主要问题。在该地区的水库中，使用高分辨率剖面技术对 Fe、P 和 S 的生物地球化学进行研究的研究很少。使用薄膜扩散梯度（DGT）技术、高分辨率透析、DGT-计算机成像密度计（CID）、DGT 诱导的沉积物通量（DIFS）和平面光学位（PO）装置来描述缺氧条件下 SWI 中 Fe-P-S 的动力学。结果表明，SWI 中 Fe-P-S 的释放是由于硫酸盐还原和铁还原的影响，而缺氧的影响很大。记录到正的表观通量表明沉积物将 Fe-P-S 释放到上覆水中。沉积物中 DGT-不稳定 Fe 和 DGT-不稳定 P 之间存在高度正相关（r>0.7），表明在还原性溶解过程中，铁结合的磷控制着 P 的释放。DGT-不稳定 Fe 和 DGT-不稳定 S 之间的相关性低（r<0.4）表明硫酸盐还原和铁还原过程之间存在竞争性。低相关性的发生是由于 Fe 和 S 之间的共沉淀，在缺氧环境中形成了单硫化物（FeS）和黄铁矿（FeS）等黑色物质。DIFS 模型表明沉积物中 P 的再供应能力（R 值）属于部分维持的情况，在 TB3（Tc=1088s，Kd=1005.61cm/g R=0.72，K=0.19 天）和 TB4（Tc=712s，Kd=712.53cm/g，R=0.78，K=0.46 天）达到稳定状态。TB1（Tc=10990s，Kd=396.3cm/g，R=0.35，K=0.07 天）和 TB2（Tc=6097s，Kd=578.5cm/g，R=0.45，K=0.10 天）的再供应率属于非稳态情况。DGT-CID-PO-DIFS 深入了解了 Fe-P-S 的机制以及 SWI 处 P 的再移动导致黑水事件和富营养化的机制。
