Savannah River Ecology Lab, University of Georgia, Aiken, South Carolina, USA.
Warnell School of Forestry and Natural Resources, University of Georgia, Aiken, South Carolina, USA.
Environ Toxicol Chem. 2023 Dec;42(12):2726-2736. doi: 10.1002/etc.5745. Epub 2023 Oct 18.
Sediments in aquatic systems often act as a major sink for contaminants. Diffusive gradient in thin films (DGTs) and in situ equilibrium dialysis samplers (peepers) are two major in situ pore water sampling devices that overcome the problems associated with conventional pore water sampling methods. In the present study, DGTs and peepers were used to study the spatial and seasonal effects (cool months, October-February; warm months, May-September) on metal bioavailability in the H-02 constructed wetland and the sink versus source role of the sediments by calculating the metal resupply capacity. Data showed similar seasonal trends in metal concentrations using passive samplers, peepers, and DGTs. Pooled Cu and Zn concentrations measured using DGTs were lower in warm months (1.67 ± 1.50 and 2.62 ± 0.68 μg L , respectively, p < 0.001) versus in cool months (2.12 ± 0.65 and 5.58 ± 1.33 μg L , respectively, p < 0.001; mean ± 95% confidence interval). Sulfate (SO ) concentrations were significantly (p = 0.0139) lower in warm months (averaged at 0.22 ± 0.05 mg L ) compared to in cool months (0.16 ± 0.05 mg L ). The increase in SO concentration is an indicator of the lower activity of sulfate-reducing bacteria, which need SO during anaerobic respiration, in which SO is reduced to sulfide (S ) that forms insoluble salts with Cu and Zn, which could partially explain the higher bioavailability of these metals in the cool season. Metal resupply capacity of the sediments was mostly <0.2 for Cu and Zn. Taken together, the H0-2 wetland sediments mostly acted as a sink to both Cu and Zn over the course of the present study. Environ Toxicol Chem 2023;42:2726-2736. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
水生系统中的沉积物通常是污染物的主要汇。扩散梯度薄膜（DGT）和原位平衡透析采样器（窥视器）是两种主要的原位孔隙水采样装置，克服了传统孔隙水采样方法相关的问题。在本研究中，使用 DGT 和窥视器研究了金属生物有效性的空间和季节性效应（冷季，10 月至 2 月；暖季，5 月至 9 月）在 H-02 人工湿地中的作用，以及通过计算金属补给能力，研究沉积物的汇源作用。数据显示，使用被动采样器、窥视器和 DGT 测量的金属浓度具有相似的季节性趋势。使用 DGT 测量的 Cu 和 Zn 浓度在暖季（分别为 1.67±1.50 和 2.62±0.68μg/L，p<0.001）比在冷季（分别为 2.12±0.65 和 5.58±1.33μg/L，p<0.001；平均值±95%置信区间）低。硫酸盐（SO ）浓度在暖季（平均为 0.22±0.05mg/L）显著低于冷季（0.16±0.05mg/L）（p=0.0139）。SO 浓度的增加表明硫酸盐还原菌的活性较低，硫酸盐还原菌在厌氧呼吸过程中需要 SO ，其中 SO 被还原为硫化物（S ），S 与 Cu 和 Zn 形成不溶性盐，这可以部分解释这些金属在冷季的较高生物可利用性。沉积物的金属补给能力对于 Cu 和 Zn 主要为<0.2。综上所述，在本研究过程中，H0-2 湿地沉积物主要对 Cu 和 Zn 表现为汇。
