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首页> 外文期刊>International Journal of Environmental Research and Public Health >Effects of Hyporheic Water Fluxes and Sediment Grain Size on the Concentration and Diffusive Flux of Heavy Metals in the Streambed
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Effects of Hyporheic Water Fluxes and Sediment Grain Size on the Concentration and Diffusive Flux of Heavy Metals in the Streambed

机译：河流水通量和泥沙粒径对河床中重金属浓度和扩散通量的影响

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摘要

The hyporheic zone regulates physicochemical processes in surface-groundwater systems and can be an important source of heavy metals in fluvial systems. This study assesses the pore water concentrations and diffusive fluxes of heavy metals with respect to the vertical water exchange flux (VWEF) and sediment grain size. Water and sediment samples were collected on August 2016 from upstream Site 1 and downstream Site 2 along the Juehe River in Shaanxi Province, China. Streambed vertical hydraulic conductivity (Kv) and the VWEF were estimated via the standpipe permeameter test method and Darcy’s law. The heavy metal concentrations in the pore water were measured and the diffusive fluxes were calculated using Fick’s first law. The VWEF patterns were dominated by upward flow, and Site 1 featured higher values of Kv and VWEF. Higher Cu and Zn concentrations occurred near the channel centre with coarse sand and gravel and greater upward VWEFs because coarser sediment and greater upward VWEFs cause stronger metal desorption capacity. Additionally, Cu and Zn at the two sites generally diffused from pore water to surface water, potentially due to the upward VWEF. The VWEF and sediment grain size are likely crucial factors influencing the heavy metal concentrations and diffusive fluxes.
机译：变流带调节地表-地下水系统中的物理化学过程，并且可能是河流系统中重金属的重要来源。这项研究评估了相对于垂直水交换通量（VWEF）和沉积物粒径的孔隙水浓度和重金属的扩散通量。 2016年8月，从中国陕西省Ju河上游站点1和下游站点2收集了水和沉积物样本。通过立管渗透率测试方法和达西定律估算了河床的垂直水力传导率（Kv）和VWEF。测量了孔隙水中的重金属浓度，并使用菲克第一定律计算了扩散通量。 VWEF模式主要受向上流动的影响，而站点1的Kv和VWEF值较高。较高的Cu和Zn浓度发生在河道中心附近，且沙粒和砾石较粗，向上的VWEF较大，这是因为较粗的沉积物和较大的VWEF引起较强的金属解吸能力。此外，这两个位置的铜和锌通常可能从孔隙水扩散到地表水，这可能是由于VWEF上升所致。 VWEF和沉积物粒度可能是影响重金属浓度和扩散通量的关键因素。

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