Interdisciplinary Science Department, Saint Vincent College, 300 Fraser-Purchase Rd., Latrobe, PA 15650, USA.
Interdisciplinary Science Department, Saint Vincent College, 300 Fraser-Purchase Rd., Latrobe, PA 15650, USA.
Sci Total Environ. 2022 Apr 1;815:152672. doi: 10.1016/j.scitotenv.2021.152672. Epub 2021 Dec 27.
Hydrous ferric-oxide (HFO) coatings on streambed sediments may attenuate dissolved phosphate (PO) concentrations at acidic to neutral pH conditions, limiting phosphorus (P) transport and availability in aquatic ecosystems. Mesh-covered tiles on which "natural" HFO from abandoned mine drainage (AMD) had precipitated were exposed to treated municipal wastewater (MWW) effluent or a mixture of stream water and effluent. Between 42 and 99% of the dissolved P in effluent was removed from the water to a thin coating (~2 μm) of HFO on the mesh. Geochemical equilibrium model results predicted the removal of 76 to 99% of PO from the water by adsorption to the HFO, depending on the HFO quantity, initial PO concentration, and pH. The measurements and model results indicated the capacity for P removal decreased as the concentration of P associated with the HFO increased. Continuing accumulation of HFO from upstream AMD sources replenish the in-stream capacity for P attenuation below the MWW discharge. This indicates AMD pollution may conceal P inputs and limit the amount of dissolved P transported to downstream ecosystems. However, HFO-rich sediments also represent a potential source of "legacy" P that could confound management practices intended to decrease nutrient and metal loadings.
水铁矿（HFO）覆盖在河床沉积物上，可能会在酸性到中性 pH 条件下降低溶解态磷酸盐（PO）的浓度，从而限制磷（P）在水生生态系统中的迁移和可用性。覆盖有网眼的瓷砖上沉淀了来自废弃矿山排水（AMD）的“天然”HFO，将这些瓷砖暴露在处理后的城市污水（MWW）流出物或溪流和流出物的混合物中。流出物中高达 99%的溶解态 P 被去除到网眼上的 HFO 薄涂层（约 2μm）中。地球化学平衡模型的结果预测，通过吸附到 HFO 上，PO 的去除率为 76%至 99%，具体取决于 HFO 的数量、初始 PO 浓度和 pH。测量结果和模型结果表明，随着与 HFO 相关的 P 浓度的增加，P 去除能力下降。来自上游 AMD 源的 HFO 的持续积累补充了 MWW 排放点以下溪流中 P 衰减的能力。这表明 AMD 污染可能掩盖了 P 的输入，并限制了输送到下游生态系统的溶解态 P 的数量。然而，富含 HFO 的沉积物也代表了“遗留”P 的潜在来源，这可能会干扰旨在减少营养物和金属负荷的管理实践。
