Division of Soil and Water Management, Department of Earth and Environmental Sciences, KU Leuven, Kasteelpark Arenberg 20 Bus 2459, 3001, Leuven, Belgium.
Soil Service of Belgium, Willem De Croylaan 48, 3001, Heverlee, Belgium.
J Environ Manage. 2023 Apr 15;332:117396. doi: 10.1016/j.jenvman.2023.117396. Epub 2023 Feb 3.
Glauconite sands (GS) are abundantly available iron (Fe)-rich minerals that are efficient in lowering the release of phosphorus (P) from sediments to the overlying water. Many river sediments are, however, net sinks for P rather than sources and it is unclear if these GS minerals also enhance the P uptake from water. This is because the concentration of Fe(III) minerals at the sediment-water interface (SWI) depends on the redox potential that is affected by physicochemical processes. This study was set-up to investigate if a sediment amendment with GS can both lower P release from the sediment and enhance P uptake from the overlying water. The P fluxes across the SWI were compared between GS-amended (added at 10% weight fraction) and non-amended river sediment in static (incubation) and dynamic (flume) systems. The net P uptake was measured in response to a pulse external P loading (0.5-5 mg P L). Sodium glutamate was added to all treatments to simulate water with a high oxygen demand. Before the P pulse, the GS-amended sediments released significantly less P to the overlying water than the non-amended sediments in both static as dynamic systems. Spiking the water reverted the net P flux over the SWI only in the dynamic system, and the net P uptake in the sediment was factor two larger in GS-amended sediment compared to the non-amended sediment. This study showed that GS addition not only reduced internal P release, but also enhanced P uptake from the overlying water. However, the long-term efficiency in streams likely decreases over time due to saturation processes.
铁蒙脱石砂（GS）是一种富含铁（Fe）的矿物质，可有效降低磷（P）从沉积物向水体释放。然而，许多河流沉积物是磷的净汇而不是源，目前尚不清楚这些 GS 矿物质是否也能促进水体中磷的吸收。这是因为沉积物-水界面（SWI）处的三价铁（Fe(III)）矿物的浓度取决于受物理化学过程影响的氧化还原电位。本研究旨在探究将 GS 沉积物添加到沉积物中是否既能降低沉积物中磷的释放，又能促进水体中磷的吸收。通过静态（培养）和动态（水槽）系统，比较了添加 GS（添加 10%重量分数）和未添加 GS 的河流水体中 SWI 两侧的磷通量。在响应外部磷脉冲（0.5-5mg P L）时，测量了净磷吸收。向所有处理中添加谷氨酸钠以模拟高需氧量的水。在磷脉冲之前，在静态和动态系统中，添加 GS 的沉积物向水体中释放的磷明显少于未添加 GS 的沉积物。在动态系统中，仅通过向水中添加 GS 就可以使 SWI 上的净磷通量反转，与未添加 GS 的沉积物相比，添加 GS 的沉积物中净磷吸收量增加了一倍。本研究表明，GS 添加不仅减少了内部磷的释放，而且还增强了对水体中磷的吸收。然而，由于饱和过程，GS 长期添加到溪流中的效率可能会随时间降低。
