Effect of external and internal loading on source-sink phosphorus dynamics of river sediment amended with iron-rich glauconite sand

• DOI: 10.1016/j.jenvman.2023.117396
• Publication Date: 2023-02-03T11:23:38Z
• Authors: Lei Xia; Mieke Verbeeck; Benoit Bergen; Erik Smolders
• Keywords: Geologic Sediments; Fe-rich glauconite sand; Iron; 0207 environmental engineering; Environmental Sciences & Ecology; 02 engineering and technology; Rivers; Sand; QUALITY; Phosphorus dynamics; LOSSES; RELEASE; Minerals; Science & Technology; Hydrodynamic disturbance; LAKE SEDIMENT; Water; Phosphorus; 6. Clean water; Lakes; Static incubation; IMMOBILIZATION; 13. Climate action; ZEOLITE; Sediment; BIOAVAILABLE PHOSPHORUS; Life Sciences & Biomedicine; WATER TREATMENT RESIDUALS; Environmental Sciences; Water Pollutants, Chemical

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-1). 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.