Details

Autor(en) / Beteiligte

• Zhou, Yanwen
• Wang, Haixiang
• Zhang, Yinlong
• Cai, Yiwei
• Yin, Hongbin
• Yang, Zhen
• Li, Qiang
• Yuan, Hezhong

Titel

Availability and diffusion kinetic process of phosphorus in the water–sediment interface assessed by the high-resolution DGT technique

Ist Teil von

• Journal of soils and sediments, 2021-10, Vol.21 (10), p.3274-3288

Ort / Verlag

Berlin/Heidelberg: Springer Berlin Heidelberg

Erscheinungsjahr

2021

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Purpose Desorption of phosphorus (P) bound to iron-containing minerals (Fe-P) is a crucial component of the eutrophication process in lakes. However, the main process and regulation mechanism of iron (Fe) and sulfur (S) on P release is little known because of a lack of in situ high-resolution data. High-resolution measurement evidence is needed to assess the availability and diffusion kinetic process of P at the water–sediment interface. Materials and methods Soluble reactive phosphate (SRP), ferrous ion (Fe 2+ ), and sulfide (S 2− ) fluxes through the water–sediment interface in a freshwater lake were detected using the novel double-sided diffusive gradients in thin films (DGT) technique. Different P forms in solid sediment were also measured using the sequential extraction procedure. The diffusion fluxes across the water–sediment interface and dynamic diffusion parameters between solid sediment and solution were calculated using the DGT-induced fluxes in sediments and soils (DIFS) model. Results and discussion There was a clear decrease of the SRP DGT , Fe 2+ DGT , and S 2− DGT fluxes from ~5 cm sediment depth to the water–sediment interface. The significant positive correlation between SRP DGT and Fe 2+ DGT fluxes in the whole profile demonstrates that Fe-P was a vitally important source of labile P in the solution phase. The significant positive fluxes of SRP DGT and Fe 2+ DGT indicated upward diffusion from the sediment particle toward the overlying water. This process further indicated the desorption and resupply of SRP and Fe 2+ from the solid sediment phase and the synergistic effect between these two parameters. In addition, a gentler decline of R curves fitted with the DIFS model was found as the sediment depths increased, which suggesting the continuous resupply process from solid phase to pore water, especially under anaerobic conditions. Conclusions The novel DGT technique in combination with DIFS analysis confirmed the considerable remobilization and transport capacity of labile P fractions including loosely adsorbed MgCl 2 -P and reductive Fe-P. These pools can diffuse from sediment particles to the interstitial and the overlying water, and can be further assimilated by organisms in shallow lacustrine ecosystem.