Interception of sedimentary phosphorus release by iron-modified calcite capping
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SEDIMENTS, SEC 5 • SEDIMENT MANAGEMENT • RESEARCH ARTICLE
Interception of sedimentary phosphorus release by iron-modified calcite capping Xiaoyun Bai 1 & Jianwei Lin 1 & Zhibin Zhang 2 & Boyang Liu 3 & Yanhui Zhan 1 & Dazhu Hu 4 Received: 11 June 2020 / Accepted: 13 August 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Purpose The main aim of this work was to determine the efficiency and mechanism of iron (Fe)-modified calcite (FMCA) capping for preventing the release of phosphorus (P) from sediments. Methods The performance of phosphate removal by FMCAs with different iron loading amounts was investigated using batch experiments, the mechanism for the phosphate removal by FMCA was explored by X-ray photoelectron spectroscopy, and the effect of FMCA capping on P mobilization in sediments at various depths was studied using high-resolution dialysis and diffusive gradient in thin films (DGT). Results FMCA possessed better phosphate adsorption ability for aqueous phosphate than raw calcite, and the phosphate removal efficiency of FMCA increased with its loading amount of Fe. The replacement of Fe-bound hydroxyl groups with phosphate anions to the inner-sphere surface complexes and the precipitation of calcium phosphate were vital to the sorption of phosphate onto FMCA. FMCA capping could effectively inhibit the release of soluble reactive P (SRP) and labile P monitored by DGT (DGT-P) from sediment to the overlying water. The decrease of DGT-P and pore water SRP in the top sediment layer is very important for the control of sediment-P release into the overlying water. FMCA capping caused reductions of the concentrations of Fe2+ and labile Fe monitored by DGT in the overlying water and the top sediment, suggesting a low risk of Fe releasing from the FMCA capping layer. Conclusion Iron-modified calcite has the potential to be an active capping material to suppress sedimentary P release. Keywords Iron-modified calcite . Sediment . Phosphorus . Release . Interception
1 Introduction Phosphorus (P) is identified to be a primary limiting nutrient driving the growth of harmful algae in freshwater bodies such Responsible editor: Shiming Ding * Jianwei Lin [email protected] 1
College of Marine Ecology and Environment, Shanghai Ocean University, Hucheng Ring Road No. 999, Shanghai 201306, People’s Republic of China
2
School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan 250101, People’s Republic of China
3
College of Ocean Science and Engineering, Shanghai Maritime University, Shanghai 201306, People’s Republic of China
4
Department of Civil Engineering, Shanghai Institute of Technology, Shanghai 201418, People’s Republic of China
as lakes, reservoirs, and ponds, and excessive P loading from the internal source (IPS, i.e., sediment) is recognized as an important cause of eutrophication in these freshwater bodies when P input from external P sources such as municipal wastewater and rain runoff is effectively controlled (Schindler et al. 2008; Némery and Garnier
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