title: High-resolution imaging of labile phosphorus and its relationship with iron redox state in lake sediments.
abstract: A thorough understanding of the labile status and dynamics of phosphorus (P) and iron (Fe) across the sediment-water interface (SWI) is essential for managing internal P release in eutrophic lakes. Fe-coupled inactivation of P in sediments is an important factor which affects internal P release in freshwater lakes. In this study, two in-situ high-resolution diffusive gradients in thin films (DGT) techniques, Zr-Oxide DGT and ZrO-Chelex DGT, were used to investigate the release characteristics of P from sediments in a large freshwater lake (Dongting Lake, China; area of 2691 km2) experiencing a regional summer algal bloom. Two-dimensional distributions of labile P in sediments were imaged with the Zr-Oxide DGT without destruction of the original structure of the sediment layer at four sites of the lake. The concentration of DGT-labile P in the sediments, ranging from 0.007 to 0.206 mg L-1, was highly heterogeneous across the profiles. The values of apparent diffusion flux (Fd) and release flux (Fr) of P varied between -0.027-0.197 mg m-2d-1and 0.037-0.332 mg m-2d-1, respectively. Labile P showed a high and positive correlation (p < 0.01) with labile Fe(II) in the profiles, providing high-resolution evidence for the key role of Fe-redox cycling in labile P variation in sediments.
authors.affiliation: Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China; Sino-Danish Center for Education and Research, Denmark.
authors.forename: Yulu
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China; Sino-Danish Center for Education and Research, Denmark. Electronic address: liangt@igsnrr.ac.cn.
authors.forename: Tao
authors.initials: T
authors.lastname: Liang
authors.affiliation: Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China; Sino-Danish Center for Education and Research, Denmark.
authors.forename: Shuhan
authors.initials: S
authors.lastname: Tian
authors.affiliation: Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China.
authors.forename: Lingqing
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark; Sino-Danish Center for Education and Research, Denmark.
authors.forename: Peter E
authors.initials: PE
authors.lastname: Holm
authors.affiliation: Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark; Sino-Danish Center for Education and Research, Denmark.
authors.forename: Hans Christian
authors.initials: HC
authors.lastname: Bruun Hansen
mesh_terms: D002681:China; D004058:Diffusion; D004784:Environmental Monitoring / Q000379:methods*; D005068:Eutrophication; D019015:Geologic Sediments / Q000737:chemistry*; D007501:Iron / Q000032:analysis* / Q000737:chemistry; D060106:Lakes / Q000737:chemistry*; D010084:Oxidation-Reduction; D010758:Phosphorus / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D014874:Water Pollutants, Chemical; D010758:Phosphorus; D007501:Iron
keywords: DGT; High resolution; Iron; Phosphorus; Sediment-water interface