title: Release mechanism and kinetic exchange for phosphorus (P) in lake sediment characterized by diffusive gradients in thin films (DGT).
abstract: Diffusive gradients in thin films (DGT) technique has been newly designed for the identification of formation mechanisms of "internal phosphorus (P)-loading" and the numerical simulation of P exchange at DGT/sediment interface in Lake Dianchi. The primary mechanism was Fe-redox controlled P release from Fe-bound P in sediments, which was revealed by CDGT(P and Fe), total P (Fe) and P (Fe) fractions in NH4Cl and BD phases in sediments and their relationships at sites (N-T). The breakdown of algae biomass in the top layer of sediments at sites (O-T) and the coupled P/Fe/sulfur reactions at two depths at site N played a minor role in P release. The "internal P-loading" was calculated to be 19.23ta-1, which was 3.0% of the "entering P-loading". At sites (1-9), DGT induced flux in sediments (DIFS) model for P was used to derive curves (i) the resupply parameter (R) against deployment time and (ii) the dissolved/sorbed concentrations against the distance at DGT/sediment interface, the variation characters of which were controlled by kinetics and sediment-P pool. Sulfide microniches in sediments related to P release were evaluated by computer imaging densitometry (CID). DGT-DIFS-CID should be a reliable method to reveal P mobilization in lake sediments.
authors.affiliation: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, PR China; State Environmental Protection Key Laboratory for Lake Pollution Control, Research Center of Lake Eco-Environment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, PR China; Dongtinghu Lake Ecological Observation and Research Station (DEORS), Yueyang, Hunan Province, 41400, PR China; Yunnan Key Laboratory of Pollution Process and Management of Plateau Lake-Watershed, Kunming, Yunnan Province, 650034, PR China.
authors.forename: Zhihao
authors.initials: Z
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, PR China; State Environmental Protection Key Laboratory for Lake Pollution Control, Research Center of Lake Eco-Environment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, PR China; Dongtinghu Lake Ecological Observation and Research Station (DEORS), Yueyang, Hunan Province, 41400, PR China; Yunnan Key Laboratory of Pollution Process and Management of Plateau Lake-Watershed, Kunming, Yunnan Province, 650034, PR China. Electronic address: wangsr@craes.org.cn.
authors.forename: Shengrui
authors.initials: S
authors.lastname: Wang
keywords: Computer imaging densitometry; DGT induced flux in sediments; Diffusive gradients in thin films; Microniche; “Internal P-loading”