title: Bioavailable phosphorus (P) reduction is less than mobile P immobilization in lake sediment for eutrophication control by inactivating agents.
abstract: Phosphorus (P) immobilization by inactivating agents in the sediment of eutrophic lakes to reduce immediately available P in lake water is often crucial for mitigating nuisance eutrophication symptoms, such as cyanobacterial blooms. Macrophytes and phytoplankton, however, can directly utilize P from the sediment for growth. Accordingly, a comprehensive analysis of the P bioavailability in lake sediment amended with two promising P-inactivation agents, namely Phoslock®and drinking water treatment residue (DWTR), was investigated in both short- and long-term studies (20 and 180 d). Phosphorus-availability was assessed using six chemical extraction methods and Hydrilla verticillata and Microcystis aeruginosa growth tests. The results showed that Phoslock®and DWTR significantly reduced mobile P (NH4Cl and Na2S2O4/NaHCO3extractable P) in lake sediment, while P bioavailability that was assessed by different methods showed considerable deviations. Interestingly, appropriate bioavailable P chemical extraction methods were determined based on linear correlation analysis, and further comparison indicated that reduction of bioavailable P by DWTR (<55% for macrophyte available P) and Phoslock®(<17% for cyanobacteria available P) were clearly less than the mobile P immobilization (>75%) at recommended dosages, which was probably caused by the capability of macrophyte and cyanobacteria to utilize various fractions of P (except the residual P) in amended sediment under proper illumination. Therefore, DWTR and Phoslock®can effectively reduce P release from lake sediment, but the potential bioavailable P may pose uncertainties for eutrophication control in lakes that typically have regular sediment re-suspension. Overall, an evaluation of the bioavailable P pool in the lake ecosystem should be essential for successful lake geo-engineering.
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Changhui
authors.initials: C
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; College of Biology and Environment, Nanjing Forestry University, Nanjing 210037, China.
authors.forename: Rui
authors.initials: R
authors.lastname: He
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; College of Biology and Environment, Nanjing Forestry University, Nanjing 210037, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Aquatic Ecology & Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands; Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), P.O. Box 50, 6700 AB Wageningen, The Netherlands.
authors.forename: Miquel
authors.initials: M
authors.lastname: Lürling
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Haiyuan
authors.initials: H
authors.lastname: Cai
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China. Electronic address: hljiang@niglas.ac.cn.
authors.forename: He-Long
authors.initials: HL
authors.lastname: Jiang
authors.affiliation: College of Biology and Environment, Nanjing Forestry University, Nanjing 210037, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
mesh_terms: D005068:Eutrophication; D019015:Geologic Sediments / Q000737:chemistry; D060106:Lakes / Q000737:chemistry*; D010758:Phosphorus; D010839:Phytoplankton
chemical_list: D010758:Phosphorus
keywords: Bioavailability; Eutrophication; Lake; Phosphorus-inactivation agents