title: Reduction of sediment internal P-loading from eutrophic lakes using thermally modified calcium-rich attapulgite-based thin-layer cap.
abstract: We conducted a laboratory evaluation of a low-cost P-capping agent-700°C-heated natural calcium-rich attapulgite (NCAP700)-in terms of its ability to reduce internal P-loading in lake sediments. Batch studies indicated that NCAP700 could effectively reduce sediment mobile P (P mobile) in various types of lake sediment, and the dosage equation required to immobilize P mobile was developed accordingly. The equation was then applied to a laboratory incubation study on intact sediment cores. The results indicated that the NCAP700-based thin-layer cap can enhance the redox potential (Eh), pH and dissolved oxygen (DO) in surface sediment. However, this enhancing effect was decreased with increasing time. P fluxes and the concentration of P in overlying water and pore water from sediment could be effectively inhibited under anaerobic conditions. P fractionation analysis indicated that 34.5% of P mobile was bound in the upper 2 cm sediment layer during a 40-day remediation period, but this only exerted a minor influence on the P mobile in the 2-4 cm sediment layer. P immobilization by NCAP700 was mainly achieved through transformation of P mobile to stable Ca-P. These results indicate that NCAP700 can be used for lake eutrophication control by means of thin-layer capping.
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, 210008 Nanjing, China. Electronic address: hbyin@niglas.ac.cn.
authors.forename: Hongbin
authors.initials: H
authors.lastname: Yin
authors.affiliation: Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection, 8 Jiangwangmiao Street, 210042 Nanjing, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Kong
mesh_terms: D002118:Calcium / Q000737:chemistry; D005068:Eutrophication; D019015:Geologic Sediments / Q000737:chemistry*; D060106:Lakes / Q000737:chemistry*; D017616:Magnesium Compounds / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D010758:Phosphorus / Q000737:chemistry*; D017655:Silicon Compounds / Q000737:chemistry; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D017616:Magnesium Compounds; D017655:Silicon Compounds; D014874:Water Pollutants, Chemical; D014867:Water; D010758:Phosphorus; D010100:Oxygen; D002118:Calcium; C026325:attapulgite
keywords: 700°C-heated natural calcium-rich attapulgite (NCAP700); Lake eutrophication control; Sediment-mobile P (P(mobile)); Thin-layer capping