title: Responses in sediment phosphorus and lanthanum concentrations and composition across 10 lakes following applications of lanthanum modified bentonite.
abstract: A combined field and laboratory scale study of 10 European lakes treated between 2006 and 2013 with a lanthanum (La) modified bentonite (LMB) to control sediment phosphorus (P) release was conducted. The study followed the responses in sediment characteristics including La and P fractions and binding forms, P adsorption capacity of discrete sediment layers, and pore water P concentrations. Lanthanum phosphate mineral phases were confirmed by solid state (31)P MAS NMR and LIII EXAFS spectroscopy. Rhabdophane (LaPO4 · nH2O) was the major phase although indications of monazite (LaPO4) formation were also reported, in the earliest treated lake. Molar ratios between La and P in the sediments were generally above 1, demonstrating excess La relative to P. Lanthanum was vertically mixed in the sediment down to a depth of 10 cm for eight of the ten lakes, and recovery of La in excess of 100% of the theoretical aerial load indicated translocation of the LMB towards the deepest areas of the lakes. Lanthanum was generally recovered from bed sediment samples following sequential chemical extraction from the HCl fraction. Soluble reactive P (SRP) release experiments on intact sediment cores indicated conditions of P retention (with the exception of two lakes) by sediments, indicating effective control of sediment P release, i.e. between two and nine years after treatment.
authors.affiliation: Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark; Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark.
authors.forename: Line
authors.initials: L
authors.lastname: Dithmer
authors.affiliation: Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark.
authors.forename: Ulla Gro
authors.initials: UG
authors.lastname: Nielsen
authors.affiliation: Aquatic Ecology & Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands.
authors.forename: Miquel
authors.initials: M
authors.lastname: Lürling
authors.affiliation: Centre for Ecology & Hydrology, Penicuik, Midlothian, Scotland EH26 0QB, UK.
authors.forename: Bryan M
authors.initials: BM
authors.lastname: Spears
authors.affiliation: Institut Dr. Nowak, Mayenbrook 1, D-28870 Ottersberg, Germany.
authors.forename: Said
authors.initials: S
authors.lastname: Yasseri
authors.affiliation: Department of Chemistry and Biotechnology, Swedish University of Agricultural Sciences, P.O. Box 7015, SE-750 07 Uppsala, Sweden.
authors.forename: Daniel
authors.initials: D
authors.lastname: Lundberg
authors.affiliation: Centre for Ecology & Hydrology, Penicuik, Midlothian, Scotland EH26 0QB, UK.
authors.forename: Alanna
authors.initials: A
authors.lastname: Moore
authors.affiliation: Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark.
authors.forename: Nicholai D
authors.initials: ND
authors.lastname: Jensen
authors.affiliation: Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark. Electronic address: reitzel@biology.sdu.dk.
authors.forename: Kasper
authors.initials: K
authors.lastname: Reitzel
mesh_terms: D001546:Bentonite / Q000737:chemistry; D019015:Geologic Sediments / Q000737:chemistry; D060106:Lakes / Q000737:chemistry*; D007811:Lanthanum / Q000737:chemistry; D010758:Phosphorus / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry
chemical_list: D014874:Water Pollutants, Chemical; D001546:Bentonite; D010758:Phosphorus; D007811:Lanthanum
keywords: 31P NMR; Dissolved organic carbon (DOC); EXAFS; Full scale; Lake restoration; Lanthanum; Lanthanum modified bentonite; P sequestration