Responses in sediment phosphorus and lanthanum concentrations and composition across 10 lakes following applications of lanthanum modified bentonite

WATER RESEARCH

卷:97

Article

Dithmer, Line^1,2  Nielsen, Ulla Gro¹  Lurling, Miquel³  Spears, Bryan M.⁴  Yasseri, Said⁵  Lundberg, Daniel⁶  Moore, Alanna⁴  Jensen, Nicholai D.¹  Reitzel, Kasper² 

[1] Univ Southern Denmark, Dept Phys Chem & Pharm, Campusvej 55, DK-5230 Odense M, Denmark

[2] Univ Southern Denmark, Dept Biol, Campusvej 55, DK-5230 Odense M, Denmark

[3] Wageningen Univ, Dept Environm Sci, Aquat Ecol & Water Qual Management Grp, POB 47, NL-6700 AA Wageningen, Netherlands

[4] Ctr Ecol & Hydrol, Penicuik EH26 0QB, Midlothian, Scotland

[5] Inst Dr Nowak, Mayenbrook 1, D-28870 Ottersberg, Germany

[6] Swedish Univ Agr Sci, Dept Chem & Biotechnol, POB 7015, SE-75007 Uppsala, Sweden

关键词: Lake restoration;    Dissolved organic carbon (DOC);    31P NMR;    Lanthanum;    P sequestration;    EXAFS;    Full scale;    Lanthanum modified bentonite;   

DOI  :  10.1016/j.watres.2016.02.011

来源: Elsevier

【 摘 要 】

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 P-31 MAS NMR and L-III EXAFS spectroscopy. Rhabdophane (LaPO4 center dot nH(2)O) 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 HCI 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. (C) 2016 Elsevier Ltd. All rights reserved.

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