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Research article2016Peer reviewed

Influence of dissolved organic carbon on the efficiency of P sequestration by a lanthanum modified clay

Dithmer, Line; Nielsen, Ulla Gro; Lundberg, Daniel; Reitzel, Kasper

Abstract

A laboratory scale experiment was set up to test the effect of dissolved organic carbon (DOC) as well as ageing of the La-P complex formed during phosphorus (P) sequestration by a La modified clay (Phoslock (R)). Short term (7 days) P adsorption studies revealed a significant negative effect of added DOC on the P sequestration of Phoslock (R), whereas a long-term P adsorption experiment revealed that the negative effect of added DOC was reduced with time. The reduced P binding efficiency is kinetic, as evident from solid-state P-31 magic-angle spinning (MAS) NMR spectroscopy, who showed that the P binding did not change in the presence of DOC. 31P MAS NMR also reveals that up to 26% of the sequestered phosphate is as loosely bound redox-sensitive P species on the surface of rhabdophane (LaPO4 center dot nH(2)O, n <= 3). The ratio between the loosely bound P and lanthanum phosphate did not change with time, however both NMR and L-III-extended x-ray absorption fine structure (EXAFS) spectroscopy shows a transformation of lanthanum phosphate from the initially formed rhabdophane towards the more stable monazite (LaPO4). Furthermore, the effect of natural DOC on the P binding capacity was tested using water and pore water from 16 Danish lakes. Whilst DOC has an immediate negative impact on P binding in the lake water, with time this effect is reduced. (C) 2015 Elsevier Ltd. All rights reserved.

Keywords

Lake restoration; Dissolved organic carbon (DOC); P-31 NMR; Lanthanum; P sequestration; EXAFS

Published in

Water Research
2016, volume: 97, pages: 39-46
Publisher: PERGAMON-ELSEVIER SCIENCE LTD

SLU Authors

  • Lundberg, Daniel

    • The Department of Chemistry and Biotechnology, Swedish University of Agricultural Sciences

Global goals (SDG)

SDG6 Clean water and sanitation

UKÄ Subject classification

Other Earth Sciences
Oceanography, Hydrology, Water Resources
Environmental Sciences

Publication identifier

  • DOI: https://doi.org/10.1016/j.watres.2015.07.003

Permanent link to this page (URI)

https://res.slu.se/id/publ/80719