The efficacy of Phoslock® in reducing internal phosphate loading varies with bottom water oxygenation.

Content Provider	Europe PMC
Author	Zeller, Mary A. Alperin, Marc J.
Copyright Year	2021
Description	Eutrophication in lakes and reservoirs has prompted interest in using sediment capping technology to reduce the sediment contribution to internal nutrient loading. One such sediment capping technology is Phoslock®, a lanthanum-embedded clay, which can bind phosphate at the sediment surface and limit its diffusion into the water column. However, in well-oxygenated lakes, naturally occurring iron can bind phosphate by a similar mechanism. We sought to test the efficacy of Phoslock® in limiting phosphate (PO43−) fluxes relative to untreated iron-rich lake sediment under conditions of bottom-water oxia and anoxia through laboratory batch core incubations of intact sediment cores from Jordan Lake, a reservoir in central North Carolina. We found that Phoslock® decreased phosphate fluxes relative to the control under anoxic conditions (7.5 ± 9.5 vs. 236 ± 74 µmol PO43−•m−2•d−1), but provided no benefit relative to the control when the water column was oxygenated (4.5 ± 4.3 vs. 7.0 ± 11.4 µmol PO43−•m−2•d−1). We also found that Phoslock® itself can act as a source of NH4+ to Jordan Lake waters. Applied at recommended levels to the whole lake, Phoslock® addition would result in a pulse increase in water column NH4+ concentrations of approximately 2.6 ± 0.8 μM (an increase of 10 to 275% compared to ambient). Highlights • Phoslock® decreases iron-rich sediment-water P flux when bottom waters are anoxic. • Phoslock® does not decrease sediment-water P flux when bottom waters are oxic. • Phoslock® is a source of N—NH4+ to the water column when dispersed in lake water.
Related Links	https://europepmc.org/backend/ptpmcrender.fcgi?accid=PMC7974025&blobtype=pdf
Volume Number	11
DOI	10.1016/j.wroa.2021.100095
PubMed Central reference number	PMC7974025
PubMed reference number	33763640
Journal	Water Research X [Water Res X]
e-ISSN	25899147
Language	English
Publisher	Elsevier
Publisher Date	2021-03-05
Access Restriction	Open
Rights License	This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). © 2021 The Author(s)
Subject Keyword	Phoslock® Phosphate flux Nutrient management Core incubations Oxia Anoxia Iron-rich sediments
Content Type	Text
Resource Type	Article
Subject	Water Science and Technology Ecological Modeling Pollution Waste Management and Disposal