Phosphorus Release and Speciation in Manganese(IV) Oxide and Zeolite-Amended Flooded Soils

Phosphorus (P) losses from flooded soils and subsequent transport to waterways contribute to eutrophication of surface waters. This study evaluated the effectiveness of MnO2 and a zeolite Y amendment in reducing P release from flooded soils and explored the underlying mechanisms controlling P releas...

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Bibliographic Details
Published in:Environmental science & technology 2022-06, Vol.56 (12), p.8082-8093
Main Authors: Attanayake, Chammi P., Kumaragamage, Darshani, Amarawansha, Geethani, Hettiarachchi, Ganga M., Indraratne, Srimathie P., Goltz, Douglas M.
Format: Article
Language:English
Subjects:
Alkaline soils
Anions
Calcium phosphates
Cations
Contaminants in Aquatic and Terrestrial Environments
Dissolution
Eutrophication
Flooded soils
Flooding
Floods
Floodwater
Fractionation
Hydroxyapatite
Manganese
Manganese dioxide
pH effects
Phosphorus
Pore water
Redox potential
Soil amendment
Soil analysis
Soils
Speciation
Spectroscopy
Surface water
Waterways
X ray absorption
Zeolites
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Summary:Phosphorus (P) losses from flooded soils and subsequent transport to waterways contribute to eutrophication of surface waters. This study evaluated the effectiveness of MnO2 and a zeolite Y amendment in reducing P release from flooded soils and explored the underlying mechanisms controlling P release. Unamended and amended (MnO2 or zeolite, surface-amended at 5 Mg ha–1) soil monoliths from four clayey–alkaline soils were flooded at 22 ± 2 °C for 56 days. Soil redox potential and dissolved reactive P (DRP), pH, and concentrations of major cations and anions in porewater and floodwater were analyzed periodically. Soil P speciation was simulated using Visual MINTEQ at 1, 28, and 56 days after flooding (DAF) and P K-edge X-ray absorption near-edge structure spectroscopy and sequential fractionation at 56 DAF. Porewater DRP increased with DAF and correlated negatively with pe+pH and positively with dissolved Fe. Reductive dissolution of Fe-associated P was the dominant mechanism of flooding-induced P release. The MnO2 amendment reduced porewater DRP by 30%–50% by favoring calcium phosphates (Ca–P) precipitation and delaying the reductive dissolution reactions. In three soils, the zeolite amendment at some DAF increased porewater and/or floodwater DRP through dissolution of Ca–P and thus was not effective in reducing P release from flooded soils.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.2c01185