Stepwise redox changes alter the speciation and mobilization of phosphorus in hydromorphic soils
Journal
Chemosphere
Journal Volume
288
Journal Volume
288
Start Page
132652
ISSN
00456535
Date Issued
2022-02
Author(s)
Shaheen, Sabry M.
Wang, Jianxu
Baumann, Karen
Ahmed, Ashour A.
Hsu, Liang-Ching
Liu, Yu-Ting
Kühn, Oliver
Leinweber, Peter
Rinklebe, Jörg
Abstract
Sustainable engineering and management of hydromorphic arable soils need deep knowledge about the redox-mediated interactions between nutrients and soil colloids. Consequently, we examined the redox-mediated interactions of P with metal oxides and organic carbon (OC) in toe-, mid-, and upper-slope arable soils under dynamic redox changes using geochemical (biogeochemical microcosm), spectroscopic (XANES), and molecular (quantum chemical calculations (QCC)) approaches. We controlled the redox potential (EH) in two directions i.e., 1) slowly oxidizing direction (SOD; EH increased from −286 to +564 mV); and 2) slowly reducing direction (SRD; EH decreased from +564 to −148 mV). In the SOD of all soils, P, Fe2+ and OC mobilized at EH ≤ 200 mV, due to the pH decrease from 7.2 to 4.1 and dissolution of Fe-oxyhydroxides/carbonates, as indicated by the decrease of Fe–P and Ca–P determined by P–K-edge-XANES. At EH > 200 mV, P immobilized due to the strong P binding with Fe3+ as suggested by QCC. In the SRD of mid-slope-soil, P immobilized with decreasing EH, due to pH increase and P retention by aromatic carbon and/or precipitation by carbonates, as supported by increase of organic-P and Ca–P. These findings help for management of P in arable soils.
Subjects
Hydromorphic arable soils
Phosphorus loss
Quantum chemical calculations
Sustainable management
XANES
Publisher
00456535
Type
journal article