Multimodal, microspectroscopic speciation of legacy phosphorus in two US mid-Atlantic agricultural soils
- Texas A & M Univ., College Station, TX (United States)
- Texas Tech Univ., Lubbock, TX (United States)
- Univ. of Texas, Dallas, TX (United States)
- Stony Brook Univ., NY (United States)
- Brookhaven National Laboratory (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)
- Univ. of Delaware, Newark, DE (United States)
To understand phosphorus (P) mobility in agricultural soils and its potential environmental risk, it is essential to directly measure solid phase P speciation. Often, bulk P K-edge X-ray absorption near edge structure (XANES) spectroscopy followed by linear combination fitting (LCF) is utilized to determine the solid P phases in soil. However, this method may limit results to only a few major phases. Additionally, XANES spectra for different P species may have very similar features, leading to an over- or underestimate of their contribution to LCF. Here, an improved P speciation by pairing multimodal microbeam-X-ray fluorescence (µ-XRF) mapping coupled with µ-XANES (microbeam-X-ray absorption near edge structure) analysis to directly speciate major and minor P phases on the micron scale is provided. We combined maps of both tender (P, sulfur, aluminum, and silicon) and hard energy (calcium, iron [Fe], and manganese) elements to evaluate the elemental co-locations with P. To better account for uncertainty assigning XANES peaks to individual compounds, a more quantitative fingerprinting by “spectral feature analysis” was completed. With this analysis, an R-factor is reported for the fit. These results were compared to traditional LCF. Pre-edge fitting results revealed the presence of a two-component pre-edge feature for phosphate adsorbed to ferrihydrite. Additionally, phytate co-precipitated with ferrihydrite (Phytate-Fe-Cop) had a pre-edge feature, indicating direct association with Fe. Lastly, a unique P species associated with manganese oxide was identified in the soil via multimodal mapping and µ-XANES. These results allow for better prediction of P dissolution and mobility.
- Research Organization:
- Brookhaven National Laboratory (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF)
- Grant/Contract Number:
- SC0012704
- OSTI ID:
- 2466134
- Report Number(s):
- BNL--226252-2024-JAAM
- Journal Information:
- Soil Science Society of America Journal, Journal Name: Soil Science Society of America Journal Journal Issue: 6 Vol. 88; ISSN 0361-5995
- Publisher:
- Alliance of Crop, Soil, and Environmental Science SocietiesCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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