The fate of calcium in temperate forest soils: a Ca K-edge XANES study
| Autor: | Prietzel, Jörg, Klysubun, Wantana, Hurtarte, Luis Carlos Colocho, Chair of Soil Science, Center of Life and Food Sciences Weihenstephan, Technical University München, Freising, Germany, Synchrotron Light Research Institute, Nakhon Ratchasima, Thailand |
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| Rok vydání: | 2020 |
| Předmět: |
XANES spectroscopy
Calcareous soils chemistry.chemical_element 010501 environmental sciences Calcium engineering.material Anorthite 01 natural sciences chemistry.chemical_compound Ca speciation Environmental Chemistry 0105 earth and related environmental sciences Earth-Surface Processes Water Science and Technology Calcite Chemistry Soil organic matter Soil Ca forms 04 agricultural and veterinary sciences ddc:631.4 XANES ddc Plant foliage Silicate soils Pedogenesis Environmental chemistry Soil water 040103 agronomy & agriculture engineering 0401 agriculture forestry and fisheries Calcareous |
| Zdroj: | Biogeochemistry. 152:195-222 |
| ISSN: | 1573-515X 0168-2563 |
| DOI: | 10.1007/s10533-020-00748-6 |
| Popis: | Calcium (Ca) plays a crucial role for plant nutrition, soil aggregation, and soil organic matter (SOM) stabilization. Turnover and ecological functions of Ca in soils depend on soil Ca speciation. For the first time, we used synchrotron-based X-ray absorption near-edge structure (XANES) spectroscopy at the Ca K-edge (4038 eV) to investigate Ca speciation in soils. We present Ca K-edge XANES spectra of standard compounds with relevance in soils (e.g. calcite, dolomite, hydroxyapatite, anorthite, clay mineral-adsorbed Ca; Ca oxalate, formate, acetate, citrate, pectate, phytate). Calcium XANES spectra with good signal-to-noise ratios were acquired in fluorescence mode for Ca concentrations between 1 and 10 mg g−1. Most standard spectra differed markedly among each other, allowing the identification of different Ca species in soils and other environmental samples as well as Ca speciation by linear combination fitting. Calcium XANES spectra obtained for samples from different horizons of twelve temperate forest soils revealed a change from dominating lithogenic Ca to clay mineral-bound and/or organically bound Ca with advancing pedogenesis. O layer Ca was almost exclusively organically bound. With increasing SOM decomposition, shares of oxalate-bound Ca decreased. Oxalate-bound Ca was absent in calcareous, but not in silicate subsoil horizons, which can be explained by microbial decomposition in the former vs. stabilization by association to pedogenic minerals in the latter soils. Synchrotron-based Ca XANES spectroscopy is a promising novel tool to investigate the fate of Ca during pedogenesis and—when performed with high spatial resolution (µ-XANES), to study aggregation and SOM stabilization mechanisms produced by Ca. BLE Waldklimafonds Projekt DEAL |
| Databáze: | OpenAIRE |
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