TY - JOUR
T1 - Biogenic calcium phosphate transformation in soils over millennial time scales
AU - Sato, Shinjiro
AU - Neves, Eduardo G.
AU - Solomon, Dawit
AU - Liang, Biqing
AU - Lehmann, Johannes
N1 - Funding Information:
Acknowledgements The authors acknowledge NSF-DEB for funding under project number DEB-0425995. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the NSF. We are thankful to Dr. Dean Hesterberg (Department of Soil Science, North Carolina State University) for providing spectral data for several aqueous phosphate species and valuable instruction and assistance for the LCF procedure of the XANES spectra. The authors also thank Dr. W. Caliebe for invaluable assistance with the spectroscopic analyses, performed at the beamline X-19A of the National Synchrotron Light Source, Project No. 4738. The NSLS is supported by the US Department of Energy under the contract No. DE-AC02-76CH00016.
PY - 2009/6
Y1 - 2009/6
N2 - Background, aim, and scope: Changes in bioavailability of phosphorus (P) during pedogenesis and ecosystem development have been shown for geogenic calcium phosphate (Ca-P). However, very little is known about long-term changes of biogenic Ca-P in soil. Materials and methods: Long-term transformation characteristics of biogenic Ca-P were examined using anthropogenic soils along a chronosequence from centennial to millennial time scales. Results and discussion: Phosphorus fractionation of Anthrosols resulted in overall consistency with the Walker and Syers model of geogenic Ca-P transformation during pedogenesis. The biogenic Ca-P (e.g., animal and fish bones) disappeared to 3% of total P within the first ca. 2,000 years of soil development. This change concurred with increases in P adsorbed on metal-oxides surfaces, organic P, and occluded P at different pedogenic time. Phosphorus K-edge X-ray absorption near-edge structure (XANES) spectroscopy revealed that the crystalline and therefore thermodynamically most stable biogenic Ca-P was transformed into more soluble forms of Ca-P over time. While crystalline hydroxyapatite (34% of total P) dominated Ca-P species after about 600-1,000 years, β-tricalcium phosphate increased to 16% of total P after 900-1,100 years, after which both Ca-P species disappeared. Iron-associated P was observable concurrently with Ca-P disappearance. Soluble P and organic P determined by XANES maintained relatively constant (58-65%) across the time scale studied. Conclusions: Disappearance of crystalline biogenic Ca-P on a time scale of a few thousand years appears to be ten times faster than that of geogenic Ca-P.
AB - Background, aim, and scope: Changes in bioavailability of phosphorus (P) during pedogenesis and ecosystem development have been shown for geogenic calcium phosphate (Ca-P). However, very little is known about long-term changes of biogenic Ca-P in soil. Materials and methods: Long-term transformation characteristics of biogenic Ca-P were examined using anthropogenic soils along a chronosequence from centennial to millennial time scales. Results and discussion: Phosphorus fractionation of Anthrosols resulted in overall consistency with the Walker and Syers model of geogenic Ca-P transformation during pedogenesis. The biogenic Ca-P (e.g., animal and fish bones) disappeared to 3% of total P within the first ca. 2,000 years of soil development. This change concurred with increases in P adsorbed on metal-oxides surfaces, organic P, and occluded P at different pedogenic time. Phosphorus K-edge X-ray absorption near-edge structure (XANES) spectroscopy revealed that the crystalline and therefore thermodynamically most stable biogenic Ca-P was transformed into more soluble forms of Ca-P over time. While crystalline hydroxyapatite (34% of total P) dominated Ca-P species after about 600-1,000 years, β-tricalcium phosphate increased to 16% of total P after 900-1,100 years, after which both Ca-P species disappeared. Iron-associated P was observable concurrently with Ca-P disappearance. Soluble P and organic P determined by XANES maintained relatively constant (58-65%) across the time scale studied. Conclusions: Disappearance of crystalline biogenic Ca-P on a time scale of a few thousand years appears to be ten times faster than that of geogenic Ca-P.
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U2 - 10.1007/s11368-009-0082-0
DO - 10.1007/s11368-009-0082-0
M3 - Article
AN - SCOPUS:67650803055
SN - 1439-0108
VL - 9
SP - 194
EP - 205
JO - Journal of Soils and Sediments
JF - Journal of Soils and Sediments
IS - 3
ER -