Univ. of Zurich (Switzerland); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Univ. of California, Davis, CA (United States)
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource (SSRL)
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
Univ. of California, Davis, CA (United States)
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Univ. of California, Davis, CA (United States)
Organo-mineral and organo-metal associations play an important role in the retention and accumulation of soil organic carbon (SOC). Recent studies have demonstrated a positive correlation between calcium (Ca) and SOC content in a range of soil types. However, most of these studies have focused on soils that contain calcium carbonate (pH > 6). To assess the importance of Ca-SOC associations in lower pH soils, we investigated their physical and chemical interaction in the grassland soils of Point Reyes National Seashore (CA, USA) at a range of spatial scales. Multivariate analyses of our bulk soil characterisation dataset showed a strong correlation between exchangeable Ca (CaExch; 5–8.3 c.molc kg–1) and SOC (0.6–4%) content. Additionally, linear combination fitting (LCF) of bulk Ca K-edge X-ray absorption near-edge structure (XANES) spectra revealed that Ca was predominantly associated with organic carbon across all samples. Scanning transmission X-ray microscopy near-edge X-ray absorption fine structure spectroscopy (STXM C/Ca NEXAFS) showed that Ca had a strong spatial correlation with C at the microscale. The STXM C NEXAFS K-edge spectra indicated that SOC had a higher abundance of aromatic/olefinic and phenolic C functional groups when associated with Ca, relative to C associated with Fe. In regions of high Ca-C association, the STXM C NEXAFS spectra were similar to the spectrum from lignin, with moderate changes in peak intensities and positions that are consistent with oxidative C transformation. Through this association, Ca thus seems to be preferentially associated with plant-like organic matter that has undergone some oxidative transformation, at depth in acidic grassland soils of California. Our study highlights the importance of Ca-SOC complexation in acidic grassland soils and provides a conceptual model of its contribution to SOC preservation, a research area that has previously been unexplored.
Rowley, Mike C., et al. "Association between soil organic carbon and calcium in acidic grassland soils from Point Reyes National Seashore, CA." Biogeochemistry, vol. 165, no. 1, Jul. 2023. https://doi.org/10.1007/s10533-023-01059-2
Rowley, Mike C., Nico, Peter S., Bone, Sharon E., Marcus, Matthew A., Pegoraro, Elaine F., Castanha, Cristina, Kang, Kyounglim, Bhattacharyya, Amrita, Torn, Margaret S., & Peña, Jasquelin (2023). Association between soil organic carbon and calcium in acidic grassland soils from Point Reyes National Seashore, CA. Biogeochemistry, 165(1). https://doi.org/10.1007/s10533-023-01059-2
Rowley, Mike C., Nico, Peter S., Bone, Sharon E., et al., "Association between soil organic carbon and calcium in acidic grassland soils from Point Reyes National Seashore, CA," Biogeochemistry 165, no. 1 (2023), https://doi.org/10.1007/s10533-023-01059-2
@article{osti_2228859,
author = {Rowley, Mike C. and Nico, Peter S. and Bone, Sharon E. and Marcus, Matthew A. and Pegoraro, Elaine F. and Castanha, Cristina and Kang, Kyounglim and Bhattacharyya, Amrita and Torn, Margaret S. and Peña, Jasquelin},
title = {Association between soil organic carbon and calcium in acidic grassland soils from Point Reyes National Seashore, CA},
annote = {Organo-mineral and organo-metal associations play an important role in the retention and accumulation of soil organic carbon (SOC). Recent studies have demonstrated a positive correlation between calcium (Ca) and SOC content in a range of soil types. However, most of these studies have focused on soils that contain calcium carbonate (pH > 6). To assess the importance of Ca-SOC associations in lower pH soils, we investigated their physical and chemical interaction in the grassland soils of Point Reyes National Seashore (CA, USA) at a range of spatial scales. Multivariate analyses of our bulk soil characterisation dataset showed a strong correlation between exchangeable Ca (CaExch; 5–8.3 c.molc kg–1) and SOC (0.6–4%) content. Additionally, linear combination fitting (LCF) of bulk Ca K-edge X-ray absorption near-edge structure (XANES) spectra revealed that Ca was predominantly associated with organic carbon across all samples. Scanning transmission X-ray microscopy near-edge X-ray absorption fine structure spectroscopy (STXM C/Ca NEXAFS) showed that Ca had a strong spatial correlation with C at the microscale. The STXM C NEXAFS K-edge spectra indicated that SOC had a higher abundance of aromatic/olefinic and phenolic C functional groups when associated with Ca, relative to C associated with Fe. In regions of high Ca-C association, the STXM C NEXAFS spectra were similar to the spectrum from lignin, with moderate changes in peak intensities and positions that are consistent with oxidative C transformation. Through this association, Ca thus seems to be preferentially associated with plant-like organic matter that has undergone some oxidative transformation, at depth in acidic grassland soils of California. Our study highlights the importance of Ca-SOC complexation in acidic grassland soils and provides a conceptual model of its contribution to SOC preservation, a research area that has previously been unexplored.},
doi = {10.1007/s10533-023-01059-2},
url = {https://www.osti.gov/biblio/2228859},
journal = {Biogeochemistry},
issn = {ISSN 0168-2563},
number = {1},
volume = {165},
place = {United States},
publisher = {Springer},
year = {2023},
month = {07}}
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF); USDOE Office of Science (SC), Biological and Environmental Research (BER)
Environmental System Science Data Infrastructure for a Virtual Ecosystem; Belowground Biogeochemistry Scientific Focus Areahttps://doi.org/10.15485/2350835