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Title: Association with pedogenic iron and aluminum: effects on soil organic carbon storage and stability in four temperate forest soils

Soil organic carbon (SOC) can be stabilized via association with iron (Fe) and aluminum (Al) minerals. Fe and Al can be strong predictors of SOC storage and turnover in soils with relatively high extractable metals content and moderately acidic to circumneutral pH. Here we test whether pedogenic Fe and Al influence SOC content and turnover in soils with low Fe and Al content and acidic pH. In soils from four sites spanning three soil orders, we quantified the amount of Fe and Al in operationally-defined poorly crystalline and organically-complexed phases using selective chemical dissolution applied to the soil fraction containing mineral-associated carbon. We evaluated the correlations of Fe and Al concentrations, mean annual precipitation (MAP), mean annual temperature (MAT), and pH with SOC content and 14C-based turnover times. We found that poorly crystalline Fe and Al content predicted SOC turnover times (p < 0.0001) consistent with findings of previous studies, while organically-complexed Fe and Al content was a better predictor of SOC concentration (p < 0.0001). Greater site-level MAP (p < 0.0001) and colder site-level MAT (p < 0.0001) were correlated with longer SOC turnover times but were not correlated with SOC content. Our results suggest that poorly crystalline Femore » and Al effectively slow the turnover of SOC in these acidic soils, even when their combined content in the soil is less than 2% by mass. However, in the strongly acidic Spodosol, organo-metal complexes tended to be less stable resulting in a more actively cycling mineral-associated SOC pool.« less
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [1]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Climate and Ecosystem Sciences Division
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Center for Accelerator Mass Spectroscopy
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Climate Change SCience Inst. and Environmental Sciences Division
Publication Date:
Report Number(s):
LLNL-JRNL-708394
Journal ID: ISSN 0168-2563
Grant/Contract Number:
AC52-07NA27344; AC05-00OR22725; AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Biogeochemistry
Additional Journal Information:
Journal Volume: 133; Journal Issue: 3; Journal ID: ISSN 0168-2563
Publisher:
Springer
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; 14C; Soil carbon stabilization; Selective chemical dissolution; Soil fractionation; Soil organic carbon; Mineral-organic associations
OSTI Identifier:
1366910
Alternate Identifier(s):
OSTI ID: 1400180; OSTI ID: 1471031

Porras, Rachel C., Hicks Pries, Caitlin E., McFarlane, Karis J., Hanson, Paul J., and Torn, Margaret S.. Association with pedogenic iron and aluminum: effects on soil organic carbon storage and stability in four temperate forest soils. United States: N. p., Web. doi:10.1007/s10533-017-0337-6.
Porras, Rachel C., Hicks Pries, Caitlin E., McFarlane, Karis J., Hanson, Paul J., & Torn, Margaret S.. Association with pedogenic iron and aluminum: effects on soil organic carbon storage and stability in four temperate forest soils. United States. doi:10.1007/s10533-017-0337-6.
Porras, Rachel C., Hicks Pries, Caitlin E., McFarlane, Karis J., Hanson, Paul J., and Torn, Margaret S.. 2017. "Association with pedogenic iron and aluminum: effects on soil organic carbon storage and stability in four temperate forest soils". United States. doi:10.1007/s10533-017-0337-6. https://www.osti.gov/servlets/purl/1366910.
@article{osti_1366910,
title = {Association with pedogenic iron and aluminum: effects on soil organic carbon storage and stability in four temperate forest soils},
author = {Porras, Rachel C. and Hicks Pries, Caitlin E. and McFarlane, Karis J. and Hanson, Paul J. and Torn, Margaret S.},
abstractNote = {Soil organic carbon (SOC) can be stabilized via association with iron (Fe) and aluminum (Al) minerals. Fe and Al can be strong predictors of SOC storage and turnover in soils with relatively high extractable metals content and moderately acidic to circumneutral pH. Here we test whether pedogenic Fe and Al influence SOC content and turnover in soils with low Fe and Al content and acidic pH. In soils from four sites spanning three soil orders, we quantified the amount of Fe and Al in operationally-defined poorly crystalline and organically-complexed phases using selective chemical dissolution applied to the soil fraction containing mineral-associated carbon. We evaluated the correlations of Fe and Al concentrations, mean annual precipitation (MAP), mean annual temperature (MAT), and pH with SOC content and 14C-based turnover times. We found that poorly crystalline Fe and Al content predicted SOC turnover times (p < 0.0001) consistent with findings of previous studies, while organically-complexed Fe and Al content was a better predictor of SOC concentration (p < 0.0001). Greater site-level MAP (p < 0.0001) and colder site-level MAT (p < 0.0001) were correlated with longer SOC turnover times but were not correlated with SOC content. Our results suggest that poorly crystalline Fe and Al effectively slow the turnover of SOC in these acidic soils, even when their combined content in the soil is less than 2% by mass. However, in the strongly acidic Spodosol, organo-metal complexes tended to be less stable resulting in a more actively cycling mineral-associated SOC pool.},
doi = {10.1007/s10533-017-0337-6},
journal = {Biogeochemistry},
number = 3,
volume = 133,
place = {United States},
year = {2017},
month = {5}
}