TY - JOUR

T1 - Depth profiles of soil organic carbon isotopes across a lithosequence

T2 - implications for drivers of soil δ 13C vertical changes

AU - Karimi Nezhad, Mohammad Tahsin

AU - Bruun, Sander

AU - Magid, Jakob

N1 - Publisher Copyright: © 2022 Informa UK Limited, trading as Taylor & Francis Group.

PY - 2022

Y1 - 2022

N2 - To addresshow parent materials are affecting organic carbon dynamics in a soil profile, soils from a lithosequence comprising six parent lithologies under a rangeland ecosystem have been explored at three depth intervals for soil organic carbon (SOC) content and its 13C depth trends. Studied parent materials ranged from metamorphic (foliated: FM and non-foliated: NFM) to sedimentary (clastic carbonate: CCS) to plutonic (intermediate: IP, felsic: FP and intermediate felsic: IFP) geological contexts. The relationship between SOC concentration and its isotopic signatures to a depth of 50 cm in FM, NFM, FP and IFP profiles was well described by the kinetic fractionation of SOC during biodegradation. For CCS and IP lithologies, strong divergence from the Rayleigh equation was observed suggesting that the 13C enrichments in these soils resulted from both mixing different SOC pools and isotope fractionation related to the C mineralization. Results suggest that SOC across the lithosequence goes through different isotopic evolutions resulting from different 13C-enriched inputs and pedogenic properties as described by the extended Rayleigh equation (0 ≤ β C≤ 0.80). These are presumably caused by the bedrock lithology implying that parent material affects C storage and dynamics.

AB - To addresshow parent materials are affecting organic carbon dynamics in a soil profile, soils from a lithosequence comprising six parent lithologies under a rangeland ecosystem have been explored at three depth intervals for soil organic carbon (SOC) content and its 13C depth trends. Studied parent materials ranged from metamorphic (foliated: FM and non-foliated: NFM) to sedimentary (clastic carbonate: CCS) to plutonic (intermediate: IP, felsic: FP and intermediate felsic: IFP) geological contexts. The relationship between SOC concentration and its isotopic signatures to a depth of 50 cm in FM, NFM, FP and IFP profiles was well described by the kinetic fractionation of SOC during biodegradation. For CCS and IP lithologies, strong divergence from the Rayleigh equation was observed suggesting that the 13C enrichments in these soils resulted from both mixing different SOC pools and isotope fractionation related to the C mineralization. Results suggest that SOC across the lithosequence goes through different isotopic evolutions resulting from different 13C-enriched inputs and pedogenic properties as described by the extended Rayleigh equation (0 ≤ β C≤ 0.80). These are presumably caused by the bedrock lithology implying that parent material affects C storage and dynamics.

KW - Carbon-13

KW - depth profiles

KW - isotope geochemistry

KW - isotopic evolution

KW - kinetic fractionation

KW - lithology

KW - Rayleigh distillation

KW - soil organic carbon

U2 - 10.1080/10256016.2022.2044806

DO - 10.1080/10256016.2022.2044806

M3 - Journal article

C2 - 35238693

AN - SCOPUS:85126057349

VL - 58

SP - 159

EP - 179

JO - Isotopes in Environmental and Health Studies

JF - Isotopes in Environmental and Health Studies

SN - 1025-6016

IS - 2

ER -