@article{fdi:010089583,
  title = {{A}djustments to the {R}ock-{E}val® thermal analysis for soil organic and inorganic carbon quantification},
  author = {{H}azera, {J}. and {S}ebag, {D}. and {K}owalewski, {I}. and {V}errecchia, {E}. and {R}avelojaona, {H}. and {C}hevallier, {T}iphaine},
  editor = {},
  language = {{ENG}},
  abstract = {{Q}uantifying both soil organic carbon ({SOC}) and soil inorganic carbon ({SIC}) is essential to understand carbon ({C}) dynamics and to assess the atmospheric {C} sequestration potential in calcareous soils. {T}he procedures usually used to quantify {SOC} and {SIC} involve pretreatments (decarbonation, carbonate removal) and calculations of the difference between {C} contents estimated by elemental analysis on raw and pretreated aliquots. {T}hese procedures lead to analytical bias associated with pretreatments, measurement deviations associated with sample heterogeneity, and cumulative errors associated with calculations. {T}he {R}ock-{E}val ({R}) analysis is a ramped thermal analysis that has been used in soil sciences since the 2000s, consisting of pyrolysis of the sample followed by oxidation of the residue. {A} single {R}ock-{E}val ({R}) analysis on non-pretreated aliquots provides two parameters estimating the organic ({TOC}) and inorganic ({M}in{C}) {C} contents of the samples. {N}evertheless, the {R}ock-{E}val ({R}) protocol was standardised in the 1970s by {IFP} {E}nergies {N}ouvelles for studying oil-bearing rocks and is thus not perfectly suited for soil study. {P}revious studies have suggested statistical corrections of the standard parameters to improve their estimations of {C} contents assessed by elemental analysis, but only a few of them have focused on the estimation of inorganic {C} content using the {M}in{C} parameter. {M}oreover, none of them have suggested adjustments to the standard {R}ock-{E}val ({R}) protocol. {T}his study proposes to adapt this protocol to optimise {SOC} and {SIC} quantifications in soil samples. {C}omparisons between {SOC} and {SIC} quantifications by elemental analysis and by {R}ock-{E}val ({R}), with and without statistical corrections of the standard {TOC} and {M}in{C} parameters, were carried out on 30 agricultural topsoils with a wide range of {SOC} and {SIC} contents. {T}he results show that the standard {R}ock-{E}val ({R}) protocol can properly estimate {SOC} contents once the {TOC} parameter is corrected. {H}owever, it cannot achieve a complete thermal breakdown of {SIC} amounts > 4 mg, leading to an underestimation of high {SIC} contents by the {M}in{C} parameter, even after correcting for this. {T}hus, the final oxidation isotherm is extended to 7 min to complete the thermal breakdown of {SIC} before the end of the analysis. {T}his work is a methodological step to measure {SOC} and {SIC} contents in a single analytical run on a non-pretreated aliquot. {M}ore work is needed (i) on a wider range of soil samples with differing land use and other forms of carbonate mineral and sampling depths and (ii) to avoid the use of statistical corrections of the {TOC} and {M}in{C} parameters.},
  keywords = {{FRANCE} ; {TUNISIE} ; {ZONE} {MEDITERRANEENNE}},
  booktitle = {},
  journal = {{B}iogeosciences},
  volume = {20},
  numero = {24},
  pages = {5229--5242},
  ISSN = {1726-4170},
  year = {2023},
  DOI = {10.5194/bg-20-5229-2023},
  URL = {https://www.documentation.ird.fr/hor/fdi:010089583},
}