Identification of thermal signature and quantification of charcoal in soil using differential scanning calorimetry and benzene polycarboxylic acid (BPCA) markers

Summary

This laboratory study evaluated differential scanning calorimetry (DSC) as a method to identify and quantify black carbon (charcoal) in soil samples from Belgium and Germany. Using soil from pre-industrial charcoal kiln sites, the researchers demonstrated that charcoal exhibits distinct thermal stability and specific exothermic combustion peaks that differ from uncharred soil organic matter, though decomposition temperature ranges overlap. Validation against the established BPCA method showed strong correlation (R² = 0.97), but highlighted that operationally defined BC quantification requires careful consideration of recovery rates, as BPCA captured only approximately one-fifth of DSC-derived charcoal carbon.

UK applicability

The findings are applicable to UK soil research, particularly for historical sites with charcoal legacy (medieval, industrial) and for understanding biochar persistence in amended soils. The methodological validation may inform UK protocols for black carbon quantification in soil monitoring and carbon sequestration studies, though the calibration of recovery rates would require testing on UK soil types and charcoal sources.

Key measures

Charcoal-carbon (charcoal-C) content quantified by DSC and BPCA; thermal signatures characterised by exothermic peak height, size and position; correlation between DSC and BPCA methods (R²); recovery rates

Outcomes reported

The study compared differential scanning calorimetry (DSC) and benzene polycarboxylic acid (BPCA) methods for quantifying charcoal-carbon content in soil samples from pre-industrial charcoal kiln sites. The two methods showed strong correlation (R² = 0.97), though BPCA-C represented approximately one-fifth of DSC-derived charcoal-C.

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