Soil carbonate decomposition by acid has little effect on δ13C of organic matter
A. J. Midwood, T. Boutton
Sep 1, 1998
Citations
252
Citations
Quality indicators
Journal
Soil Biology & Biochemistry
Full text
Semantic Scholar
Key Takeaway Key Takeaway: Soil carbonate decomposition by acid has little effect on the 13C of organic matter, making it suitable for isotopic analysis of soil organic matter.
Abstract
Abstract The δ13C of soil organic C is often utilized to document vegetation changes and to estimate rates of soil organic C turnover. Soil carbonate C is isotopically distinct from organic C, and must be removed by acidification prior to isotopic analysis of soil organic matter. We determined the effects of acid concentration (0.1, 0.5, 1, or 6 m HCl) and duration of treatment (1, 2, 3, or 8 d) on soil δ13C and the concentration of C and N in a carbonate-free entisol and a calcareous vertisol both obtained from Texas. δ13C values of organic C in the entisol were reduced significantly by treatment with 6 m HCl for more than 1 d; however, all other combinations of acid strength and treatment duration had no effect on δ13C of organic C in that soil. In the calcareous soil, δ13C of organic C was largely unaffected by acid concentration or duration of treatment; however, soils treated with 0.1 m HCl required 3 d to fully remove all carbonate and achieve δ13C values comparable to those in other treatment combinations. Treatment of calcareous soils with 0.5 m HCl for 24 h appears sufficient to remove all carbonate C prior to isotopic analysis, and this treatment has no discernible effect on the δ13C of the soil organic matter.