Determination of the amount of carbon and the isotopic ratio 14C: 12C of a ferrallitic horizon under isovolumetric weathering in the humid tropical region of Bahia (Brazil)

Authors

  • J.L. Rapaire Scientific Centre of Monaco, Principality of Monaco
  • P.F.S. Lobo Laboratory of Nuclear Geophysics, Institute of Physics, Federal University of Bahia, Brazil
  • J.M. Flexor Overseas Bureau of Technical and Scientific Research (O.R.S.T.O.M.)

Abstract

A study was made of the horizon under isovolumetric weathering, made up of halloysite, of a ferrallitic soil in the humid zone of the State of Bahia, Brazil. After two treatments with concentrated hydrogen peroxide and combustion of the sample at 800°C the residual carbon was 0·3 per cent. Determination of the isotopic ratio 14C/12C indicated an age of 3550 ± 150 years. Three hypotheses can be considered to explain the presence of this carbon in the horizon under isovolumetric alteration at a depth of 6 m: (i) it may have been derived from organic compounds originating in the upper horizons of the soil; (ii) it may be due to residual organic substances of microbiological origin; (iii) it may be carbon from the crystalline lattice of the clay minerals. No definite position has been adopted in favour of any of these hypotheses.

How to Cite

Rapaire, J., Lobo, P., & Flexor, J. (1974). Determination of the amount of carbon and the isotopic ratio 14C: 12C of a ferrallitic horizon under isovolumetric weathering in the humid tropical region of Bahia (Brazil). Tropical Agriculture, 51(2). Retrieved from https://journals.sta.uwi.edu/ojs/index.php/ta/article/view/3248

Issue

Section

Research Papers