Carbon dioxide concentrations in some tropical karst soils, west malaysia

Abstract

Summary Regular measurements of carbon dioxide at depths of 15, 30 and 60 cm were made over a period of one year in six karst soils of the Malay peninsula. The data exhibit wide spatial, depth and temporal variations. Mean carbon dioxide concentrations increase with depth and differences in soil properties, especially in air porosity, account for much of the inter-site variability, with the highest carbon dioxide levels occurring in the denser soils formed on impure limestones and on colluvial or alluvial footslope deposits, and the lowest being in the more porous hillslope soils formed on pure limestones. Carbon dioxide concentrations at individual sites vary directly with the amount of antecedent rainfall in periods of 1–32, 1–64 or 1–128 days before sampling. These findings indicate the difficulties of obtaining a reliable mean figure for carbon dioxide in tropical soils, but do suggest that mean concentrations recorded in tropical karst soils probably underestimate the true solutional potential of percolation waters, whereas over-estimation is likely in temperate regions.