Effect of Cacodylic Acid and MSMA on Microbes in Forest Floor and Soil

Abstract

Cacodylic acid (hydroxydimethylarsine oxide) and MSMA (monosodium methanearsonate) gave slightly-visible inhibition of bacterial growth in pure culture at 1000 mg/L arsenic and moderate inhibition at 10,000 mg/L arsenic. There were no effects at 100 mg/L arsenic. Carbon dioxide evolution from three kinds of forest floor declined with increasing concentrations of MSMA and cacodylic acid. Increasing concentrations of MSMA caused an increase in carbon dioxide evolution from soil but cacodylic acid had no effect. Concentrations less than 10 mg/kg arsenic forest floor including L, F, and H horizons, or soil had no pronounced effect on organic matter decomposition.