Decomposition and colonization of grass tissue, containing HG and AS, by soil microorganisms

Abstract

Incubation experiments were conducted for 40 days at 28+-1*C to determine the effect of Hg and As in leaf, stem, and root tissues of common bermudagrass added to a Norwood silt loam and a Houston Black clay on microbial respiration, microbial populations, and nitrification. The concentrations of Hg in leaf, stem, and root tissues ranged from 0.2 to 6.9, 0.05 to 0.18, and 0.3 to 542 ppm, respectively. The concentrations of As in leaf, stem, and root tissues ranged from 0 to 19.9, to 0 to 16.8, and 0 to 304 ppm, respectively. In no case was there a significant difference in CO2 evolution from the solids due to Hg and As content of the plant tissues. The maximum rate of CO2 evolution from amended soils occurred within the first 7 days of incubation. Despite the presence of Hg and As in leaf and root tissues nitrification was not reduced. Immobilization of nitrogen occurred in soils treated with stem tissues, therefore, the effect of Hg and As in stem tissue on nitrification was not determined.