Dados do Trabalho

Título

BIOLOGICAL INFLUENCE IN THE TRANSFORMATION OF REDOXIMORPHIC METALS UNDER OXYGEN FLUCTUATION IN TEMPERATE FOREST SOIL

Resumo

The temperate forest soils in southern Chile are subject to constant redox changes due to persistent rainfall during the year. This favors the displacement of dissolved oxygen, making soil macrosites anaerobic. This cycling commands the proliferation and microbial distribution that play important roles in the biogeochemical processes of pedogenesis. So, we hypothesized that the soil oxygen content affects the microbial dynamics and mechanisms of oxidative transformation in Mn and Fe. We evaluate the contribution of soil microbial communities in oxic and anoxic environments to functional oxidative processes on Mn, Fe, soil organic matter, ATP, and microbial dynamics. The analysis was carried out in soils from Tolhuaca National Park (TNP) in long-term incubation (30 min to 360 h) under oxic (O) and anoxic (AN) conditions (purged with helium). At 30 min, 3 h, 6 h, 12 h, 72 h, and 360 h, soil subsamples were taken for functional analyses. The results indicated that the oxidation processes are mostly favored under the oxic condition, increasing the oxidized Fe and Mn, CO2 efflux, and ATP content. Lower rates of microbial respiration under anoxic conditions were observed, and the ATP content did not exceed 15% with respect to the oxic group. In anoxia, the content of Fe (III) and Mn (III/IV) was reduced with respect to the oxic group due to the reductive conditions. Both groups showed increased microbial ROS production in a ratio of 1:3 (anoxic: oxic) in a time-dependent manner. Under oxic conditions, the bacterial groups did not modify their diversity, but the load (4.4%) and microbial distribution increased at 360 h. Under anoxic conditions, new microbial patterns and density (43%), were observed after 72 h. These results suggest a high microbial influence on redoximorphic metal transformation under oxic and anoxic conditions, in accordance with the microbial transition.

Palavras-chave

soil redox, geomicrobiology

Instituição financiadora

Fondecyt 3200758 and Fondecyt 11230807