Dados do Trabalho

Título

EVOLUTION OF REDOXIMORPHIC METALS AND CO2 EMISSION ACROSS THE GLACIER RETREAT IN SOILS OF KING GEORGE ISLAND, MARITIME ANTARCTICA

Resumo

The advance of climate change has generated a retreat of glaciers, a process that is especially noticeable in the Antarctic Peninsula, which causes large land areas to be exposed and soil formation processes to begin, with the consequent release of greenhouse gasses. This work aims to study the release of greenhouse gasses as glaciers retreat on King George Island, maritime Antarctica. For this purpose, the oxide-reduction states of Fe and Mn were evaluated in two chronosequences composed of four sampling points each, located at Bellingshausen Dome, Fildes Peninsula. The soil organic matter quality (FTIR), C, N, H content (Elemental Analyzer), CO2 emissions (Infrared Gas Analyzer), Iron (II) and (III), Mn (III) were determined by colorimetric reactions. Microbial distribution was evaluated by barcoding sequencing using a Nanopore sequencer (>1000bp). The soils had low organic matter, high mineral content, and low polysaccharides, indicating a low microbial C input. As they moved away from the glacier, both chronosequences showed higher CO2 fluxes, indicating aerobic microbe proliferation and abiotic reactions by oxidation, likely of the limited and labile organic materials. Redoximorphic transformations showed an increase in Fe (III) levels and total Fe as one moves away from the glacier, which is also related to Mn(III) content, which may be enhanced by Fe and Mn oxidizing microorganisms and O2, which promotes abiotic oxidation reactions due to exposure to the gas. The longer the exposure duration, the more bacteria of the Acidobacterium phylum and Actinomycetes were found, indicating the colonization of aerobic microbes that stimulate oxidative activities in the soil.In conclusion, extended exposure times increase mineral and labile organic matter oxidation, which soil microbes may consume to colonize and emit more CO2. However, soils farther from the glacier with higher microbial maturity have metal values that imply Fe and Mn biogeochemical cycle development.

Palavras-chave

Climate change, oxide-reduction, soil formation

Instituição financiadora

PROYECTO INACH RT_12_21

Agradecimentos

Laboratory of Geomicrobiology and Laboratory of Conservation and Dynamic of Volcanic Soils. Universidad de La Frontera, Temuco, Chile.