Dados do Trabalho

Título

EFFECT OF THE FENTON REACTION WITH DIFFERENT H2O2 CONCENTRATIONS ON MICROBIAL COMMUNITIES IN SOUTHERN CHILE SOILS

Resumo

Soils of humid temperate forests experience changes in dissolved oxygen levels as a result of fluctuations in water saturation caused by rains that last from hours to weeks. This results in anoxic environments promoting reduction processes. Under these conditions, the Fenton reaction plays an important role, leading to the abiotic oxidation of Fe(II) using hydrogen peroxide (H2O2), generating Fe(III) and hydroxyls radicals, attacking the soil organic matter (SOM), and releasing CO2. This study aimed to assess the impact of Fenton reaction on biological communities in four soils from Chilean National Parks, Conguillio (PNC), Puyehue (PNP), Alerce Costero (PNAC), and Valdivian Coastal Reserve (CVR). Incubations were performed in microcosms under oxygen-free conditions. The treatments were 1:1, 5:1, 10:1, and 20:1 of H2O2 (0.1M): Fe (0.1M FeCl2) and an untreated control for 48 hours. After that, the Fe concentration was measured using ferrozine, H2O2, and OH-, metabarcoding, and the quality of SOM by FTIR was determined. The results showed that the Fenton reaction occurred at a higher proportion in the 1:1 treatment in all soils. This is due to the amounts of Fe obtained by ferrozine being greater for Fe(III) at the end of the reaction, especially in the 20:1 treatment of PNAC (1.67 mg Fe(III)/g soil). The SOM showed a similar quality in PNP, PNAC, and RCV soils. Mineral-associated organic matter and C-O bound were observed in all treatments at 995-1004 wavenumbers (wn). PNC soil presents a higher pick at 993 nm than the rest of the soils in the 1:1 treatment, but this peak decreased as the amount of H2O2 increased, indicating an attack of the H2O2 in the easily available and exposed SOM. In all soils, the phylum proteobacteria, acidobacteria, and planctomycetes were the most abundant, while the genus Mucilaginibacter spp. increased as H2O2 increased. In conclusion, Fenton reaction caused cell death, phylum inhibition, and soil activity reduction, mostly at 20:1 ratio.

Palavras-chave

Redox; SOM; Microbial diversity

Instituição financiadora

Fondecyt 1220116

Agradecimentos

Laboratory of Geomicrobiology and Laboratory of Conservation and Dynamic of Volcanic Soils from the Department of Chemical Sciences and Natural Resources, Universidad de La Frontera. Also Scientific and Technological Bioresources Nucleus, BIOREN, Universidad de La Frontera, Temuco, Chile.