Características físico-químicas da matéria orgânica e potencial de emissão de C-CO2 em solos da Antártica Marítima

• Autor(a) principal: Carvalho, Juliana Vanir de Souza
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2093
• topic: Substâncias húmicas; Potencial redox; Q10; Humic substances; Redox potential; Q10; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ANALITICA

Polar regions are one of the most important reservoirs of carbon (C) of the planet. Monitoring of soil carbon storage in a changing global climate context may indicate possible effects of climate change on the terrestrial environment. So, it is necessary to understand the processes of changes in soil organic matter (SOM), the contents of total organic carbon (TOC) into the soil and the mineralization rate and the determination of redox potential and chemical characteristics of organic matter that influence these processes. The present study aimed to evaluate the influence of redox potential and chemical characteristics of humic substances (HS) on the process of mineralization of SOM of Antarctic. For this, were used five soils of Keller Peninsula, King George Island. Were evaluated the content of total organic carbon (TOC), oxidizable C fractions, total nitrogen (TN) and compartments of SOM. Were extracted, quantified and characterized in the HS. Were conducted an experiment in situ during two summers in order to evaluate the emissions of C-CO2 in relation to temperature variation. SOM of Antarctic presented low state of decomposition and reduced microbial activity, resulting in low values for carbon storage of these soils. HS of these soils have greater aliphatic character, low content of phenolic groups, lower acidity and less formal standard potential of electrode (FEº H), when compared to HS of soils from other regions of the planet, suggesting that they are more likely to be oxidized. The emission of C-CO2 showed significant exponential relationship (p <0.05) with temperature for studied soils. The sensitivity of the emission of C-CO2 in relation to temperature correlated significantly with the degree of humification, content of phenolic groups and activity of the microorganisms. Values of Q10 didn t differ, however, were higher than those observed values by several authors, and may predict a sharp increase in the emission of C-CO2 with increasing temperature.