Matéria orgânica de solos da Antártica Marítima: impacto do aquecimento global sobre os estoques de carbono e nitrogênio, e sua modelagem

• Ano de defesa: 2010
• Autor(a) principal: Pires, Cleverson Vieira
• Orientador(a): Mendonça, Eduardo de Sá
• Banca de defesa: Simas, Felipe Nogueira Bello , Reis, César
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Solos e Nutrição de Plantas
• Departamento: Fertilidade do solo e nutrição de plantas; Gênese, Morfologia e Classificação, Mineralogia, Química,
• País: BR
• Palavras-chave em Português: Antártica; Matéria orgânica; Carbono
• Palavras-chave em Inglês: Antarctic; Organic matter; Carbon
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::CIENCIA DO SOLO
• Link de acesso: http://locus.ufv.br/handle/123456789/5467

There are few studies on quality, quantity and dynamics of organic matter in Antarctic terrestrial ecosystems. These ecosystems are restricted to ice-free areas which represent only 2% of the continent total area. The Maritime Antarctic region has the highest values of temperature and precipitation across the whole continent, promoting primary production, pedogenesis and biological activity. This study aimed at evaluating the potential of C-CO2 emission on soils of these environments in relation to the global warming. For this soil samples were collected at seven different points of King George Island. Five of them where on the Keller Peninsula (P1, P2, P3, P4 and P5) and two on the west coast of Admiralty Bay, on a place called Arctowski (P6 and P7). Two of these soils are originated from basalt and andesite (P1 and P2) and three are affected by sulfides (P3, P4 and P5). The last two have a strong ornitogenic influence (P6 and P7). The samples were collected at two different depths, 0 to 10 cm (0-10) and 10-20 cm (10-20). The contents of total organic C and N (TOC and TN) and their levels in different fractions of humic substances (HSs) were analyzed. In addition, the mineralization rates of these nutrients were evaluated in four different temperatures (2, 5, 8 and 11 ° C). All these data were led to the modeling process. The Century model was used to model the future stocks of C and N considering the context of global warming possibilities. The contents of TOC and NT on ornitogenic soils were the highest: P6 (0-10), TOC= 40.14 g/kg and NT = 3.73 g/kg, P6 (10-20), TOC = 30.85 g/kg and NT = 2.54 g/kg; P7 (0-10), TOC = 43.15 g/kg and NT = 5.22 g/kg; P7 (10-20), TOC = 31.56 g/kg and NT = 3.57 g/kg. Beside, these soils had the lowest C/N ratio. Soils P1 and P2 showed the lowest levels of TOC and TN and the highest C/N ratio due to the low content of NT. Intermediate values were found on soils P3, P4 and P5. At all sites, most of the TOC and TN were on the humin fraction (FH). The mineralization of organic matter, measured through soil C-CO2 emission, assumed distinct behavior at both studied depths. Only at the 0 to 10 cm depth, continuous growth was observed with the temperature. At the depth of 10 to 20 cm, the mineralization was greater with temperature up to 8ºC, but at the temperature of 11°C the mineralization decreased. Probably it happens because the microorganisms of this environment were not adapted to these temperatures, unusual at this depth in Antarctic environments. Soils with higher emission sensitivity related to the temperature variation from 2 to 11ºC were ormitogenic, with an increase of 102% and 61% in the flow of C- CO2 for the samples P6 (0-10) and P7 (0-10), respectively. These results were used to the modeling process. Literature data were also used to feed the model, but no consistent data could be used due to the lack of essential data (plants physiology and contribution of animal waste to each environment). Therefore it is expected that the studied soils, specially ornitogenic, due to the high content of organic matter, exert an important role in the emission of C-CO2 if the global warming is confirmed. These environments would become gas emitters instead accumulators, further contributing to increase the global temperature.