Characterization and dating of soil humic material in holocene progradational sequence, N. Santa Catarina Littoral, Brasil

Póster 230 presentado en la Session 2: Soil and peat and terrestrial OM 1.-- Congreso celebrado del 18-23, en septiembre de 2011, en Interlaken, Austria.
Piçarras (a vernacular term for podzols) occur along the South Eastern costal zone of Brazil between Rio Grande do Sul and Rio de Janeiro States. Piçarras are formed as a result of cemenentation of the soil B horizon formed on mostly sandy littoral barrier sediments covered by the lush Atlantic forest. The cementing material is composed by the mixture of sesquioxides (2-4%) and humic material exhibiting the elemental C content between 1 and 3%, calculated per dry weight of the sediment. It is assumed that the colonization of the accreted littoral bodies by vegetation occurred rapidly and contributed to the accumulation of humic material. Our study was carried out along a 3 km trench profile, perpendicular to the shore line in Volta Velha which is a private biological reserve area situated in the municipal district of Itapoá, in the northeast of Santa Catarina State, and is part of the area considered as the Atlantic Forest Biosphere Reserve. The investigated trench profile is also roughly perpendicular to the front of prograding Holocene barriers composed of fine to medium sand weekly cemented by humic material and sesquioxides produced by the weathering of heavy minerals. 14 samples were collected from the studied transect and submitted to inorganic, and organic elemental analyses, lipid extract GC-MS determination based on flash pyrolisis and 13C nuclear magnetic resonance (NMR) characterisation of organic matter, which was further dated by 14C AMS method.