O uso do registro esporo-polínico combinado a geoquímica sedimentar para a identificação de paleo-tempestades, impactos do clima e processos erosivos para a Lagoa do Sombrio

Abstract

The meteorological records are recent when compared to the earth's history of 4.5 billion years, so it is difficult to say whether the frequency of cyclones is natural or is a result influenced by anthropic actions. It is expected that the combined analysis of meteorological, palynological, and geochemical records in dated lacustrine sedimentary cores can help to identify hurricanes in the past, contributing this information over time. Thus, the present work aimed to identify and systematically analyze the main studies that relate the influence of cyclones on the dispersion of pollen grains into the atmosphere and the lithosphere, as well as verifying whether the palynological records in the sedimentary layers of Lagoa do Sombrio constitute a good marker for hurricane Catarina in the extreme south of the state of Santa Catarina. Few studies were found on the subject, but anticyclones that provide dry and sunny weather are related to the increase in the concentration of pollen grains in the atmosphere, while cyclones seem to promote the transport of these palynomorphs for long distances (wind force) or deposit them (precipitations). Because they cause pollen deposition, they can be considered a marker for records of cyclones in the quaternary, in regions with characteristic vegetation. However, the analyzed data did not show a clear correlation between pollen concentration and Hurricane Catarina. A probable hypothesis for this result is related to the flowering time not being consistent with the period of occurrence of Hurricane Catarina, as well as the possibility of obliteration of the signal caused by the pioneer plant formation, associated with anthropogenic interference in the surroundings of Lagoa do Sombrio. As a complement to the main objective of the work, it was possible to characterize the vegetation around the lagoon through palynology and to verify the works with the greatest anthropic impact in this lagoon through XRF elemental analyses. In this sense, it is possible to predict that shell mortality is related to the entry of salt water into the lagoon, evident after the opening of the channel that connects the Sombrio lagoon to the Mampituba River.