Testemunhos de Lama - Conhecer o passado, compreender o presente e pensar o futuro: reconstituição da contaminação nos manguezais da costa brasileira e dimensões socioeconômicas de seu entorno

Abstract

This thesis shows a study on the accumulation of organic matter in mangrove sediments using lipid molecular markers (aliphatic hydrocarbons - AHT, polycyclic aromatic hydrocarbons - PAHs - and sterols) and socioeconomic indicators, with the objective of evaluating the historical process of mangrove contamination along the coast of Brazil. Eight (8) sediment cores were sampled in mangrove forests, distributed in areas with pristine characteristics and under anthropic influence, representative of the four Brazilian coastal geographic regions. The organic compounds were obtained by extraction in Sohxlet (EPA 3540C) and separation on liquid chromatography on an open column of silica / alumina (EPA 3630C). Identification and quantification were performed by gas chromatography with flame ionization detector (GC / FID - EPA 8015B) for TAH and coupled to mass spectrometry (EPA 8270D) for PAHs and sterols. The obtained concentrations of hydrocarbons (TAH: 0.5 to 381.7 μg.g-1, PAHs: 4.2 to 4,877 ng g -1, and Σ16PAH: 2.3 to 630 ng g -1) and sterols (Total: 3.09 to 451.4 μg g-1 and 27Δ0β: 0.22 to 8.75 μg g-1) represent low to moderate contamination levels in the sediments. A more expressive contribution of these compounds was observed in the last decades, reflecting a recent contamination mainly for the mangroves adjacent to metropolitan areas, corresponding to local anthropic activities. Through an integrated approach applying multivariate statistical analysis and interpretation of socioeconomic indicators, it was possible to discern the historical profiles of natural and anthropogenic contributions (pyrolytic, petrogenetic and/or fecal) in the mangroves sediments in response to the evolution of the processes of urban, agrarian and industrial occupation, as a result of Brazil's development policies in the last century. The sharp trend of increasing levels of contamination in recent decades requires special attention. In this way, for the conservation of mangroves,it is evident the importance of exposing the knowledge generated here and of new knowledge for the whole Brazilian society