Uso dos fenóis da lignina no estudo da material orgânica na Várzea do Lago Grande Curuái, Pará e no Lago do Caçó, Maranhão, Brasil

Abstract

This study aims to characterize the superficial sediments of lakes in black and white waters of an Amazonian floodplain system in terms of carbon content and quality of lignin phenols. "Várzea do Lago Grande Curuái" floodplain is located on the right bank of the Amazon River about 850 km from the estuary. Superficial sediments samples were compared with superficial samples from Lake Caçó, located in Maranhão, the edge of the Amazon ecosystem. Concentration of lignin (λ), Total Organic Carbon (COT), nitrogen and isotope of carbon (δ13C) were undertaken. The results indicate that, in general, the superficial sediments of lakes of white water have low values of COT (1,5 to 3,6%), low concentrations of λ (0,73 to 1,28 mg.100mg CO-1) and high degradation index (0.29 to 2.01). Superficial sediments of lakes of black water had higher values of COT (6,0 to 12,1%) and λ (1,44 to 1,93 mg.100mg CO-1) than the sediments of lakes of white waters, but lower in comparison with the sediments of Caçó Lake. Through such analysis, it was possible to identify different contributions of organic matter sources and the preservation states to the superficial sediments at both sites.