Organic and inorganic geochemical characterization of mangrove sediments of the São Francisco Estuary, Sergipe

Abstract

Mangrove ecosystems develop in coastal areas and possess intrinsic characteristics being considered in Brazil environmental preservation areas, however, anthropogenic impacts associated with property speculation and petroleum activities are altering the landscape of these ecosystems. This study aimed to perform organic and inorganic geochemical characterization (pH, organic matter content (MO), elemental analysis, determination of metals-Al, Na, K, Fe, Cd, Cr, Cu, Ni and Pb) in mangrove sediments of the São Francisco Estuary, Sergipe. Mineralogical characteristics defined the sediments as high acidity (pH <4.9), consisting of little decomposed organic matter and low humification. Measurements of elemental analysis with C/N ratio > 10% and MO greater than 15% are related to the proximity of the sampling stations to urban and industrial centers, intrinsic characteristics of native vegetation and different contributions from biomass. The Cd, Cu and Ni metals in sediments showed some upper bounds when compared to the legislation Threshold Effect Level (TEL) e Probable Effect Level (PEL) of Canadian Sediment Quality Guidelines for the Protection of Aquatic Life and Conselho Nacional do Meio Ambiente (CONAMA), being linked to anthropogenic activity in the region and alerting for toxicological reasons.