Integrated assessment of marine and terrestrial inputs in sediments from a southeastern Brazilian coastal bay using geochemical and molecular markers

C) indicate a predominance of marine-derived organic matter, with some terrestrial influence in the southern sector of the cove. Lipid biomarkers such as long-chain n-alcohols and high-molecular-weight n-alkanes reveal more specific terrigenous inputs, highlighting the contribution of vascular plants. Polycyclic aromatic hydrocarbons (PAHs) were detected at all sites in low concentrations, predominantly of pyrogenic origin linked to biomass combustion, with localized petrogenic inputs near the marina. Perylene presence suggests in situ diagenetic formation under anoxic conditions. PAH levels were generally below sediment quality guideline thresholds, indicating low ecological risk. The results emphasize the need for continued monitoring and management to preserve sediment quality in this environmentally sensitive coastal area.