Influence of the dry and rainy period on trace metal enrichments in sediments of the southern coast of the state of Pernambuco, Brazil

Marine sediment contamination by trace metals is an important environmental concern due to their persistence and potential ecological impacts. This study evaluated the environmentally available concentrations of trace metals in surface sediments from six beaches along the southern coast of Pernambuco, northeastern Brazil, during the dry and rainy seasons. Sediments were characterized by granulometry, organic matter, decarbonation, FTIR, TGA, and ICP OES after partial extraction with 0.1 mol L⁻¹ HCl. High carbonate contents and variable organic matter were observed, while FTIR and TGA confirmed carbonate and silicate minerals associated with metal retention. Ba, Co, Cr, Fe, Mn, Ni, and Zn were detected, whereas Cd and Cu were below quantification limits and Pb was detected only at one site. In general, metal concentrations were higher during the rainy season, indicating seasonal influences on metal availability. All concentrations remained below the limits established by Brazilian and international sediment quality guidelines. Contamination and ecological risk indices classified all sampling sites as presenting low environmental risk. These results provide important baseline data for environmental monitoring and management of tropical coastal ecosystems.