Temporal variability of emerging contaminants and estrogenic activity in sediments of a tropical coastal lagoon.

The increasing occurrence of emerging contaminants in aquatic environments has raised concerns about their persistence and ecological impacts, particularly in coastal lagoons subjected to anthropogenic pressure. Here, we investigated the occurrence of pharmaceuticals, alkylphenols, bisphenol A (BPA), and steroid estrogens, together with their estrogenic activity, in surface sediments from Maricá Lagoon (Rio de Janeiro, Brazil), testing the hypothesis that contaminant occurrence and biological responses vary between sampling years despite persistent anthropogenic inputs. Surface sediments were collected from seven fixed sites during dry-season campaigns in 2021 and 2023. Grain size distribution was determined by sediment texture analysis, organic contaminants were identified and quantified using gas chromatography-mass spectrometry (GC-MS), and estrogenic activity was assessed using the yeast estrogen screen (YES) bioassay. Chemical analyses detected alkylphenols (4-octylphenol and 4-nonylphenol), BPA, steroid estrogens, and pharmaceutical-related compounds. BPA was the most frequently detected contaminant (0.10-0.465 ng g⁻1), followed by 4-octylphenol (0.010-0.390 ng g⁻1) and 4-nonylphenol (0.033-0.344 ng g⁻1). Station M7 exhibited the greatest contaminant diversity, with 9 of 12 target compounds detected, identifying it as a localized contamination hotspot. Estrogenic activity was detected in selected samples, whereas pronounced cytotoxicity in one sample may have masked estrogenic responses. Comparisons between campaigns revealed temporal variability in contaminant occurrence and biological responses, although several compounds persisted across both years. These findings demonstrate persistent and spatially heterogeneous contamination and highlight the value of integrating targeted chemical analyses with bioanalytical tools to assess contaminant occurrence and biological effects in coastal ecosystems.