Polycyclic aromatic hydrocarbons and polychlorinated biphenyls in tissue of mangrove Rhizophora mangle from the Colombian Caribbean

The expansion of human activities has led to organic compound contamination. These compounds have adverse ecosystem effects, yet research on their bioaccumulation is insufficient globally. This study aimed to (i) determine PAH and PCB concentration levels in Rhizophora mangle root tissue, and (ii) evaluate seasonal variations in PAH and PCB levels between rainy and dry seasons in two estuarine areas: the Ciénaga Grande de Santa Marta (CGSM) and Cispatá Bay (CIS). Samples from three places per area, collected in September 2022 and April 2023, were analyzed by gas chromatography-mass spectrometry. Results revealed that PAH concentrations were highest during the rainy season, in the Cispatá Bay, with an average of 180.5 ± 21.4 ng g^-1. In contrast, PCB concentrations peaked during the dry season, in CGSM, with an average of 10.7 ± 11.6 ng g^-1. A significant positive correlation was observed between silt and total PAH concentrations during the rainy season. Conversely, total PCBs showed a significant negative correlation with pH and fine sediment during the rainy season, and with coarse sediment during the dry season. Using the Biota-Sediment Accumulation Factor (BSAF), it was found that root tissues can only accumulate small amounts of PAHs from sediments. Additionally, the presence of albino mangrove individuals in the Cispatá area suggests potential mutagenic stress. These findings underscore the urgent need to mitigate contamination and standardize monitoring protocols to protect biodiversity in the Colombian coastal ecosystems.