The Distribution of Xenobiotics of Terrigenous Origin in the Nearshore Waters of a Caribbean Island.

Anthropogenic pollutants known as xenobiotics, such as pharmaceuticals, pesticides, or human metabolites, primarily originate on land and accumulate near populated coasts, where rainfall further increases their transport and harmful impacts on marine ecosystems. However, empirical evidence for such dynamics remains limited. Here, we investigate spatial and seasonal patterns of terrigenous xenobiotics along the land-sea continuum of Curaçao. Using solid-phase extraction and untargeted LC-HR-MS/MS metabolomics, we detected approximately 30,000 molecular features, including 1,394 xenobiotics that were most abundant in terrestrial waters, declined offshore, and correlated strongly with other terrestrial input indicators (fDOM). Results from three cross-seasonal campaigns (2021-2022) revealed that rainfall and increased water residence times were dominant drivers for xenobiotic abundances along the shore, with 3.5 times higher abundances during the 2022 wet season compared to drier periods. Additional factors were local landscape features, distance to fluvial runoff, hydrodynamic connectivity, and, for specific substance groups (e.g., human metabolites or personal care products), human activities in proximity to sampling locations. Our findings show that terrigenous xenobiotics spread island-wide, making them a broader concern beyond discharge sites. This first island-wide, seasonally resolved assessment provides a baseline for managing emerging contaminants and understanding their wider impact on Caribbean coastal ecosystems.