Mapping chemical footprints: A baseline assessment for organochlorine pesticides and polychlorinated biphenyls in coastal sediments of Greece (eastern Mediterranean Sea)

Studying organochlorinated compounds in coastal sediments is necessary because these substances are persistent, bioaccumulative, toxic, and still detectable decades after their ban, whereas sediments act as long-term archives of pollution and as secondary sources that can remobilize contaminants into marine ecosystems. Herein, we provide for the first time a comprehensive overview of pollution levels and potential sources of a broad range of organochlorine pesticides (24 substances) and polychlorinated biphenyls (25 substances) in coastal sediments of Greece. Surface sediments from 48 coastal areas were collected during March 2023 and March 2024 and analyzed for a wide range of chlorinated pesticides and polychlorinated biphenyls using gas chromatography - tandem mass spectrometry. The results revealed a significant spatial variability in pollution levels consistent with the heterogeneous anthropogenic pressures along the Greek coastline. Total pesticide concentrations varied between 0.01 and 0.75 ng g −1 , while total polychlorinated biphenyls ranged from 0.01 to 50.7 ng g −1 . The Saronikos Gulf was by far the most polluted region, while stations in the Aegean Sea and southern Crete were found to be the least affected ones, and could be accounted as representative of background organochlorine levels. Considering the fact that the studied legacy organic contaminants remain detectable in Greek coastal sediments decades after their prohibition, the current dataset provides a valuable baseline for monitoring their temporal trends in future sampling surveys, ensuring long-term environmental management, ecosystem quality protection and sustainable coastal development, especially in urbanized and industrialized embayments of Greece and beyond.