Long-term (1979-2024) trends and remobilization process of mercury pollution, the case study of Haifa Bay, Southeast Mediterranean Sea.

This study examines the interlink between long-term (1979-2024) trends of Hg contamination in sediments and commercial target fish species (Sargocentron rubrum, Diplodus sargus) and industrial Hg loads and their modes of entry to the marine system, using Haifa Bay (HB) in northern Israel and unpolluted reference sites as a case study. Historically, Hg levels in sediments and fish in HB fluctuated in response to industrial discharge from a former PVC factory. Despite a drastic regulatory reduction during the 1990s and the factory's closure in 2004, Hg levels in target fish species have shown an unexpected increasing trend, at rates of 1.45-1.94 % yr-1 over the last two decades (exceeding safe consumption limits), while the sediment levels remained enriched but stable over time. No similar trends were detected in the fish or sediments of unpolluted reference sites. We show that soils and groundwater under the former PVC factory site are anomalously Hg-enriched, acting as a source of total, and methylmercury (MeHg) pollution in Northern HB. We discuss possible explanations for the temporal decoupling trends in fish and sediments. This study highlights the ongoing risk of relic industrial Hg pollution buried in coastal areas to commercial fish species and human health.