Spatial and seasonal assessment of heavy metal contamination in Golden Horn sediments, İstanbul, Türkiye: Ecological impacts, human health risks, and environmental monitoring.

This study investigates the concentrations of heavy metals (As, Hg, Cd, Cr, Cu, Ni, Pb, Zn) in surface sediments of the Golden Horn, a historically significant natural harbor and UNESCO World Heritage Site inlet of the Bosphorus in İstanbul, Türkiye. The novelty of this research lies in providing the first comprehensive dual-risk assessment for the Golden Horn estuary, integrating ecological impact evaluation with human health risk characterization via ingestion and dermal contact pathways, considering both carcinogenic and non-carcinogenic effects of sediment-bound heavy metals. Concentrations exhibited significant seasonal variation, with summer months showing peak levels, notably for for Cu (1279.70 mg/kg)), Zn (1071.96 mg/kg), and Pb (894.14 mg/kg). Several metals exceeded Probable Effect Concentration (PEC) thresholds, indicating potential ecological risks such as biodiversity decline and food chain contamination. Pollution Load Index (PLI) values ranged from 2.09 to 10.25 (PLI > 1), confirming substantial sediment pollution. Enrichment Factor (EF) values varied between 0.80 and 17.44, highlighting considerable contamination, particularly by Cu, Pb, As, Zn, Cd, and Cr. Potantial Ecological Risk Factor (Er) values for Cu, Pb, and Zn indicate a very high ecological threat. Potantial Ecological Risk Index (RI) values ranged from 1045.69 to 7317.72, suggesting severe ecological risks, whereas the Toxic Risk Index (TRI) indicated low toxic risk for Cu (5.78). Health risk assessments revealed increased vulnerability in children, with carcinogenic risk values exceeding acceptable limits for both children and adults. These results underscore the urgent need for remediation to mitigate environmental and human health risks posed by heavy metal contamination in the Golden Horn sediments. ENVIRONMENTAL IMPLICATION: This study highlights the presence and distribution of heavy metals in the sediments of the Golden Horn, indicating potential ecological degradation and risks to marine biodiversity. The findings indicate that certain locations exceed sediment quality guidelines, posing threats to benthic organisms and the safety of the food chain. Ecological and human health risk assessments suggest that prolonged exposure may lead to bioaccumulation and adverse health effects. These results underscore the urgent need for pollution control strategies, sustainable management of industrial discharges, and continuous environmental monitoring to protect coastal ecosystems and safeguard public health in the region.