ASSESSMENT OF METAL CONTAMINATION AND ASSOCIATED ECOLOGICAL AND HEALT RISKS IN CREEKS DISCHARGING INTO GOKOVA BAY, TURKİYE

Abstract

This study presents a comprehensive assessment of metal contamination and associated ecological and human health risks in three freshwater systems (Azmak, Ak & ccedil;ap & imath;nar, and & Ccedil;etibeli Creeks) discharging into G & ouml;kova Bay, a Special Environmental Protection Area on the southwestern coast of T & uuml;rkiye. Surface water and sediment samples were collected monthly from six stations between April 2023 and March 2024, and concentrations of Fe, Cu, Mn, Zn, and Cd were determined using atomic absorption spectrometry. Sediment contamination was evaluated using the Contamination Factor (CF), Enrichment Factor (EF), Geoaccumulation Index (Igeo), and Potential Ecological Risk Index (ER and RI), while non-carcinogenic and carcinogenic risks were assessed through Average Daily Dose (ADD), Hazard Quotient (HQ), Hazard Index (HI), and Cancer Risk (CR) according to U.S. Environmental Protection Agency methodologies. Multivariate statistical analyses, including Spearman correlation, principal component analysis, and non-parametric tests, were employed to identify spatial and seasonal patterns. Sediment concentrations followed the order Fe > Mn > Zn > Cu > Cd, with Cd exhibiting exceptionally high levels (mean: 8.75 mg kg(-1)), substantially exceeding international sediment quality guidelines. Cd showed very high contamination (CF = 89.35), extreme enrichment (EF = 455.05), and strong geoaccumulation (Igeo = 5.77), indicating severe anthropogenic input. The overall ecological risk index (RI = 2688.42) revealed a very high ecological risk, overwhelmingly driven by Cd. Spatial analyses identified Ak & ccedil;ap & imath;nar downstream station as the principal contamination hotspot, whereas seasonal variation was limited except for Cd, which peaked during spring. Human health risk assessment indicated that sediment ingestion poses significant non-carcinogenic risks, particularly for children (HI = 181.34), and carcinogenic risk from Cd exposure in children (CR = 6.25 x 10(-4)) exceeded the acceptable threshold recommended by the USEPA.