Urban Wetlands as EcoHaven Oasis: Hydrogeochemical Insights from the Inciralti-Cakalburnu Urban Wetland (ICUW) in Izmir, Turkiye

Urban wetlands provide vital ecological services, yet their hydrogeochemical dynamics and associated risks remain insufficiently explored, especially within urban contexts. This study aims to evaluate the Inciralti-Cakalburnu Urban Wetland (ICUW) in Izmir, Turkey, as a case study for understanding the complex interactions between water quality, contamination risks, and urban development. The ICUW, a unique example of a natural coastal urban wetland, offers critical services such as flood regulation, water purification, and carbon sequestration, while also being vulnerable to contamination from agricultural runoff, seawater and geothermal water intrusion. Key findings include significant variations in water quality parameters: pH values range from 6.73 to 9.00, electrical conductivity (EC) from 911 to 61,700 μS/cm, and total dissolved solids (TDS) from 631 to 42,935 mg/L. Notably, concentrations of heavy metals such as arsenic (0.002–0.0048 mg/L), boron (0.060–39.6 mg/L), bromide (0.100–80.8 mg/L), fluoride (0.130–4.2 mg/L) and nitrate (0.5–193 mg/L) exceed recommended levels, posing health risks. The Water Quality Index (WQI) classification shows a wide range from "excellent" to "unsuitable for drinking," indicating significant spatial variability. Health Risk Assessments (HRA) identify B, Br, F, and NO3 as the primary contaminants of concern, especially in areas impacted by seawater intrusion, agricultural activities and natural geothermal fluids mixing. The use of stable isotope analysis reveals marine and freshwater interactions, which influence the water's chemical composition. This study underscores the importance of sustainable management practices to mitigate contamination risks, safeguard public health, and preserve the multifunctional role of urban wetlands in enhancing urban resilience and climate adaptation.