https://hdl.handle.net/20.500.12809/11035 Fri, 03 Jul 2026 21:39:18 GMT 2026-07-03T21:39:18Z https://hdl.handle.net/20.500.12809/11221 ASSESSMENT OF METAL CONTAMINATION AND ASSOCIATED ECOLOGICAL AND HEALT RISKS IN CREEKS DISCHARGING INTO GOKOVA BAY, TURKİYE Genç, Tuncer Okan; Yılmaz, Fevzi; Yılmaz, Ersin; Yıldız, Dilek; Kabanka, Göktuğ 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. Thu, 01 Jan 2026 00:00:00 GMT https://hdl.handle.net/20.500.12809/11221 2026-01-01T00:00:00Z https://hdl.handle.net/20.500.12809/11220 A Hybrid Nanomaterial-Based Electrochemical Sensor for Melatonin Measurement in Human Saliva: A Diagnostic Tool for Anxiety Disorder Özyurt, Vasfiye Hazal; Çaylayık, Nil Su; Çitil, Burak Ekrem; Türkiş, Fulden Cantaş; Anık, Ülkü Since the diagnosis of anxiety disorder is primarily based on questionnaires, accurate identification of the disorder can be challenging. Melatonin has been identified as a potential biomarker for the detection of anxiety disorders. By targeting this biomarker, it will be possible to get more accurate results and diagnose anxiety disorder more properly. In this study, a carbon screen-printed electrode modified with multi-walled carbon nanotube-gold-platinum (MWCNT-Au-Pt) nanocomposite-based electrochemical sensor was developed for the detection of melatonin. To enhance the sensor's performance, key experimental parameters-including the amount of MWCNT-Au-Pt nanoparticle and the pH of the solution-were systematically optimized. The sensor exhibited two linear response ranges for melatonin: from 0.5 to 50 & micro;M with a limit of detection (LOD) of 0.23 & micro;M, and from 100 to 1000 & micro;M with an LOD of 2.14 & micro;M. The sensor's specificity was evaluated in the presence of potential interfering substances. It was subsequently applied successfully to the detection of melatonin in 25 real human saliva samples. As a result, the first MWCNT-Au-Pt modified electrochemical sensor for melatonin detection, which will lead to proper anxiety disorder diagnosis, was fabricated. Thu, 01 Jan 2026 00:00:00 GMT https://hdl.handle.net/20.500.12809/11220 2026-01-01T00:00:00Z