Environmental impact and analytical characterization of water samples from the Caspian Sea

This study assesses the environmental conditions of the Caspian Sea by analysing water samples collected from four key locations along the Azerbaijani coast: Bilgah, Sumgait, Pirallahi, and Neftchala. Given the region’s extensive industrial, agricultural, and oil extraction activities, marine pollution is a growing concern. To evaluate contamination levels, we employed thermogravimetric analysis (TGA), dynamic light scattering (DLS), and X-ray diffraction (XRD) to examine the chemical composition and particle size distribution of residues from evaporated water samples. Our findings revealed significant variations in pollution levels across the study sites. Sumgait exhibited the highest residue mass (4.3 g/100 ml), indicating severe contamination, followed by Neftchala (3.7 g/100 ml). In contrast, Bilgah and Pirallahi had significantly lower residue masses (1.1 g and 1.2 g/100 ml, respectively). TGA results identified sodium chloride (NaCl) as the dominant component, with substantial mass losses of 11.55% in Sumgait and 12.24% in Neftchala, indicating high salt contamination, likely from industrial discharges and oil refining activities. XRD analysis confirmed NaCl as the principal mineral and detected calcium sulfate (CaSO4) in Neftchala, suggesting additional contamination sources, potentially from agricultural runoff. DLS analysis revealed finer particle sizes in Sumgait, raising concerns about pollutant dispersion over broader areas. These findings highlight the urgent need for continuous environmental monitoring and mitigation strategies to manage pollution in the Caspian Sea. By integrating advanced analytical techniques, this study provides a comprehensive assessment of water quality, offering valuable data for environmental policymakers and marine conservation efforts. Keywords: Caspian Sea; Marine environmental monitoring; thermogravimetric analysis (TGA, X-ray Diffraction (XRD); water quality analysis