Spatial and Temporal Assessment of Heavy Metal Contamination in the Black Sea Surface Waters
Hakan Atabay, Ertuğrul Aslan, İbrahim Tan, Leyla Gamze Tolun, Nuray Çağlar BalkısThis study presents a comprehensive spatial and temporal analysis of heavy metal contamination in the surface sea waters of the Black Sea. A total of 382 samples were collected from 56 sampling stations across seven sampling periods and subsequently analysed. The concentration levels, spatial and temporal distribution, contamination degree, and correlations with environmental parameters for eight heavy metals (Cu, Zn, As, Ni, Cr, Pb, Cd, and Co) were examined. The findings revealed that heavy metal contamination was mainly observed in areas influenced by rivers with high industrial discharges and agricultural activities, regions affected by deep sea discharges, and locations associated with port operations.
In the Black Sea, unfavourable land conditions have led to the discharge of untreated domestic and industrial waste water, mainly through deep sea outfalls. In addition, the siting of industrial facilities in coastal areas and riverine discharges contribute to localised water pollution problems. Heavy metal concentrations were found in the following order: Cu>Zn>As>Ni>Cr>Pb>Cd>Co. Heavy metal concentrations were generally higher in winter than in summer. Copper concentrations exceeded Türkiye's seawater quality standards during the winter seasons. Based on contamination factor (CF) values, 57.3% of the measurements indicated low contamination, 7.6% moderate, 8.9% considerable, and 26.2% very high levels of copper contamination. The CF values for As and Cd at stations influenced by the Samsun deep sea discharge occasionally reached considerable and high levels. The contamination factor (CF) values for all other heavy metals measured along the Black Sea coast were <1, indicating low levels of contamination.