Investigation of the Effects of Metal and Heavy Metal Pollution on Surface Waters Before and During the COVID-19 Lockdown Period in Bursa, Turkiye

The first confirmed COVID-19 case in Türkiye was reported on March 10, 2020, followed by weekend lockdowns starting April 11–12, 2020. These measures, although limited to weekends and official holidays, led to noticeable reductions in industrial activities, traffic, and human mobility, offering a unique opportunity to evaluate anthropogenic impacts on surface water quality. This study investigates temporal changes in aluminium (Al) and six heavy metals (Fe, Mn, Cu, Cr, Ni, and Zn) in surface waters before and during the lockdown, while assessing potential carcinogenic and non-carcinogenic health risks via ingestion and dermal exposure. Results indicate that, except for Ni, metal concentrations increased during the lockdown, with changes ranging from 7.92% to 83.33% compared to pre-lockdown levels. Both the Heavy Metal Pollution Index and the Heavy Metal Evaluation Index were elevated during the lockdown. Carcinogenic risk assessment revealed significant health risks for both adults and children, and correlation analyses suggest that metals originated from similar sources across both periods. These findings underscore the persistent influence of human activities on water quality, even under temporary mobility restrictions.