Dynamic characteristics of heavy metals in a eutrophic reservoir in subtropical China

Eutrophication can alter the transformation of heavy metals in water. This study investigated the dynamic characteristics and particle-water interaction of heavy metals in the waters of a subtropical eutrophic reservoir in China. Monthly concentrations of Fe, Mn, Cu, Cr, Cd, As, and Pb in solution and suspension were analyzed in the Shanzi Reservoir from 2013 to 2014 using inductively coupled plasma optical emission spectroscopy. Results showed that there were significant differences in the dynamic characteristics of heavy metals. Suspension was the main transportation phase for Fe, Mn, Cr, and Pb, while Cd and As existed mainly in solution. Cu was evenly distributed between the two phases. Seasonal variability of the particle-water distribution coefficient (KD) showed lowest value during winter and spring for Fe and Mn, during winter for Cu and Cr, during autumn and winter for Cd, during summer and winter for As, and during spring for Pb. The low KD suggested a direct ecological hazard during these seasons. Transport of Fe, Mn, Cu, As, and Pb along the water flow were generally consistent and transitioned from the suspended to dissolved phase downstream. Eutrophication had an impact on the migration and transformation of Fe, Mn, Cu, Cr, and Cd. This study highlights the importance of thorough and regular monitoring of heavy metals in eutrophic reservoirs to reduce and prevent metal pollution in reservoir-type drinking water sources. •Monthly concentrations of seven heavy metals were analyzed in Shanzi Reservoir.•Significant differences were found in the dynamic characteristics of heavy metals.•Low KD was indicative of high ecological hazard.•Eutrophication influenced the migration and transformation of heavy metals.