Assessment of Heavy Metal Pollution in the Surface Water of the Doi Canal, the Cho Dem and Ben Luc Rivers, Vietnam

The Doi Canal and the Cho Dem and Ben Luc Rivers play the key roles in irrigation, navigation and ecological restoration. It is important to clearly identify the pollution, influencing factors, ecological risks and possible sources of heavy metals in the surface water of this river system. The surface water of 7 sampling sites was collected over 7 consecutive periods from April 2019 to October 2021. Each surface water sample was analyzed for 9 heavy metals including Fe, Mn, Cr, Zn, Cu, Pb, Cd, Ni, As. Sampling and sample handling techniques were performed based on the Standard Methods for the Examination of Water and Wastewater. Among all nine heavy metals examined in the study area, the concentrations of Fe (1.00 5.06 mg/L) and Mn (0.14 0.28 mg/L) were the highest and the concentrations of Cr, Cd and As were below the lower limit of detection. The results showed that the average Fe and Mn contents both exceeded the permissible thresholds of the National technical regulation on surface water quality (QCVN 08-MT: 2015/BTNMT). Additionally, the content of Fe, Mn, Zn, Cu, Pb, Ni did not meet the water quality standards for aquatic life (United State Environmental Protection Agency)