Impacts of wastewater discharge from Kalar city on Diyala-Sirwan river water quality, Iraq: pollution evaluation, health risks of heavy metals contamination

In this work, a comprehensive assessment has been performed to understand impact of wastewater discharge from Kalar city on water quality parameters of Diyala-Sirwan river, Iraq. Levels of physicochemical parameters of Ca, K, Na, Mg, pH, electrical conductivity, dissolved oxygen, total dissolved solid, turbidity, biological oxygen demand, and total hardness, and heavy metals of Fe, Mn, Ni, Cu, Zn, Hg, Al, Ba, Se, and As have been determined by inductively coupled plasma optical emission spectroscopy and other devices. Pollution indices, health risk assessment, and multivariate analysis have been applied to evaluate pollution intensity originated from wastewater discharge on river water quality at different locations, before and after the impact point. Pollution levels of slight to moderate have been identified using different indices for the river water at all sampling locations after the wastewater discharge point. Cluster and correlation analyses showed that the impact of wastewater discharge on the river water quality was occurring along the river within the study area. Non-carcinogenic health risk assessment for heavy metals in the river, indicating a potential risk, might on people's health, especially after discharge point. Furthermore, a significant effect of carcinogenic risk by heavy metals of As and Hg was recognized in the same area. This study thus helps to understand clearly the alteration that happened in the water quality of Diyala-Sirwan river due to the discharge of untreated wastewater from Kalar city.