Water quality and impacting factors on heavy metals levels in Shatt Al-Arab River, Basra, Iraq

Abstract

The aim of this study was to evaluate the water quality of Shatt Al-Arab River (SAR) and investigate the influences on the variations of heavy metals levels. The surface water and bed sediments samples at four stations have been collected (4 months) during 2017–2018, and seven heavy metals (Ni2+, Cr3+, Pb2+, As3+, Hg2+, U4+ and Cd2+), as well as 11 parameters including total dissolved solids, the concentration of hydrogen ions, dissolved oxygen, nitrate, chlorides, turbidity, total hardness, electrical conductivity and alkalinity were investigated. The results indicated that the water quality in the SAR depend on the combined effects of natural and anthropogenic factors. The variation of water quality of SAR influenced by the chemical ions inflow from the Tigris River and the marine salt from Arabian Gulf. The highest value of TDS was in S4 it reached to 42,844 mg/l. The results showed that most of the ions increase their concentration by more than 200%, especially in summer season at Fao area due to the effect of the seawater intrusions. In comparison to the sediments, low concentrations and a uniform distribution of most metals were observed in the river water. The river sediments were polluted with heavy metals, while pollution levels in the water were still within permissible limits for drinking, irrigation and aquatic life. These findings indicated that the major sources of river contamination with heavy metals were the atmospheric deposit of gaseous emissions from oil production and electric generators and the surface runoff from agricultural areas after rainfall. Additionally, the tide greatly controls the distribution heavy metals in the river.