Water quality assessment and phosphorus effect using water quality indices: Euphrates River- Iraq as a case study

Abstract

Most rivers in developing countries are facing water contamination problem. Therefore, saving water quality by complying with the industrial, drinking, and agricultural allowable standard limits has been difficult. This study aims to assess Shatt Al-Kufa water quality as one branch of the Euphrates River by calculating three types of water quality indices in two cases, excluding and including the phosphate (PO4) consentration, as it was the parameter that most met the standard. The used water quality indices are the Weight Arithmetic Water Quality Index (WAWQI), the Canadian Council of Ministers of the Environment Water Quality Index (CCMEWQI) and the Oregon Water Quality Index (OWQI). Fifteen parameters were analyzed, including pH value, Biological Oxygen Demand, Turbidity, Total Hardness, Orthophosphate, Sulphate, Nitrate, Alkalinity, Potassium, Sodium, Magnesium, Chloride, Dissolved Oxygen, Calcium and Total Dissolved Solids. The results show that the average WAWQI for three stations, including PO4, were 33.79, 43.75 and 37.62, which is good water. However, in excluding PO4, the water quality was characterized as very poor depending on the resulting values (86.62, 88.86 and 91.91, respectively). The CCMEWQI values for three stations were 63.83, 60.40 and 55.69, including PO4, so the water quality was fair and marginal. According to OWQI, the water quality for three stations was very poor in two cases since the OWQI value less than 59. Pearson correlation shows a good link, especially total hardness and total dissolved solids with salt.