A multivariate approach and water quality index for evaluating the changes in water quality of Tigris River.

This study was conducted on the Tigris River in Baghdad City from July 2020 to April 2021. Five sites were chosen along the Tigris River to investigate the river's water quality through the 26 parameters. These were; Water Temperature (WT), Total Dissolved Solids (TDS), Turbidity, Dissolved Oxygen (DO), Alkalinity, Total Hardness (TH), pH, Calcium (Ca), Magnesium (Mg), Potassium (K), Sodium (Na), Bicarbonate (HCO3), Chloride (Cl), Fluoride, Nitrite (NO), Nitrate (NO), Phosphorus (PO4), Sulfate (SO4), Aluminum (Al), Biological oxygen demand (BOD), Chromium (Cr), Cyanide (CN), Iron (Fe), lead (pb), Nickle (Ni), and Zinc (Zn). Canadian Council of Ministers of the Environment water quality index (CCMEWQI) was calculated to show the differences in water quality between the sites and seasons, where the results come from Poor to Fair (45.74 to 68.82) in the dry season and Marginal to Fair (60.53 76.77) in the wet season. Principal Component Analysis (PCA) was used to identify the most influential parameters in Tigris River, where factor loadings1 (f1) were represented by turbidity, alkalinity, magnesium, BOD, and cyanide. In contrast, factor loadings 2 (f2) was distinguished by TDS, nitrite, sulfate, and total hardness as the major affected parameters. Both factors (f1 and f2) indicate the contribution of point pollution from industrial and agricultural activity and conclude that the main problem in the Tigris River is salinity. The correlation matrix shows a strong and positive relationship between total hardness and aluminum (+0.855**), sodium and iron (+0.81**), phosphorus and zinc (+0.66*), lead, and zinc (+0.85**). And negative Correlation between alkalinity and pH (-0.83**), total hardness and potassium (-0.71*), BOD and aluminum (-0.81**). [ABSTRACT FROM AUTHOR]