Unveiling the Nexus the link between water quality index and phthalic acid ester concentrations in Tigris River

Abstract

Monitoring water quality in an aquatic system is a crucial objective in pursuing sustainable development, despite the challenges posed by water scarcity and the impact of climate change. The objective of the present study was to examine the water quality of the Tigris River along its course from the point of entry into Baghdad city to its exit, particularly in the presence of Phthalic Acid Esters (PAEs). In both dry and wet seasons and from five sites of the river, nine environmental factors (Turbidity, Total dissolved solids, pH, dissolved oxygen, Chloride, nitrate, phosphate, sulfate, and Biological oxygen demand) and three PAEs (di-n-butyl phthalate (DBP), di-isononyl phthalate (DiNP), and di-2-ethyl hexyl phthalate (DEHP)) were investigated. Results revealed that the river has high levels of turbidity and Total dissolved solids, slightly alkaline, and well-aerated (dissolved oxygen >7 mg/L). Chloride, nitrate, phosphate, and sulfate values varied between seasons, as high values were recorded in the wet season. Biochemical oxygen demand levels were higher during the dry season. The highest value of total PAEs (2.20 μg/L) was observed during the dry season, and the lowest value was in the wet season (1.16 μg/L). The HQ results revealed that the river was ranked as a moderate risk area. However the water quality index and environmental risk index classified the water quality as a poor category, with a high-risk score in the study sites within Baghdad city. Therefore, despite the acceptable limit of PAEs in the river's water (<3 μg/L), its presence is an early alarm to withdraw attention to its environmental risk. These findings highlight the need for appropriate measures to control and remove pollutants to ensure a safe and healthy water supply in the Tigris River.