Seasonal Occurrence and Ecological Risk Assessment of Polycyclic Aromatic Hydrocarbons in sediments and water of Left-Bank canals of Indus River, Pakistan

Abstract

Abstract Kotri Barrage Left Bank Canals, i.e., Akram Pinyari, and Phuleli Wah, pass through Hyderabad Sindh, Pakistan. These canals are utilized for industrial, domestic, and agricultural purposes. These canals are badly affected by anthropogenic activities, which are major sources of organic content, especially PAHs. The present study aimed to investigate the presence, distribution, source, and ecological risk assessment of sixteen ∑16 polycyclic aromatic hydrocarbons (PAHs) in water and sediments of Left-bank canals of River Indus-Pakistan in both pre & post monsoon seasons. From each canal 3 water and 2 sediment samples were collected in pre-monsoon and post-monsoon seasons. After collection of sample EPA liquid-liquid extraction were used for the extraction of samples then GC-chromatography was used to investigate the concentration of PAHs. The cumulative concentrations of ∑16PAHs in the pre-monsoon season ranged between 22.26–836.46 ng/l and 26.95–49560 ng/g in water and sediments respectively. The total concentration of water and sediments in the post-monsoon season ranged between 76.51-5663.1 ng/L and 2976.70 -15238.33 ng/g respectively. The Principal Component Analysis (PCA) revealed that industrial and domestic wastewater discharge, solid waste burning, heavy vehicular exhaust, biomass combustion, and petroleum residues are the primary sources of PAH contamination. The toxic equivalent factor (TEF) depicted that Benzo(a)Pyrene and Banzo(a,h)anthracene are the contributing PAHs with higher carcinogenic exposure equivalent in both water and sediments. The left-bank canals of River Indus are highly contaminated with PAHs, thus posing a severe health issue to humans and aquatic life.