Environmental monitoring of phthalic acid esters in northwest Persian Gulf estuary: Concentrations, distribution, and risk assessment

The present study investigates the concentration level, distribution, and risk assessment of six high-priority phthalic acid esters (PAEs) in seawaters and sediments of the Musa estuary, northwest of the Persian Gulf, Iran. Additionally, the industrial and urban effluents terminating in this estuary were also analyzed. The overall variations of Σ₆PAEs were 10.65–164.80 µg/L in seawaters, 0.53–26.18 µg/g in sediments, and 181.09–764.57 µg/L in effluent samples. Di–n–butyl phthalate (DnBP) and di(2–ethylhexyl) phthalate (DEHP), together accounted for 57.2 %–99.5 % and 59 %–100 % of the Σ₆PAEs concentrations in seawaters and sediments, respectively. A relatively similar trend was also detected in the effluent waters. While industrial runoffs exhibited greater shares and concentrations compared to urban areas, the levels of PAEs were higher in waters and sediments near urban regions due to restricted water circulation. A significant correlation was found (r = 0.8385) between Σ₆PAEs in seawater and sediment. Given its consistent detection frequency of 100 % across all stations, DEHP can be served as a reliable indicator for PAE contamination. In nearly all stations, the pollution levels of DnBP and DEHP exceeded the environmental risk level (ERL). The ecological risk quotient (RQ) for at least two PAEs appeared at medium to high levels in both seawaters and sediments. Establishing baseline data on PAEs in the Musa estuary will guide future strategies for pollutant control across the Persian Gulf network.