Occurrence, distribution, and ecological risks of phthalate esters in the seawater and sediment of Changjiang River Estuary and its adjacent area

Highlights: • All of the 16 PAE congeners were detected in the CRE area. • PAE concentrations in the bottom were higher than those in the surface samples. • DEHP, DiBP and DBP dominated the PAEs. • Changjiang River runoff was a driving factor influencing PAEs' distribution. • DEHP in seawater, DEHP and DnBP in sediment exceed the environmental risk levels. A total of 133 seawater samples and 17 sediment samples were collected from 81 sampling sites in the Changjiang River Estuary and its adjacent area and were analyzed for 16 phthalate esters (PAEs). The Σ₁₆ PAE concentrations in the seawater and sediment samples ranged from 180.3 ng·L^{− 1} to 3421 ng·L^{− 1} and from 0.48 μg·g^{− 1} to 29.94 μg·g^{− 1} dry weight (dw), respectively, with mean values of 943.6 ng·L^{− 1} and 12.88 μg·g^{− 1}. The distribution of ∑₁₆PAE concentrations in the water column showed that PAE concentrations in the bottom samples were higher than those in the surface samples (except the transect C located inside the Changjiang River Estuary), with the maxima appearing in the bottom layer at the offshore stations. Among the 16 PAEs, di (2-ethylhexyl) phthalate (DEHP), diisobutyl phthalate (DiBP), and dibutyl phthalate (DnBP) dominated the PAEs, with 25.1%, 21.1%, and 18.9% of the Σ₁₆PAEs in seawater, respectively. The comparison of ∑₁₆PAEs and salinities in transects C and A6 suggested that the Changjiang River runoff was an important driving factor influencing the distribution of PAEs. DEHP concentrations in water samples and DEHP and DnBP concentrations in sediment samples exceeded the environmental risk levels (ERL), indicating their potential hazard to the ocean environment.