Phthalic acid esters (PAEs) in surface water from five tropical estuaries: Spatial distribution, seasonal variations,...

Information about the occurrence of phthalic acid esters (PAEs) in water environments in Vietnam and Southeast Asia is still limited. In this study, we analyzed ten PAEs in surface water samples collected from five estuaries in Thanh Hoa Province, central Vietnam, to elucidate pollution levels and patterns, seasonal variations, potential sources, and mass loads of these typical pollutants in tropical estuarine regions. Concentrations of total PAEs ranged from 663 to 4782 ng/L, with higher levels found in the dry season (median 2747; range 1267-4782 ng/L) than in the rainy season (1493; 663-3512 ng/L). Di(2-ethylhexyl) phthalate was the most predominant compound, followed by di-n-butyl phthalate, di-n-octyl phthalate, and diisobutyl phthalate. Complicated sources from domestic, industrial, and agricultural activities can contribute to the emission of PAEs in these estuaries. The mass loads of total PAEs estimated for dry and rainy seasons in one estuary were 12.76 and 28.64 tons/year, respectively.