In this work, we investigated possible contamination of phthalates in seawater and sediment around the eastern coast of Thailand in the area of Chonburi, Rayong, and Chanthaburi. The main focus was on Pradu Bay east of Map Ta Phut, a well-known industrial and economic hub in Thailand. Among six selected phthalates of interest, diethyl phthalate (DEP), and benzyl butyl phthalate (BBP) were not found in any sample, while the concentrations of dimethyl phthalate (DMP) and dioctyl phthalate (DnOP) were very low or undetectable in most samples. In December 2014, the concentration of dibutyl phthalate (DBP) and diethylhexyl phthalate (DEHP) in Pradu Bay were 0.23-0.77 and 0.31-0.91 μg L-1 in seawater, respectively and non-detected (ND)-0.80 and ND-1.65 μg g-1 for 11 out of 20 sediment samples. DBP and DEHP were considered as the predominant congeners. A surface mapping system provided us an overview concentration distribution of DBP and DEHP congeners in seawater and sediment in Pradu Bay, showing a correlation between water and sediment and allowing a prediction of a possible point source. A comparison with the EU standard concentration limit in surface water confirmed that the phthalate concentration in this area was acceptable. However, continuous monitoring of phthalate congeners in the matrices should be done to detect a possible increase in their concentrations. To the best of our knowledge, this is the first study to determine concentrations of phthalates in seawater and sediment along the east coast of Thailand.
Keywords: Phthalate esters; Seawater; Sediment; Thailand.