Sources of Polycyclic Aromatic Hydrocarbons in the Marine Environment of Ko Sichang-Siracha, Thailand

Abstract

The levels and distribution of polycyclic aromatic hydrocarbons (PAHs) were investigated in surface sediments of Ko Sichang and Siracha coastal marine area, Thailand using gas chromatography with flame-ionization detection (GC/FID).  The total concentrations of 16 PAHs US EPA priority pollutants ranged from 65.2 to 18,970 ng/g dry weight (median concentration was 282.5 ng/g), which indicated that the level of total PAHs concentrations were at moderate level compared to those observed in other regions. PAH compositional signatures among Ko Sichang-Siracha coastal marine sediments are remarkably similar, with a prevalence of high-molecular weight PAHs (>3rings) comprising about 87 per cent of total PAH concentrations. Dibenzo[a,h]anthracene, benzo[b]fluoranthene, benzo[g,h,i]perylene, benzo[a]pyrene, fluoranthene, indeno(1,2,3-cd)pyrene, and pyrene represented the highest fractions in most surface sediment samples.  Source identification using diagnostic PAH ratios indicated that composition of PAHs in most sediment samples originated mainly from incomplete combustion of organic matter (pyrolytic origin), with a mixture of pyrolytic and petrogenic PAHs were observed in some of the study sites. The presence of almost all human carcinogenic PAHs in the analysed area indicate that these sediments can be considered contaminated sites, suggesting that future monitoring programs together with an effective coastal management program must be implemented to ensure health and safety for all.