Concentrations and sources of polycyclic aromatic hydrocarbons in the seawater around Langkawi Island, Malaysia

Abstract

This paper reports the levels of polycyclic aromatic hydrocarbons (PAHs) in the water around the Island and their probable sources. Water samples were collected from four jetties and three marine fish farms around the main Langkawi Island and analysed for 18 polycyclic aromatic hydrocarbons (PAHs) in December 2010. The total PAH concentrations ranged from 6.1 ± 0.43 to 46 ± 0.42 gL-1, which exceed the maximum admissible concentrations of PAHs (0.20 gL-1) for the water standard of European Union. The calculated diagnostic benzo[a]anthracene: benzo[a]anthracene + chrysene ratio of between 0.52 and 1.0 suggests that the sources of PAHs at the majority of the stations studied are derived primarily from pyrogenic sources, from incomplete fuel combustion of the boats and vehicle engines, with lesser amounts of PAHs contributed from petrogenic sources. Some stations displayed mixed sources. A significant positive correlation was found between total organic carbon (TOC) and the concentrations of the high-molecular-weight PAHs (r 2 = 0.86, P < 0.05), which suggests significant secondary sources of PAHs, such as those from atmospheric deposition