Aim: To determine the concentration of PAHs by layers in each core sediment around one of Malaysia's tourism-oriented areas and to distinguish and classify the origin of PAHs in core sediments using index of molecular ratios. Methodology: The individual compounds and sources of polycyclic aromatic hydrocarbon (PAHs) were studied in 72 cm and 54 cm long sediment core, each that were taken in the Kuah Jetty and a rural area between Tanjung Ayer and Tanjung Batu Kulat of Langkawi Island. A total of 12 PAHs were determined and quantified by gas chromatography coupled with mass spectrometry (GC-MS). Results: Kuah Jetty, Langkawi's total PAH concentrations of sediment core layers ranged from 45.82 ng g-1 to 252.43 ng g-1. Furthermore, the total PAH concentrations of the sediment core layers from the rural area between Tanjung Ayer and Tanjung Batu Kulat ranged between 28.97 ng g-1 to 312.20 ng g-1. Interpretation: The potential application of a combination of molecular ratios and individual concentrations of PAH in determining the origin and source of pollution in sediments resulted in the determination of low to moderate pollution and indicated mixed sources of PAHs in the study area.

Abstract. Sediment core was collected from Labuan port and analyzed to determine the radioactivity of thorium (Th) isotopes. The objectives of this study are to determine the possible sources of Th isotopes at Labuan port and estimates the sedimentation rate based on 228 230 Th at the recent years which might be contributed from the anthropogenic sources. The sedimentation rate of core sediment from Labuan Port was successfully estimated by using 228 Th/ 232 Th model. The result show high sedimentation rate with 4.67 cm/year indicates rapid deposition occurred at this study area due to the high physical activity at the Labuan port. By assume the constant sedimentation rate at this area; we estimated the age of 142 cm core sediment obtained from Labuan port is 32 years started from 1981 to 2012. This chronology will be used in forthcoming research to investigate the historical profile of anthropogenic activities affecting the Labuan port.