[en] ²¹⁰Pb dating, Mn and total organic carbon have been used in this study to determine the sedimentation rate and the productivity in coastal of Kelantan. Four sediment cores which are SF1, SF3, SF5 and SF7 were taken using the gravity corer on June 2008. The 125 μm dry sediment with particle mesh was used to determine the concentration of ²¹⁰Pb, Mn and total organic carbon. Activity level of ²¹⁰Pb was determined using the Tennelec XLB-5 Gross Alpha-Beta Counter, Canberra, after the ingrowth of ²¹⁰Pb by the outgrowth of ²¹⁰Bi. While the content of Mn was measured using the Perkin Elmer SCIEX Inductively Coupled Plasma Mass Spectrometry ELAN 9000 technique and the organic carbon content was estimated using combustion method. The analysed result showed the ²¹⁰Pb activity for all samples were decreasing from top to the bottom sediment. While the vertical profile of Mn concentration had scattered distribution throughout the core sediments. However, Mn concentrations in the samples were lower than the Mn concentration in the earth crust that is 770.00 mg/kg. Values of the total organic carbon (TOC) content are higher in sites that are closer with land and lower in offshore sites. The value of sedimentation rate was 0.59 cm yr^-1, 0.47 cm yr^-1, 0.36 cm yr^-1 and 0.46 cm yr^-1 for SF1, SF3, SF5 and SF7, respectively. This indicates various sediment age ranges and year of accumulation of sediments. It shows that the organic carbon contents produced Mn²⁺ during anaerobic decomposition process in the sediment. (Author)

[en] Biogenic burning as forest fire phenomena occurring from April to August each year in the Sumatra and Borneo islands are major sources of biogenic uranium–thorium decay series in marine systems. 30 samples were collected during the Ekspedisi Pelayaran Saintifik Perdana 2009 cruise (EPSP 2009 cruise) between 12th June and 1st August 2009 from the Straits of Malacca to the Sulu and Sulawesi Seas to study the effect of haze and the monsoon season on the deposition rate of ²¹⁰Po and ²¹⁰Pb in Malaysian waters. All samples were spiked with 1 ml of lead [Pb(NO₃)₂; 25 mg ml^-1] and 0.05 ml of Polonium-209 tracer (26.08 dpm ml^-1). ²¹⁰Po activity was determined by auto plating onto silver foil and counting using an alpha spectrometry system (Canberra model Alpha Analyst with a silicon-surface barrier detector). Lead that was collected via electrodeposition, formed lead sulphate (PbSO₄) precipitation. This precipitate was wrapped onto plastic discs and counted for ²¹⁰Pb beta activity using a gross alpha-beta counting system (Tennelec model LB-5100 low background gas-flowing anti-coincidence alpha/beta counter) after 1 month to allow bismuth ingrowths. The range of ²¹⁰Po activities varied between 51.08 ± 15.1 and 742.08 ± 220.34 Bq/kg, whereas the activity of ²¹⁰Pb ranged from 31.10 ± 4.20 to 880.23 ± 123.86 Bq/kg and ²¹⁰Po/²¹⁰Pb ratio value varied between sampling stations from 0.19 to 13.77. The contents of ²¹⁰Po were also statistically positively correlated with the amount of total suspended particulate especially those recorded during heavy haze period events. (author)

[en] Full-text: 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 ²²⁸Th/ ²³²Th model. The results suggest the ²³⁰Th and ²³²Th might be originated from terrestrial sedimentary rock while ²²⁸Th originated by authigenic origin. High ratio value of ²³⁰Th/ ²³²Th detected at the top surface sediment indicates the increasing of ²³⁰Th 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 ²²⁸Th/ ²³²Th 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. (author)

[en] The activity concentration of ²¹⁰Po from six different samples consisting of raw charcoal, surface sediment, rainwater (suspended solids (SSrw) and dissolved phase (Drw) and estuarine water (suspended solids (SSew) and dissolved phase (Dew)), were analyzed. The activity concentration of ²¹⁰Po in solid samples was between 7.63 ± 0.67 and 744.28 ± 21.12 Bqkg^-1 and in dissolved samples varied between 0.34 ± 0.03 and 86.33 ± 6.51 mBqL^-1. On average, ²¹⁰Po activity in SSrw sample was the highest, at nearly three times its original form (charcoal). SSew and surface sediment samples were similarly distributed between 15^th March and 1^st August samplings, but were relatively lower than charcoal and SSrw samples. The natural meteorological variability also enhanced ²¹⁰Po distribution and dispersion to a few kilometers from the coal-fired power plant. (author)