A terrestrial gamma radiation survey for the state of Selangor, Kuala Lumpur and Putrajaya was conducted to obtain baseline data for environmental radiological health practices. Based on soil type, geological background and information from airborne survey maps, 95 survey points statistically representing the study area were determined. The measured doses varied according to geological background and soil types. They ranged from 17 nGy h(-1) to 500 nGy h(-1). The mean terrestrial gamma dose rate in air above the ground was 182 ± 81 nGy h(-1). This is two times higher than the average dose rate of terrestrial gamma radiation in Malaysia which is 92 nGy h(-1) (UNSCEAR 2000). An isodose map was produced to represent exposure rate from natural sources of terrestrial gamma radiation.
Soil-to-plant transfer factors (TFs) are of fundamental importance in assessing the environmental impact due to the presence of radioactivity in soil and agricultural crops. Tapioca and sweet potato, both root crops, are popular foodstuffs for a significant fraction of the Malaysian population, and result in intake of radionuclides. For the natural field conditions experienced in production of these foodstuffs, TFs and the annual effective dose were evaluated for the natural radionuclides (226)Ra, (232)Th, (40)K, and for the anthropogenic radionuclide (88)Y, the latter being a component of fallout. An experimental tapioca field was developed for study of the time dependence of plant uptake. For soil samples from all study locations other than the experimental field, it has been shown that these contain the artificial radionuclide (88)Y, although the uptake of (88)Y has only been observed in the roots of the plant Manihot esculenta (from which tapioca is derived) grown in mining soil. The estimated TFs for (226)Ra and (232)Th for tapioca and sweet potato are very much higher than that reported by the IAEA. For all study areas, the annual effective dose from ingestion of tapioca and sweet potato are estimated to be lower than the world average (290 μSv y(-1)).
In this study, the radiobiological analysis of natural alpha emitters in extracted human teeth and animal bones from Malaysia was estimated. The microdistributions of alpha particles in tooth and bone samples were measured using CR-39 alpha-particle track detectors. The lowest and highest alpha emission rates in teeth in the Kedah and Perak states were 0.0080 ± 0.0005 mBq cm(-2) and 0.061 ± 0.008 mBq cm(-2), whereas those of bones in the Perlis and Kedah states were 0.0140 ± 0.0001 mBq cm(-2) and 0.7700 ± 0.0282 mBq cm(-2), respectively. The average alpha emission rate in male teeth was 0.0209 ± 0.0008 mBq cm(-2), whereas that of female teeth was 0.0199 ± 0.0010 mBq cm(-2). The alpha emission rate in teeth is higher in smokers (0.0228 ± 0.0008 mBq cm(-2)) than in non-smokers (0.0179 ± 0.0008 mBq cm(-2)). Such difference was found statistically significant (p < 0.01).
Since several high level natural radiation areas (HLNRAs) exist on our planet, considerable attention has been drawn to health issues that may develop as the result of visiting or living in such places. City of Ramsar in Iran is an HNLRA, and is a tourist attraction mainly due to its hot spas. However, the growing awareness over its natural radiation sources has prompted widespread scientific investigation at national level. In this study, using an ELISA method, the level of expression of three tumor markers known as carcinoembryonic antigen (CEA), prostate-specific antigen (PSA) and carcino antigen 19-9 (CA19-9) in blood serum of 40 local men of Ramsar (subject group) was investigated and compared to 40 men from the city of Noshahr (control group). Noshahr was previously identified as a normal level natural radiation area (NLNRA) that is some 85 km far from Ramsar. According to statistical analysis, there was a significant difference in the levels of PSA and CA19-9 markers between the two groups (p
Following gas generation in a Geological Disposal Facility (GDF), (14)C-containing gases could migrate through the geosphere, eventually diffusing into soils at the Earth's surface. This paper reports summary results from laboratory and field experiments to obtain information on the probable rates of a) diffusive transport and b) oxidation of (12/13)CH(4) (as a surrogate for (14)CH4) in a typical agricultural soil in the UK. Rates of CH(4) oxidation were generally low in the field and undisturbed soil columns, though a re-packed column of homogenised topsoil oxidised ambient atmospheric CH(4) 20× faster than an undisturbed soil column. In contrast to low observed rates of CH(4) oxidation, the effective diffusion of CH(4) through the soil was rapid. Isotopically labelled CH(4) injected at a depth of 45 cm in the field diffused to the surface and exited the soil over a time period ranging from 8 to 24 h. The rate of CH(4) diffusion through the soil was increased by the presence of ryegrass roots which increased soil porosity and decreased water content. δ(13)C values for laboratory column soils after labelled CH(4) injection experiments showed no sign of residual (13)C, despite the extremely high δ(13)C values of the injected (12/13)CH(4). If laboratory observations are confirmed by measurements in field samples it can be concluded that the majority of (14)CH(4) from a GDF which enters a soil with low methanotrophic activity will be lost to the free atmosphere after diffusing rapidly through the soil column.
Extensive environmental survey and measurements of gamma radioactivity in the soil samples collected from Segamat District were conducted. Two gamma detectors were used for the measurements of background radiation in the area and the results were used in the computation of the mean external radiation dose rate and mean weighted dose rate, which are 276 nGy h(-1) and 1.169 mSv y(-1), respectively. A high purity germanium (HPGe) detector was used in the assessment of activity concentrations of (232)Th, (226)Ra and (40)K. The results of the gamma spectrometry range from 11 ± 1 to 1210 ± 41 Bq kg(-1) for (232)Th, 12 ± 1 to 968 ± 27 Bq kg(-1) for (226)Ra, and 12 ± 2 to 2450 ± 86 Bq kg(-1) for (40)K. Gross alpha and gross beta activity concentrations range from 170 ± 50 to 4360 ± 170 Bq kg(-1) and 70 ± 20 to 4690 ± 90 Bq kg(-1), respectively. These results were used in the plotting of digital maps (using ARCGIS 9.3) for isodose. The results are compared with values giving in UNSCEAR 2000.
This work presents a study of human hair as a bio-indicator for detection of heavy metals as part of environmental health surveillance programs project to develop a subject of interest in the biomedical and environmental sciences. A total of 34 hair samples were analyzed that consisting of 29 samples from sanitation workers and five samples from students. The hair samples were prepared and treated in accordance to the International Atomic Energy Agency (IAEA) recommendations. The concentrations of heavy metals were analyzed using the energy dispersive X-ray fluorescence (EDXRF) technique by X-50 Mobile X-ray Fluorescence (XRF) at Oceanography Institute, Universiti Malaysia Terengganu. The performance of EDXRF analyzer was tested by Standard Reference Material (SRM 2711) Montana Soil which was in good agreement with certified value within 14% deviations except for Hg. While seven heavy metals: Mn, Fe, Ni, Cu, Zn, Se, and Sb were detected in both groups, three additional elements, i.e. As, Hg and Pb, were detected only in sanitation workers group. For sanitation workers group, the mean concentration of six elements, Mn, Fe, Cu, Zn, Se, and Sb, shows elevated concentration as compared to the control samples concentration. Results from both groups were compared and discussed in relation to their respective heavy metals concentrations.
Natural background gamma radiation and radioactivity concentrations were investigated from 2003 to 2005 in Kinta District, Perak, Malaysia. Sample locations were distant from any 'amang' processing plants. The external gamma dose rates ranged from 39 to 1039 nGy h(-1). The mean external gamma dose rate was 222+/-191 nG yh(-1). Small areas of relatively enhanced activity were located having external gamma dose rates of up to 1039+/-104 nGy h(-1). The activity concentrations of (238)U, (232)Th and (40)K were analyzed by using a high-resolution co-axial HPGe detector system. The activity concentration ranges were 12-426 Bq kg(-1) for (238)U, 19-1377 Bq kg(-1) for (232)Th and <19-2204 Bq kg(-1) for (40)K. Based on the radioactivity levels determined, the gamma-absorbed dose rates in air at 1m above the ground were calculated. The calculated dose rates and measured dose rates had a good correlation coefficient, R of 0.94. To evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity, the gamma-absorbed dose rate and the mean population weighted dose rate were calculated. An isodose map for the Kinta District was also produced.
The processing of amang, or tin tailings, for valuable minerals has been shown to technologically enhance NORM and this has stirred significant radiological safety and health concerns among Malaysia's regulatory authority. A growing radiological concern is now focused on the amang effluent containing NORM in recycling ponds, since these ponds may be reclaimed for future residential developments. A study was carried out to assess the radiological risk associated with amang processing and the accumulated effluent in the recycling ponds. Twenty-six sediment samples from the recycling ponds of two amang plants in the states of Selangor and Perak, Malaysia, were collected and analyzed. The maximum activity concentrations of (238)U, (226)Ra, (232)Th and (40)K recorded in sediments from these ponds were higher than Malaysia's and the world's natural highest. Correspondingly, the mean radium equivalent activity concentration indices, Ra(eq), and gamma radiation representative level index, I(gammar), were higher than the world's average. The enhancement of NORM in effluent sediments as a consequence of amang processing, and the use of a closed water management recycling system created Effective Dose Rates, E (nSv h(-1)), that signal potential environmental radiological risks in these ponds, should they be reclaimed for future land use.
Concentrations of uranium-238 and thorium-232 in soil, water, grass, moss and oil-palm fruit samples collected from an area of high background radiation were determined using neutron activation analysis (NAA). U-238 concentration in soil ranged from 4.9 mg kg(-1) (58.8 Bq kg(-1)) to 40.4 mg kg(-1) (484.8 Bq kg(-1)), Th-232 concentration ranged from 14.9 mg kg(-1) (59.6 Bq kg(-1)) to 301.0 mg kg(-1) (1204 Bq kg(-1)). The concentration of U-238 in grass samples ranged from below the detection limit to 0.076 mg kg(-1) (912 mBq kg(-1)), and Th-232 ranged from 0.008 mg kg(-1) (32 mBq kg(-1)) to 0.343 mg kg(-1) (1.372 Bq kg(-1)). U-238 content in water samples ranged from 0.33 mg kg(-1) (4.0 Bq L(-1)) to 1.40 mg kg(-1) (16.8 Bq L(-1)), and Th-232 ranged from 0.19 mg kg(-1) (0.76 Bq L(-1)) to 0.66 mg kg(-1) (2.64 Bq L(-1)). It can be said that the concentrations of environmental U-238 and Th-232 in grass and water samples in the study area are insignificant. Mosses were found to be possible bio-radiological indicators due to their high absorption of the heavy radioelements from the environment.
Natural radionuclides, such as (210)Po and (210)Pb were measured in the water samples collected from six stations at Kuala Selangor, Malaysia. Results for (210)Po and (210)Pb in dissolved and particulate phases have showed the difference in distribution and chemical behavior. The fluctuation activities of (210)Po and (210)Pb depend on wave action, geology and degree of fresh water input occurring at study areas and probably due to different sampling dates. The distribution coefficient, K(d), values of (210)Po and (210)Pb ranged from 2.0 x 10(3)lg(-1) to 265.15 x 10(5)lg(-1), and from 3.0 x 10(3)lg(-1) to 558.16 x 10(5)lg(-1), respectively. High K(d) values of (210)Po and (210)Pb indicated that a strong adsorption of (210)Po and (210)Pb onto suspended particles, and the sinking of both nuclides on the seabed at study locations were controlled by the characteristics of suspended particles.
This study aims to predict and estimate unmeasured terrestrial gamma dose rate (TGDR) using statistical analysis methods to derive a model from the actual measurement based on geological formation and soil type. The measurements of TGDR were conducted in the state of Johor with a total of 3873 measured points which covered all geological formations, soil types and districts. The measurements were taken 1 m above the soil surface using NaI [Ti] detector. The measured gamma dose rates ranged from 9 nGy h(-1) to 1237 nGy h(-1) with a mean value of 151 nGy h(-1). The data have been normalized to fit a normal distribution. Tests of significance were conducted among all geological formations and soil types, using the unbalanced one way ANOVA. The results indicated strong significant differences due to the different geological formations and soil types present in Johor State. Pearson Correlation was used to measure the relations between gamma dose rate based on geological formation and soil type (D(G,S)) with the gamma dose rate based on geological formation (D(G)) or soil type (D(s)). A very good correlation was found between D(G,S) and D(G) or D(G,S) and D(s). A total of 118 pairs of geological formations and soil types were used to derive the statistical contribution of geological formations and soil types to gamma dose rates. The contribution of the gamma dose rate from geological formation and soil type were found to be 0.594 and 0.399, respectively. The null hypotheses were accepted for 83% of examined data, therefore, the model could be used to predict gamma dose rates based on geological formation and soil type information.
Crude oil terminal sludge contains technologically enhanced naturally occurring radionuclides such as (232)Th, (238)U, (228)Ra and (226)Ra, thus cannot be disposed of freely without proper control. The current method of disposal, such as land farming and storing in plastic drums is not recommended because it will have a long-term impact on the environment. Due to its organic nature, there is a move to treat this sludge by thermal methods such as incineration. This study has been carried out to determine the behaviors of (232)Th, (238)U, (228)Ra and (226)Ra present in the sludge during combustion at a certain temperature and time. The percentage of volatilization was found to vary between 2% and 70%, (238)U was the most volatile in comparison with (232)Th, (228)Ra and (226)Ra. (238)U is found to be significantly volatilized above 500 degrees C, and might reach maximum volatilization at above 700 degrees C. A mathematical model was developed to predict the percentage of volatilization of (232)Th, (238)U, (228)Ra and (226)Ra contained in the sludge. With this known percentage of volatilization, the concentration of (232)Th, (238)U, (228)Ra and (226)Ra present in the bottom and filter ashes can be calculated.
Radiocesium (RCs) is selectively adsorbed on interlayer sites of weathered micaceous minerals, which can reduce the mobility of RCs in soil. Therefore, soils developed from mica-deficient materials (e.g. serpentine soils) may have a higher risk of soil-to-plant transfer of RCs. Soils were collected from three serpentine soil profiles; Udepts in Oeyama, Japan, and Udepts and Udox in Kinabalu, Malaysia. Soil was sampled every 3 cm from 0 to 30 cm depth and sieved to isolate soil particles of ≤20 μm diameter for the assessment of radiocesium interception potential (RIP) after a series of pretreatments. One subset was treated with H2O2 to remove organic matter (OM). Another subset was further treated with hot sodium citrate to remove hydroxy-Al polymers (Al(OH)x). RIPuntreated was <0.4 mol kg-1 whereas mica-K content was <0.02% by weight for ≤20-μm soil particles from Udepts and Udox in Kinabalu, Malaysia, values as low as those of non-micaceous minerals (e.g. kaolinite and smectite). Neither OM nor Al(OH)x removal resulted in a large increase in RIP value for these soils. These results clearly indicated that serpentine soils in Malaysia have very few RCs selective adsorption sites due to the absence of micaceous minerals. In contrast, soil from Udepts in Oeyama, Japan showed average RIPuntreated of 5.6 mol kg-1 and mica-K content of 0.72% by weight for the ≤20-μm particles. Furthermore, the RIP value was significantly increased to an average of 22.5 mol kg-1 after removing both OM and Al(OH)x. These results strongly suggest that weathered micaceous minerals primarily control the ability to retain RCs. These micaceous minerals cannot originate from serpentine minerals, and are probably incorporated as an exotic material, such as Asian dust. This hypothesis is supported by the δ18O value of quartz isolated from the ≤20-μm soil particles from Oeyama, Japan (+16.13‰±0.11‰), very similar to that of Asian dust. In conclusion, serpentine soils in Japan may exhibit a reduced risk of soil-to-plant transfer of RCs due to the historical deposition of Asian dust.