Masud Kamal

Attenuation coefficients of soils and some building materials of Bangladesh in the energy range 276–1332 keV

The linear and mass attenuation coefficients of different types of soil, sand, building materials and heavy beach mineral samples from the Chittagong and Coxs Bazar area of Bangladesh were measured using a high-resolution HPGe detector and the gamma-ray energies 276.1, 302.8, 356.0, 383.8, 661.6 and 1173.2 and 1332.5 keV emitted from point sources of 133Ba, 137Cs and 60Co, respectively. The linear attenuation coefficients show a linear relationship with the corresponding densities of the samples studied. The variations of the mass attenuation coefficient with gamma-ray energy were exponential in nature. The measured mass attenuation coefficient values were compared with measurements made in other countries for similar kinds of materials. The values are in good agreement with each other in most cases.

Radioactivity in chemical fertilizers used in Bangladesh

Abstract The radioactivity concentrations of 226 Ra, 228 Th and 40 K in different chemical fertilizers, triple superphosphate (TSP), single superphosphate (SSP), diammonium phosphate (DAP), phosphogypsum, muriate of potash (MOP), urea, zinc sulfate and zinc oxysulfate used in the agricultural soil of Bangladesh have been analyzed by gamma spectrometry using a high purity germanium (HPGe) detector. In the fertilizer samples, 226 Ra ranged from 4.8 ± 0.8 to 323.8 ± 24.4 Bq kg −1 , 228 Th ranged from 3.4 ± 1.7 to 22.0 ± 2.8 Bq kg −1 , and 40 K ranged from 7.9 ± 2.4 to 12628.5 ± 169.0 Bq kg −1 . The ratio of radium to thorium was determined, the 226 Ra/ 228 Th ratio ranged from 0.237 to 18.69. This study could be useful as baseline data for radiation exposure to fertilizers, and their impact on human health.

Radionuclide concentrations in mussels collected from the southern coast of Bangladesh.

Abstract Concentrations of 226 Ra , 232 Th , 238 U , 40 K and 137 Cs were determined in whole soft tissues (WST) and shells of groups of different size of marine mussel Perna viridis L. and estuarine mussel Modiolus striatulus H. and water samples which were collected from the southern coast of Bangladesh. Correlation analysis showed that the concentrations of radionuclides vary with mussel size. A positive correlation existed for 238 U and 40 K and a negative one for 232 Th between the radionuclide concentration and mussel size; 232 Th concentrations in WST and shells of the mussels showed an inverse relationship with those of 238 U and 40 K , while 238 U showed positive correlation with 40 K . The concentration factors (CF) for 226 Ra , 232 Th and 238 U in both P. viridis and M. striatulus were higher than those for 40 K . The contents of 137 Cs in both mussels were below the detection limit.

RADIOACTIVITY IN MARINE FISH OF THE BAY OF BENGAL

The concentrations of natural radionuclides of 40K, 232Th and 238U and artificial radionuclides of 137Cs and 134Cs in different marine fish samples from the Bay of Bengal were determined. In some of the fish samples contamination of the 137Cs radionuclide was observed, but 134Cs was below detection level.

Radioactivity of 134Cs, 137Cs and 40K in sea-water on the Bay of Bengal

Abstract The radioactivity of 134 Cs, 137 Cs and 40 K in sea-water samples of the Bay of Bengal off the coast of Bangladesh were measured. The caesium and potassium radionuclides were collected on a ammonium phosphomolybdate precipitate and measured by HPGe γ-spectrometry.

Assessment of radionuclides in the soil of residential areas of the Chittagong metropolitan city, Bangladesh and evaluation of associated radiological risk

Soil samples from the three residential hubs of Chittagong city, Bangladesh were analyzed using gamma spectrometry to estimate radiation hazard due to natural radioactive sources and anthropogenic nuclide 137Cs. The activity concentration of 226Ra was found to be in the range 11–25 Bq.kg−1, 232Th in the range 38–59 Bq.kg−1 and 40K in the range 246–414 Bq.kg−1. These results were used to calculate the radiological hazard parameters including Excess of Lifetime Cancer Risk (ELCR). The estimated outdoor gamma exposure rates were 40.6–63.8 nGy.h−1. The radiation hazard index (radium equivalent activity) ranged from 90–140 Bq.kg−1. The average value of the ELCR was found to be 0.21 × 10−3, which is lower than the world average. Sporadic fallout of 137Cs was observed with an average value of 2.0 Bq.kg−1.

Investigation of elemental and radiological contamination of soils in two shipyards in Chittagong, Bangladesh

Abstract An analysis of metallic elements and natural radioactivity in soils collected from two shipyards and their surroundings in Chittagong, Bangladesh is presented. The elemental concentrations of the metals Cr, Mn, Fe, Ni and Cu were obtained by PIXE analysis with a 3 MV Tandem Accelerator, and the radioactivity of 226Ra, 232Th and 40K was determined using HPGe gamma-ray spectrometry. From the mean specific activities of the three radionuclides in soil samples, the radium equivalent activity, the gamma absorbed dose rate, the annual effective dose rate and the external hazard index were calculated. The study was focused on investigation of soil contamination via shipbreaking activities, if any. The somewhat higher contents of Cr, Mn, Fe, Ni and Cu in soil samples of shipyards, as compared to other locations, seem to be caused by the shipbreaking activities. The specific radioactivities as well as radium equivalent activity in soils of shipyards are also higher and thus possibly an indirect result of shipbreaking activities.

Prawn biomonitors of nutrient and trace metal pollution along Asia-Pacific coastlines

ABSTRACT To assess coastal ecosystem status and pollution baselines, prawns were collected from the commercial catches of eight Asia-Pacific countries (Australia, Bangladesh, Indonesia, Myanmar, Philippines, Pakistan, Sri Lanka and Thailand). Samples collected from 21 sites along regional coastlines were analysed for trace metal and stable isotopic compositions of H, C, N, O and S. A combination of simple averaging and multivariate analyses was used to evaluate the data. Sites could be assigned to easily recognise polluted and unpolluted groups based on the prawn results. Some filter-feeding clams were also collected and analysed together with the benthic-feeding prawns, and the prawns generally had lower trace metal burdens. Climate change effects were not strongly evident at this time, but altered ocean circulation and watershed run-off patterns accompanying future climate change are expected to change chemical patterns recorded by prawns along these and other coastlines. Stable isotopes, especially 15N, can help to distinguish between relatively polluted and unpolluted sites.

Study on radiological contamination of ship scraps and environmental materials in ship breaking area of Chittagong, Bangladesh

The environmental radioactivity levels, both natural and anthropogenic, in the ship scrapped materials such as metal, rubber and foam and tree bark of ship breaking area of Bhatiari, Chittagong in the southern part of Bangladesh were analyzed by using a high purity germanium γ-ray spectrometry. The specific radioactivities of Radium ( 226 Ra), Thorium ( 232 Th) and Potassium ( 40 K) were measured in the above samples. From the measured specific radioactivities of the above three natural radionuclides, the radium equivalent activity (Ra eq ) and the external hazard index (H ex ) were calculated. The natural radioactivity in scrapped metal collected from the engine of a ship is found to be a bit higher. In other samples, the Ra eq values were in the range of 21 → 145 Bq/kg and the H ex varied from 0.06 to 0.39, which indicates that the working environment of the ship breaking area of Chittagong is radiologically safe.

Measurement of physiochemical parameters and determination of the level of radiological threat to the population associated with the Karnaphuli River sediment containing municipal and industrial wastes of Chittagong city in Bangladesh

The research work has been aimed to assess the radiological and chemical threat caused due to urban and industrial wastage drainage to the inhabitants of the Chittagong city in Bangladesh. For finding the chemical effects along with the measurement of radiological threat, the physiochemical characteristics (temperature, pH value and oxidation-reduction potential) of the sediment samples have been analysed. The activity concentrations of naturally occurring radionuclides (238)U, (232)Th, (226)Ra and (40)K in the investigated samples have been found to be higher than those of the world average values. The artificial radionuclide (137)Cs in the samples studied has not been detected. The mean value of the radium equivalent activity and outdoor exposure rate in the study region have been found to be 240.94 ± 23.12 Bq kg(-1) and 115.82 ± 10.81 nGy h(-1), respectively. The radiation doses have been measured directly by employing beta-gamma survey meter (model: LUDLUM 44-9) from where the samples have been collected. The average values of the radiological parameters have been calculated from the activity concentrations of the radionuclides mentioned in the sediment samples found to be higher than those of the corresponding world average values.