Marine radioactivity concentration in the Exclusive Economic Zone of Peninsular Malaysia: 226Ra, 228Ra and 228Ra/226Ra

The present occurrence of ²²⁶Ra and ²²⁸Ra in marine sediment core and fish from the Exclusive Economic Zone in the east coast of Peninsular Malaysia were studied. Sediment core and biota in respectively was collected using multicorer device and purchased from local fishermen at identified stations during the cruise expedition conducted in 2008. The purpose of this study was to determine and to make available an inventory of activity concentration levels and activity ratio for these radionuclides in this region. The activity concentrations of ²²⁶Ra and ²²⁸Ra in sediment core and edible part of fish were ranged between 15.9–46.5 and 27.7–87.1 Bq/kg dry wt and; 0.80–2.13 and <0.95–3.57 Bq/kg fresh wt, respectively. Meanwhile, the activity ratios of ²²⁸Ra/²²⁶Ra in sediment core and fish were varied with the range between 1.63–2.09 and 0.45–2.38, respectively. Refer to those ranges the activity concentrations of radium isotopes were comparable with other region. Thus, it can be concluded that the occurrence of radium isotopes mainly supplied from terrestrial sources and the factors of assimilation efficiency and transfer coefficient of radium may probably effect to the variation activity concentration of ²²⁶Ra and ²²⁸Ra and its activity ratio in edible part of pelagic and demersal fish obtained in this study.     

226Ra, 228Ra and 228Ra/226Ra in surface marine sediment of Malaysia

Surface sediment samples were collected at the West (east coast and west coast of Peninsular Malaysia) and East (Sabah and Sarawak) Malaysia in several expeditions within August 2003 until June 2008 for determining the level of natural radium isotopes. Activity concentrations of ²²⁶Ra and ²²⁸Ra in surface marine sediment at 176 sampling stations were measured. The activity concentrations of both radionuclides in Malaysia (East and West Malaysia) display varied with the range from 9 to 158 Bq/kg dry wt. and 13 to 104 Bq/kg dry wt., respectively. Meanwhile, the ratio distributions of ²²⁸Ra/²²⁶Ra were ranged from 0.62 to 3.75. This indicated that the ratios were slightly high at west coast of Peninsular Malaysia compared to other regions (east coast of Peninsular Malaysia, Sabah and Sarawak). The variation of activity concentrations of ²²⁶Ra and ²²⁸Ra and its ratios were also supported by the statistical analyses of one-way ANOVA and t test at 95 % confidence level, whereby there were proved that the measured values were different between the regions. These different were strictly related to their half-life, potential input sources (included their parents, ²³⁸U and ²³²Th), parent’s characteristic, the geological setting/formation of the study area, environment origin and behavior.     

Improvement of quality in the evaluation of radium isotopes 224,226,228Ra in oil scale samples

Elevated concentrations of the radium isotopes ^224,226,228Ra exist in the scale and produced water in oil exploration. The activity concentration of ²²⁶Ra was calculated from 186.2 keV peak with no usual spectral interference of 185.7 from ²³⁵U. The activity concentration of ²²⁸Ra was calculated from its first daughter product ²²⁸Ac using the 911.2 keV gamma rays since it is a pure beta emitter. The activity concentration of ²²⁴Ra was calculated from ²¹²Pb using the 238.6 keV gamma-ray and the secular equilibrium equation with ²²⁸Ra. The IAEA 448 (oil contaminated field soil) reference material was used as a quality control for ^226,228Ra and but was unreliable for ²²⁴Ra using ²¹²Pb.

     

Radioactivity in coffee

This research was dedicated to the study of the background levels of ²¹⁰Po and natural gamma emitters as ⁴⁰K, ²¹⁴Pb, ²¹⁴Bi, ²²⁸Ac, ²¹²Pb and ²¹²Bi in coffee powder and in coffee beverage; also the artificial ¹³⁷Cs was determined. In the coffee powder the mean ²¹⁰Po activity resulted 7.25 ± 2.25 × 10^?2 Bq kg^?1. ⁴⁰K showed a mean activity of 907.4 ± 115.6 Bq kg^?1. The mean activity concentration of ²¹⁴Pb and ²¹⁴Bi, indicators of ²²⁶Ra, given as mean value of the two radionuclides, resulted 10.61 ± 4.02 Bq kg^?1. ²²⁸Ac, ²²⁸Ra indicator, showed a mean activity concentration of 13.73 ± 3.20 Bq kg^?1. The mean activity concentration of ²¹²Pb, ²²⁴Ra indicator, was 8.28 ± 2.88 Bq kg^?1. ²⁰⁸Tl, ²²⁴Ra indicator, presented a mean activity concentration of 11.03 ± 4.34 Bq kg^?1. In all samples, the artifical ¹³⁷Cs resulted below the detection limit (2.0 Bq kg^?1). The arithmetical mean value of percentage of ²¹⁰Po extraction in coffee beverage resulted 20.5 ± 6.9. The percentage of transfer of gamma emitters,⁴⁰K, ²¹⁴Pb, ²¹⁴Bi, ²²⁸Ac, ²¹²Pb, ²⁰⁸Tl resulted of 80.0, 33.5, 24.7, 30.0, 35.1 and 53.5 % for ⁴⁰K, ²¹⁴Pb, ²¹⁴Bi, ²²⁸Ac, ²¹²Pb and ²⁰⁸Tl respectively.     

Spatial distribution of radium in coastal marine waters of Tamil Nadu

An investigation on the distribution of radium activity levels in the entire south eastern coast of Tamil Nadu, India, from Chennai to Kanyakumari was carried out. Insitu preconcentration technique was adopted by passing 1,000?L of seawater through MnO₂ impregnated cartridge filters at all the locations. In the coastal waters, ²²⁶Ra and ²²⁸Ra concentration was observed to be in the range of 1 to 1.81 and 3.1 to 7.5?mBq/L, respectively with an average of 1.52 and 4.53?mBq/L. respectively, while the sediment samples showed ²²⁶Ra activity levels from 8.1 to 129.0?Bq/kg and ²²⁸Ra varied from 14.7 to 430.01?Bq/kg. The Kd values for ²²⁶Ra was observed to be from 5.3E03 to 3.5E05?L/kg and for ²²⁸Ra it was in the range of 2.3E03 to 5.9E04. It was observed that the concentration of ²²⁸Ra was more than ²²⁶Ra in all the locations. The spatial distribution of the activity with respect to location is discussed in the paper. The radioactive database obtained, represents reference values for coastal environment of Tamil Nadu.     

Determination of radium isotopes in soil samples by alpha-spectrometry

A sensitive and accurate method for determination of radium isotopes in soil samples by α-spectrometry has been developed ²²⁵Ra, which is in equilibrium with its mother ²²⁹Th, was used as a yield tracer. Radium in soil samples was fused together with Na₂CO₃ and Na₂O₂ at 600 °C, leached with HNO₃, HCl and HF, preconcentrated by coprecipitation with BaSO₄, separated from uranium, thorium and iron using a Microthene-TOPO chromatographic column, isolated from barium in a cation-exchange resin column using 0.05M 1,2-cyclohexylene-dinitrilo-tetraacetic acid monohydrate as an eluant, electrodeposited on a stainless steel disc, and counted by α-spectrometry. The detection limit of the method is 0.43 Bq·kg⁻¹ for ²²⁶Ra, ²²⁸Ra and ²²⁴Ra if 0.50 g of soil sample are analyzed. The method was checked with two certified reference materials supplied by the IAEA, and reliable results were obtained Fourteen soil samples collected from the refractory industry in Italy were also analyzed. The mean radiochemical yields for radium were 85.7±4.3%, and the obtained radium concentrations in the soil samples were in the range of 8.08–3878 Bq·kg⁻¹ for ²²⁶Ra, of 1.60–678 Bq·kg⁻¹ for ²²⁸Ra and 1.25–550 Bq·kg⁻¹ for ²²⁴Ra, with ²²⁸Ra/²²⁶Ra and ²²⁴Ra/²²⁶Ra ratios ranged from 0.159–0.821 and from 0.142 to 0.525, respectively.     

Measurement of naturally occurring radioactive materials (NORM) in beach sand minerals using HPGe based gamma-ray spectrometry

This paper discusses the measurement of naturally occurring radioactivity materials (NORM) in beach sand minerals using high resolution gamma spectrometry. In India, the beach sand minerals of economic interest from coastal Kerala, Tamil Nadu and Orissa are enriched with NORM due to the occurrence of monazite deposits and heavy minerals such as zircon, ilmenite, magnetite, garnet, rutile etc. Since many of these ores are rich in ²³²Th and other radio elements, certification of radioactivity levels has become mandatory in recent years. The average activity concentrations of ²²⁶Ra in zircon, rutile and garnet were 3,531, 1,134 and 17 Bq kg^?1, respectively. The average activity concentration of ²³²Th observed in zircon, rutile and garnet were 618, 454 and 64 Bq kg^?1, respectively. Concentration of ²²⁶Ra, ²³²Th, and ⁴⁰K in ilmenite ore ranged from 17.6–444 Bq kg^?1, 80.4–1971 Bq kg^?1 and ≤5.5–25.0 Bq kg^?1, respectively.     

Estimation of growth rate of hokutolite from Tamagawa hot-spring,Akita, Japan

The concentrations of radium isotopes and the progenies (²²⁶Ra; ²²⁸Ra and ²²⁸Th) in three hokutolite samples from Tamagawa hot-spring were measured. These isotopes were analyzed by a well-type HPGe γ-ray spectrometer for the 351, 911 and 583 keV γ-ray from ²¹⁴Pb, ²²⁸Ac and ²⁰⁸Tl, respectively, each being in radioactive equilibrium with precursors. Concentration of ²²⁶Ra and ²²⁸Ra were observed to be in the range of 52–85 and 7.1–85 Bq/g, respectively. The activity ratios of ²²⁸Ra/²²⁶Ra and ²²⁸Th/²²⁶Ra provided the estimation of the growth rate (0.09–0.15 mm/y). Estimated ²²⁸Ra/²²⁶Ra activity ratios in hot-spring water from surface of three hokutolite were concordant.     

Methodological advances for measuring low-level radium isotopes in seawater

A new approach for quantifying radium isotopes in seawater was developed in advance of the international GEOTRACES program, which has the goal of identifying processes and quantifying fluxes that control the distribution of trace elements and isotopes (TEIs) in the ocean. High-resolution water column samples were collected via a commercially available in situ pump modified to accept multiple filter media including a manganese-oxide (MnO₂) impregnated acrylic cartridge for extracting dissolved radionuclides from seawater. The modifications mitigated prefilter clogging and allowed for up to 1,800 L filtrations in 4 h of pumping. Different MnO₂ cartridge preparation methods were investigated to achieve maximum radium (Ra) extraction efficiency under high sample flow rates. Full-ocean depth profiles were measured for short-lived radium isotopes (²²³Ra and ²²⁴Ra) in shipboard laboratories using a delayed coincidence alpha scintillation counter (RaDeCC). Samples were reanalyzed 4 weeks and 2 months after collection for ²²⁸Th and ²²⁷Ac to correct for supported ²²⁴Ra and ²²³Ra, respectively. Finally, the cartridges were measured on a gamma-ray spectrometer for the long-lived radium isotopes (²²⁶Ra and ²²⁸Ra). Parallel 20 L samples at each pumping depth were collected from Niskin bottles and analyzed via alpha scintillation for ²²⁶Ra to determine radium extraction efficiencies for the cartridges. These modified methods will allow for increased sample throughput, and hence higher spatial resolution for radium isotopes in the ocean. Such resolution will greatly improve the determination of oceanic vertical and horizontal mixing rates over small and large scales, which in turn can be used to calculate fluxes of TEIs into the ocean.     

Natural radionuclides in Italian diet and their annual intake

This study was dedicated to the evaluation of the background activity concentration of natural radionuclides as ²²⁸Ra and ²²⁸Th of ²³²Th family, ²²⁶Ra of ²³⁸U family and ⁴⁰K in the Italian daily diet. These radionuclides were determined by gamma spectrometry. ⁴⁰K activity concentration, in the samples taken into account in the present paper, ranged between 70.5 (milk) and 181.1 Bq kg _ww ^?1 (pasta), ²²⁶Ra activity concentration ranged between 1.1 (milk) and 5.7 Bq kg _ww ^?1 (pasta), ²²⁸Ra and ²²⁸Th activity concentration, in the same samples, ranged between 0.7 (milk) and 3.7 Bq kg _ww ^?1 (pasta) and between 1.4 (milk) and 6.1 Bq kg _ww ^?1 (flours) respectively. The annual intake of every radionuclide from foodstuffs ingestion was also calculated. The 94–95 % of the total intake comes from ⁴⁰K. For adults and children, the highest activity intake of all radioisotopes was from grain products, for infants it was from milk products.     

Rapid method for 226Ra and 228Ra analysis in water samples

Summary The measurement of radium isotopes in natural waters is important for oceanographic studies and for public health reasons. Radium-226 (T_1/2 = 1620 y) is one of the most toxic of the long-lived alpha-emitters present in the environment due to its long life and its tendency to concentrate in bones, which increases the internal radiation dose of individuals. The analysis of ²²⁶Ra and ²²⁸Ra in natural waters can be tedious and time-consuming. Different sample preparation methods are often required to prepare ²²⁶Ra and ²²⁸Ra for separate analyses. A rapid method has been developed at the Savannah River Environmental Laboratory that effectively separates both ²²⁶Ra and ²²⁸Ra (via ²²⁸Ac) for assay. This method uses MnO₂ Resin from Eichrom Technologies (Darien, IL, USA) to preconcentrate ²²⁶Ra and ²²⁸Ra rapidly from water samples, along with ¹³³Ba tracer. DGA Resin^ò (Eichrom) and Ln-Resin^ò (Eichrom) are employed in tandem to prepare ²²⁶Ra for assay by alpha-spectrometry and to determine ²²⁸Ra via the measurement of ²²⁸Ac by gas proportional counting. After preconcentration, the manganese dioxide is dissolved from the resin and passed through stacked Ln-Resin-DGA Resin cartridges that remove uranium and thorium interferences and retain ²²⁸Ac on DGA Resin. The eluate that passed through this column is evaporated, redissolved in a lower acidity and passed through Ln-Resin again to further remove interferences before performing a barium sulfate microprecipitation. The ²²⁸Ac is stripped from the resin, collected using cerium fluoride microprecipitation and counted by gas proportional counting. By using vacuum box cartridge technology with rapid flow rates, sample preparation time is minimized.     

Dose rates and seasonal variations of 238U, 232Th, 226Ra 40K and 137Cs radionuclides in soils along Thrace, Turkey

Concentrations of ²³⁸U, ²³²Th, ²²⁶Ra, ⁴⁰K and ¹³⁷Cs are measured in collected soil samples from various locations in the Thrace region of Turkey. The activity concentrations range from 12.82 to 101.75 Bq kg^?1 d.w. (dry weight) for ²³⁸U, from 5.16 to 73.34 Bq kg^?1 d.w. for ²³²Th, from 185.54 to 5399 Bq kg^?1 d.w. for ⁴⁰K and from 11.42 to 90.73 Bq kg^?1 d.w. for ²²⁶Ra. In addition to naturally occurring radionuclides, ¹³⁷Cs activity concentration is determined between 3.05 and 46.78 Bq kg^?1 d.w. for soil samples. Determination of the radiological hazard is achieved through calculations of the external terrestrial gamma dose rate in air (nGy h^?1) and annual effective dose rate (mSv year^?1) and the results are compared with the similar works in different countries.     

Pre-concentration of short-lived radionuclides using manganese dioxide precipitation from surface waters

Rapid determination of ²²²Rn and ²²⁰Rn progeny (²¹⁴Pb, ²¹²Pb, ²¹⁴Bi, ²¹²Bi) is achievable using manganese dioxide (MnO₂) precipitation with analysis by γ-spectrometry. This is of interest to environmental monitoring programmes that utilise gross activity methods to screen for anthropogenic radionuclides. The contribution from these naturally occurring radionuclides (NOR) varies, and is difficult to experimentally measure due to short half-lives (t _½ = 19.9 m–10.64 h) and low environmental activity (<0.1 Bq L^?1). The extraction efficiency of the technique is above 90%, and above 80% for other nuclides (²³²Th, ²³⁸U, ²³⁵U, ²²⁸Ac, ²²⁶Ra, ²²⁴Ra, ²¹⁰Pb, ⁵⁴Mn). Short-lived NOR have been measured at two surface water locations, and indicates elevated ²¹⁴Bi activity of 4.0 ± 1.1 Bq L^?1.     

<Superscript>226</Superscript>Ra and <Superscript>228</Superscript>Ra determination in environmental samples by alpha-particle spectrometry

A complete methodology for ²²⁶Ra and ²²⁸Ra determination by alpha-particle spectrometry in environmental samples is being applied in our laboratory using ²²⁵Ra as an isotopic tracer. This methodology can be considered highly suitable for the determination of these nuclides when very low absolute limits of detection need to be achieved. The ²²⁶Ra determination can be performed at any time after the isolation of the radium isotopes from the analyzed samples while the ²²⁸Ra determination needs to be carried out at least six months later through the measurement of one of its grand-daughters. The method has been validated by its application to samples with known concentrations of these Ra nuclides, and by comparison with other radiometric methods.     

Rapid method for determination of 228Ra in water samples

A new rapid method for the determination of ²²⁸Ra in natural water samples has been developed at the SRNL/EBL (Savannah River National Lab/Environmental Bioassay Laboratory) that can be used for emergency response or routine samples. While gamma spectrometry can be employed with sufficient detection limits to determine ²²⁸Ra in solid samples (via ²²⁸Ac), radiochemical methods that employ gas flow proportional counting techniques typically provide lower minimal detectable activity levels for the determination of ²²⁸Ra in water samples. Most radiochemical methods for ²²⁸Ra collect and purify ²²⁸Ra and allow for ²²⁸Ac daughter ingrowth for ~36 h. In this new SRNL/EBL approach, ²²⁸Ac is collected and purified from the water sample without waiting to eliminate this delay. The sample preparation requires only about 4 h so that ²²⁸Ra assay results on water samples can be achieved in <6 h. The method uses a rapid calcium carbonate precipitation enhanced with a small amount of phosphate added to enhance chemical yields (typically >90 %), followed by rapid cation exchange removal of calcium. Lead, bismuth, uranium, thorium and protactinium isotopes are also removed by the cation exchange separation. ²²⁸Ac is eluted from the cation resin directly onto a DGA Resin cartridge attached to the bottom of the cation column to purify ²²⁸Ac. DGA Resin also removes lead and bismuth isotopes, along with Sr isotopes and ⁹⁰Y. La is used to determine ²²⁸Ac chemical yield via ICP-MS, but ¹³³Ba can also be used instead if ICP-MS assay is not available. Unlike some older methods, no lead or strontium holdback carriers or continual readjustment of sample pH is required.     

Studies on radionuclides around Hemavathi river basin of Karnataka,India

The activity concentration and total annual effective dose of the terrestrial naturally occurring radionuclides (²³²Th, ²²⁶Ra and ⁴⁰K) were measured in soil and rock samples collected from various locations of Hemavathi river basin in Karnataka, using HPGe detector. The results revealed that activity concentration of radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K in the soil had geometrical mean values of 16.7 ± 0.6, 33.9 ± 1.2 and 359.9 ± 9.2 Bq kg^?1, respectively. In rock samples activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K had geometrical mean values of 20.2 ± 0.7, 18.0 ± 0.9 and 276 ± 9.6 Bq kg^?1, respectively. The external Hazard index and indoor hazard index were found to be within safety limits prescribed by European commission 1999 report.     

226Ra uptake from soils into different plant species

Accumulation of ²²⁶Ra into different plant species from contaminated soils was measured on site within the area of an uranium mill. Marinelli beakers and Nal(Tl) spectrometer were used for measurement of dried and weighted samples. While the ²²⁶Ra activity concentration in soil on site ranged from 7.12 to 25.60 Bq·g⁻¹ (1 SD<±10%), in the plant species tested it ranged from 0.66 to 5.70 Bq·g⁻¹ (1 SD<±10%). No significant differences in ²²⁶Ra accumulation were found after cultivation of selected plant species in a glasshouse in relation to the outdoor experiments. This revised version was published online in July 2006 with corrections to the Cover Date.     

Studies on natural and anthropogenic radionuclides in sediment and biota of Mumbai Harbour Bay

Mumbai Harbour Bay (MHB) is a recipient of low level treated effluents from BARC, Trombay and its also a recipient of domestic and industrial wastes from the city of Mumbai and adjoining areas. Sediment samples were collected from various locations of MHB to determine the concentrations of naturally occurring radionuclides like ²²⁶Ra, ²²⁸Ra and ⁴⁰K which varied between 4.0 and 26.0, 5.5 and 19.9, 249.6 and 557.6 Bq kg _(dry) ^?1 respectively and are comparable to the worldwide average concentration. The mean value ratio of ²²⁸Ra/²²⁶Ra in sediment was found to be 1.4, indicating a relatively higher mobility of ²³⁸U compared to ²³²Th. The concentration of anthropogenic radionuclide ¹³⁷Cs in sediment and biota ranged between 3.6 and 54.5 Bq kg _(dry) ^?1 , <0.08 and 0.5 Bq kg _(wet) ^?1 respectively. The ingestion dose to ‘General Public’ due to ¹³⁷Cs intake is 0.02 μSv years^?1 which is negligible compared to the internationally accepted limit of 1,000 μSv years^?1 to ‘members of public’.     

Radiometric analysis of rock and soil samples of Leepa Valley; Azad Kashmir, Pakistan

In this article, we present results obtained from a radiometric survey that was conducted in the Leepa Valley of Azad Jammu & Kashmir, Pakistan. The purpose of current study is to appraise the radioactivity levels and the associated health hazards due to the terrestrial radionuclide in soil and rock samples. In this regard, 16 soil and 17 rock samples were collected from different locations of the Leepa Valley. After processing the samples, activity concentrations of primordial (²³²Th, ²²⁶Ra and ⁴⁰K) and anthropogenic (¹³⁷Cs) radionuclides were determined using a P-type coaxial high purity germanium detector. From the results obtained the mean activity concentrations of radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K in the soil samples were found to be 31.25 ± 0.46, 44.1 ± 1.07 and 575 ± 8.89 Bq kg^?1 respectively. Whilst, in rock samples ²²⁶Ra, ²³²Th and ⁴⁰K mean activities were found as 28.46 ± 0.45, 48.63 ± 1.12 and 666.7 ± 9.39 Bq kg^?1, respectively. The ¹³⁷Cs concentration level in soil and rock samples is found to be 15.04 ± 0.29 and 5.7 ± 0.16 Bq kg^?1, respectively. The average radium equivalent activity (R _aeq) was found as 143.16 and 142.93 Bq kg^?1 in soil and rock samples, respectively. These findings are less than the recommended safe value of 370 Bq kg^?1 as given in OECD report (1979). The values of external (H _ex) and internal hazard index (H _in) are also less than unity. Mean value of absorbed dose rate was found as 69.78 nGy h^?1 for the soil samples, which is in good agreement with the world wide average value (70 nGy h^?1). Mean value of absorbed dose rate from rock samples was found as 70.01 nGy h^?1. Mean values of the annual effective dose is also lower than the values reported for different other countries of the world.     

Contribution to the simultaneous determination of228Ra and226Ra by using 3M's EMPORETM radium rad disks

New method for simultaneous determination of²²⁸Ra and²²⁶Ra by using 3M's EMPORE^TM Radium Rad Disks in water has been developed. Both radionuclides²²⁶Ra and²²⁸Ra were counted through their daughter products,²²⁶Ra by conventional radon emanation techniques and²²⁸Ra through its daughter²²⁸Ac by using a proportional counter. Different molarity of diammonium hydrogen citrate were used for elution of²²⁸Ac and²²⁶Ra from EMPORE^TM Radium Rad Disks. 79% of²²⁸Ac was eluted in 10 ml of 0.0003M diammonium hydrogen citrate. The recovery of²²⁶Ra was 99% by using 40 ml of 0.2M diammonium hydrogen citrate adjusted by ammonium to pH 7.8.