Activity Concentration Values Research Articles

Eco-friendly Mycogenic Synthesis of ZnO and CuO Nanoparticles for In Vitro Antibacterial, Antibiofilm, and Antifungal Applications.

Mycogenic synthesis of medically applied zinc oxide (ZnO) and copper oxide (CuO) nanoparticles (NPs) were exploited using Penicillium chrysogenum. The biogenesis and capping processes of the produced nano-metals were conducted by functional fungal extracellular enzymes and proteins. The obtained ZnO-NPs and CuO-NPs were characterized. Also, the antibacterial activity and minimum inhibitory concentration (MIC) values of ZnO-NPs and CuO-NPs were determined. Also, antibiofilm and antifungal activities were investigated. Results have demonstrated the ability of the bio-secreted proteins to cape and reduce ZnO and CuO to hexagonal and spherical ZnO-NPs and CuO-NPs with particle size at 9.0-35.0nm and 10.5-59.7nm, respectively. Both ZnO-NPs and CuO-NPs showed high antimicrobial activities not only against Gram-positive and Gram-negative bacteria but also against some phytopathogenic fungal strains. Besides this, those NPs showed varied antibiofilm effects against different microorganisms. Quantitative and qualitative analyses indicated that CuO-NPs had an effective antibiofilm activity against Staphylococcus aureus and therefore can be applied in diverse medical devices. Thus, the mycogenic green synthesized ZnO-NPs and CuO-NPs have the potential as smart nano-materials to be used in the medical field to limit the spread of some pathogenic microbes.

Measurement of 226Ra, 232Th and 40K and the associated radiological hazards in Ponnai river sand, Tamilnadu, India using Gamma ray spectrometry

ABSTRACT River sand is a one of the important and commonly used building material in India and hence in the present study, activity concentration of natural radionuclides such as 226Ra, 232Th and 40 K have been measured in sand samples collected from Ponnai river, Tamilnadu using HPGe detector-based gamma ray spectroscopy. The measured activity concentrations vary from 13.30 to 54.83 Bq kg−1 with a mean value of 31.07 Bq kg−1 for 226Ra, from 26.15 to 245.33 Bq kg−1 with a mean value of 83.61 Bq kg−1 for 232Th, from 218.76 to 581.88 Bq kg−1 with a mean value of 416.36 Bq kg−1 for 40 K. These mean values of activity concentration of radionuclides have been compared with recommended limit and other similar work carried in the world. In order to assess the radiation associated with sands, radiological parameters such as air absorbed dose rate, annual indoor and outdoor effective dose rate, excess lifetime cancer risk, were calculated. The result shows that excess lifetime cancer risk (ELCR) for the indoor exposure varied from 0.775 × 10−3 to 3.216 × 10−3 with an average value of 1.440 × 10−3. An average ELCR for Ponnai river sand samples is slightly higher than the world average value of 1.16 × 10−3 mSv y−1. Finally, to assess the delivery of gamma radiation to organs, effective dose to body organ (Dorgn) was calculated for all river sand samples in the study area.

Impact of a massive dust storm on the gross alpha, gross beta, 40K, 137Cs, 210Pb, 7Be activities measured in atmospheric aerosols collected in Tenerife, Canary Islands

Abstract From February 22 to 24, 2020, an intense dust storm affected the Spanish archipelago of the Canary Islands. Here we assess the radiological impact on the Canary Islands population of several natural and artificial radionuclides (40K, 137Cs, 210Pb, 7Be), and other radiological parameters (gross alpha and gross beta activity concentrations) measured in atmospheric aerosols before, during and after the dust storm. Total Suspended Matter highly correlated with PM10 (Pearson's correlation coefficient, ro = 0.98), showed increments ranging from 849% to 1778% against the background average levels, reaching levels of >3000 μg m−3. 40K and 137Cs radionuclides showed activity values over the minimum detection activity from January to March 2020, coupled with dust intrusion episodes during the study. This finding supports the use of these radionuclides as radiotracers for African low altitude dust intrusions occurring particularly during winter months over the Canary Islands. A high correlation between gross beta and 210Pb activities suggests that the latter is the main source for gross beta emitters in aerosol samples collected in the study region. 210Pb and 7Be showed a moderate positive correlation and did not show any significant change during the storm, suggesting a similar dynamics of alpha and beta emitters in the low atmosphere. A Principal Component Analysis of these observations showed two components representing a Saharan component (based on 40K, 137Cs, gross alpha, and PM10) and a heterogeneous component representing North Atlantic and Europe air masses (based on 7Be, 210Pb, and gross beta). In addition, a K-means cluster analysis helped to disentangle the origin of air masses arriving at the archipelago. Three different clusters were identified: a continental cluster (based on gross beta, 210Pb, and 7Be activity concentrations); an oceanic cluster (with low values of PM10 air concentrations, gross beta, gross alpha, and 210Pb, and 7Be and 40K activity concentrations), reflecting the Atlantic air contributions with lower radionuclide activity and microparticulate matter; and a dust intrusion cluster (with high PM10 values and 137Cs, 40K and gross alpha activity concentrations) representing dust intrusion episodes observed in Tenerife Island. These studies allow the detection and monitoring of radioactive elements, estimating the potential radiological risk to the population associated with mineral dust intrusions.

Variation of radon-radium gas in geothermal region of Omer-Gecek

In this study, radon gas and radium activity concentrations in the geothermal waters in the Omer-Gecek region of Afyonkarahisar province were measured for a period of 9 months. During this period, the measured radon activity concentration value of Omer region source ranged between 8.997 and 0.076 Bq/L with the average radon activity concentration of 2.714 Bq/L. The radium activity concentration ranged from 0.028 to 0.552 Bq/L with the average radium activity concentration found to be 0.239 Bq/L. The Gecek region radon activity concentration ranged from 0.081 to 3.685 Bq/L with the radium activity concentration of 0.026 to 0.443 Bq/L. The measurement results were compared with the relevant international standards and found that no source exceeds the determined limit values.

THE CONTENT OF RADIONUCLIDES IN MUSHROOMS IN THE IMPACT ZONE OF SEMIPALATINSK TEST SITE

The article provides research findings of levels and parameters of naturally occurring (40K, 226Ra, 232Th) and artificial (241Am, 137Cs, 90Sr, 239+240Pu) radionuclides accumulation by mushrooms in the territory adjacent to Semipalatinsk Test Site (STS), in the zone of fallout plume passing after the first nuclear test (August 29, 1949). It was found that, as a whole, none of activity concentration values, resulted for radionuclides in mushrooms, exceeds the permissible level. The main contribution to the total dose of internal exposure through ingestion of radionuclides, when mushrooms are consumed in the territory of interest, is made by the dose from naturally occurring radionuclides.

ASSESSMENT OF THE IMPACT OF INDIVIDUAL BIOLOGICAL FEATURES OF PLANTS ON THE CONTENT OF CERTAIN CHEMICAL ELEMENTS AND RADIONUCLIDES

The paper addresses quantitative values of the content of certain chemical elements and radionuclides in the aboveground part of sunflower in conditions of radioactive contamination at Semipalatinsk Test Site (STS). It was found that the content of chemical elements and radionuclides of interest in soil, in the same soil and climatic conditions, varies less significantly (variation factor on average does not exceed 20%) that the one in plants (variation factor is 20–40%). The widest range of activity concentration values in the aboveground part of sunflower is characteristic of 241Am, the radioactive element, which is alien to the plant body – the variation factor is more than 40%.

Synergy Between Radionuclide and Infrasound Observations and Atmospheric Transport Modelling Simulations: Case of Bogoslof

To demonstrate a synergy between radionuclide (RN) and infrasound observations and Atmospheric Transport Modelling (ATM), the volcanic activity of Bogoslof in Alaska, USA, is used as an example. The study period covers 3 months of intense eruptive activity, from 19 December 2016 to 8 March 2017. During that period, the International Monitoring System (IMS) infrasound station located in Alaska, USA, recorded signals from three eruptive sequences. The second sequence was reported in the International Data Centre (IDC) Reviewed Event Bulletin (REB) with 3 infrasound stations: in Alaska, USA, in Kamchatka, Russian Federation and in Hawaii, USA. As reported by The Alaska Volcano Observatory (AVO), during each of these events ash plumes reaching the altitude of more than 10 km were observed for several consecutive days. These observations were used to identify the length of each eruptive episode. To demonstrate the influence of volcanic ash on the berillium-7 (Be-7) activity concentration values measured by two IMS RN stations in Alaska, the ATM was used. To monitor the arrival time of a volcanic ash plume at the IMS stations, a series of 14 days forward simulations released daily from Bogoslof during each of these events, was generated. Comparison of Be-7 daily surface values with the seasonal median for the period of 9 years (2009–2017), revealed that an influx of volcanic ash up to the tropopause (1.5–12 km) tends to locally increase surface Be-7 concentrations in area under the influence of subsiding ash plume. It is also demonstrated that with the arrival of volcanic ash at the surface level, the enrichment in radioactive particulates like uranium, thorium, and potassium was observed.

RADIATION SITUATION IN THE TERRITORIES AFFECTED BY MINING ACTIVITIES IN STEPNOGORSK AREAS, REPUBLIC OF KAZAKHSTAN: PILOT STUDY.

The Republic of Kazakhstan has a long history of mining activities, viz., gold and uranium. Mining activities represent sources of potential naturally occurring radionuclides contamination of the environment and human health of population. The aim of this study was to investigate the radiation situation of industrially modified environment in Stepnogorsk areas of Kazakhstan to understand the sources of contamination. Quite high values of ambient equivalent dose rates in air ~2.87μSvh-1 were found in the Aqsu gold-mining site. The radon equivalent equilibrium volume activity (indoor) were in the range of 313-858Bqm-3 in the study area buildings. The high values of activity concentration of natural radionuclides found in Aqsu soil samples were 226Ra-4060, 232Th-1170 and 40K-4080Bqkg-1, respectively. However, our comprehensive surveys implied that the increased natural radiation background caused by the radionuclide transport from the tailing area did not have an impact, while evaluation of its potential radiation risks and remediation of the territories of the former gold mining should be needed.

Alkyl β-D-xyloside synthesis from black liquor xylan using Aureobasidium pullulans CBS 135684 β-xylosidases immobilized on spent expanded perlite

The crude β-xylosidase from Aureobasidium pullulans CBS 135684 was immobilized on the surface of the modified spent expanded perlite via (3-aminopropyl) triethoxy-silane and glutaraldehyde cross-linking reaction. Over 80% of the initial free enzyme activity was detected on the bound enzyme. The immobilized β-xylosidase (204.7 ± 6.5 U g-1 of perlite) exhibited transxylosylation activity when sugars from black liquor xylan hydrolysate and a variety of alcohols (C1-6) were used as donor and acceptor molecules, respectively, yielding a number of alkyl xylosides. The synthesized hexyl xyloside exhibited some interesting properties comparable with those of a commercial hexyl glucoside, including an antioxidant activity (IC50 = 8.9 ± 2.0 mg mL-1), wetting time (43 s), and critical micelle concentration value (252 mmol L-1). Optimization for hexyl xyloside synthesis was performed via statistical analysis using a Box and Behnken design. The maximum predicted yield of hexyl xyloside (499.0 ± 1.1 mg g-1 xylan hydrolysate) was obtained with 10% (w/v) xylan hydrolysate, 10 U g-1 immobilized β-xylosidase, and 13% (v/v) hexanol at 70 °C, pH 6.0 for 4 h, and it was validated by the following experimental yield (498.9 ± 4.8 mg g-1 xylan hydrolysate). The maximum production yield remained relatively stable after the immobilized enzyme was reused for 12 cycles with a 471.5 ± 15.1 mg g-1 hexyl xyloside yield (94.4% of the first cycle). Thus, the immobilized β-xylosidase has a high potential as a robust catalyst for application in alkyl xyloside production.

222Rn Concentration in Groundwaters Circulating in Granitoid Massifs of Poland

The authors’ research has shown that the maximum values of 222Rn activity concentration in all granitoid massifs of Poland exceed 100 Bq·L−1, i.e. the value allowed for waters intended for human consumption. Such waters should be de-radoned prior to being distributed through the water supply networks. Even more common in these areas is the occurrence of potentially medicinal radon waters, i.e. waters characterized, in accordance with Polish law, by radon activity concentration of at least 74 Bq·L−1. Such waters may be used for balneotherapeutic treatments. For the Karkonosze, Strzegom-Sobótka, Kłodzko-Złoty Stok and Kudowa massifs, the range of hydrogeochemical background of 222Rn exceeds both 74 and 100 Bq·L−1. This indicates common occurrence in these areas of both potentially medicinal radon waters and waters which require de-radoning before being supplied for human consumption. More than 50% of groundwaters from the Karkonosze granite area contain over 100 Bq·L−1 of 222Rn. This means that these waters are mostly radon and high-radon waters. The remaining massifs contain predominantly low-radon waters and radon-poor waters. The 222Rn concentrations obtained by the authors are comparable to values measured in groundwaters in other granitoid massifs in the world, creating both problems and new application possibilities.

Measurements of 22Na in the Atmosphere: Ground Level Activity Concentration Values from Wet and Dry Deposition Samples

Sodium-22 (22Na, half-life 2.603 years) is a cosmogenic radionuclide mainly produced in the stratosphere by nuclear spallation reactions of cosmic rays on 40Ar. Due to the very low concentration levels normally reached in the environment, 22Na poses no significant radioprotection threats: actually, the effective doses delivered to humans can hardly exceed a few nSv per year, a very negligible value. However, the measurements of this radionuclides can be very interesting for atmospheric circulation and climatic studies. Unfortunately, the difficulty of 22Na detection, due to its very low concentration levels, has prevented the gathering of large and widespread time series of this radionuclide. In this paper, a method for the retrospective measurements of 22Na in the atmosphere, starting from the gamma spectra (hyperpure germanium detectors (HPGe) detectors) of wet and dry deposition samples stored in our databases is proposed and validated. The method was applied to spectra samples gathered in the context of the Italian National Radioactivity Monitoring Network (RESORAD) and allowed the detection of the very low atmospheric activity concentration values of 22Na present at ground level. The results obtained with the new method are discussed and compared for validation with the available experimental values. Finally, some possible applications to environmental studies are also highlighted and suggested.

Measurement of natural radioactivity in river sediments of Thamirabarani, Tamilnadu, India using gamma ray spectroscopic technique

ABSTRACT Natural radioactivity is diffuse in earth’s environment and occurs in various geological formations like sand, soil and rocks as well as in plants, water and air. Among the various building materials, river sediment is commonly used in building constructions. Sediment samples were collected from Thamirabarani river belt, Tamilnadu, India. Radiometric analysis was carried out using Gamma ray spectrometry for the sediment samples in this area. Activity concentrations of the natural radionuclides such as 226Ra, 232Th and 40K were determined and other radiological parameters were calculated. The average activity concentration values for 226Ra, 232Th and 40K were 40.85, 51.87 and 838.19 Bq kg−1, respectively. Radium equivalent (Raeq), absorbed dose rate (DR), annual effective dose equivalent (AEDE), hazard indices (Hex and Hin) and activity utilisation index (AUI) were also calculated and compared with world average values. The mean values of the radiological parameters are less than the recommended limit. Hence, there is no radiological hazard involved in using river sediments for construction from in this study area.

Use of Fertilizers in Agriculture: Individual Effective Dose Estimate

Natural radioactivity might be present in fertilizers above ordinary levels, in particular for 40K and for the radionuclides of the 238U series. A modeling evaluation of the individual effective dose deriving from the use of fertilizers in agriculture is presented here. Dose assessment is useful in the transposition of Directive 2013/59/Euratom, which rules the individual exposure to commodities containing radionuclides of natural origin, such as fertilizers. The following input data have been considered for this study: the amount of fertilizers used in the region of Veneto and in Italy; the utilized agricultural area (to estimate the density of spread fertilizers); and, the average values of activity concentrations in fertilizers for 40K and 238U series radionuclides, derived from scientific literature. The individual effective dose was evaluated while using the Resrad calculation model, making assumptions on the characteristics of the interested soil. This study is focused on the region of Veneto, where the use of fertilizers is higher with respect to the rest of Italy, such providing a more conservative estimate of the individual effective dose to the population. The results show that the estimated individual effective dose values do not exceed few µSv per year. The category that most contributes to the dose is that of compound fertilizers and radon and 40K are the most significant radionuclides.

Natural Radioactivity Level of <sup>238</sup>U, <sup>232</sup>Th, and <sup>40</sup>K in Baby Food and Committed Annual Effective Dose Assessment in Bangladesh

Worldwide, the contagion of chronic diseases like diabetes and cancer among children has made the nutritionists thoughtful. Food contamination with radioactivity, became a severe health threat for children below five since they are under developing immune systems and cannot fight off infections like adults. Radioactivity concentrated in food chain may be transferred to human body and increase the cumulative risk of developing cancer and some other diseases. Therefore the assessment of radioactivity levels in baby food and their associated doses are of crucial importance for health safety. The study is focused on the radiation contamination of baby food due to the nuclear disasters and make public awareness about infant’s nutrition followed by the health safety. The natural radioactivity level due to 238U, 232Th and 40K in baby food (cereals and powder milk) samples, marketed in Bangladesh were estimated and annual effective dose was assessed. Gamma spectrometry was performed by HPGe detector coupled with MCA, and certified reference materials were used for quantification and quality control. The average concentrations of 238U, 232Th and 40K were found to be 5.42±0.42, 5.71±0.50 and 334.4±12 Bq.Kg-1 in milk sample and 2.98±0.38, 3.94±0.29 and 155.7±7.5 Bq.Kg-1 in cereal sample respectively. The committed effective doses due to ingestion of natural radionuclides (238U, 232Th and 40K) from the consumption of milk and cereals for age group <1 year were 1.30 and 0.51 mSv/yr and for age group 1-2 year were 0.31 and 0.15 mSv/yr respectively. The age group < 1yr, who are completely depend on formula milk are under highly threat since their annual effective dose 1.30 mSv/yr exceeds the recommended permissible limit of 1 mSv/yr. The data generated in this study will provide base-line radiometric values of activity concentration and annual effective dose attributed from baby foods in Bangladesh.

A COMPREHENSIVE CHARACTERISTIC OF 222Rn ACTIVITY CONCENTRATION CHANGES AND IONISING RADIATION EXPOSURE IN NEWLY DISCOVERED PARTS OF BEAR CAVE IN KLETNO, POLAND.

The article presents the results of research into 222Rn activity concentration changes and ionising radiation exposure in newly discovered parts of Bear Cave in Kletno, unknown until 2012. 222Rn activity concentration was registered at three measurement points located inside over 500-m-long newly discovered cave passages. The air in these parts of the cave is characterised by a stable temperature of about 5°C and a relative humidity of 100%. The measurements started in September 2013 and were completed by mid-July 2016. The measured data were recorded continuously, including hourly registration of 222Rn activity concentration with the use of three Polish semiconductor detectors SRDN-3a. Three data sets were obtained. Two of them, containing the same numbers of data, were recorded between 4 September 2013 and 10 July 2016 by SRDN-3a detectors no 7 and 9 located at sites no 1 and no 3, respectively. The third set comprises data registered between 27 October 2014 and 10 July 2016 by SRDN-3a probe no 8 at site no 2. Distinct daily changes in 222Rn activity concentration in the new parts of Bear Cave occur in early spring (from March to May) and in autumn (October). This observation confirms the notion that radon concentration changes depend on natural convective air exchange between the cave and the atmosphere. It has been shown that daily radon concentration changes in other seasons are irregular and rather small. The highest values of 222Rn activity concentration inside the cave are more frequent in daytime, i.e. from the morning to midday. The recorded annual mean values of 222Rn activity concentration in successive measurement years are comparable for all the three sites and range from 2690 to 3179Bqm-3 in 2013, from 2676 to 2973Bqm-3 in 2014, from 2587 to 2917Bqm-3 in 2015 and from 2581 to 3719Bqm-3 in 2016. These values exceed those recommended as maximum allowable radon concentrations in such spaces (0.5-1.5kBqm-3) and are many times as high as the values recommended for workplaces (0.3kBqm-3). The recorded values of 222Rn activity concentration in the air of the new parts of Bear Cave in Kletno result in a risk of exposure to a radiation dose higher than the national standard of 1mSv per year adopted for the general public. In the most unfavourable conditions, it appears as early as after 25hours spent inside the cave. The minimum effective dose to which a person staying inside the cave is exposed within 1hour is 0.002mSv, and the maximum dose is 0.04mSv. The results of the conducted measurements demonstrate the necessity of introducing appropriate solutions, crucial in terms of radiological protection and legislation, that would minimise the risk of exposure to ionising radiation in the new parts of Bear Cave.

Natural and anthropogenic radionuclides in urban soil around non-nuclear industries (Northern Al Jubail), Saudi Arabia: assessment of health risk.

The residential areas are located around one of the oldest and largest non-nuclear industrial cities in Saudi Arabia, Arabian Gulf. Therefore, it is important to study the radioactivity levels in the urban soil in order to estimate the potential risk of radiation in environment and for public. The activity concentrations of 226Ra, 232Th, 40K, and 137Cs in urban soil around non-nuclear industries were measured using gamma ray spectrometric technique. The mean values of activity concentrations were found to be 7.64 ± 0.4, 3.76 ± 0.2, 174 ± 3.7, and 0.391 ± 0.03 (Bq/kg) for 226Ra, 232Th, 40K, and 137Cs, respectively. Radium equivalent activity (Raeq), gamma absorbed dose rate in air (D), and annual effective dose equivalent (E) for outdoor were calculated. The mean values of these radiological parameters were found to be less than the allowed limits in soil. The obtained results were compared with other studies from Arabian Gulf and other regions of the world. Consequently, the direct gamma radiation exposure from the urban soil in the study area was found to be safe for public. Additionally, the present study is the first in this area which could be used as a baseline for radioactivity levels in soil nearby industrial areas of the Arabian Gulf region.

Dietary butyric acid improved growth, digestive enzyme activities and humoral immune parameters in Barramundi (Lates calcarifer)

A six-week feeding trial was conducted to determine the effect of butyric acid (BA) inclusion in diet on performance of Barramundi (Lates calcarifer). Fish (12.0 ± 0.2 g) were fed with four experimental diets contained 0.0 (control), 2.5, 5.0 and 10.0 g BA/kg in triplicate. Fish fed on 5 and 10 g BA/kg diets had higher growth and total alkaline protease and lipase activities than the other treatments. Fillet protein content in BA-supplemented groups was higher than the control. Liver catalase activity was highest in 2.5 g BA/kg group compared with the other groups. The values of liver superoxide dismutase activity and serum total protein concentration in 5 and 10 g BA/kg treatments were higher than those in the control (p < .05). Moreover, the highest and the lowest levels of serum lysozyme activity were noticed in the 10 g BA/kg and the control groups, respectively (p < .05). Also, the highest respiratory burst activity was observed in fish fed 5 g BA/kg feed. Supplementing diet with 2.5 or 5 g BA/kg resulted in higher serum haemolytic activity in fish compared with the other groups. The number of red and white blood cells increased in fish fed BA-supplemented diets compared with the control (p < .05). In conclusion, the results of this study showed inclusion of BA at 5 g/kg diet in L. calcarifer juveniles improved growth and upgraded the general health condition by enhancing fish antioxidant enzyme activities and haemato-immunological responses.

Activity concentrations of 137Cs, 40K, and 210Pb radionuclides in selected medicinal herbs from Central Serbia and their effective dose due to ingestion

Specific activity of 137Cs, 40K, and 210Pb radionuclides in fifteen selected medicinal herbs from three locations in Central Serbia (two mountains, Kopaonik and Zlatar, and a valley, Sokobanja) was measured using two semiconductor HPGe spectrometer systems. The obtained values are in intervals (<0.3 ÷ 9.7) Bq/kg, (<0.2 ÷ 24.7) Bq/kg, and (<0.2 ÷ 5.7) Bq/kg for 137Cs; in intervals (125 ÷ 1100) Bq/kg, (104 ÷ 872) Bq/kg, and (103 ÷ 954) Bq/kg for 40K, and in intervals (3.6 ÷ 49.0) Bq/kg, (3.9 ÷ 57.9) Bq/kg, and (2.8 ÷ 103) Bq/kg for 210Pb, for herbs from Kopaonik, Sokobanja and Zlatar, respectively. The highest activity measured in individual herbs was: 24.7 Bq/kg for 137Cs (Sokobanja valley), 1100 Bq/kg for 40K (Mt. Kopaonik) and 103 Bq/kg for 210Pb (Mt. Zlatar). The corresponding individual annual effective doses due to ingestion calculated from the measured activity concentrations, of the radionuclides are: in intervals (<1.7 ÷ 82.9) nSv, (<1.4 ÷ 211) nSv, and (<1.1 ÷ 48.7) nSv for 137Cs; in intervals (0.76 ÷ 4.5) μSv, (0.64 ÷ 4.4) μSv, and (0.63 ÷ 4.9) μSv for 40K, and in intervals (1.1 ÷ 18.2) μSv, (1.3 ÷ 21.6) μSv, (0.9 ÷ 38.3) μSv for 210Pb, respectively. The specific activity concentration values of 137Cs and 40K obtained for the investigated herbs are similar to the literature data, while no information was found in literature about specific activity concentration of 210Pb. The all values obtained for individual annual effective dose due to ingestion are less than 100 μSv, which means that the daily use of 200 mL of herbal infusion during a year made from the investigated herbs does not represent a radiological risk for health. However, a high individual annual effective dose of ingestion of 210Pb obtained for some herbs indicate that their consumption in larger amounts 2–3 cups of infusion daily over a year could make the dose to exceed the recommended level, and points to necessity for extensive investigation of 210Pb activity concentration worldwide.

Sum-peak method with two NaI(Tl) crystals: 68(Ge+Ga) standardization

A 68(Ge+Ga) commercial solution has been standardized in LNMRI in Brazil, by sum-peak method, in which a 3”x3” NaI(Tl) gamma-ray detector is positioned at the top of a well-type 5”x5” NaI(Tl) gamma-ray detector, resulting in a set up approximately 4p geometry. In this work the known germanium volatility was tested using three dried sources and three liquid sources in the sum-peak method measurements and the activity results showed a standard deviation of 0.41%. The activities were compared with another primary method: 4pb-g live-timed anti-coincidence counting. The two methods gave activity concentration values with differences from the certified value of +0.8 % (anticoincidence method) and -3.4% (sum-peak method).

Annual Effective Dose and Lifetime Cancer Risks Due to Natural Radioactivity in Hand –Dug Well Water of Tai Rivers State, Nigeria

The presence of radionuclide in water poses a number of health hazards, especially when the radionuclide is deposited in the human body through drinking water. The aim of this study was to evaluate natural radioactivity and its associated health risk in hand dug well water of Tai Local Government Area of Rivers State, Nigeria by means of gamma spectroscopy techniques and radiation models. The well water was collected from five selected coastal communities of Tai and chemically treated by adding nitric acid and then pre-concentrated further by evaporating to certain levels and kept in marineli beaker properly sealed for 28 days, after which was counted with NaI(Ti) detector. The mean values of specific activity concentration of 40K, 226Ra and 228Ra(232Th) were 25.90, 19.21 and 18.50 Bql-1 respectively. The annual effective doses for different age categories were estimated taking into consideration the ingested dose conversion factors as well as their yearly average water consumption. The average annual effective dose estimated for infants, children, teenagers and adult population were 0.115, 0.027, 0.071 and 0.013 Svy-1 respectively. The annual effective dose due to ingestion of the sampled water were above the recommended values by WHO, IAEA and UNSCEAR for the age brackets. The paper presents the overview of the techniques used and the summary of the findings. The result of this study gives the radiological baseline data for effective monitoring of the study area.