Pb-210 dating of freshwater and coastal sediments have been extensively conducted over the past 40 years for historical pollution reconstruction studies, sediment focusing, sediment accumulation and ...mixing rate determination. In areas where there is large scale disturbance of sediments and the watershed, the vertical profiles of excess (210)Pb ((210)Pbxs) could provide erroneous or less reliable information on sediment accumulation rates. We analyzed one sediment core from Hendrix Lake in southwestern Arkansas for excess (210)Pb and (137)Cs. There is no decrease in excess (210)Pb activity with depth while the (137)Cs profile indicates sharp peak corresponding to 1963 and the (137)Cs penetration depth of (137)Cs corresponds to 1952. The historical data on the accelerated mercury mining during 1931-1944 resulted in large-scale Hg input to this watershed. Using the peak Hg activity as a time marker, the obtained sediment accumulation rates agree well with the (137)Cs-based rates. Four independent evidences (two-marker events based on (137)Cs and two marker events based on Hg mining activity) result in about the same sedimentation rates and thus, we endorse earlier suggestion that (210)Pb profile always needs to be validated with at least one another independent method. We also present a concise discussion on what important factors that can affect the vertical profiles of (210)Pbxs in relatively smaller lakes.
The air exchange rate (AER) is a critical parameter that governs the levels of exposure to indoor pollutants impacting occupants’ health. It has been recognized as a crucial metric in spreading ...COVID-19 disease through airborne routes in shared indoor spaces. Assessing the AER in various human habitations is essential to combat such detrimental exposures. In this context, the development of techniques for the rapid determination of the AER has assumed importance. AER is generally determined using CO2 concentration decay data or other trace gas injection methods. We have developed a new method, referred to as the “222Rn incremented method”, in which 222Rn from naturally available soil gas was injected into the workplace for a short duration (∼30 min), homogenized and the profile of decrease of 222Rn concentration was monitored for about 2 h to evaluate AER. The method was validated against the established 222Rn time-series method. After ascertaining the suitability of the method, several experiments were performed to measure the AER under different indoor conditions. The AER values, thus determined, varied in a wide range of 0.36–4.8 h−1 depending upon the ventilation rate. The potential advantages of the technique developed in this study over conventional methods are discussed.
•A new method was developed for air exchange rate (AER) determination referred to as the “222Rn incremented method”.•Radon from natural soil gas was used as tracer in the method.•The method is user friendly and enables rapid determination of AER.•The 222Rn incremented method was validated against the 222Rn time-series method.•The new method has many advantages over conventional methods.
This article aims to study the modification in the structural, optical and electrical properties of indium oxide thin film after gamma irradiation and estimation of sensitivity for gamma sensing ...applications. The thin film of indium oxide was deposited on a 450 °C preheated glass substrate using the spray pyrolysis technique. The deposited thin film of molar concentration 0.15 M and thickness of around 600 nm was irradiated with different gamma doses (100 Gy, 200 Gy, 300 Gy and 400 Gy). The optical properties of the irradiated film are studied using UV–Visible spectroscopy. Transmittance increased after irradiation up to 200 Gy and beyond that, it decreased. Indium oxide is an
n
-type semiconductor which exhibits both direct and indirect transitions. Both direct and indirect bandgap energy are calculated using Tauc’s plot. Extinction coefficient and refractive index variation with irradiation were also estimated. Photoluminescence study confirmed the gamma-induced defect formation and annihilation for an irradiation dose of 400 Gy and 200 Gy, respectively. Resistivity also decreased up to 200 Gy and beyond that, it increased. The sensitivity of the deposited film was estimated from the electrical measurements, and it lies between 10.7 and 53.4 mA/cm
2
/Gy.
Graphical abstract
Measurement of radiation dose has the utmost importance in the field of medicine and research. This work aims the estimation of the sensitivity of Indium oxide thin film for dosimetry application. ...Indium oxide thin film prepared using spray pyrolysis on a glass substrate with an optimized concentration of 0.1 M and temperature of 450 0C was exposed to different gamma radiation doses using Co- 60 as the radiation source. The impact of irradiation on the structural properties of the film was investigated by XRD and a higher crystallite size was obtained for a dose of 200 Gy. The phase purity and vibrational modes of the irradiated films were investigated using Raman spectra. The optical characterization of the irradiated film shows negligible variation in bandgap with irradiation. The optical parameters like refractive index and extinction coefficient are also extracted from optical data. The reduction in the intensity of PL peaks after irradiation was attributed to the annihilation of gamma-induced defect levels. The thermoluminescence curve indicates the suitability of In2O3 as dosimeters. XPS analysis also supports the annihilation of defects at 200 Gy. The electrical measurement was used to find the sensitivity of the film at different applied voltages and it lies in the range of 101 − 380 mA/cm2/Gy. The fact that irradiated material undergoes a change in physical properties due to the influence of gamma-ray can be utilized for gamma dosimetry applications. The changes induced by gamma-ray in structural, optical and electrical properties have been investigated in detail.
Display omitted
•Sensitivity estimation of INO up to a gamma dose of 200 Gy was carried out for gamma dosimetry applications.•The variation in the intensity of the Raman peak can be ascribed to dampened vibrational modes of INO.•XPS analysis supports the annihilation of defects occurring at 200 Gy.•The thermoluminescence curve indicate the suitability of indium oxide for dosimeters.•The estimated sensitivity lies in the 101-308 mA/cm2/Gy range.
The radionuclide transfer between compartments is commonly described by transfer parameters representing the ratio of concentrations of an element in two compartments for equilibrium conditions. This ...is a comprehensive study on the soil-to-grass transfer factor (F
) and grass-to-cow milk transfer coefficient (F
) for stable strontium (Sr) for soil-grass (pasture)-cow (Bos taurus) milk environmental pathway under field conditions for a high rainfall tropical monsoonal climatic region of the Indian subcontinent. The study was conducted in the vicinity of the Kaiga nuclear power plant (NPP), situated ~ 58 km inland of the West Coast of the Indian subcontinent. A grass field was developed exclusively for this study, and two cows of the native breed were raised to graze on it. The soil, grass, and milk were analyzed to evaluate the F
and the F
values for the stable Sr. For comparison, several pasture lands and the cows raised by the villagers and a dairy farm were also studied. The F
values were in the range 0.18-8.6, the geometric mean (GM) being 1.8. The correlations of F
values with a range of physicochemical parameters are presented. The GM values for F
were 2.2 × 10
d L
and 7.2 × 10
d L
for the two cows raised for this study, 2.6 × 10
d L
for those raised by the villagers, and 4.2 × 10
d L
for the dairy farm. The site-specific F
value for the region was determined as 3.2 × 10
d L
. The concentration ratio (CR), defined as the ratio of Sr concentration in milk to that in feed under equilibrium conditions, exhibited less variability (1.8 × 10
-5.4 × 10
) among the three categories of cows.
The study assessed natural radioactivity in Rohtak and Jind districts, Haryana, India. Concentrations of radionuclides in soil and building materials were measured using gamma-ray spectroscopy. The ...“Canister Technique” was employed to estimate radon mass exhalation and surface exhalation rates. Results showed low radiation doses from soil radioactivity, with activity concentrations ranging from 3.7 to 51.7 Bq/kg for radium, 7.3 to 96 Bq/kg for thorium, and 52.2 to 585 Bq/kg for potassium. The findings also calculated radium equivalent activity, annual effective dose rate, hazard indices, and excess life time cancer risk. This research highlights the importance of understanding natural radioactivity for assessing environmental radiation exposure.
This is the first detailed study on 14C activity in the environment surrounding a nuclear facility in India. Samples of food matrices and wild plants from the off-site locations of the PHWR nuclear ...power plant (NPP) at Kaiga were analysed by liquid scintillation spectrometry, results were validated by accelerator mass spectrometry, and an extensive database (N = 142) was established. The stable isotope ratio of carbon (δ13C) in terrestrial plants varied from −33.5 to −23.3 ‰. The maximum excess 14C activity recorded in terrestrial biota was 44 Bq kg−1C (19 pMC). About 75 % of the samples exhibited specific activity in the range 228–249 Bq kg−1C (101–110 pMC). Statistical tests on the 14C specific activity dataset for 2.3–5, 5–10, and 10–20 km radial zones confirmed that the impact of the operation of the NPP on the environment beyond 5 km is minimal. The study suggests that the 14C activity released through gaseous effluents from Kaiga NPP is transported to greater distances along the axis of the valley than that predicted by the Gaussian plume model and those reported for other NPP sites worldwide. This is due to the unique topography of the Kaiga valley in which wind flow channelling, strong winds in the valley mouth, and calm wind within the valley due to the blocking effect by hills for the south-westerly wind regime play dominant roles in the transport of gaseous effluents. The 14C specific activity values at upwind monitoring stations located at >5 km distance from the NPP during the south-westerly wind regime were higher than those observed during the north-easterly wind regime when the same monitoring stations were located on the downwind side. The ingestion dose to the population in the 2.3–5 km radius zone, attributable to the release of 14C from the NPP, was 0.75 μSv y−1. This is a negligibly small fraction of the ICRP recommended dose limit of 1000 μSv y−1 for the public from other than natural sources. The dose due to the natural 14C activity in the Kaiga region was 12 µSv y-1, corresponding to the ambient natural activity of 230 Bq kg-1 C.
Display omitted
•First study on 14C in environmental matrices in the vicinity of an NPP in India.•Maximum excess 14C activity in the vicinity of NPP was 44 Bq kg−1C.•Wind channelling plays a dominant role in dispersion of gaseous effluents.•Ingestion dose to the population, attributable to the NPP, was 0.75 μSv y−1.
Thorium (232Th), long lived (14.05 billion years) most stable thorium isotope, is thrice naturally abundant than uranium. 232Th occurs as rocky deposits and black monazite sands on the earth's crust ...geographically distributed in coastal South India and other places globally. Monazite sand comprises of cerium and large quantities of radioactive thorium. The environmental hazard lies in monazite rich area being termed as High Background Radiation Area (HBRA). In this study, we mimicked the HBRA under controlled chamber conditions using thorium oxalate as a thorium source for BALB/c mice exposure. Furthermore, sequential radio-disintegration of 232 Th leads to thoron (220Rn), the noble gas and other daughter products/progeny predominantly via alpha decay/emissions. Such progeny tend to attach to aerosol and dust particles having potential inhalation hazard followed by alpha emissions and damages that we evaluated in mouse lung tissues post thoron inhalation. Secondly, along with the radio disintegration and alpha emission, high energy gamma is also generated that can travel to various distant organs through the systemic circulation, as significant findings of our study as damages to the liver and kidney. The mechanistic findings include the damages to the hematological, immunological and cellular antioxidant systems along with activation of canonical NF-κβ pathway via double stranded DNA damage.
Display omitted
•Thorium toxicity ascertained via inhaled thorium progeny deposition & organ damage.•Inhaled thorium progeny induced systemic, as well as, lung inflammation.•Highest progeny mean equivalent dose deposition was observed in lungs.•Progeny toxicity altered haematological, immunological & antioxidant machinery.•Oxidative stress induced double stranded DNA damage following activation of NF-κβ pathway.
Very high uranium concentrations of ⁓3000 μgL
−1
or more have been found in groundwater held in the granitic aquifers of four villages in eastern Karnataka, India. The highest uranium concentration ...was 8649 μgL
−1
(calculated 218.7 BqL
−1
) and a maximum radon activity of 101.4 BqL
−1
. The ingestion doses of uranium for males and females of all age groups are very much higher compared to the corresponding dose calculated for World Health Organization and Atomic Energy Regulatory Board recommended concentrations of 30 and 60 μgL
−1
for drinking water. It is therefore recommended that alternative sources for drinking water need to be made to meet United Nations Sustainable Development Goals 3 and 6 to ensure good health from safe drinking water.
Abstract
Elevated levels of natural background radiation due to scattered patches of monazite sand around the beaches of Mangalore, India, have been reported earlier. A comparative study of gamma ...dose rates was performed in both normal background and high natural background radiation areas around Mangalore using different types of portable gamma dosimeters. In addition to this, gamma-ray energy spectra were acquired, in situ, using a NaI(Tl) based portable gamma spectrometer. Soil and sand samples were collected for laboratory analysis with HPGe detectors. Measurements were carried out during the years 2016–18 revealed that in majority of the locations the gamma dose rates were similar to the normal background regions, whereas, in certain locations the dose rates were higher with values up to 530 nSv/h.
