Measurements of background radiation levels around Indian station Bharati, during 33rd Indian Scientific Expedition to Antarctica

Investigations on baseline levels for natural radioactivity in soils, rocks, and lakes of Larsemann Hills in East Antarctica

A comprehensive measurement of concentrations of the natural radionuclides ²³⁸U, ²³²Th and ⁴⁰K, and ²²⁶Ra in the soil and rocks along with natural uranium and tritium activity levels in lake water were carried out during the Indian expedition to Antarctica. The samples were collected from the Larsemann Hills region in Antarctica (latitude 69°20' S to 69°25'S, longitude 76°6' E to 76°23'E). The data on the natural radioactivity for this region is limited. The study was carried out to establish baseline levels of radioactivity in different terrestrial matrices of this region such as soil, rocks, and lake water. A radiation survey mapping for terrestrial radioactivity was conducted in the region before collection of soil and rock samples. The soil and rock samples were analyzed for natural radioactivity concentrations using high-resolution gamma spectroscopy system. The major contributor to elevated gamma radiation background is attributed to the higher concentration of ²³²Th and ⁴⁰K radionuclides in both soil and rocks. Terrestrial components of gamma dose rate due to natural radioactivity have been estimated from the measured radioactivity concentrations and dose conversion coefficients. Several "hotspots" and high background areas in the region have been identified having significantly higher concentration of ²³²Th and ⁴⁰K. Rocks in Larsemann Hills region showed high reserve of thorium mineralization in monazites and ⁴⁰K in K-feldspar. The concentrations of ²³²Th in soil are found to be in the range of 106-603 Bq/kg, whereas in rock it is in the range of 8-4514 Bq/kg. Natural radioactivity U (nat) and ³H contents in the lake water samples in Larsemann Hills region were estimated as 0.4 and 1.3 Bq/L and are well within the prescribed limit of radioactivity in drinking water as recommended by World Health Organization.

Improvement in resilience and stress-related blood markers following ten months yoga practice in Antarctica

BACKGROUND

Wintering is associated with distress to humans who work in the isolated and confined environment of Antarctica and yoga has been proved helpful for coping with stress. Therefore, a study was conducted on 14 winter expedition members of Indian Scientific Antarctic Expedition (2016) to find out the effects of yoga on stress-related markers.

METHODS

Participants were divided into yoga, and control (non-yoga) groups. The yoga group practiced yoga for 10 months (from January to October 2016) daily in the morning for an hour. The Resilience test questionnaire was administrated at baseline and endpoint of the study. Blood samples were collected during the study at different intervals for the estimation of 8-hydroxydeoxyguanosine (8-OHdG), brain-derived neurotrophic factor (BDNF), serotonin and cortisol using ELISA.

RESULTS

A trend of improvement was observed in the resilience test score in the yoga group. From January to October, 8-OHdG serum values in the yoga group declined by 55.9% from 1010.0 ± 67.8 pg/mL to 445.6 ± 60.5 pg/mL (Mean ± SD); in the control group, the decline was 49.9% from 1060.4 ± 54.6 pg/mL to 531.1 ± 81.8 pg/mL. In serotonin serum levels in the yoga group, there was a 3.1% increase from 6.4 ± 1.6 ng/mL to 6.6 ± 0.4 ng/mL while no increase was noticed in the control group. Cortisol values in the yoga group decreased by 19.9% from 321.0 ± 189.6 ng/mL to 257.1 ± 133.8 ng/mL; in the control group it increased by 2.8% from 241.2 ± 51.8 ng/mL to 247.8 ± 90.9 ng/mL.

CONCLUSIONS

It could be concluded from the present study that following 10 months yoga practice may be useful for better resilience and management of stress-related blood markers for the polar sojourners.

Investigation of 220Rn emanation and exhalation from soil samples of Larsemann Hills region, Antarctica

In the present study, thoron exhalation flux density were measured in the soil samples collected around the Indian station namely Bharati (69° 24.41' S, 76° 11.72' E) and its nearby islands in the Larsemann hills region of Antarctica. Further, dependency of thoron mass emanation rate and emanation coefficient on the soil grain size was studied by segregating the soil samples into four different grain size groups: 50-100 μm, 100-200 μm, 200-500 μm and 500-1000 μm which showed that both of them follow a decreasing trend with increase in grain size. A comparison of measured mass emanation rate between different soil samples showed that it had a larger variation for the smaller grain size which eventually decreased as grain size increased while emanation coefficient was observed to be nearly constant for all the grain size groups. The variation in emanation coefficient with respect to mean grain size has been investigated and an empirical exponential model has been proposed for predicting emanation coefficient for different grain sizes.

Dosimetry of indigenously developed 177Lu patch source for surface brachytherapy-Experimental and Monte Carlo methods

This paper describes the evaluation of dosimetry characteristics of an in-house developed ¹⁷⁷Lu skin patch source for treatment of non-melanoma skin cancer. A ¹⁷⁷Lu skin patch source based on Nafion-115 membrane backbone containing 3.46 ± 0.01 mCi of activity was used. Activity measurement of the patch source was based on gamma ray spectrometry using a HPGe detector. The efficiencies of the HPGe detector were fitted using an orthogonal polynomial function. The absorbed dose rate to water at 5 μm depth in water was determined using an extrapolation chamber, EBT3 Gafchromic film and compared with Monte Carlo methods. The correction factors such as Bragg-Gray stopping power ratio of water-to-air and chamber wall material being different from water, needed to be applied on measurements for establishing the dose rate at 5 μm depth, were calculated using the Monte Carlo method. Absorbed dose rate at 5 μm depth in water (surface dose rate) measured using an extrapolation chamber and EBT3 Gafchromic film were 9.9 ± 0.7 and 8.2 ± 0.1 Gy h^-1 mCi^-1 respectively for the source activity of 3.46 ± 0.01 mCi. The surface dose rate calculated using the Monte Carlo method was 8.7 ± 0.2 Gy h^-1 mCi^-1, which agrees reasonably well with measurement. The measured dose rate per mCi offers scope for ascertaining treatment time required to deliver the dose for propitious therapeutic outcome. Additionally, on-axis depth dose and lateral dose profiles at 5 μm and 1 mm depth in water phantom were also calculated using the Monte Carlo method.

RADIOACTIVITY MEASUREMENT AND RADIOLOGICAL HAZARD ASSESSMENT OF THE COMMONLY USED GRANITE AND MARBLE IN JORDAN

Natural radioactivity of common commercial marble and granite types used in Jordanian dwellings are measured using high-resolution gamma spectrometry. The activity concentrations of 226Ra, 232Th and 40K ranged from 8.57 ± 1.55 to 152.07 ± 3.26 Bq kg-1, 6.83 ± 1.25 to 365.43 ± 4.84 Bq kg-1 and 121.25 ± 9.10 to 1604.90 ± 31.28 Bq kg-1 in granite and from 0.53 ± 0.12 to 18.61 ± 1.60 Bq kg-1, 0.51 ± 0.19 to 4.87 ± 2.13 Bq kg-1 and 3.21 ± 0.96 to 58.09 ± 6.40 Bq kg-1 in marble, respectively. Various radiological hazard indices like gamma index, internal and external hazard indices and annual effective dose equivalent were calculated and compared with the international limits. Our results show that some granite types may pose a radiation hazard.