Uranium record from a 3 m snow pit at Dome Argus, East 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.

Assessment of heavy metal contamination in the atmospheric deposition during 1950-2016 A.D. from a snow pit at Dome A, East Antarctica

Antarctic trace element records could provide important insights into the impact of human activities on the environment over the past few centuries. In this study, we investigated the atmospheric concentrations of 14 representative heavy metals (Al, As, Cd, Co, Cu, Fe, K, Mg, Mn, Pb, Sb, Sr, Tl and V) from 174 samples collected in a 4-m snow pit at Dome Argus (Dome A) on the East Antarctic Plateau, covering the period from 1950 to 2016 A.D. We found great variability in the annual concentration of all metals. The crustal enrichment factors suggest that the concentrations of some heavy metals (Cd, Sb, Cu, As and Pb) were likely influenced by anthropogenic activities in recent decades. An analysis of source regions suggests that heavy metal pollution at Dome A was largely caused by human activities in Australia and South America (e.g. mining production, leaded gasoline). Based on the relationship between the trace elements fluxes and sea ice concentration (SIC), sea surface temperature (SST) and annual mean air temperature at 2 m above the ground (T_2m), our analysis shows that deposition and transport of atmospheric aerosol at Dome A were influenced by circum-Antarctic atmospheric circulations.