Improvements of 210Po determination method in thermal water samples

Determination of naturally radionuclides have been known well as an important topic in environmental study in recently. One of the most toxic radioisotope in nature, a daughter product of 238U decay chain is 210Po (polonium). The improvement and optimizations methods for determination of this attractive isotope are still presenting so far. In this paper, a new improved method was elaborated for 210Po determination in thermal water sample. In the proposed method, analytical optimization of spontaneous/auto deposition does not use Teflon cup, magnetic stirring or any preparing equipment/item only normal glass and a side of square silver. In addition, the optimization was neglected with absent of purification of polonium (Liquid-liquid extraction methods/Ion exchange chromatography/Extraction chromatographic separations). The outcome of optimal procedure were simplify, less time consuming, great reduction of costs with chemical recovery >80% and could apply for any liquid environmental samples.

Tracking Recent DDT Contamination in a Northern New England Watershed

Ecological research since 2005 into potential causes of declines in loon population at Squam Lake, New Hampshire, U.S.A., revealed multiple potential causes, but no particular source of contaminants. In 2017, tributary sediment analyses revealed specific sub-watersheds transporting contaminants to the lake (Vogel, 2019). For this study, from 2018 to 2020, we used an approach to this problem that allowed for rapid source area determination of DDT using soil and sediment analyses. We find modern presence of p,p’ isomers of DDT and DDE within the Bennett Brook sub-watershed, arising from 60-year-old orchard applications and a former barn. Highest concentrations, 723 μg/kg p,p’ DDT and 721 μg/kg p,p’ DDE, occur near the barn’s foundation rubble. DDT exceeds that of the daughter product, DDE, in some of the sub-watershed’s soils, including but not limited to the barn site. In the soils where DDT>DDE, we infer delayed breakdown of DDT. DDT<DDE occurs in the streambed and lake deposits, as well as some soils. A Pb-210 dated sediment core, collected near the outlet of Bennet Brook, shows continuous accumulation of the daughter products, DDE and DDD, from 1951 to the present. Residuals are derived from multiple sources within the sub-watershed, including orchard soils, the barn site, and sediment accumulations in the stream. These DDT residues fall below mandatory soil remediation levels for the State of New Hampshire, but exceed some sediment quality guidelines for protection of aquatic life. Bioaccumulation of p,p’ DDE is evident in crayfish that reside in Bennett Brook.

Academic Reminiscences and Thermodynamics-Kinetics of Thermo-Barometry-Chronology

This article has three major components that include, in addition to the technical aspects, reminiscences of my academic upbringing, my move to the USA from India, and my professional career. I have recounted many stories that I hope convey some sense of time, especially in these two countries with vastly different cultures, my personal journey with its ups and downs and how I made the transition to an academic career path in USA even though that was not in my future plan as a young man. The development of the field of thermobarometry and its integration with diffusion and crystal kinetic modelling of compositional zoning (or lack thereof) and cation ordering in minerals have led to important quantitative constraints on the pressure-temperature-time evolution of terrestrial rocks and meteorites. I review the historical developments in these areas and a segment of my own research spanning the period of 1964-2021. The foundational works of the thermometry of metamorphic rocks and palaeothermometry were laid at the University of Chicago around 1950. Subsequently, the synergetic growth of thermodynamics and experimental studies in petrology in the 1960s and 1970s, along with the introduction of electron microprobe as a nondestructive analytical tool with micron scale resolution, gave a major boost to the field of thermobarometry. There were also significant new developments in the field of thermodynamics of solid solutions in the petrology community and demonstration from observational data, countering strong scepticism, that the principles of classical thermodynamics were applicable to “complex natural systems”. The section on thermodynamic basis of thermobarometry concludes with a discussion of the thermodynamics of trace element and single mineral thermometry. I further deal with the experimental protocols, along with selected examples, for phase equilibrium studies that provide the bedrock foundation for the field of thermobarometry based on elemental compositions of coexisting minerals in a rock. It is followed by an account of the controversies and international meetings relating to the aluminum silicate and peridotite phase diagrams that play crucial roles in the thermobarometry of metamorphic rocks and mantle xenoliths, respectively. The construction of quantitative petrogenetic grids to display stability relations of minerals in multicomponent–multiphase systems came into play in the field of metamorphic petrology in the mid-1960s and early 1970s. Augmented by experimental data, these petrogenetic grids led to important discoveries about the P-T-<em>f</em>(O₂) and bulk compositional controls on the stability of certain “index” minerals that are used to define metamorphic isograds and different types of regional metamorphism; one such grid also opened up a new field that came to be known as ultra-high temperature metamorphism. The construction of petrogenetic grids has now evolved to computer based calculations of complex equilibrium P-T phase diagrams, commonly referred to as “pseudosections”, by minimisation of Gibbs free energy of a system with fixed bulk composition. I discuss these historical developments and modern advancements. Subsequently I highlight some aspects of thermobarometry and diffusion kinetic modelling of selected natural samples along with their broader implications and present a critical discussion of different protocols for thermobarometry of natural assemblages. Following up on the introductory historical perspective of development of palaeothermometry, I discuss the modern advancements using density functional theory (DFT). Examples of DFT based calculations have been shown for hydrogen isotope fractionation in mineral-water/hydrogen systems and “clumped isotope” thermometry. The hydrogen isotope fractionation data led the development of new low temperature palaeothermometers using serpentine-talc/brucite mineral pairs. These results enable simultaneous solutions of both temperature and source of fluid in the serpentinisation process of rocks. The final section is devoted to high temperature thermochronology dealing with the problems of closure temperature of decay systems in minerals and the use of bulk and spatial resetting of mineral age according to a specific decay system to determine cooling rates of the host rocks. Complications arise in the interpretation of mineral ages determined by such decay systems as ¹⁷⁶Lu-¹⁷⁶Hf or the short- lived system ⁵³Mn-⁵³Cr in which the parent nuclide has a much lower closure temperature than the corresponding daughter product. Numerical simulations help explain the discrepancy between the ¹⁷⁶Lu-¹⁷⁶Hf and ¹⁴⁷Sm-¹⁴³Nd ages of garnets in metamorphic rocks and enable construction of the entire T-t cycle from the discrepant ages and some additional constraints.

Temporal Variability of Bismuth-214 Activity Concentration in the Atmospheric Surface Layer of Sevastopol Region

The article presents the results of monitoring of bismuth-214 activity concentration in atmospheric aerosols in the atmospheric surface layer of the Sevastopol region in 2007– 2020. Bismuth-214 is a daughter product of the decay of radon-222. It is one of the main radionuclides that form the natural gamma background of the surface atmosphere. The aim of this work is to obtain quantitative characteristics of the temporal variability of the concentration of bismuth-214 in the atmospheric surface layer of the Sevastopol region and to estimate the annual effective dose due to outdoor radon-222 exposure. During the study period, 2701 aerosol samples were taken and processed. Measurements of the activity of bismuth-214 in atmospheric aerosol samples were performed using a lowbackground gamma-spectrometer with a NaI (Tl) scintillation detector. The concentration of the radionuclide in individual samples varied from 0.1 to 11.4 Bq m –3 , the average value was 2.7 ± 1.5 Bq m –3 . There is periodicity of 29, 66, 110 days and 1 year in the temporal variability of the activity concentration of bismuth-214. Higher values of bismuth-214 activity concentration are typical for the period from July to October (3.1– 3.5 Bq m –3 ), lower values are typical for the period from December to April (2.1– 2.2 Bq m –3 ). It is shown that the seasonal variation in the origin of atmospheric aerosol in the region under study can be the factor determining the change in the seasonal cycle of bismuth-214 concentration in comparison with the expected cycle of radon-222. In the last year of observations, there is an increase in the concentration of bismuth-214 by an average of 22% compared with the average long-term value of its concentration and a change in its annual cycle, which is probably associated with construction work carried out in the central part of the city. Quantitative estimates of the effective dose due to outdoor radon-222 exposure have been obtained.

Behaviour of Tritium and Tritiogenic Helium in Freshwater Lens Groundwater Systems: Insights from Langeoog Island, Germany

Tritium (3H) and its daughter product 3He have been widely used as tracers in hydrological studies, but quantitative analyses of their behaviour in freshwater lenses and the transition zone in coastal aquifers are presently lacking. In this paper, the fate of 3H and 3He in the freshwater lens and the transition zone as well as the saltwater wedge is studied using numerical variable-density flow and transport models of different degrees of complexity. The models are based on the conditions on the German island of Langeoog, which is uniquely suited for this purpose because of the high 3H concentration of the North Sea. It is found that most bomb-related tritiogenic 3He still resides in the freshwater lens, making it a useful tracer for young (<60 years) groundwater. Differences in dispersive transport between 3H and 3He can cause an apparent age bias on the order of 10 years. Under favourable conditions, 3H from seawater can penetrate deep into the offshore part of the aquifer and has potential to be used as a tracer to study saltwater circulation patterns. Our modelling suggests that the field-observed 3H in the transition zone does not originate from seawater but from freshwater affected by the bomb peak. Yet in models with a low (αL=0.5 m) dispersivity, no 3H was sequestered into the transition zone and the transition zone width was underestimated. Better results were obtained with αL=5 m, a value that is higher than in comparable modelling studies, which suggests that further work is needed to better understand the controls (tides, lithological heterogeneity, or transience of recharge and pumping) on transition zone mixing processes.

Photoenhanced transformation of hydroxylated fullerene (fullerol) by free chlorine in water

Water-soluble, oxidized fullerenes, termed as fullerols or fullerenols, have gained increasing attention as they have been identified as primary daughter product(s) when C60 is exposed to ubiquitous, reactive (oxidative) environmental scenarios including UV light (including sunlight UVA), radical oxygen species (ROS), and ozone.