Assessing the present levels of 137Cs in the remote ecosystem of Bjornoya (South Svalbard).

The remoteness and small size of Bjornoya (S Svalbard) make the island one of the most unreachable places in the Arctic. Limited accessibility contributes to still-existing knowledge gap on isotope accumulation in compartments of its ecosystem. Therefore, in this study we aimed to investigate the current concentration of 137Cs in the terrestrial samples of vascular plants, cryptogams, and soil collected on Bjornoya in 2021. The measured average activity of 137Cs in bryophytes was 56.5 Bq kg-1, lichens 27.6 Bq kg-1, vascular plants 7.26 Bq kg-1, and soil 9.63 Bq kg-1. In the case of bryophytes, 137Cs activity was negatively correlated with δ15N. Our results suggest that bird guano was the main source of nitrogen and 137Cs for vascular plants. For bryophytes, significantly lower values of δ15N than in vascular plants suggests that this group is more sensitive to atmospheric N intake, with fallout being the main source of 137Cs.

Distribution of 137Cs in the marine environment from King George Island (Southern Shetlands, maritime Antarctica).

The article presents data on the activity of the radionuclide 137Cs in seawater, sediment, macroalgae, and zoobenthos from different locations in Admiralty Bay, King George Island, maritime Antarctica. The activity of 137Cs in the macrophytobenthos remained relatively stable across species, oscillating at the level of 1 Bq kg-1dw. However, a few individuals exhibited higher activity, particularly at stations closer to the glacier front. This result could have been caused by specific conditions resulting from melting glaciers and meltwater inflow and mixing with oceanic water. The activities of 137Cs in zoobenthic were in the range from 0.12 Bq kg-1dw (Asteroidea) to 24.2 Bq kg-1dw (Porifera) and the total doses in marine species were several orders of magnitude lower than reference levels. Stable isotopes of δ13C and δ15N suggest that the main factor influencing 137Cs activity may be the source of carbon (marine vs. terrestrial/glacial), rather than feeding strategy or trophic niches.

Computational Investigations of Position-Specific Vapor Pressure Isotope Effects in Ethanol-Toward More Powerful Isotope Models for Food Forensics.

With the advent of new experimental techniques, measurements of individual, per-position, vapor pressure isotope effects (VPIEs) became possible. Frequently, they are in opposite directions (larger and smaller than unity), leading to the cancellation when only bulk values are determined. This progress has not been yet paralleled by the theoretical description of phase change processes that would allow for computational prediction of the values of these isotope effects. Herein, we present the first computational protocol that allowed us to predict carbon VPIEs for ethanol-the molecule of great importance in authentication protocols that rely on the precise information about position-specific isotopic composition. Only the model comprising explicit treatment of the surrounding first-shell molecules provided good agreement with the measured values of isotope effects. Additionally, we find that the internal vibrations of molecules of the model to predict isotope effects work better than the entire set of normal modes of the system.

The influence of experimental parameters on quantitative deuterium measurements for ethyl alcohols of different origin.

BACKGROUND: Quantitative determination with site-specific natural isotope fractionation nuclear magnetic resonance (SNIF-NMR) has been exploited widely in detecting adulteration and for the classification of natural products by their geographical origin. RESULTS: We compared isotopic parameters such as deuterium / hydrogen (D/H) site specific ratios and the R parameter for alcoholic beverages, obtained using (i) a 500 MHz spectrometer equipped with a dedicated probe for isotopic measurements, and (ii) a 700 MHz spectrometer equipped with a standard probe. The factors affecting the accuracy and precision of quantitative NMR with the second instrument have been explored. CONCLUSIONS: It has been demonstrated that, in laboratories with a spectrometer that is not equipped with a specific deuterium probe, the selection of the appropriate experimental parameters enables measurements with a similar precision and accuracy as in the case of the official method adopted by the International Organisation of Vine and Wine. © 2019 Society of Chemical Industry.

Comparison of quantitative NMR and IRMS for the authentication of 'Polish Vodka'.

BACKGROUND: The production of 'Polish Vodka' is restricted by law to the ethyl alcohol of agricultural origins obtained from rye, wheat, barley, oat, triticale and potatoes grown on the territory of the Republic of Poland. The current labeling system should guarantee that the spirit is authentic and of good quality but not all producers are honest. Unfortunately, authentic 'Polish Vodka' is the most often counterfeited by the addition of cheaper and more accessible maize spirits. These illegal practices significantly reduce costs of the spirit production. Therefore, determination of the botanical origin of alcohol in Poland is highly relevant. RESULTS: Quantitative 2 H nuclear magnetic resonance and isotope ratio mass spectrometry were used to investigate the authenticity of 30 samples of Polish spirits. Several isotopic parameters were used to determine the botanical origin of 10 unknown samples. Both approaches led to the same conclusions regarding the percentage of maize-derived ethanol addition. CONCLUSIONS: Applied techniques are a valuable tool in the fight against counterfeiting of products. © 2018 Society of Chemical Industry.

Resolving Discrepancy between Theory and Experiment in 4-Nitrotoluene Oxidation.

We have performed calculations of possible oxidation pathways of 4-nitrotoluene (4NT) by permanganate anion and evaluated relative contributions of oxidation of the methyl group and aromatic ring. Although a few theory levels matched the experimental results obtained by compound specific isotope analysis (CSIA) for 4NT, they failed in reproducing results for other nitrotoluene derivatives studied previously [Wijker, R.S.; Adamczyk, P.; Bolotin, J.; Paneth, P.; Hofstetter, T.B. Environ. Sci. Technol., 2013, 47, 13459-13468]. This discrepancy prompted us to reevaluate the experimental isotopic fractionation of carbon and hydrogen for 4NT on which the relative contributions of the oxidation channels has been based. Using position specific isotope analysis (PSIA) for hydrogen isotopic fractionation we have found that the previously determined value was incorrect. Reexamination of theory levels that are in agreement with these new findings indicated that while a better agreement for this particular case can be reached, overall, the previously used B3LYP functional expressed in the 6-31+G(d,p) basis set with inclusion of the polarized continuum model (PCM) of aqueous solution remains the theoretical level of choice in modeling oxidation of nitrotoluene derivatives by permanganate.