Isotopic Composition of Glacier Ice and Meltwater in the Arid Parts of the Altai Mountains (Central Asia)

The objective of this study is to reveal the isotopic composition of ice and meltwater in glaciated regions of South-Eastern Altai. The paper depicts differences between the isotopic composition of glacier ice from several types of glaciers and from various locations. Detected differences between the isotopic composition of glacier ice in diversified parts of the study region are related to local climate patterns. Isotopic composition of meltwater and isotopic separation for glacier rivers runoff showed that in the Tavan-Bogd massif, seasonal snow participates more in the formation of glacier runoff due to better conditions for snow accumulation on the surface of glaciers. In other research areas pure glacier meltwater prevails in runoff.

Silver Isotopes in Silver Suggest Phoenician Innovation in Metal Production

The current study presents Ag isotopic values of 45 silver artifacts with known Pb isotopic composition from the Southern Levant. These items originate from seven pre-coinage silver hoards, dating from the Middle Bronze Age IIC to the end of the Iron Age (~1650–600 BCE). These are the earliest silver artifacts analyzed for Ag isotopes; all former studies were performed on coins. All the sampled silver in this study contains relatively unfractionated Ag (−2 ≤ ε109Ag ≤ 1.5) that was more likely produced from hypogene, primary Ag-bearing minerals (e.g., galena and jarosite) and not from native, supergene silver. Four of the sampled hoards containing silver from Anatolia and the West Mediterranean (Iberia and Sardinia) are associated with the Phoenician quest for silver (~950–700 BCE). A significant amount of this Phoenician silver (12/28 items) plots within a narrower range of −0.5 ≤ ε109Ag ≤ 0.5. This is in contrast to non-Phoenician silver, which mostly underwent some degree of fractionation (16/17 items ε109Ag ≥ I0.5I). The results suggest that while all silver was exploited from primary ore sources, the Phoenicians dug deeper into the deposits, reaching ore minerals that did not undergo any weathering-associated fractionation. The results also call for further investigation regarding the influence of sealing and bundling in silver hoards on post-depositional fractionation of Ag isotopes.

Phosphorus dynamics during early soil development in a cold desert: insights from oxygen isotopes in phosphate

At the early stages of pedogenesis, the dynamics of phosphorus (P) in soils are controlled by microbial communities, the physicochemical properties of the soil and the environmental conditions. While various microorganisms involved in carrying out biogeochemical processes have been identified, little is known about the actual contribution of microbial processes, such as organic P hydrolysis and microbial P turnover, to P cycling. We thus focused on processes driven by microbes and how they affect the size and cycling of organic and inorganic soil P pools along a soil chronosequence in the Chamser Kangri glacier forefield (Western Himalayas). The rapid retreat of the glacier allowed us to study the early stages of soil formation under a cold arid climate. Biological P transformations were studied with the help of the isotopic composition of oxygen (O) in phosphate (δ18OP) coupled to sequential P fractionation performed on soil samples (0–5 cm depth) from four sites of different age spanning 0 to 100–150 years. The P bound to Ca, i.e., 1 M HCl-extractable P, still represented 95 % of the total P stock after approximately 100 years of soil development. Its isotopic composition was similar to the parent material at the most developed site. Primary phosphate minerals, possibly apatite, mostly comprised this pool. The δ18OP of the available P and the NaOH-extractable inorganic P instead differed from that of the parent material, suggesting that these pools underwent biological turnover. The δ18OP of the available P was mostly controlled by the microbial P, suggesting fast exchanges occurred between these two pools possibly fostered by repeated freezing–thawing and drying–rewetting cycles. The release of P from organic P becomes increasingly important with soil age, constituting one-third of the P flux to available P at the oldest site. Accordingly, the lighter isotopic composition of the P bound to Fe and Al oxides at the oldest site indicated that this pool contained phosphate released by organic P mineralization. Compared to previous studies on early pedogenesis under alpine or cold climate, our findings suggest a much slower decrease of the P-bearing primary minerals during the first 100 years of soil development under extreme conditions. However, they provide evidence that, by driving short-term P dynamics, microbes play an important role in controlling the redistribution of primary P into inorganic and organic soil P pools.

A new local meteoric water line for Inuvik (NT, Canada)

The paper presents a new local meteoric water line (LMWL) of stable oxygen and hydrogen isotopes in precipitation from Inuvik in the western Canadian Arctic. Data were obtained over 37 months between August 2015 and August 2018 resulting in 134 measurements of the isotopic composition of both types of precipitation, snow and rain. For 33 months of the sampling period each month is represented at least two times from different years. The new LMWL from Inuvik is characterized by a slope of 7.39 and an intercept of −6.70 and fills a data gap in the western Arctic, where isotopic composition data of precipitation are scarce and stem predominantly from before the year 1990. Regional studies of meteorology, hydrology, environmental geochemistry and paleoclimate will likely benefit from the new Inuvik LMWL. Data are available on the PANGAEA repository under https://doi.org/10.1594/PANGAEA.935027 (Fritz et al., 2021).

Factors Influencing Changes of the Initial Stable Water Isotopes Composition in the Seasonal Snowpack of the South of Western Siberia, Russia

Stable water isotopes in snowpack and snowfalls are widely used for understanding hydrological processes occurring in the seasonally snow-covered territories. The present study examines the main factors influencing changes of the initial stable water isotopes composition in the seasonal snow cover of the south of Western Siberia. Studies of the isotopic composition of snow precipitation and snow cover, as well as experiments with them, were carried out during two cold seasons of 2019–2021, and laser spectroscopy PICARRO L2130-i (WS-CRDS) was used for the determination of water isotope composition (δ18O and δD). The main changes in the isotopic composition of the snow cover layers in the studied region are associated with the existence of a vertical temperature gradient between the layers and with the penetration of soil moisture into the bottom layers in the absence of soil freezing. During the winter period, the sublimation from the top layer of snow is observed only at the moments of a sharp increase in the daily air temperature. At the end of winter, the contrast between day and night air temperatures determines the direction of the shift in the isotopic composition of the top layer of snow relative to the initial snow precipitation.

SPECIFIC FEATURES OF APPLICATION OF CADMIUM AS A NEUTRON-ABSORBING SCREEN WHILE DOPING SILICON IN A NUCLEAR REACTOR

The gradient of the neutron field in a nuclear reactor and the requirements for the permissible spread of the specific electrical resistance over the volume of the silicon ingot makes it necessary to develop an irradiation device. This is especially true for large silicon ingots. One of the options for reducing the gradient of the neutron flux along the height of the ingot is the use of neutron-absorbing screens in the design of the irradiation device. At the WWR-K reactor, cadmium with a natural isotopic composition is used as a neutron-absorbing screen material. The paper presents the results of a study of an irradiation device with a cadmium screen. The effect of a cadmium screen on the neutron-physical characteristics of an irradiation device for silicon doping is shown.

Reconstructed Paleodiets and Subsistence Strategies of the Central Ciscaucasian Population (1000 BC to 1000 AD), Based on Collagen Isotope Analysis of Bone Samples from the Kichmalka II Burial Ground

Settlement and economy patterns of the Iron Age and early medieval population of the Central North Caucasus evidence complex cultural processes in the region. The ecological approach including the evaluation of carbon and nitrogen isotopes in the local biota opens up new prospects in the study of environments, climate, anthropogenic effect, land use, and nutrition. We analyze the isotopic composition of collagen in 19 human and 11 animal bone samples from Kichmalka II—a cemetery successively used by the Koban people, those of the Sarmatian stage, and Alans. The isotopic composition of the Alanian sample indicates a heavy predominance of plants with the C3-type photosynthesis in the diet of humans and animals. People who lived during the Koban and Sarmatian stages consumed also C4-plants, such as common millet (Panicum miliaceum), suggesting the rise of the trophic step for carbon (Δδ13Chuman-animal). Statistically signifi cant differences in the isotopic composition of carbon were found within the Koban population, apparently evidencing two dietary models. The Δδ15Nhuman-animal values fall within the trophic step, mirroring a focus on meat and dairy products in the diet of all groups. Comparison with respective data on the Klin-Yar III cemetery revealed differences in isotopic signatures in the diet of both humans and domestic animals during the Koban period. The possible reason is climatic change in the Iron Age and the variable share of millet in the diet of the Koban people. The low proportion of δ15N (below 4 ‰) in the bone collagen of goat, sheep, and horse of the Alanian period may attest to vertical transhumance.

Identification of Two-Dimensional Copper Signatures in Human Blood for Bladder Cancer with Machine Learning

Currently, almost all available cancer biomarkers are based on concentrations of compounds, often suffering from low sensitivity, poor specificity, and false positive or negative results. Stable isotopic composition of elements...