The isotopic signature of the “arthropod rain” in a temperate forest

Forest canopy is densely populated by phyto-, sapro-, and microbiphages, as well as predators and parasitoids. Eventually, many of crown inhabitants fall down, forming so-called ‘arthropod rain’. Although arthropod rain can be an important food source for litter-dwelling predators and saprophages, its origin and composition remains unexplored. We measured stable isotope composition of the arthropod rain in a temperate mixed forest throughout the growing season. Invertebrates forming arthropod rain were on average depleted in 13C and 15N by 1.6‰ and 2.7‰, respectively, compared to the soil-dwelling animals. This difference can be used to detect the contribution of the arthropod rain to detrital food webs. Low average δ13C and δ15N values of the arthropod rain were primarily driven by the presence of wingless microhytophages, represented mainly by Collembola and Psocoptera, and macrophytophages, mainly aphids, caterpillars, and heteropterans. Winged arthropods were enriched in heavy isotopes relative to wingless specimens, being similar in the isotopic composition to soil-dwelling invertebrates. Moreover, there was no consistent difference in δ13C and δ15N values between saprophages and predators among winged insects, suggesting that winged insects in the arthropod rain represented a random assemblage of specimens originating in different biotopes, and are tightly linked to soil food webs.

Cave monitoring in Hungary: An overview

In this study, already published and new monitoring data are compiled from the Baradla and Béke caves in the Aggtelek Karst, from the Vacska Cave in the Pilis Mountains as well as from the Szemlőhegy and Pálvölgy caves in the Buda Hills. Recent investigations (2019–2020) include monitoring of climatological parameters (e.g., temperature, CO2) measured inside and outside the caves, and the chemical, trace element and stable isotopic compositions of drip waters. In the Baradla Cave, the main focus of the investigation was on the stable isotope composition and the temperature measurements of drip water. In the Vacska Cave, which belongs to the Ajándék-Ariadne cave system, CO2 measurements and drip water collection were conducted in order to perform chemical and stable isotope measurements. In the Szemlőhegy and Pálvölgy caves, the chemical and stable isotope compositions of drip waters at six sites were determined. These datasets were used to characterize the studied caves and the hydrological processes taking place in the karst, and to trace anthropogenic influences. Climatological investigation revealed seasonality in CO2 concentration related to outside temperature variation, indicating a variable ventilation regime in the caves. In addition, the contributions of the winter and summer precipitation to the drip water were also estimated, in order to evaluate the main infiltration period. The knowledge of these parameters plays a crucial role in constraining the carbonate precipitation within the cave. Thus, the dataset compiled in this study can provide a basis for the interpretation of speleothem-based proxies.

Storage Changes Stable Isotope Composition of Cucumbers

Vegetable food stuff produced under controlled and identical conditions from one farm of identical “age” (batch) has a similar isotopic composition. This fact can be used to control the origin of vegetables. This question is of special relevance when food-contaminations have to be traced back to the producer, or certain production claims have to be controlled. However, as vegetables are harvested, brought to whole-sale merchants and to retail shops, where they remain until being bought by the consumer, one has to consider possible changes in isotopic composition during this transfer period, when comparing vegetables of questioned origin with reference samples taken directly from the field/producer. We investigated changes in the isotope composition of vegetables during storage by studying as an example cucumbers from one batch. We stored the cucumbers in a vegetable storage under controlled conditions and removed one sample every day and analyzed its isotopic composition. We found changes in the δ15N and δ18O isotope values over the investigated period of 21 days, with both parameters showing positive linear correlations, and maximum enrichments with time of more than 1.5‰ for δ15N and more than 2‰ for δ18O. However, within the interval the samples remained in a saleable condition the isotope variations remained more or less within the variability of the sample batch. Our study demonstrates that changes in the isotopic signature in vegetables might occur after harvest during storage and have to be taken into account when (commercial) samples collected in a market are investigated.

Stable isotopes in global lakes integrate catchment and climatic controls on evaporation

Global warming is considered a major threat to Earth’s lakes water budgets and quality. However, flow regulation, over-exploitation, lack of hydrological data, and disparate evaluation methods hamper comparative global estimates of lake vulnerability to evaporation. We have analyzed the stable isotope composition of 1257 global lakes and we find that most lakes depend on precipitation and groundwater recharge subsequently altered by catchment and lake evaporation processes. Isotope mass-balance modeling shows that ca. 20% of water inflow in global lakes is lost through evaporation and ca. 10% of lakes in arid and temperate zones experience extreme evaporative losses >40 % of the total inflow. Precipitation amount, limnicity, wind speed, relative humidity, and solar radiation are predominant controls on lake isotope composition and evaporation, regardless of the climatic zone. The promotion of systematic global isotopic monitoring of Earth’s lakes provides a direct and comparative approach to detect the impacts of climatic and catchment-scale changes on water-balance and evaporation trends.

ON IMPACT OF THE BONE TYPE ON THE RESULTS OF PALEODIET RECONSTRUCTIONS ON THE BASIS OF THE STABLE ISOTOPE ANALYSIS

Анализ стабильных изотопов азота и углерода активно применяется в палеодиетических реконструкциях археологического материала. Однако на результаты изотопного исследования могут повлиять существующие отличия в соотношениях изотопов разных типов костей одного индивида, которые могут возникать из-за разницы в скорости ремоделирования (разрушение старой кости и образование новой) различных костей скелета. Данные отличия часто не учитываются при выборе образцов для проведения изотопного исследования. Таким образом, перед настоящей статьей ставятся следующие задачи. Во-первых, показать существование разницы в изотопных соотношениях костей скелета на основе материалов, представленных древнерусским сельским населением из могильника Шекшово 9 в Суздальском Ополье (X-XII вв.). И, во-вторых, предоставить основные рекомендации при отборе проб для изучения изотопного состава археологических материалов. В ходе исследования удалось установить, что при выборе образцов для проведения изотопного анализа следует отдавать предпочтения костям со схожей скоростью ремоделирования. The analysis of stable nitrogen and carbon isotopes is actively used in paleodiet reconstructions of archaeological materials. However, the results of the stable isotope study can be affected by differences in the isotope ratios of collagen in different types of bones of the same individual. This can arise due the different speed of remodeling (the process by which osteoclasts breakdown the tissue in bones and new bones form) of various bones in the skeleton. These differences are often disregarded when selecting samples for isotope studies. Therefore, this paper is intended to address the following tasks: (i) to show that there exists difference in the isotope ratios of the skeleton bones by analyzing human remnants of the Medieval Russia rural population from the Shekshovo-9 cemetery in Suzdal Opolye (10th-12th centuries); (ii) to provide basic recommendations for selecting samples for the studies of the stable isotope composition of archaeological materials. Our research evidences that. when selecting samples for the isotope analysis. preference should be given to the bones with similar remodeling speed.

Mercury abundance and isotopic composition indicate subaerial volcanism prior to the end-Archean “whiff” of oxygen

Earth’s early atmosphere witnessed multiple transient episodes of oxygenation before the Great Oxidation Event 2.4 billion years ago (Ga) [e.g., A. D. Anbar et al., Science 317, 1903–1906 (2007); M. C. Koehler, R. Buick, M. E. Barley, Precambrian Res. 320, 281–290 (2019)], but the triggers for these short-lived events are so far unknown. Here, we use mercury (Hg) abundance and stable isotope composition to investigate atmospheric evolution and its driving mechanisms across the well-studied “whiff” of O2 recorded in the ∼2.5-Ga Mt. McRae Shale from the Pilbara Craton in Western Australia [A. D. Anbar et al., Science 317, 1903–1906 (2007)]. Our data from the oxygenated interval show strong Hg enrichment paired with slightly negative ∆199Hg and near-zero ∆200Hg, suggestive of increased oxidative weathering. In contrast, slightly older beds, which were evidently deposited under an anoxic atmosphere in ferruginous waters [C. T. Reinhard, R. Raiswell, C. Scott, A. D. Anbar, T. W. Lyons, Science 326, 713–716 (2009)], show Hg enrichment coupled with positive ∆199Hg and slightly negative ∆200Hg values. This pattern is consistent with photochemical reactions associated with subaerial volcanism under intense UV radiation. Our results therefore suggest that the whiff of O2 was preceded by subaerial volcanism. The transient interval of O2 accumulation may thus have been triggered by diminished volcanic O2 sinks, followed by enhanced nutrient supply to the ocean from weathering of volcanic rocks causing increased biological productivity.

Isotope Analysis (13C, 18O) of Wine From Central and Eastern Europe and Argentina, 2008 and 2009 Vintages: Differentiation of Origin, Environmental Indications, and Variations Within Countries

In this study, we compare the stable isotope composition of oxygen and carbon of wines from four Central and Southeastern European countries and from Argentina to study the similarities and differences in the isotope signatures and, thus, the potential of differentiation of the various wine-growing countries. We observe similar trends for wines from Austria, Slovenia, and Romania with respect to the vintages 2008 and 2009, which are absent in the Montenegrin and Argentinean samples. It is speculated that the weather develops similarly for Austria, Slovenia, and Romania, as these countries are positioned at a similar latitude and not too far away from each other (general central and eastern European weather situation), whereas Montenegro is not influenced by the latter being situated farther south and dominantly influenced by the Adriatic Sea. Investigations on further vintages are needed to test this assumption.