Nawi Graz

Rock glaciers are key components of alpine hydrology, regulating groundwater flow and shaping catchment responses in permafrost-affected environments. While traditional models represent subsurface flow as diffuse through a porous matrix, field evidence increasingly demonstrates that channelized flow exerts a critical influence on groundwater dynamics. This review explores the hydrological processes governed by these channel networks, which enable rapid, turbulent water movement along distinct pathways. Observations of channels and hydraulically related features from 73 sites across mountain regions worldwide, viewed through a range of disciplinary perspectives, are synthesized into a unified conceptual framework. Building on this body of field evidence, we analyze the implications of channelized flow for groundwater movement, water quality, solute and heat transfer, permafrost degradation, and slope stability, advancing understanding of these interconnected processes. Our synthesis suggest that channels enhance water transport efficiency, accelerate permafrost thaw, and trigger debris flows and thermokarst lake outburst floods. The rapid transfer of suspended and dissolved matter makes downstream springs vulnerable to contamination and affects their suitability for water supply. Through integrating field observations, geophysical surveys, tracer experiments, borehole data, and ground temperatures, we reveal key processes governing water movement and its interconnected effects on heat, solutes, and permafrost structure in rock glaciers and related periglacial systems. We propose a novel conceptual model that integrates preferential flow paths into the framework of permafrost hydrology and identifies new directions for investigating hydrological processes in alpine aquifers. • Synthesis of cross-disciplinary data across mountain ranges reveals flow patterns. • Preferential flow paths control groundwater, solute transport, and permafrost thawing. • Concentrated flow drives rock glacier creep, slope failures, and sediment transport. • Heat and flow coupling in channels governs thermokarst lake outburst floods. • New conceptual model unifies hydraulic, thermal, chemical, and geomorphic impacts.

In situ garnet U-Pb geochronology by laser ablation-inductively coupled mass spectrometry (LA-ICPMS) is a powerful tool for rapid and high-spatial resolution dating of metamorphic pressure-temperature–time histories. Yet, the substitution of U and Pb into the structure of common pyralspite garnet and its influence on diffusion and potential age-resetting is poorly constrained. Studies by Mezger et al. (1989), Burton et al. (1995), and Dahl (1997) estimate U-Pb system closure temperatures in garnet of >800 °C. Similarly, Shu et al. (2024) proposed a closure temperature of >1100 °C but suggested that recrystallization may have reset some garnet U-Pb ages. However, there is little information on how dynamic processes, such as recrystallization, may impact the closure of the U-Pb system in garnet. Here we examine the impacts of garnet recrystallization on U-Pb ages by examining ultrahigh-temperature (UHT) crustal xenoliths from the southwestern USA and northern Mexico. These metapelitic granulites experienced isobaric heating at >900 °C between 36 and 30 Ma and UHT conditions were maintained until eruption at

There are two primary mechanisms for carbon transfer into the geological record within the ocean: the organic sink and the inorganic carbon sink. The inorganic carbon sink (i.e., the long-term preservation of carbonate minerals in the geologic record), in particular, is not well constrained. Over the past several years, theoretical and experimental work has significantly improved our understanding of the inorganic carbon cycle, particularly in the context of carbonate minerals. This work reviews the state-of-the-art of marine calcium carbonate production, dissolution, and accumulation, representing a comprehensive update on the works of Milliman (1993) and Smith and Mackenzie (2016). We combine updated estimates with recent advances in understanding the carbonic acid system and the global ocean carbon cycle. These processes are supplemented by organismal to ecosystem-level responses of calcifying organisms to future climate change, enabling estimates of future global marine carbonate budget development. Our synthesis offers a comprehensive perspective on the long-term balance of carbonate preservation under current boundary conditions and projected future climate scenarios.Present-day net global annual gross production of CaCO3 throughout all carbonate-producing ecosystems is estimated between 176.1*1012 mol yr-1 (= 17.61 Gt yr-1) and 437.1*1012 mol yr-1 (= 437.1 Gt yr-1). However, only 8 to 20% of CaCO3 sediment is preserved each year, according to literature data. This leads to ~35*1012 mol yr-1 (= 3.5 Gt yr-1) of CaCO3 accumulation per year. Today, nearly all CaCO3 production is estimated to be biologically mediated or biologically controlled, while contributions from abiogenic carbonates are assumed to be minor. Dissolution of CaCO3 in the marine realm buffers excess CO2 from organic matter oxidation in the water column and sediment. The carbonate buffer effect within the carbonic acid system is expected to decline in future climate change scenarios, likely leading to more intense carbonate dissolution.Anthropogenic climate change, including excess CO2 in surface oceans, is further proposed to impact the CaCO3 production capabilities of all CaCO3-producing ecosystems in the ocean by affecting the diversity, abundance, and calcification potential of organisms. Predicting the future development of CaCO3 accumulation in the oceans is an evolving process. With the currently available data, estimating future CaCO3 accumulation is challenging due to multiple unknowns regarding disruptions and adaptations of the producers. The herein-reviewed data suggest that the global net CaCO3 accumulation will decrease by over 50 % to 19*1012 mol yr-1 (= 1.90 Gt yr-1) by 2050 AD, and further to 10.3*1012 mol yr-1 (= 1.03 Gt yr-1) by 2100 AD based on a “business as usual” CO2 emission model. ReferencesMilliman, J. D.: Production and accumulation of calcium carbonate in the ocean: Budget of a nonsteady state, Global Biogeochem Cy, 7, 927–957, https://doi.org/10.1029/93gb02524, 1993.Smith, S. V. and Mackenzie, F. T.: The Role of CaCO3 Reactions in the Contemporary Oceanic CO2 Cycle, Aquat Geochem, 22, 153–175, https://doi.org/10.1007/s10498-015-9282-y, 2016.

Monazite U–Th–Pb ages are commonly coupled with Y and heavy rare earth element (HREE) contents to link reactions, particularly those involving the formation and breakdown of garnet, with pressure–temperature (P–T) paths to constrain and uncover orogenic processes. This link assumes that changes in garnet modal abundances reflect changes in P–T and no other processes. Here we show that protracted and cryptic fluid-driven dissolution-reprecipitation of garnet and monazite disturbed the P–T–time(t) relationship between these two minerals.We collected samples of metapelitic schists from the Yardoi gneiss dome, southern Tibet. The central portion of the Yardoi dome comprises orthogneiss and metapelites intruded by Eocene (43–35 Ma) to Miocene (17 Ma) granitoids, providing a critical window investigate fluid–rock interaction in mid-crustal metamorphic rocks. Our data constrain prograde to peak metamorphism from 5.7 kbar and 550°C to 7.5–8.5 kbar and 650–750 °C, followed by retrograde metamorphism at 5.5–6.5 kbar and 650–700°C. Low Y+HREE monazite domains dated to 41–46 Ma indicate peak metamorphism in the presence of garnet at this time, whereas high Y+HREE contents between 23 and 15 Ma indicate the timing of garnet breakdown during isothermal decompression. These data indicate 20–30 Myr at 650–700°C, consistent with near complete resetting of garnet major element zoning in most samples.One sample near the core of the dome displays atoll garnets along with biotite, muscovite, plagioclase, quartz, and rutile. Annuli of plagioclase, quartz, and biotite grains separate the garnet core from the rim. Monazite from this sample show a quasi-continuous age spread from 50 Ma to 19 Ma, with an increase in Y + HREE between 45 and 38 Ma, followed by a decrease after ~38 Ma. These data suggest a period of garnet breakdown followed by (re-)growth between 45 and 20 Ma. Phase diagram models show very limited variation in garnet modal abundance at >7 kbar and 600–700 °C, indicating that changes in P–T are unlikely to influence garnet modes. Additionally, there are no other phases like staurolite, which may have reacted with garnet.We propose instead cryptic dissolution-reprecipitation of garnet. Maps of grossular content (XGrs) shows a pebbly texture with interconnected moats of low XGrs garnet surrounding islands of high XGrs garnet, whereas other endmember fractions show flat garnet cores and mantles with slight increases in spessartine at the rim. We suggest that garnet recrystallization was driven by the release of magmatic-hydrothermal fluids from nearby 43–35 Ma granite intrusions. We suggest that fluid-assisted recrystallization can generate age-composition trends that mimic monazite zoning patterns of P–T path controlled garnet breakdown or growth. Misinterpretations of such data would propagating significant errors into tectono-metamorphic reconstructions, emphasizing the necessity of microstructurally constrained petrochronology when interpreting monazite U–Th–Pb ages.

Partial melting during the tectono-metamorphic evolution of collisional orogens results in the formation of migmatites or granitoids and partial to full resorption of the precursor’s accessory phases, such as zircon and monazite. While in many cases both minerals newly crystallize from partial melt, they can also show contrasting degrees of preservation/dissolution. This study presents an example of nearly full zircon preservation but completely new monazite growth during partial melting of a mildly peraluminous orthogneiss from Mt. Papuk, Croatia. We combine U-Pb zircon and Th-U-total Pb monazite dating, zircon trace element and whole rock geochemical data with phase equilibria modelling and use solubility models of accessory phases to constrain the P-T conditions of partial melting. Zircon textures support igneous crystallization while trace elements are characteristic for an S-type granite composition. Zircon yields a Cambrian crystallization age of the protolith at 498.9 ± 6.9 Ma. Conversely, monazite records only Carboniferous anatexis of the orthogneiss at ca. 350 Ma, while zircon mostly remains unaffected. The results of phase equilibria modelling that account for nearly full zircon preservation (< 10% dissolution) and complete monazite dissolution and regrowth indicate P-T conditions of 5-8.5 kbar and 760–800 °C. Our results suggest that a low degree of partial melting (< 10 vol%) in an orthogneiss with an S-type granite signature may occur without water influx at < 800 °C. This will preserve protolith ages in zircon but erase them in original monazite. The contrasting behaviour of these accessory chronometers can be used as a tool to bracket the temperature conditions of anatexis.

Abstract The possibility of searching for right-handed neutrinos at the MoEDAL’s Apparatus for Penetrating Particles (MAPP) detector is investigated in this work. In particular, pair-production of right-handed (RH) neutrinos N from either a $$B-L$$ B - L gauge boson $$Z'$$ Z ′ , as well as a Standard Model (SM) Z boson are considered. Under a no-background assumption, we show that the MAPP detector can be sensitive to active-sterile neutrino mixing strengths as low as $$V_{\mu N}^2 \approx 10^{-12}$$ V μ N 2 ≈ 10 - 12 for multiple choices of $$m_N / m_{Z'}$$ m N / m Z ′ values, when taking the $$B-L$$ B - L gauge coupling $$g_{B-L} = 10^{-3}$$ g B - L = 10 - 3 near its current limit. The SM Z boson portal can reach a similar sensitivity, when the effective mixing between the $$B-L$$ B - L and SM gauge boson is $$\alpha \approx 0.002$$ α ≈ 0.002 .

Freshwater amphipods often exhibit cryptic diversity and are undergoing range shifts driven by environmental changes. Gammarus roeselii, a species inhabiting streams, rivers and lakes across Europe, diversified into ancient genetic lineages in the Balkan Peninsula and the Pannonian Basin, with only one lineage colonizing Central and Western Europe after the ice ages. We investigated the distribution and genetic diversity of G. roeselii by sampling over 1,000 sites across the eastern Alpine region and the Western Pannonian Basin. Cytochrome oxidase I barcoding assigned all sequenced G. roeselii (528 individuals from 174 sites) to the Central-Western European lineage. The occurrence of G. roeselii was associated with low elevation, high summer temperature and gentle stream and river slopes and was biased towards downstream reaches and rivers with large drainage sizes. Its distribution partially overlapped with G. fossarum, which predominates in cooler, faster-flowing streams. Species distribution modelling under future climate scenarios predicted a range expansion of G. roeselii into current G. fossarum habitat. Genetic diversity patterns are consistent with longstanding stable populations in the Southwestern Pannonian Basin, a post-glacial range expansion across alpine forelands, and recent colonization of some alpine valleys.

The performance of enzyme electrodes depends critically on the interactions between the enzyme and the electrode surface. In this study, L-lactate oxidase with an N-terminal His-tag (His-LOx) was immobilized on planar gold electrode modified with self-assembled monolayers (SAMs) engineered to provide distinct surface characteristics: hydrophilic, hydrophobic, or Ni²⁺-chelating for His-tag affinity binding. Electrochemical measurements revealed that the hydrophilic 1-thioglycerol (TG) SAM supported the highest initial activity (10.5 µA/cm²), whereas the hydrophobic 1-octanethiolled to a substantially lowered activity. Ni²⁺-complexed nitrilotriacetic acid (Ni-NTA) SAM markedly enhanced the operational stability of His-LOx, retaining over 65% of activity after 20 h compared to less than 20% for TG. A mixed SAM combining TG and Ni-NTA enabled the simultaneous achievement of high activity and improved stability, demonstrating a synergistic effect of hydrophilic and affinity-based interactions. These results provide mechanistic insight into how SAM surface properties and enzyme-surface interactions govern both activity and stability of LOx, offering practical design principles for the development of robust and sensitive LOx electrodes for biosensing applications.

Purpose: Physical activity has consistently shown positive effects on psychological functioning and brain structure – particularly within the hippocampus, a region implicated in both exercise and mood regulation. Clinical findings suggest reduced hippocampal volume in individuals with depression compared to healthy controls. However, longitudinal intervention studies on young, healthy populations remain scarce. This preregistered study aimed to investigate the biological and social mechanisms driving structural brain, affective, and fitness-related changes during a running intervention, with a novel comparison between individual and group-based running formats. Methods: A four-week longitudinal intervention included 129 participants aged 18–35 who engaged in less than the WHO-recommended 150 minutes/week of aerobic activity. Participants were randomly assigned to one of three groups: (1) individual running, (2) small group running, or (3) waiting control. The running route, frequency, and duration were identical across intervention groups. Assessments were conducted at three timepoints and included magnetic resonance imaging (MRI), psychometric evaluations, electrocardiography (ECG), and estimated V̇O₂max via the UKK Walking Test. Preliminary Results: Previous intervention studies conducted in our laboratory have demonstrated significant volumetric changes in subfields of the hippocampus, which were associated with a reduction in depressive symptoms. In this study, we will follow up on these results by not only examining intervention-related volumetric changes in the hippocampus subfields but also by taking into account a broad range of psychometric measures and cardiac responses to gain insights into various facets of wellbeing induced by physical activity. It is anticipated that the study presented here, with a larger sample and a more rigorous methodological design, will more specifically bolster the results from previous research. Conclusion: Taken together, the findings of our laboratory suggest that regular running induces beneficial changes in brain and mood in previously rather inactive young adults. This work highlights the holistic benefits of running and supports its promotion as a tool for maintaining mental and brain health. Support/Funding Source: This research was funded by the Austrian Science Fund (FWF).