Combining methane clumped and bulk isotopes, temporal variations in molecular and isotopic composition, and hydrochemical and geological proxies to understand methane’s origin in the Ronda peridotite massifs (Spain)

In serpentinised peridotite and ultramafic rock systems, methane (CH4) origin is frequently considered abiotic, but variable microbial and thermogenic components can also exist. Typically, the origin of CH4 is studied using bulk, 13C/12C and 2H/H isotopic composition, molecular gas composition, occasionally radiocarbon (14C), microbiology and geological context. Recent advances in CH4-clumped isotope methods have yielded novel insights into the formation of CH4: nonetheless, their interpretation in natural gas samples is often uncertain and requires additional research. Here, we study the origin of the gas released in hyperalkaline (pH > 10) springs in the Ronda Peridotite Massifs (southern Spain), combining bulk and clumped CH4 isotopes with molecular gas composition, hydrochemical (Total Organic Carbon and Platinum Group Elements in water), geothermal and geo-structural data. Five springs analysed in 2014 have been re-examined for changes in gas chemistry over time, and three newly discovered gas-bearing springs are analysed for the first time. Regardless of whether springs have microbial or abiotic isotopic fingerprints, we find that bulk CH4 isotopes are fairly stable over a seven-year period. This suggests that the CH4 source(s) or postgenetic processes (such as oxidation and diffusion) have not undergone significant temporal changes. Major variations in H2 and CH4 concentrations in certain springs may be the result of changes in gas pressure and migration intensity. Paired CH4 clumped isotopes (Δ12CH2D2 - Δ13CH3D) were analysed in two bubbling springs, where the presence of CH4 can be interpreted as non-microbial based on 13C enrichment, absence of 14C, and the presence of ethane and propane. However, these isotopes are in disequilibrium, which prevents the quantification of the gas formation temperature. Within the Δ12CH2D2 - Δ13CH3D diagram, the data lie within both the microbialgenic zone, suggested by previous authors, and the abiotic zone that results combining data from laboratory gas synthesis and other natural gas samples. Therefore, attributing a microbial origin to CH4 based only on clumped isotopes is less definite than previously assumed. The amount of Total Organic Carbon appears to be correlated with the origin of CH4, as it is higher in 13Cdepleted CH4 samples and lower in 13C-enriched samples. Palladium (Pd) and Rhodium (Rh) dissolved in water (the more soluble Platinum Group Elements) can be a proxy for the chromitite ore deposits contained in plagioclase tectonite layers throughout the investigated area, which may act as catalysts for abiotic CO2 hydrogenation. Clumped isotope disequilibrium and the reported absence of diffuse CH4-bearing fluid inclusions in the peridotites appear to rule out high temperature gas genesis in post-magmatic inclusions. These observations, along with the moderate temperatures at the base of the peridotite massifs and the consistent occurrence of gasEuropean Regional Development Fund (FEDER)Junta de AndalucíaUniversidad de MálagaFunding charge open access: University of Malaga / CBU

Post-Collisional Reorganisation of the Eastern Alps in 4D – Crust and Mantle Structure

The Eastern Alps were affected by a profound post-collisional tectonic reorganisation in Neogene time, featuring indentation by the Adriatic upper plate, rapid uplift and filling of the eastern Molasse Basin, exhumation and eastward orogen-parallel transport of Paleogene metamorphic units in the orogenic core, and a shift from northward thrust propagation in the European plate to southward propagation in the Adriatic plate. We test the idea that these events were triggered by slab detachment by reconstructing the indentation process. This involves sequentially restoring N-S and E-W cross-sections of the orogenic wedge and correcting for out-of-section orogen-parallel transport with a map-view reconstruction. We propose two phases of indentation: Initially (23 and 14 Ma), the whole Adriatic crust acted as an indenter. Its northward motion was accommodated by upright folding and orogen-parallel extensional exhumation in the Tauern Window. This phase was followed (14 Ma to Present) by continued orogen-parallel transport of the orogenic wedge into the Pannonian Basin and deformation of the leading edge of the Adriatic indenter, forming the Southern Alps fold-thrust belt. The lower crust of the Southern Alps indented the base of the Venediger Nappes in the Tauern Window, forming a high-velocity (6.8–7.25 km/s) ridge in map view at 30–45 km depth. By correlating the post-23 Ma orogenic evolution with presently imaged European slab segments in P-wave teleseismic tomography, we discern two possible Neogene slab removal events: One from 23 to 19 Ma triggering tectonic reorganisation of the Eastern Alps and its foreland basin, and potentially a second event after 14 Ma

The interaction of Solar Radiation Modification and Earth System Tipping Elements

The avoidance of hitting tipping points is often considered a key benefit of Solar Radiation Modification (SRM) techniques, however, the physical science underpinning this has thus far not been comprehensively assessed. This review assesses the available evidence for the interaction of SRM with a number of earth system tipping elements in the cryosphere, the oceans, the atmosphere and the biosphere , with a particular focus on the impact of SAI. We review the scant available literature directly addressing the interaction of SRM with the tipping elements or for closely related proxies to these elements. However, given how limited this evidence is, we also identify and describe the drivers of the tipping elements, and then assess the available evidence for the impact of SRM on these. We then briefly assess whether SRM could halt or reverse tipping once feedbacks have been initiated. Finally, we suggest pathways for further research. We find that SRM mostly reduces the risk of hitting tipping points relative to same emission pathway scenarios without SRM, although this conclusion is not clear for every tipping element, and large uncertainties remain

Similarities between sea ice area variations and satellite-derived terrestrial biosphere and cryosphere parameters across the Arctic

Abstract. Satellite time series availability for the Arctic Ocean and adjacent land areas allows cross-comparisons for cryosphere vs. vegetation parameters. Previous studies focused on correlation analyses between vegetation indices (time-integrated normalized difference vegetation index (TI-NDVI) and maximum normalized difference vegetation index (MaxNDVI)) of tundra regions and sea ice extent for selected months. We have refined these analyses through the consideration of distinct sea ice basins and all months and through an extension to south of the treeline, and we have included cryosphere essential climate variables such as snow water equivalent (SWE; March as proxy for annual maximum) and mean annual ground temperature (MAGT) in permafrost areas. The focus was on 2000–2019, reflecting data availability. As a first step, we derived trends. Changes across all the different parameters could be specifically determined for eastern Siberia. Then, time series were de-trended and correlations determined. Linkages between sea ice area (SIA) and normalized difference vegetation index (NDVI) across tundra regions were confirmed, where lower sea ice extent coincides with higher NDVI. The regional extension beyond the treeline revealed linkages for northern European Russia and partially over northern Scandinavia. Differences compared to previous studies ending in 2008 were found for the Kara Sea region and adjacent land area, indicating recent changes. In the case of MAGT, high significant correlations were found for more distant sea ice basins than for the NDVI derivatives, indicating influences of large-scale atmospheric circulation patterns. Negative and positive significant correlations were found for March SWE depending on the SIA month and region. Also, months other than September (sea ice extent minimum) were found to have high correlations vs. land-based variables, with distinct differences across sea ice basins. The fraction of data points with significant correlations north of 60° N was higher for SWE and MAGT than for the NDVI derivatives. Fractions for SWE were higher for Eurasia than northern America. Autumn (incl. October and November) and mid-winter (incl. February, March) were most relevant for both investigated cryosphere-related parameters, MAGT and SWE. Although similar patterns could be found for TI-NDVI and MaxNDVI, a higher proportion of significant correlations was observed for TI-NDVI. The datasets provide a baseline for future studies on common drivers of essential climate parameters and causative effects across the Arctic.</jats:p

Multi-year total ozone column variability at three Norwegian sites and the influence of Northern Hemisphere Climatic indices

Total ozone column (TOC) measurements are retrieved from the Ozone Monitoring Instrument (OMI) onboard the NASA Earth Observing System (EOS) Aura satellite at the three Norwegian sites: Oslo (59.9 degrees N 10.7 degrees E, 1 m a.s. l.), Trondheim (63.4 degrees N 10.4 degrees E, 3 m a.s.l.) and Andoya (69.1 degrees N 15.7 degrees E, 32 m a.s.l.). TOC data have been analysed from 2005 to 2021, in order to detect annual and multi-years total ozone variability. The relationship between geopotential height (GPH) at 250 hPa and total ozone column has been evaluated after showing that monthly anomalies in GPH and TOC are correlated amongst the three sites. The influence of the three Northern Hemisphere Tele Connection (TC) indices (North Atlantic Oscillation, Arctic Oscillation and Scandinavia) on TOC variability has been investigated. It is found that Scandinavia index plays a prominent role for the northernmost latitudes of Andoya and Trondheim while North Atlantic Oscillation and Arctic Oscillation indices are weakly correlated (negatively) to TOC and (positively) to GPH at Oslo. The response of TOC variability to the solar activity at the three sites is also explored and it is noticed that in the period of increasing variation of solar activity, significant TOC anomaly events are only observed in Andoya and Trondheim

Study on Argument Pair Extraction in Dialogue by Integrating Graph Neural Networks with Pre-trained Language Models

早稲田大学博士(工学)早大学位記番号:新9640doctoral thesi

Rebutting 33 False Claims About Solar, Wind, and Electric Vehicles

Achieving the United States’ ambitious emissions reduction goals depends in large part on the rapid adoption of wind and solar energy and the electrification of consumer vehicles. However, misinformation and coordinated disinformation about renewable energy is widespread and threatens to undermine the transition. In this report, the Sabin Center identifies and examines 33 of the most pervasive false claims about solar energy, wind energy, and electric vehicles, with the aim of promoting a more informed discussion

FOCA: a new quality-controlled database of floods and catchment descriptors in Italy

Here we present FOCA (Italian FlOod and Catchment Atlas), the first systematic collection of data on Italian river catchments for which historical discharge time series are available. Hydrometric information, including the annual maximum peak discharge and average daily annual maximum discharge, is complemented by several geomorphological, climatological, extreme rainfall, land-cover and soil-related catchment attributes. All hydrological information derives from the most recently released datasets of discharge and rainfall measurements. To enhance the reproducibility and transferability of the analysis, this paper provides a description of all the raw data and the algorithms used to build the basin attribute dataset. We also describe the approaches adopted to solve problems encountered during the digital elevation model elaboration in areas characterized by a complex morphology. Details about the data quality-control procedure developed to detect and correct errors are also reported. One of the main novelties of FOCA with respect to other national-scale datasets is the inclusion of a rich set of geomorphological attributes and extreme rainfall features for a large set of basins covering a wide range of elevations and areas. Using this first nationwide data collection (available at https://doi.org/10.5281/zenodo.10446258, Claps et al., 2023), a wide range of environmental applications, with a particular focus on flood studies, can be undertaken within the Italian territor