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AbstractEarly Palaeozoic sites with soft-tissue preservation are predominantly found in Cambrian rocks and tend to capture past tropical and temperate ecosystems. In this study, we describe the diversity and preservation of the Cabrières Biota, a newly discovered Early Ordovician Lagerstätte from Montagne Noire, southern France. The Cabrières Biota showcases a diverse polar assemblage of both biomineralized and soft-bodied organisms predominantly preserved in iron oxides. Echinoderms are extremely scarce, while sponges and algae are abundantly represented. Non-biomineralized arthropod fragments are also preserved, along with faunal elements reminiscent of Cambrian Burgess Shale-type ecosystems, such as armoured lobopodians. The taxonomic diversity observed in the Cabrières Biota mixes Early Ordovician Lagerstätten taxa with Cambrian forms. By potentially being the closest Lagerstätte to the South Pole, the Cabrières Biota probably served as a biotic refuge amid the high-water temperatures of the Early Ordovician, and shows comparable ecological structuring to modern polar communities.

Special attention has been given to chromium (Cr) as a paleoproxy tracing redox cycling throughout Earth's history, due to differences in the solubility of its primary redox species at Earth's surface (Cr(III) and Cr(VI)) and isotope fractionation associated with their interconversion. In turn, chromium's paleoproxy potential has motivated studies of the modern ocean to better understand which processes drive its cycling and to constrain their impact on the Cr isotope composition (δ53Cr) of seawater. Here, we present total dissolved seawater Cr concentrations and δ53Cr along the GEOTRACES GP13 section. This section is a zonal transect extending from Australia in the subtropical southwest Pacific Ocean. Surface signals of local biological Cr cycling are minimal, in agreement with distributions of dissolved major nutrients as well as biologically-controlled trace metals in this low productivity, oligotrophic environment. Depth profiles have Cr concentration minima in surface waters and maxima at depth, and are largely shaped by the advection of nutrient- and Cr-rich subsurface waters rather than vertically-driven processes. Samples close to the sediment–water interface indicate important benthic Cr fluxes across the section. The GP13 transect crosses the hydrothermally-active Kermadec Arc. Hydrothermal fluids (consisting of <15% background seawater) were collected from three venting sites at the Brothers Volcano (along the Kermadec Arc). These fluids yielded near-crustal δ53Cr values (−0.17 to +0.08‰) and elevated [Cr] (7.5–23 nmol kg−1, hydrothermal endmember [Cr] ≈ 8–27 nmol kg−1), indicating that the Kermadec Arc may be an isotopically light Cr source. Dissolved [Fe] enrichments have been reported previously in deep waters (∼1600–3000 m) along the GP13 transect, east of the Kermadec Arc. These same waters show elevated [Cr] compared to Circumpolar Deep Water ([Cr] = 3.88 ± 0.11, δ53Cr = 0.89 ± 0.08, n = 32), with an average [Cr] accumulation of 0.71 ± 0.11 nmol kg−1 (1 SD), and an estimated δ53Cr of +0.46 ± 0.30‰ (2 SD, n = 9) for the accumulated Cr. Comparing high-temperature vent and neutrally buoyant plume data, hydrothermal-sourced Cr is likely negligable compared to Cr contributions from other processes (benthic fluxes, release from particles), and the advection of more Cr-rich Pacific Deep Water. It is unlikely that hydrothermal vents would be a major contributor within the regional or global biogeochemical Cr cycle, even if hydrothermal fluxes change by orders of magnitude, and therefore δ53Cr trends in the paleorecord may be attributable, at least in part, to major changes in other controls on Cr (e.g. widespread anoxia). Geochimica et Cosmochimica Acta, 342 ISSN:1872-9533 ISSN:0016-7037

The ISONET project has been striving to improve greatly our understanding of European climate systems providing independent quantitative data for model verification and policy making. A network of 24 sites provides dendrochronological coverage from Iberia to Fennoscandia, Caledonia and the Tyrol. The stable isotope (C, H, O) ratios of these annually resolved time series shall be analysed within this project, to reconstruct past climate regimes (temperature, relative humidity and precipitation characteristics) for the last 400 years. Climate variability shall be addressed on three timescales; decade-century (source water/air mass dominance); inter-annual (quantifying baseline variability, extreme events and recent trends); and intra-annual (high resolution exploration of seasonality signals within tree-rings). ISONET goes far beyond existing tree-ring analyses in its spatial based investigation and interpretation (see also https://cordis.europa.eu/project/id/EVK2-CT-2002-00147). 24 European annually resolved stable isotope chronologies have been constructed from tree ring cellulose for the last 400 years (1600CE – 2003CE) for carbon and oxygen and for the last 100 years for hydrogen. Data was produced within the ISONET project (400 Years of Annual Reconstructions of European Climate Variability Using a Highly Resolved Isotopic Network,) to initiate an extensive spatiotemporal tree-ring stable isotope network across Europe funded as part of the fifth EC Framework Programme “Energy, Environment and Sustainable Development”. This data set comprises the ISONET δ13C records. Wood increment cores of 15 or more Pinus sylvestris, Quercus robur/petraea or Cedrus atlantica tree individuals were taken. Dendro-dated tree-ring material of 4-5 individuals per site was dissected and pooled year by year. After cellulose extraction and homogenization, 18O/16O-ratios of annually resolved samples were determined by Isotope Ratio Mass Spectrometry (IRMS). Time series of 13C/12C are given as d-values versus PDB. Details can be found in the downloadable “data description” file.

In this paper we present the Open Software Services for Classrooms and Research (OSSCAR) platform. OSSCAR provides an open collaborative environment to develop, deploy and access educational resources in the form of web applications. To minimize efforts in the creation and use of new educational material, it combines software tools that have emerged as standards with custom domain-specific ones. The technical solutions adopted to create and distribute content are described and motivated on the basis of reliability, sustainability, ease of uptake and use. Examples from courses in the domains of physics, chemistry, and materials science are shown to demonstrate the style and level of interactivity of typical applications. The tools presented are easy to use, and create a uniform and open environment exploitable by a large community of teachers, students, and researchers with the goal of facilitating learning and avoiding, when possible, duplication of efforts in creating teaching material. Contributions to expand the educational content of the OSSCAR project are welcome. Comment: 15 pages, 8 figures

The ISONET project has been striving to improve greatly our understanding of European climate systems providing independent quantitative data for model verification and policy making. A network of 24 sites provides dendrochronological coverage from Iberia to Fennoscandia, Caledonia and the Tyrol. The stable isotope (C, H, O) ratios of these annually resolved time series shall be analysed within this project, to reconstruct past climate regimes (temperature, relative humidity and precipitation characteristics) for the last 400 years. Climate variability shall be addressed on three timescales; decade-century (source water/air mass dominance); inter-annual (quantifying baseline variability, extreme events and recent trends); and intra-annual (high resolution exploration of seasonality signals within tree-rings). ISONET goes far beyond existing tree-ring analyses in its spatial based investigation and interpretation (see also https://cordis.europa.eu/project/id/EVK2-CT-2002-00147). 24 European annually resolved stable isotope chronologies have been constructed from tree ring cellulose for the last 400 years (1600CE – 2003CE) for carbon and oxygen and for the last 100 years for hydrogen. Data was produced within the ISONET project (400 Years of Annual Reconstructions of European Climate Variability Using a Highly Resolved Isotopic Network,) to initiate an extensive spatiotemporal tree-ring stable isotope network across Europe funded as part of the fifth EC Framework Programme “Energy, Environment and Sustainable Development”. This data set comprises the ISONET δ18O records. Wood increment cores of 15 or more Pinus sylvestris, Quercus robur/petraea or Cedrus atlantica tree individuals were taken. Dendro-dated tree-ring material of 4-5 individuals per site was dissected and pooled year by year. After cellulose extraction and homogenization, 18O/16O-ratios of annually resolved samples were determined by Isotope Ratio Mass Spectrometry (IRMS). Time series of 18O/16O are given as d-values versus SMOW. Details can be found in the downloadable “data description” file.

Despite the importance of high-latitude surface energy budgets (SEBs) for land-climate interactions in the rapidly changing Arctic, uncertainties in their prediction persist. Here, we harmonize SEB observations across a network of vegetated and glaciated sites at circumpolar scale (1994-2021). Our variance-partitioning analysis identifies vegetation type as an important predictor for SEB-components during Arctic summer (June-August), compared to other SEB-drivers including climate, latitude and permafrost characteristics. Differences among vegetation types can be of similar magnitude as between vegetation and glacier surfaces and are especially high for summer sensible and latent heat fluxes. The timing of SEB-flux summer-regimes (when daily mean values exceed 0 Wm(-2)) relative to snow-free and -onset dates varies substantially depending on vegetation type, implying vegetation controls on snow-cover and SEB-flux seasonality. Our results indicate complex shifts in surface energy fluxes with land-cover transitions and a lengthening summer season, and highlight the potential for improving future Earth system models via a refined representation of Arctic vegetation types.An international team of researchers finds high potential for improving climate projections by a more comprehensive treatment of largely ignored Arctic vegetation types, underscoring the importance of Arctic energy exchange measuring stations. Peer reviewed