Geochemistry of surface sediments from the fjords of Northern Chilean Patagonia (44–47°S) : spatial variability and implications for paleoclimate reconstructions

Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 76 (2012): 125-146, doi:10.1016/j.gca.2011.10.028.The Patagonian fjords have a clear potential to provide high-resolution sedimentary and geochemical records of past climate and environmental change in the Southern Andes. To improve our ability to interpret these proxy records, we investigated the processes that control fjord sediment inorganic geochemistry through a geochemical, mineralogical and sedimentological analysis of surface sediment samples from the fjords of Northern Chilean Patagonia. A simple terrestrial index based on measurements of salinity and fraction of terrestrial carbon was used to estimate the terrestrial input/river discharge at each site. Our results demonstrate that, under the cold climate conditions of Patagonia, chemical weathering is weak and the inorganic geochemical composition of the fjord sediments is primarily controlled by hydrodynamic mineralogical sorting, i.e., the intensity of river discharge. Our results suggest that the distribution of Fe, Ti and Zr in surface sediments is controlled by their association with heavy and/or coarse minerals, whereas Al is independent of hydrodynamic processes. The elemental ratios Fe/Al, Ti/Al and Zr/Al are therefore well suited for estimating changes in the energy of terrestrial sediment supply into the fjords through time. Zr/Al is particularly sensitive in proximal environments, while Fe/Al is most useful in the outer fjords and on the continental margin. In the most proximal environments, however, Fe/Al is inversely related to hydrodynamic conditions. Caution should therefore be exercised when interpreting Fe/Al ratios in terms of past river discharge. The application of these proxies to long sediment cores from Quitralco fjord and Golfo Elefantes validates our interpretations. Our results also emphasize the need to measure Al-based elemental ratios at high precision, which can be achieved using simultaneous acquisition ICP-AES technology. This study therefore constitutes a strong basis for the interpretation of sedimentary records from the Chilean Fjords.This research was supported by a BAEF fellowship (Belgian American Educational Foundation) and an EU FP6 Marie Curie Outgoing Fellowship to S. Bertrand. J. Sepúlveda was supported by Fundación Andes through the WHOI/University of Concepción agreement, and by a scholarship from the Graduate School of the University of Concepción

Polarization networks around the SDGs in the press from 2020 to 2023

Polarization in the media is a phenomenon classified as ambivalent and volatile because radical positions change to moderate and neutral. The objective of the study was to demonstrate this process in press releases and expert evaluations regarding the Sustainable Development Goals (SDG). A documentary, cross-sectional, exploratory, and retrospective work was carried out with a sample of press releases with national circulation and published from 2020 to 2023 headed with SDGs. The results verify the null hypothesis of significant differences between the theoretical structures concerning the empirical observations. The scope and limits of the study are discussed, as well as a local risk communication policy

Organic geochemistry of the early Toarcian oceanic anoxic event in Hawsker Bottoms, Yorkshire, England

A comprehensive organic geochemical investigation of the Hawsker Bottoms outcrop section in Yorkshire, England has provided new insights about environmental conditions leading into and during the Toarcian oceanic anoxic event (T-OAE; ~183 Ma). Rock-Eval and molecular analyses demonstrate that the section is uniformly within the early oil window. Hydrogen index (HI), organic petrography, polycyclic aromatic hydrocarbon (PAH) distributions, and tricyclic terpane ratios mark a shift to a lower relative abundance of terrigenous organic matter supplied to the sampling locality during the onset of the T-OAE and across a lithological transition. Unlike other ancient intervals of anoxia and extinction, biomarker indices of planktonic community structure do not display major changes or anomalous values. Depositional environment and redox indicators support a shift towards more reducing conditions in the sediment porewaters and the development of a seasonally stratified water column during the T-OAE. In addition to carotenoid biomarkers for green sulfur bacteria (GSB), we report the first occurrence of okenane, a marker of purple sulfur bacteria (PSB), in marine samples younger than ~1.64 Ga. Based on modern observations, a planktonic source of okenane's precursor, okenone, would require extremely shallow photic zone euxinia (PZE) and a highly restricted depositional environment. However, due to coastal vertical mixing, the lack of planktonic okenone production in modern marine sulfidic environments, and building evidence of okenone production in mat-dwelling Chromatiaceae, we propose a sedimentary source of okenone as an alternative. Lastly, we report the first parallel compound-specific δ[superscript 13]C record in marine- and terrestrial-derived biomarkers across the T-OAE. The δ[superscript 13]C records of short-chain n-alkanes, acyclic isoprenoids, and long-chain n -alkanes all encode negative carbon isotope excursions (CIEs), and together, they support an injection of isotopically light carbon that impacted both the atmospheric and marine carbon reservoirs. To date, molecular δ[superscript 13]C records of the T-OAE display a negative CIE that is smaller in magnitude compared to the bulk organic δ[superscript 13]C excursion. Although multiple mechanisms could explain this observation, our molecular, petrographic, and Rock-Eval data suggest that variable mixing of terrigenous and marine organic matter is an important factor affecting the bulk organic δ[superscript 13]C records of the T-OAE.NASA Astrobiology InstituteExobiology Program (U.S.)National Science Foundation (U.S.). Graduate Research Fellowshi

Archaeal and bacterial assemblages in the Oxygen Minimum Zone of the upwelling ecosystem off Central Chile as determined by organic biomarkers

Organic biomarkers were used to investigate the infl uence of seasonal changes in oxygenation and water chemistry on the distribution of archaea and bacteria in the water column and surface sediments of the continental shelf off central Chile (ca. 36°S), an area infl uenced by seasonal upwelling and the development of an oxygen minimum zone. We were interested in establishing if occurrence of archaea and bacteria responds to oxygenation and water chemistry for which we analyzed archaeal isoprenoid (i) and bacterial branched (br) glycerol dialkyl glycerol tetraethers (GDGTs). Our results combined with molecular data from a year round observational program at the same sampling site and depths indicatives the occurrence and dominance of the marine pelagic group Thaumarchaeota. Changes in the distribution of iGDGTs might be explained by (i) the presence of archaeal populations in sub-oxic waters, phylogenetically different from those in surface water, (ii) changes in the relative contribution of Euryarchaeota with depth, and (iii) a relationship between Thaumarchaeota and environmental factors other than temperature. Branched GDGTs were more abundant in the upper, oxic layer during the non-upwelling season, may be a result of higher river runoff, whereas their diversity was higher within sub-oxic waters. Our results indicate a vertical segregation of iGDGTs and brGDGTs, with predominance of archaeal biomarkers during the low productivity season. KEYWORDS: Glycerol dialkyl glycerol tetraethers (GDGTs); archaea; bacteria; oxygen minimum zone; upwelling; Chil

Privacy Preserving Multi Party Computation for Data-Analytics in the IoT-Fog-Cloud Ecosystem

International audienceIn this paper, we propose an architecture for privacy pre- serving protocols in an IoT-Fog-Cloud ecosystem computing hierarchy. We consider the paradigms of Fog and Edge computing, together with a multi-party computation mechanism that enables secure privacy-preserving data processing in terms of exchanged messages and distributed comput- ing. We discuss the potential use of such an architecture in a scenario of pandemics where social distancing monitoring and privacy are pivotal to manage public health yet providing confidence to citizens

Episodic photic zone euxinia in the northeastern Panthalassic Ocean during the end-Triassic extinction

Severe changes in ocean redox, nutrient cycling, and marine productivity accompanied most Phanerozoic mass extinctions. However, evidence for marine photic zone euxinia (PZE) as a globally important extinction mechanism for the end-Triassic extinction (ETE) is currently lacking. Fossil molecular (biomarker) and nitrogen isotopic records from a sedimentary sequence in western Canada provide the first conclusive evidence of PZE and disrupted biogeochemistry in neritic waters of the Panthalassic Ocean during the end Triassic. Increasing water-column stratification and deoxygenation across the ETE led to PZE in the Early Jurassic, paralleled by a perturbed nitrogen cycle and ecological turnovers among noncalcifying groups, including eukaryotic algae and prokaryotic plankton. If such conditions developed widely in the Panthalassic Ocean, PZE might have been a potent mechanism for the ETE.National Science Foundation (U.S.) (Grant EAR-1147402)Exobiology Program (U.S.) (Grants NNX09AM88G and NNA08CN84A)American Association of Petroleum Geologists (Grant-In-Aid)Mary-Hill and Bevan M. French Fund for Impact Geolog

K-2P channels in plants and animals

Two-pore domain potassium (K2P) channels are membrane proteins widely identified in mammals, plants, and other organisms. A functional channel is a dimer with each subunit comprising two pore-forming loops and four transmembrane domains. The genome of the model plant Arabidopsis thaliana harbors five genes coding for K2P channels. Homologs of Arabidopsis K2P channels have been found in all higher plants sequenced so far. As with the K2P channels in mammals, plant K2P channels are targets of external and internal stimuli, which fine-tune the electrical properties of the membrane for specialized transport and/or signaling tasks. Plant K2P channels are modulated by signaling molecules such as intracellular H+ and calcium and physical factors like temperature and pressure. In this review, we ask the following: What are the similarities and differences between K2P channels in plants and animals in terms of their physiology? What is the nature of the last common ancestor (LCA) of these two groups of proteins? To answer these questions, we present physiological, structural, and phylogenetic evidence that discards the hypothesis proposing that the duplication and fusion that gave rise to the K2P channels occurred in a prokaryote LCA. Conversely, we argue that the K2P LCA was most likely a eukaryote organism. Consideration of plant and animal K2P channels in the same study is novel and likely to stimulate further exchange of ideas between students of these fields

Analytical and computational advances, opportunities, and challenges in marine organic biogeochemistry in an era of "Omics"

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Steen, A. D., Kusch, S., Abdulla, H. A., Cakic, N., Coffinet, S., Dittmar, T., Fulton, J. M., Galy, V., Hinrichs, K., Ingalls, A. E., Koch, B. P., Kujawinski, E., Liu, Z., Osterholz, H., Rush, D., Seidel, M., Sepulveda, J., & Wakeham, S. G. Analytical and computational advances, opportunities, and challenges in marine organic biogeochemistry in an era of "Omics". Frontiers in Marine Science, 7, (2020): 718, doi:10.3389/fmars.2020.00718.Advances in sampling tools, analytical methods, and data handling capabilities have been fundamental to the growth of marine organic biogeochemistry over the past four decades. There has always been a strong feedback between analytical advances and scientific advances. However, whereas advances in analytical technology were often the driving force that made possible progress in elucidating the sources and fate of organic matter in the ocean in the first decades of marine organic biogeochemistry, today process-based scientific questions should drive analytical developments. Several paradigm shifts and challenges for the future are related to the intersection between analytical progress and scientific evolution. Untargeted “molecular headhunting” for its own sake is now being subsumed into process-driven targeted investigations that ask new questions and thus require new analytical capabilities. However, there are still major gaps in characterizing the chemical composition and biochemical behavior of macromolecules, as well as in generating reference standards for relevant types of organic matter. Field-based measurements are now routinely complemented by controlled laboratory experiments and in situ rate measurements of key biogeochemical processes. And finally, the multidisciplinary investigations that are becoming more common generate large and diverse datasets, requiring innovative computational tools to integrate often disparate data sets, including better global coverage and mapping. Here, we compile examples of developments in analytical methods that have enabled transformative scientific advances since 2004, and we project some challenges and opportunities in the near future. We believe that addressing these challenges and capitalizing on these opportunities will ensure continued progress in understanding the cycling of organic carbon in the ocean.The Hanse-Wissenschaftskolleg Delmenhorst, Germany, sponsored the “Marine Organic Biogeochemistry” workshop in April 2019, of which this working group report was a part. The workshop was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – project number: 422798570. The Geochemical Society provided additional funding for the conference. AS was supported by DOE grant DE-SC0020369

The Changing Landscape for Stroke\ua0Prevention in AF: Findings From the GLORIA-AF Registry Phase 2

Background GLORIA-AF (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation) is a prospective, global registry program describing antithrombotic treatment patterns in patients with newly diagnosed nonvalvular atrial fibrillation at risk of stroke. Phase 2 began when dabigatran, the first non\u2013vitamin K antagonist oral anticoagulant (NOAC), became available. Objectives This study sought to describe phase 2 baseline data and compare these with the pre-NOAC era collected during phase 1. Methods During phase 2, 15,641 consenting patients were enrolled (November 2011 to December 2014); 15,092 were eligible. This pre-specified cross-sectional analysis describes eligible patients\u2019 baseline characteristics. Atrial fibrillation disease characteristics, medical outcomes, and concomitant diseases and medications were collected. Data were analyzed using descriptive statistics. Results Of the total patients, 45.5% were female; median age was 71 (interquartile range: 64, 78) years. Patients were from Europe (47.1%), North America (22.5%), Asia (20.3%), Latin America (6.0%), and the Middle East/Africa (4.0%). Most had high stroke risk (CHA2DS2-VASc [Congestive heart failure, Hypertension, Age  6575 years, Diabetes mellitus, previous Stroke, Vascular disease, Age 65 to 74 years, Sex category] score  652; 86.1%); 13.9% had moderate risk (CHA2DS2-VASc = 1). Overall, 79.9% received oral anticoagulants, of whom 47.6% received NOAC and 32.3% vitamin K antagonists (VKA); 12.1% received antiplatelet agents; 7.8% received no antithrombotic treatment. For comparison, the proportion of phase 1 patients (of N = 1,063 all eligible) prescribed VKA was 32.8%, acetylsalicylic acid 41.7%, and no therapy 20.2%. In Europe in phase 2, treatment with NOAC was more common than VKA (52.3% and 37.8%, respectively); 6.0% of patients received antiplatelet treatment; and 3.8% received no antithrombotic treatment. In North America, 52.1%, 26.2%, and 14.0% of patients received NOAC, VKA, and antiplatelet drugs, respectively; 7.5% received no antithrombotic treatment. NOAC use was less common in Asia (27.7%), where 27.5% of patients received VKA, 25.0% antiplatelet drugs, and 19.8% no antithrombotic treatment. Conclusions The baseline data from GLORIA-AF phase 2 demonstrate that in newly diagnosed nonvalvular atrial fibrillation patients, NOAC have been highly adopted into practice, becoming more frequently prescribed than VKA in Europe and North America. Worldwide, however, a large proportion of patients remain undertreated, particularly in Asia and North America. (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients With Atrial Fibrillation [GLORIA-AF]; NCT01468701