Effects of early marine diagenesis and site-specific depositional controls on carbonate-associated sulfate : insights from paired S and O isotopic analyses

Acknowledgment is made to the donors of the American Chemical Society Petroleum Research Fund (#57548-ND2) to D.F. for partial support of this research and from the Estonian Research Council (#PUT611, #PRG836) to O.H and A.L.Carbon, sulfur and oxygen isotope profiles in Silurian strata of the Baltoscandian Basin (Estonia), coincident with the Ireviken Bioevent, provide insights into basin-scale and platform-specific depositional processes. Paired carbon isotope records preserve a positive isotope excursion during the early Wenlock, coincident with faunal turnover, yet δ13C variability of this excursion compared to other locations within the paleobasin reflects local depositional influences superimposed on a global signal. In comparison, sulfur isotope records do not preserve a systematic isotopic excursion over the same interval. Instead, sulfur isotope records have high sample-to-sample stratigraphic variability, particularly in shallow-water carbonate rocks (scatter up to ~10‰ for δ34SCAS and ~ 25‰ for δ34Spyr). This pattern of isotopic variability is also found between sites from the same carbonate platform, where the magnitude and isotopic variability in δ34SCAS and δ34Spyr differ depending on relative local sea level (and therefore facies). Such facies-dependent variability reflects more closed- versus more open-system diagenetic conditions where pulses of increased sedimentation rate in the shallow water environments generates greater isotopic variability in both δ34SCAS and δ34Spyr. Increased reworking and proximity to the shoreline results in local sulfide oxidation, seen as a decrease in δ34SCAS in the most proximal settings. Platform-scale evolution of isotopically distilled pore-fluids associated with dolomitization results in increased δ34SCAS in deep water settings. Correlations in paired δ34SCAS-δ18OCAS data support these conclusions, demonstrating the local alteration of CAS during deposition and early marine diagenesis. We present a framework to assess the sequence of diagenetic and depositional environmental processes that have altered δ34SCAS and find that δ34S of ~27–28‰ approximates Silurian seawater sulfate. Our findings provide a mechanism to understand the elevated variability in many deep-time δ34SCAS records that cannot otherwise be reconciled with behavior of the marine sulfate reservoir.PostprintPeer reviewe

Depositional and diagenetic constraints on the abundance and spatial variability of carbonate-associated sulfate

Acknowledgment is made to the donors of the American Chemical Society Petroleum Research Fund (#57548-ND2) for partial support of this research.Marine carbonate rocks are composed, in varying abundance, of cement, micrite, abiotic grains and fossils, which can provide information about the physical and chemical environments in which they formed. Geochemical analyses of these carbonates are not always interpreted alongside the wealth of geologic (including petrographic) information available, resulting in potentially faulty reconstructions of biogeochemical and environmental conditions. These concerns have prompted closer scrutiny of the effect of depositional lithofacies and diagenesis on carbonate proxies. Here, we have combined X-ray Absorption Near Edge Structure (XANES) spectroscopy and μ-X-ray Fluorescence (μ-XRF) imaging to map the speciation and abundance of sulfur in carbonate petrographic thin sections in Upper Ordovician carbonates from Anticosti Island, Canada and early Silurian carbonates from Gotland, Sweden, across multiple depositional facies. Lithofacies and fossil communities between Anticosti Island and Gotland are similar, which allows for comparison of changes in the dominant S species and their abundance in separate basins, associated with variations in (glacio)eustatic sea level. Sulfide abundance is greatest in mudstone, wackestone and packstone facies, where interstitial micrite hosts abundant pyrite. Sulfate abundance, as carbonate-associated sulfate (CAS), varies within individual fossil fragments, as well as within the same fossil phylum and is particularly high in unaltered brachiopods. In contrast, sulfate abundance is generally very low in micrite (near the detection limit) and generally arises in situ from sulfide that has been oxidized as opposed to true CAS. In different cement fabrics, sulfate abundance is greatest in drusy, pore-filling cements. Organic sulfur compounds are also detected and, although low in abundance, are mostly found within micrite. The detection and characterization of both inorganic sulfur and organic sulfur compounds provides a platform to understand early processes of biomineralization. This approach will broaden our understanding of the source of inorganically bound sulfate in ancient carbonates, as well as the effect of depositional setting and diagenesis on CAS incorporation, (re)mobilization, and ultimate abundance in sedimentary carbonates. Additionally, this work has implications for the CAS isotopic value of individual carbonate components that may affect interpretations of stratigraphic variability of numerous CAS sections throughout Earth history.PostprintPeer reviewe

Insights into past ocean proxies from micron-scale mapping of sulfur species in carbonates

Laboratory work and analyses were supported by a Steve Fossett Fellowship awarded to Rose; a U.S. Department of Energy (DOE) Biological and Environmental Research grant (DE-SC0014613), U.S. National Science Foundation (NSF) grants (EAR-0951509, 1229370), an Agouron Institute (California, USA) grant, a Packard (The David and Lucile Packard Foundation, California, USA) Fellowship, and a Hanse-Wissenschaftskolleg (Germany) Fellowship awarded to Fike; and an NSF Career Grant (EAR-1056480) awarded to Catalano. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory (California, USA), is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under contract DE-AC02-76SF00515. GeoSoilEnviroCARS is supported by the NSF–Earth Sciences (EAR-1634415) and DOE–GeoSciences (DE-FG02-94ER14466).Geological reconstructions of global ocean chemistry and atmospheric oxygen concentrations over Earth history commonly rely on the abundance and stable isotopic composition (δ34S) of sulfur-bearing compounds. Carbonate-associated sulfate (CAS), sulfate bound within a calcium carbonate mineral matrix, is among the most commonly interrogated sulfur mineral phases. However, recent work has revealed variability in δ34SCAS values that cannot be explained by evolution of the marine sulfate reservoir, challenging the common interpretation that CAS is inherently a high-fidelity record of seawater sulfate. To investigate the source of this inconsistency, we used X-ray spectromicroscopy to map the micron-scale distribution of S-bearing sedimentary phases in Ordovician-aged (ca. 444 Ma) shallow marine carbonates from Anticosti Island, Québec, Canada. Clear differences in the abundance of CAS are observed between cements and fossils, suggesting that variance in bulk-rock data could be a consequence of component mixing and that coupled synchrotron-petrographic screening can identify the carbonate components that are most likely to retain primary CAS. Furthermore, we observe multiple, distinct forms of sulfate (both inorganic and organic). Differences in these forms among fossil clades could provide new insights into biomineralization mechanisms in extinct organisms.PostprintPeer reviewe

The impact of the COVID-19 lockdown on greenhouse gases: a multi-city analysis of in situ atmospheric observations

We tested the capabilities of urban greenhouse gas (GHG) measurement networks to detect abrupt changes in emissions, such as those caused by the roughly 6-week COVID-19 lockdown in March 2020 using hourly in situ GHG mole fraction measurements from six North American cities. We compared observed changes in CO2, CO, and CH4 for different mole fraction metrics (diurnal amplitude, vertical gradients, enhancements, within-hour variances, and multi-gas enhancement ratios) during 2020 relative to previous years for three periods: pre-lockdown, lockdown, and ongoing recovery. The networks showed decreases in CO2 and CO metrics during the lockdown period in all cities for all metrics, while changes in the CH4 metrics were variable across cities and not statistically significant. Traffic decreases in 2020 were correlated with the changes in GHG metrics, whereas changes in meteorology and biology were not, implying that decreases in the CO2 and CO metrics were related to reduced emissions from traffic and demonstrating the sensitivity of these tower networks to rapid changes in urban emissions. The enhancements showed signatures of the lockdowns more consistently than the three micrometeorological methods, possibly because the urban measurements are collected at relatively high altitudes to be sensitive to whole-city emissions. This suggests that urban observatories might benefit from a mixture of measurement altitudes to improve observational network sensitivity to both city-scale and more local fluxes. &nbsp;</p

The Indianapolis Flux Experiment (INFLUX): A test-bed for developing urban greenhouse gas emission measurements

The objective of the Indianapolis Flux Experiment (INFLUX) is to develop, evaluate and improve methods for measuring greenhouse gas (GHG) emissions from cities. INFLUX’s scientific objectives are to quantify CO2 and CH4 emission rates at 1 km2 resolution with a 10% or better accuracy and precision, to determine whole-city emissions with similar skill, and to achieve high (weekly or finer) temporal resolution at both spatial resolutions. The experiment employs atmospheric GHG measurements from both towers and aircraft, atmospheric transport observations and models, and activity-based inventory products to quantify urban GHG emissions. Multiple, independent methods for estimating urban emissions are a central facet of our experimental design. INFLUX was initiated in 2010 and measurements and analyses are ongoing. To date we have quantified urban atmospheric GHG enhancements using aircraft and towers with measurements collected over multiple years, and have estimated whole-city CO2 and CH4 emissions using aircraft and tower GHG measurements, and inventory methods. Significant differences exist across methods; these differences have not yet been resolved; research to reduce uncertainties and reconcile these differences is underway. Sectorally- and spatially-resolved flux estimates, and detection of changes of fluxes over time, are also active research topics. Major challenges include developing methods for distinguishing anthropogenic from biogenic CO2 fluxes, improving our ability to interpret atmospheric GHG measurements close to urban GHG sources and across a broader range of atmospheric stability conditions, and quantifying uncertainties in inventory data products. INFLUX data and tools are intended to serve as an open resource and test bed for future investigations. Well-documented, public archival of data and methods is under development in support of this objective

A database of marine phytoplankton abundance, biomass and species composition in Australian waters

There have been many individual phytoplankton datasets collected across Australia since the mid 1900s, but most are unavailable to the research community. We have searched archives, contacted researchers, and scanned the primary and grey literature to collate 3,621,847 records of marine phytoplankton species from Australian waters from 1844 to the present. Many of these are small datasets collected for local questions, but combined they provide over 170 years of data on phytoplankton communities in Australian waters. Units and taxonomy have been standardised, obviously erroneous data removed, and all metadata included. We have lodged this dataset with the Australian Ocean Data Network (http://portal.aodn.org.au/) allowing public access. The Australian Phytoplankton Database will be invaluable for global change studies, as it allows analysis of ecological indicators of climate change and eutrophication (e.g., changes in distribution; diatom:dinoflagellate ratios). In addition, the standardised conversion of abundance records to biomass provides modellers with quantifiable data to initialise and validate ecosystem models of lower marine trophic levels

Effectiveness of a new model of primary care management on knee pain and function in patients with knee osteoarthritis: Protocol for THE PARTNER STUDY

© 2018 The Author(s). Background: To increase the uptake of key clinical recommendations for non-surgical management of knee osteoarthritis (OA) and improve patient outcomes, we developed a new model of service delivery (PARTNER model) and an intervention to implement the model in the Australian primary care setting. We will evaluate the effectiveness and cost-effectiveness of this model compared to usual general practice care. Methods: We will conduct a mixed-methods study, including a two-arm, cluster randomised controlled trial, with quantitative, qualitative and economic evaluations. We will recruit 44 general practices and 572 patients with knee OA in urban and regional practices in Victoria and New South Wales. The interventions will target both general practitioners (GPs) and their patients at the practice level. Practices will be randomised at a 1:1 ratio. Patients will be recruited if they are aged =45 years and have experienced knee pain =4/10 on a numerical rating scale for more than three months. Outcomes are self-reported, patient-level validated measures with the primary outcomes being change in pain and function at 12 months. Secondary outcomes will be assessed at 6 and 12 months. The implementation intervention will support and provide education to intervention group GPs to deliver effective management for patients with knee OA using tailored online training and electronic medical record support. Participants with knee OA will have an initial GP visit to confirm their diagnosis and receive management according to GP intervention or control group allocation. As part of the intervention group GP management, participants with knee OA will be referred to a centralised multidisciplinary service: the PARTNER Care Support Team (CST). The CST will be trained in behaviour change support and evidence-based knee OA management. They will work with patients to develop a collaborative action plan focussed on key self-management behaviours, and communicate with the patients' GPs. Patients receiving care by intervention group GPs will receive tailored OA educational materials, a leg muscle strengthening program, and access to a weight-loss program as appropriate and agreed. GPs in the control group will receive no additional training and their patients will receive usual care. Discussion: This project aims to address a major evidence-to-practice gap in primary care management of OA by evaluating a new service delivery model implemented with an intervention targeting GP practice behaviours to improve the health of people with knee OA. Trial Registration: Australian New Zealand Clinical Trials Registry: ACTRN12617001595303, date of registration 1/12/2017

International genome-wide meta-analysis identifies new primary biliary cirrhosis risk loci and targetable pathogenic pathways.

Primary biliary cirrhosis (PBC) is a classical autoimmune liver disease for which effective immunomodulatory therapy is lacking. Here we perform meta-analyses of discovery data sets from genome-wide association studies of European subjects (n=2,764 cases and 10,475 controls) followed by validation genotyping in an independent cohort (n=3,716 cases and 4,261 controls). We discover and validate six previously unknown risk loci for PBC (Pcombined<5 × 10(-8)) and used pathway analysis to identify JAK-STAT/IL12/IL27 signalling and cytokine-cytokine pathways, for which relevant therapies exist