Sedimentological control on the reservoir and caprock properties of a bleached palaeoreservoir in the Entrada Formation at Salt Wash Graben, Green River, Utah

The stratigraphy and sedimentology of the Entrada Formation are central to understanding the origin of the bleached palaeoreservoir exposed at Salt Wash Graben. Aeolian sandstones of the Slick Rock Member formed high-permeability carrier beds which distributed reducing fluids laterally within the formation. The overlying Earthy Member is a massively-bedded succession of low permeability mudflat/sabkha deposits which acted as a caprock: albeit one that formed an imperfect seal and allowed the upward diffusion of reducing fluids for a distance of up to 4 m above the top of the reservoir. The Salt Wash Graben is located on the crest of the Green River Anticline and was filled by buoyant fluids that may have migrated updip along this north plunging fold; alternatively these fluids may have entered via the northern fault of the Salt Wash Graben. The role of this structure in forming an updip seal during the filling of the reservoir is uncertain. The reservoir was probably filled in the early Cretaceous at a depth of around 1 km or less, during the subsidence phase of the Paradox Basin. The fluids are likely to have been an admixture of H2S, CO2 and CH4. The reservoir was later breached by NNW-trending fractures related to extension across the crest of the Green River Anticline

The importance of lithofacies control on fluid migration in heterogeneous aeolian formations for geological CO2 storage: Lessons from observational evidence and modelling of bleached palaeoreservoirs at Salt Wash Graben, Utah

Exhumed bleached palaeoreservoirs provide a means of understanding fluid flow processes in geological media because the former movement of fluids is preserved as visible geochemical changes (grey bleaching of continental red-beds). The bleached palaeoreservoirs of the Jurassic Entrada Sandstone occur in a region (Utah) where there are high fluxes of naturally-occurring CO2 and form outcrop analogues for processes related to geological storage of CO2. In this paper a bleached palaeoreservoir now exposed at outcrop is used to test the importance of geological heterogeneity on fluid flow. The bleached palaeoreservoir is developed in ‘wet aeolian’ lithofacies composed of alternating layers of sandstone and cemented muddy sandstone that range across three or more orders of magnitude in permeability. Despite these permeability contrasts the bleaching shows a remarkably uniform distribution within the palaeoreservoir that crosses lithofacies boundaries. Evidence from bleaching therefore suggests that geological heterogeneity within the range 1–103 millidarcies should not greatly impede the relatively uniform distribution of low-viscosity CO2 charged fluids throughout a reservoir: a conclusion that has been substantiated here by flow modelling. Residence time is an important factor and where flows are transient the distribution of bleaching and modelling shows that flows are confined to high-permeability lithofacies

Investigation of rising nitrate concentrations in groundwater in the Eden Valley, Cumbria: Phase 1 project scoping study

This is the Investigation of rising nitrate concentrations in groundwater in the Eden Valley, Cumbria report produced by the Environment Agency in 2003. This report focuses on groundwater nitrate concentrations in the Eden Valley. Most boreholes in the Eden Valley had nitrate concentrations less than 20 mg/l but a significant number had higher concentrations, some exceeding the EC maximum admissible concentration for drinking water of 50 mg/l. The main objectives of this report were to investigate the causes of rising nitrate concentrations in groundwater in the Permo-Triassic sandstone aquifers of the Eden Valley area and provide sufficient understanding of the groundwater and surface water flow system, including the sources of the nitrate contamination and the processes controlling nitrate movement, so that possible management options for reversing this trend can be considered

Age and quality stratification of groundwater in the Triassic Sherwood Sandstone aquifer of South Yorkshire and the East Midlands, UK

Groundwater from the Triassic Sherwood Sandstone aquifer of the English East Midlands shows a well-documented evolution in chemistry and residence time as it flows downgradient from shallow unconfined conditions to greater depths, confined by Mercia Mudstone. The flow path covers a lateral distance of some 40 km and depths approaching 800 m. The presence of fresh groundwater (Cl = 15 mg/L, Na = 17 mg/L, SO4 = 144 mg/L, TDS = 500 mg/L) of likely Pleistocene age can be demonstrated down to about 500 m depth in the aquifer, some 10 km downgradient of its confined/unconfined interface. This is amongst the deepest fresh groundwater identified in the UK. Beyond that zone, salinity increases in response to dissolution of gypsum or anhydrite, giving Ca-SO4 groundwater. Further downgradient still, saline groundwater (TDS = 10 g/L) is encountered in the deepest part of the confined aquifer. Downgradient geochemical evolution and increasing residence time are also observed in the South Yorkshire section of the aquifer, to the north of the East Midlands flow path. Here, analogous sequential geochemical changes are observed, controlled by carbonate and sulphate mineral reactions, redox changes and silicate hydrolysis, with evidence of increased inputs of e.g. Na, Cl and SO4 from modern pollution at shallow depths in the unconfined aquifer. Redox conditions are more variable in the western part of the South Yorkshire aquifer, due to local confinement or semi-confinement by fine-grained Quaternary deposits overlying the Sherwood Sandstone. Ratios of δ13C in this section of aquifer increase from −14‰ at outcrop to −11‰ in Mercia-Mudstone-confined conditions as a result of gradual equilibration with aquifer carbonate under closed-system conditions. Ratios of δ18O and δ2H become more depleted, reaching −9‰ and −61‰ respectively, suggesting recharge under climatic conditions significantly cooler than the modern era. Increasing residence time is also indicated by increasing concentrations of a number of trace elements (e.g. Li, Rb, Sr, Mo). These transitions are also observed vertically within investigated boreholes in unconfined and semi-confined sections of the aquifer. Deep groundwater (160–170 m depth) from a borehole within the unconfined aquifer of South Yorkshire has δ18O and δ2H ratios as depleted as −9.2‰ and −67‰ respectively. Such depth stratification indicates that good-quality palaeowater, likely of Pleistocene age, can exist at depth even in the unconfined Sherwood Sandstone aquifer, and that vertical hydraulic conductivity is much lower than lateral. A paucity of boreholes in the Mercia-Mudstone-confined section of the South Yorkshire aquifer makes estimation of the lateral extent of fresh groundwater there more problematic, though brackish groundwater (Cl = 1300 mg/L, TDS = 5.5 g/L) has been identified 12 km east of the aquifer's confined margin

A 3D geological model of post Carboniferous strata in the south Fylde area of the West Lancashire Basin, Blackpool, UK

The British Geological Survey (BGS), together with a number of partners is undertaking an independent environmental monitoring programme to characterise baseline conditions in the south Fylde east of Blackpool in an area proposed for shale-gas exploration and production. The monitoring will include measurement of: water quality (groundwater and surface water), seismicity, ground motion, air quality including radon, and soil gas. The programme aims to establish the environmental baseline before any shale-gas explorations begin. This report presents the results of a desk study to develop an initial summary of the post- Carboniferous bedrock geology of the south Fylde. It is a component and specific deliverable of the environmental baseline project. The bedrock deposits form a number of shallow aquifers that are used locally for drinking water supply and agriculture. A separate report considers the superficial geology. The geological information in this report will form the basis for identifying aquifer dimensions and configurations, groundwater flow paths and potential contaminant migration pathways, as well as determining optimum locations for sampling and monitoring. It will also provide information to support the locating of new borehole infrastructure (suitable for groundwater sampling and seismometers) and will underpin the interpretation of acquired hydrogeochemical data

Tracing groundwater flow and sources of organic carbon in sandstone aquifers using fluorescence properties of dissolved organic matter (DOM)

The fluorescence properties of groundwaters from sites in two UK aquifers, the Penrith Sandstone of Cumbria and the Sherwood Sandstone of South Yorkshire, were investigated using excitation-emission matrix (EEM) fluorescence spectroscopy. Both aquifers are regionally important sources of public supply water and are locally impacted by anthropogenic pollution. The Penrith Sandstone site is in a rural setting while the Sherwood Sandstone site is in suburban Doncaster. Fluorescence analysis of samples from discrete sample depths in the Penrith Sandstone shows decreasing fulvic-like intensities with depth and also shows a good correlation with CFC-12, an anthropogenic groundwater tracer. Tryptophan- like fluorescence centres in the depth profile may also provide evidence of rapid routing of relatively recent applications of organic slurry along fractures. Fluorescence analysis of groundwater sampled from multi-level piezometers installed within the Sherwood Sandstone aquifer also shows regions of tryptophan-like and relatively higher fulvic-like signatures. The fluorescence intensity profile in the piezometers shows tryptophan-like peaks at depths in excess of 50 metres and mirrors the pattern exhibited by microbial species and CFCs highlighting the deep and rapid penetration of modern recharge due to rapid fracture flow. Fluorescence analysis has allowed the rapid assessment of different types and relative abundances of dissolved organic matter (DOM), and the fingerprinting of different sources of organic carbon within the groundwater system. The tryptophan:fulvic ratios found in the Penrith Sandstone were found to be between (0.5–3.0) and are characteristic of ratios from sheep waste sources. The Sherwood Sandstone has the lowest ratios (0.2–0.4) indicating a different source of DOM, most likely a mixture of terrestrial and microbial sources, although there is little evidence of pollution from leaking urban sewage systems. Results from these two studies suggest that intrinsic fluorescence may be used as a proxy for, or complimentary tool to, other groundwater investigation methods in helping provide a conceptual model of groundwater flow and identifying different sources of DOM within the groundwater system

Preliminary assessment of the environmental baseline in the Fylde, Lancashire

This report presents the collated preliminary results from the British Geological Survey (BGS) led project Science-based environmental baseline monitoring associated with shale gas development in the Fylde, Lancashire. The project has been funded by a combination of BGS National Capability funding, in-kind contributions from project partners and a grant awarded by the Department of Business Energy and Investment Strategy (BEIS). It complements an on-going project, in which similar activities are being carried out, in the Vale of Pickering, North Yorkshire. Further information on the projects can be found on the BGS website: www.bgs.ac.uk. The project has initiated a wide-ranging environmental baseline monitoring programme that includes water quality (groundwater and surface water), seismicity, ground motion, atmospheric composition (greenhouse gases and air quality), soil gas and radon in air (indoors and outdoors). The motivation behind the project(s) was to establish independent monitoring in the area around the proposed shale gas hydraulic fracturing sites in the Fylde, Lancashire (Cuadrilla Resources Ltd) before any shale gas operations take place. As part of the project, instrumentation has been deployed to measure, in real-time or near real-time, a range of environmental variables (water quality, seismicity, atmospheric composition). These data are being displayed on the project’s web site (www.bgs.ac.uk/lancashire). Additional survey, sampling and monitoring has also been carried out through a co-ordinated programme of fieldwork and laboratory analysis, which has included installation of new monitoring infrastructure, to allow compilation of one of the most comprehensive environmental datasets in the UK. The monitoring programme is continuing. However, there are already some very important findings emerging from the limited datasets which should be taken into account when developing future monitoring strategy, policy and regulation. The information is not only relevant to Lancashire but will be applicable more widely in the UK and internationally. Although shale gas operations in other parts of the world are well-established, there is a paucity of good baseline data and effective guidance on monitoring. The project will also allow the experience gained, and the scientifically-robust findings to be used, to develop and establish effective environmental monitoring strategies for shale gas and similar industrial activities

Diving into the vertical dimension of elasmobranch movement ecology

Knowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species. Elasmobranchs displayed high intra- and interspecific variability in vertical movement patterns. Substantial vertical overlap was observed for many epipelagic elasmobranchs, indicating an increased likelihood to display spatial overlap, biologically interact, and share similar risk to anthropogenic threats that vary on a vertical gradient. We highlight the critical next steps toward incorporating vertical movement into global management and monitoring strategies for elasmobranchs, emphasizing the need to address geographic and taxonomic biases in deployments and to concurrently consider both horizontal and vertical movements

COVID-19: Rapid antigen detection for SARS-CoV-2 by lateral flow assay: A national systematic evaluation of sensitivity and specificity for mass-testing

Background Lateral flow device (LFD) viral antigen immunoassays have been developed around the world as diagnostic tests for SARS-CoV-2 infection. They have been proposed to deliver an infrastructure-light, cost-economical solution giving results within half an hour. Methods LFDs were initially reviewed by a Department of Health and Social Care team, part of the UK government, from which 64 were selected for further evaluation from 1st August to 15th December 2020. Standardised laboratory evaluations, and for those that met the published criteria, field testing in the Falcon-C19 research study and UK pilots were performed (UK COVID-19 testing centres, hospital, schools, armed forces). Findings 4/64 LFDs so far have desirable performance characteristics (orient Gene, Deepblue, Abbott and Innova SARS-CoV-2 Antigen Rapid Qualitative Test). All these LFDs have a viral antigen detection of >90% at 100,000 RNA copies/ml. 8951 Innova LFD tests were performed with a kit failure rate of 5.6% (502/8951, 95% CI: 5.1–6.1), false positive rate of 0.32% (22/6954, 95% CI: 0.20–0.48). Viral antigen detection/sensitivity across the sampling cohort when performed by laboratory scientists was 78.8% (156/198, 95% CI 72.4–84.3). Interpretation Our results suggest LFDs have promising performance characteristics for mass population testing and can be used to identify infectious positive individuals. The Innova LFD shows good viral antigen detection/sensitivity with excellent specificity, although kit failure rates and the impact of training are potential issues. These results support the expanded evaluation of LFDs, and assessment of greater access to testing on COVID-19 transmission. Funding Department of Health and Social Care. University of Oxford. Public Health England Porton Down, Manchester University NHS Foundation Trust, National Institute of Health Research

On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection

A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)