Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonics
NERC Open Research ArchiveNot a member yet
52556 research outputs found
Sort by
The effect of workplace mobility on air pollution exposure inequality – a case study in the Central Belt of Scotland
Get PDFA large number of epidemiological studies have identified air pollution as a major risk to human health. Exposures to the pollutants PM2.5, NO2 and O3 cause cardiovascular and respiratory diseases, cancer and premature mortality. Whilst previous studies have reported demographic inequalities in exposure, with the most deprived and susceptible often being disproportionately exposed to the highest pollutant concentrations, the vast majority of these studies have quantified exposure based only on individuals' place of residence. Here we use anonymised personal data from UK Census 2011, and hourly modelled air pollution concentrations at 0.8 km × 1.4 km spatial resolution in the Central Belt of Scotland, to investigate how inclusion of time spent at place of work or study affects demographic inequalities in exposure. We split the population by sex, ethnic group, age and socio-economic status. Exposure gradients are observed across all demographic characteristics. Air pollution exposures of males are more affected by workplace exposures than females. The White ethnic group has the lowest exposures to NO2 and PM2.5, and highest to O3. Exposures to NO2 and PM2.5 tend to peak between the ages of 21 and 30, but those aged 31 to 50 tend to be most impacted by the inclusion of time spent at workplace in the exposure assessment. People in the two least deprived deciles consistently have the lowest residential-only and combined residential-workplace exposure to NO2 and PM2.5, but experience the highest increase in exposure when including workplace. Overall, including workplace exposure results in relatively small change in median exposure but attenuates some of the exposure inequalities associated with ethnicity and socioeconomic status observed in exposure assessments based only on place of residence
CO2 Mineralization of Deccan Trap Basalts
No full textIntroduction
Many of India’s large emission sources are located far from sedimentary basin settings where CO2 storage might otherwise be considered. Continental flood basalts of the Deccan Traps cover an estimated 500,000 km3 in west-central India, and there is much interest in their potential to permanently store and trap CO2 through mineral carbonation processes. The Deccan Traps consist of layers of solidified flood basalt more than 2,000 m in thickness. The volume of basalt exceeds 1,000,000 km3 and provides a significant theoretical potential for high-volume storage of CO2. Carbon capture and storage by mineralization (CCSM) has been studied in several regions, including the Wallula Basalt Project in Columbia River, USA, and the Carbfix project in Iceland. Although some previous studies on the trapping potential of basalts have shown promising results, there remains significant uncertainty as to the practicality of storing CO2 volumes at industrial scale in the Deccan Traps.
Theory and/or Method
To gain a preliminary insight into the types of reactions that may be expected during CCSM in Deccan Trap basalts, a core sample taken from the Killari borehole was reacted with CO2-rich water. Prior to reaction the sample was crushed to produce a 125 to 250 μm fraction, which increases the mineral surface area and enhances the rate at which the reactions occur. Future experiments using whole-rock samples will provide more realistic reaction rates, requiring the experiments to be run over a longer period of time to produce detectable mineralogical reactions. To produce basalt-equilibrated fluid for the experiment, this powder was placed in a 1 liter container of deionized water at 70°C for one week. A preliminary study was conducted using three batch vessels containing crushed starting material and the equilibrated fluid pressurized first with nitrogen, and then with CO2 to 90 bar. Each vessel was subjected to a different temperature (50, 100, and 150°C), and reacted for up to 43 days. The selected temperature range reflects the significant variation in geothermal gradient across the Deccan Volcanic Province. Fluid samples were collected at regular intervals for geochemical analysis, while post-reaction solids were examined using Scanning Electron Microscopy (SEM) to provide evidence for mineral dissolution and precipitation.
Example
Little evidence of mineral dissolution or precipitation was observed in the 50˚C experiment, whereas notable dissolution of plagioclase was observed in the 100˚C experiment. There was no clear evidence of carbonate precipitation in either experiment. In contrast, the 150˚C experiment resulted in significant dissolution of plagioclase and precipitation of secondary phases, including rhombohedral crystals of siderite (40-50 μm) and silicate minerals, likely smectite and phases belonging to the zeolite mineral group based on SEM qualitative analysis. Figure 1 shows evidence of the rhombohedral siderite crystals and Figure 2 shows fibrous silicate minerals formed during the 150˚C experiment. Platy silicate minerals were also observed which may be smectite. A significant amount of calcium carbonate and amorphous silica precipitate eventually blocked the fluid sampling tube.
Conclusions
The preliminary data indicates that while dissolution and carbonate mineral precipitation occurred during experiments at 150˚C, the reaction rates were significantly reduced at lower temperatures resulting in less CO2 trapped in mineral form. This indicates that targeting of regions with higher geothermal gradients might be worthwhile for future laboratory and field studies. Ongoing work continues to analyze the fluid geochemistry data, which provide a sensitive analytical means of determining the relative timing and rates of reactions
Computed Laminography for the study of biogenic structures in sediment cores: A step between two- and three-dimensional imaging
Get PDFThe study of trace fossils —ecological indicators of environmental parameters such as organic-matter content, oxygenation or sedimentation rate, among others— is a powerful tool for analysing cores from deep-sea sediment. However, the visualization of biogenic structures in soft sediment cores is commonly poor. This problem has usually been solved by using X-ray radiographs from core slabs, and later by non-destructive Computed Tomography (CT). Yet the latter requires complex processing and computer resources to deal with a vast dataset. Computed Laminography (CL) stands as an alternative, non-destructive technique able to manage a small amount of data, providing results similar to X-ray radiographs. This technique is frequently used in other disciplines (e.g. material sciences), but rarely applied in geosciences. In the present study, we explore the usefulness of CL for studying the ichnological content of modern deep-sea deposits from boxcores collected from the Porcupine Abyssal Plain (NE Atlantic). Additionally, we compare results from Linear CL (LCL) and Circumferential CL (CCL) to discuss which is recommended depending on the goal involved. The obtained results confirm the usefulness of CL for the ichnological analysis of sediment cores, with similar results from LCL and CCL. However, recommendations are made to resolve doubtful scenarios and to save time. In light of our findings, the use of CL as a non-destructive technique, calling for a much smaller dataset than CT, can be highly recommended for the study of ichnological content or other internal structures
Can Recurrence Quantification Analysis Be Useful in the Interpretation of Airborne Turbulence Measurements?
Get PDFIn airborne data or model outputs, clouds are often defined using information about Liquid Water Content (LWC). Unfortunately LWC is not enough to retrieve information about the dynamical boundary of the cloud, that is, volume of turbulent air around the cloud. In this work, we propose an algorithmic approach to this problem based on a method used in time series analysis of dynamical systems, namely Recurrence Plot (RP) and Recurrence Quantification Analysis (RQA). We construct RPs using time series of turbulence kinetic energy, vertical velocity and temperature fluctuations as variables important for cloud dynamics. Then, by studying time series of laminarity (LAM), a variable which is calculated using RPs, we distinguish between turbulent and non-turbulent segments along a horizontal flight leg. By selecting a single threshold of this quantity, we are able to reduce the number of subjective variables and their thresholds used in the definition of the dynamical cloud boundary
Damage to tropical forests caused by cyclones is driven by wind speed but mediated by topographical exposure and tree characteristics
Get PDFEach year, an average of 45 tropical cyclones affect coastal areas and potentially impact forests. The proportion of the most intense cyclones has increased over the past four decades and is predicted to continue to do so. Yet, it remains uncertain how topographical exposure and tree characteristics can mediate the damage caused by increasing wind speed. Here, we compiled empirical data on the damage caused by 11 cyclones occurring over the past 40 years, from 74 forest plots representing tropical regions worldwide, encompassing field data for 22,176 trees and 815 species. We reconstructed the wind structure of those tropical cyclones to estimate the maximum sustained wind speed (MSW) and wind direction at the studied plots. Then, we used a causal inference framework combined with Bayesian generalised linear mixed models to understand and quantify the causal effects of MSW, topographical exposure to wind (EXP), tree size (DBH) and species wood density (ρ) on the proportion of damaged trees at the community level, and on the probability of snapping or uprooting at the tree level. The probability of snapping or uprooting at the tree level and, hence, the proportion of damaged trees at the community level, increased with increasing MSW, and with increasing EXP accentuating the damaging effects of cyclones, in particular at higher wind speeds. Higher ρ decreased the probability of snapping and to a lesser extent of uprooting. Larger trees tended to have lower probabilities of snapping but increased probabilities of uprooting. Importantly, the effect of ρ decreasing the probabilities of snapping was more marked for smaller than larger trees and was further accentuated at higher MSW. Our work emphasises how local topography, tree size and species wood density together mediate cyclone damage to tropical forests, facilitating better predictions of the impacts of such disturbances in an increasingly windier world
CMIP6 Models Rarely Simulate Antarctic Winter Sea‐Ice Anomalies as Large as Observed in 2023
Get PDFIn 2023, Antarctic sea-ice extent (SIE) reached record lows, with winter SIE falling to 2.5Mkm2 below the satellite era average. With this multi-model study, we investigate the occurrence of anomalies of this magnitude in latest-generation global climate models. When these anomalies occur, SIE takes decades to recover: this indicates that SIE may transition to a new, lower, state over the next few decades. Under internal variability alone, models are extremely unlikely to simulate these anomalies, with return period >1000 years for most models. The only models with return period <1000 years for these anomalies have likely unrealistically large interannual variability. Based on extreme value theory, the return period is reduced from 2650 years under internal variability to 580 years under a strong climate change forcing scenario
Growth and ecophysiology of two Antarctic benthic predators; Isotealia antarctica and Urticinopsis antarctica
Get PDFThere is a dearth of basic life history and physiological data from Southern Ocean species, particularly from benthic vagile predators. This is an important data gap because species inhabiting the Southern Ocean live in a more temperature stable but seasonally varying environment than temperate and tropical counterparts. For many species living below 0 ◦C for a significant proportion of the year, bodily functions are slowed to disproportionately lower rates than would be predicted by temperature alone. Certain life history and physiological processes are often aligned with the short summer season of productivity. However, predators may behave differently because they are decoupled from the phytoplankton bloom and some have been shown to exhibit less
seasonal physiological change. To further our understanding of Antarctic predator growth and seasonal ecophysiology, field growth rates were measured for two soft-bodied Antarctic anemone benthic predators, Isotealia antarctica and Urticinopsis antarctica, using in situ sampling of anemones on uniquely marked tiles. Ex situ measurements of oxygen consumption and seven-day faecal output were obtained from recently collected specimens in aquaria and compared between summer and winter. Winter physiological data for Antarctic species are rare, and we tested the hypothesis that generalist feeders or predators continue to feed during the winter. Growth rates differed between species and between years. I. antarctica and U. antarctica both exhibited overall positive field growth rates across a 15 month period between 2020 and 2021; with U. antarctica increasing 199.80% (± SE 25.8) in mass compared to a 16.85% (± SE 8.9) increase in I. antarctica. There was no significant difference in I. antarctica’s growth between 15 and 25 months field deployment. After 25 months, I. antarctica showed an average 7.96% (± SE 8.05) increase in buoyant weight. Ex situ oxygen consumption and faecal egestion did not differ seasonally, which, demonstrates that anemones fed at similar rates during the winter and summer. In contrast to some members of the Antarctica benthos, I. antarctica and U. antarctica actively feed all year round, whereas several other species have been reported to enter a state of torpor in winter
The impact of lake discontinuities on nitrogen biogeochemistry in river networks
Get PDFRiver networks connect terrestrial and marine ecosystems through transport of pollutants and nutrients. Lakes represent discontinuities within these river networks, which can be important biogeochemical hotspots, introducing substantial changes to the aquatic environment. Nitrogen is a key macronutrient that can potentially limit or co-limit primary production, but the processes that determine the fate of nitrogen during transport through river-lake networks are poorly understood. We studied three river systems and their lake discontinuities, spanning a range of trophic states and average water residence times, to understand the changes introduced to riverine nitrogen biogeochemistry by lake discontinuities. In-lake processes noticeably altered the concentration and speciation of nitrogen. Annually, lakes reduced up to 44% of nitrate compared to main inflow concentrations, while there was large variability in nitrate dynamics seasonally. The drawdown in surface nitrate concentrations resulted at times in phytoplankton co-limitation by nitrogen in-lake, as well as in the downstream river, where altered nitrogen patterns could persist for several kilometers. However, lakes occasionally subsidized N to downstream rivers as ammonium or dissolved organic nitrogen. Assimilation of nitrate in lake surface waters was one of the dominant processes impacting nitrogen availability; however, stable isotope data revealed an unexpected contribution of nitrification on nitrogen cycling in the epilimnion throughout the year and across trophic gradients. These changes in nitrogen concentration, as well as speciation introduced by lake discontinuities have potentially important consequences for the composition and metabolism of communities in downstream rivers and contribute to our fundamental understanding of freshwater processes
Linking marine habitats and economic values: A spatial scaling methodology for valuing societal benefits
No full textThere is a growing call to better understand society's relationship with the natural environment and the environment's economic contribution to the economy and human well-being. This paper presents a new methodology for estimating the spatial monetary value of the marine environment at sub-national scales which integrates recent developments in the spatial mapping of marine habitats with those in marine natural capital accounting, coupled with an improved understanding of the links between natural capital and ecosystem services. While this methodology has direct relevance to environmental planning, management and natural capital accounting across the world, for demonstration purposes, the application here focuses on Northern Ireland's marine waters, and its marine protected areas, from UK-wide evidence. Through this method, indicative monetary values of societal benefits gained from Northern Ireland marine waters in 2019 are in the region of £51.1–83.3 million (US$65.2–106.4 million) when considering eight societal benefits currently amenable to valuation at the national UK level. The strengths and limitations of the approach are acknowledged and to operationalise this approach, an Excel-based decision support tool, the BEACH (Benefit Evaluation through Assessment of Component Habitats) tool, has been developed to make value estimations accessible to a wider range of stakeholders
