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  • Journal article
    Kia A, Wong H, Cheeseman C, 2019,

    High-strength clogging resistant permeable pavement

    , International Journal of Pavement Engineering, ISSN: 1029-8436

    Permeable pavement is utilised in order to alleviate flooding in towns, cities and other urban areas, but it is prone to clogging, has relatively low strength and requires regular maintenance. We have developed a novel permeable pavement with low tortuosity pore structure that can be cast on-site that is not only resistant to clogging, but also has high permeability and strength. This high strength clogging resistant permeable pavement (CRP) was prepared by introducing straight pore channels of varying size and number into self-compacting mortar. Samples with porosity ranging from 2 to 32% were tested. In all cases, permeability and compressive strength were substantially higher than conventional permeable concrete. More significantly, CRP can be engineered with low porosity (5%), high strength (> 50 MPa) and high permeability (> 2 cm/s), but does not clog despite extensive cyclic exposure to flow containing sand and clay. A simple method to model the permeability of CRP from the pore structure is described. We report for the first time a high strength clogging resistant permeable pavement capable of retaining sufficient porosity and permeability for storm-water infiltration without requiring frequent maintenance. This innovative system will help alleviate urban flooding and contribute towards a more sustainable urbanisation.
  • Journal article
    Gschwend F, Chambon C, Biedka M, Brandt-Talbot A, Fennell P, Hallett Jet al., 2019,

    Quantitative glucose release from softwood after pretreatment with low-cost ionic liquids

    , Green Chemistry, Vol: 21, Pages: 692-703, ISSN: 1463-9262

    Softwood is an abundantly available feedstock for the bio-based industry, however, achieving cost-effective sugar release is particularly challenging owing to its guaiacyl-only lignin. Here, we report the highly effective pretreatment of the softwood pine (Pinus sylvestris) using ionoSolv pretreatment, a novel ionic liquid-based lignocellulose fractionation technology. Three protic, low-cost ionic liquids, 1-butylimidazolium hydrogen sulfate, triethylammonium hydrogen sulfate and N,N-dimethylbutylammonium hydrogen sulfate, were used to fractionate the biomass into a carbohydrate-rich pulp and a lignin. The carbohydrate-rich pulp was hydrolysed into fermentable sugars by enzymatic saccharification. Under the most successful pretreatment conditions, quantitative glucose release from the pulp was achieved, which equates to a projected glucose release of 464 mg per gram of pine wood entering the process. We further intensified the process by increasing the solid to solvent ratio up to 1:2 g/g while maintaining saccharification yields of 75% of the theoretical maximum. We also demonstrate for the first time that N,N-dimethylbutylammonium hydrogen sulfate, [DMBA][HSO4] is an excellent low-cost pretreatment solvent, surpassing the pretreatment effectiveness of its symmetrically substituted analogue triethylammonium hydrogen sulfate. This shows that ionoSolv pretreatment with protic hydrogen sulfate ionic liquids is a truly feedstock-independent pretreatment option, further increasing the commercial potential of this pretreatment technology.
  • Journal article
    Vineis P, Fecht D, 2018,

    Environment, cancer and inequalities-The urgent need for prevention

    , European Journal of Cancer, Vol: 103, Pages: 317-326, ISSN: 0959-8049

    The proportion of total deaths attributable to environmental factors is estimated to be 23% of global deaths and 22% of global disability-adjusted life years (DALYs) according to one review. These estimates encompass all environmental agents including infectious agents but excluding behavioural factors. The authors of the review also estimated that 16% (95% CI: 7-41%) of cancer deaths are attributable to environmental risk factors (and 36% [95% CI: 17-52%] for lung cancer). In this article, we focus on the reasons why epidemiology is often unable to account for the whole burden of environmental carcinogens. The experience of air pollution is particularly instructive. While in the 1970s and early 1980s, air pollution was considered as a relatively marginal exposure in terms of attributable risks, the most recent estimate is that it accounts for 7.6% of global deaths and 4.2% of global DALYs world-wide (with East and South Asia accounting for 59% of the total). According to a review, ambient fine particulate matter air pollution contributed to 17.1% of ischaemic heart disease, 14.2% of cerebrovascular disease, 16.5% of lung cancer, 24.7% of low respiratory infections, and 27.1% of COPD mortality in 2015. Estimates for cancer as a whole are not available. The change in appreciation of the role of air pollution has been mainly due to the refinement of exposure assessment methods and the new generations of longitudinal studies. Mechanistic evidence via omic technologies is now rapidly increasing, thus lending credibility to previous epidemiological ('black box') associations. Much less is known about other environmental contaminants, some of which are widespread and pervasive, thus suggesting the need for the same rigourous methods as those applied to air pollution. Finally, a crucial issue remains inequality across different population groups, with uneven exposure to hazards and acquired susceptibilities due to multiple concomitant exposures and poorer health status.
  • Journal article
    Bull R, Romanowicz J, Jennings N, Laskari M, Stuart G, Everitt Det al., 2018,

    Competing priorities: lessons in engaging students to achieve energy savings in universities

    , International Journal of Sustainability in Higher Education, Vol: 19, ISSN: 1467-6370

    PurposeThis paper aims to present findings from an EU-funded international student-led energy saving competition (SAVES) on a scale previously unseen. There are multiple accounts of short-term projects and energy saving competitions encouraging pro-environmental behaviour change amongst students in university dormitories, but the purpose of this research is to provide evidence of consistent and sustained energy savings from student-led energy savings competitions, underpinned by practical action.Design/methodology/approachA mixed-methods approach (pre- and post-intervention surveys, focus groups and analysis of energy meter data) was used to determine the level of energy savings and quantifiable behaviour change delivered by students across participating university dormitories.FindingsThis research has provided further insight into the potential for savings and behaviour change in university dormitories through relatively simple actions. Whilst other interventions have shown greater savings, this project provided consistent savings over two years of 7 per cent across a large number of university dormitories in five countries through simple behaviour changes.Research limitations/implicationsAn energy dashboard displaying near a real-time leaderboard was added to the engagement in the second year of the project. Whilst students were optimistic about the role that energy dashboards could play, the evidence is not here to quantify the impact of dashboards. Further research is required to understand the potential of dashboards to contribute to behavioural change savings and in constructing competitions between people and dormitories that are known to each other.Social implicationsSAVES provided engagement with students, enabling, empowering and motivating them to save energy – focusing specifically on the last stage of the “Awareness, Interest, Desire, Action” framework. Automated meter reading data was used in the majority of participating dormitories
  • Journal article
    Chambon C, Mkhize T, Reddy P, Brandt-Talbot A, Deenadayalu N, Fennell P, Hallett Jet al., 2018,

    Pretreatment of South African sugarcane bagasse using a low-cost protic ionic liquid: a comparison of whole, depithed, fibrous and pith bagasse fractions

    , Biotechnology for Biofuels, Vol: 11, ISSN: 1754-6834

    BackgroundSugarcane bagasse is an abundant and geographically widespread agro-industrial residue with high carbohydrate content, making it a strong candidate feedstock for the bio-based economy. This study examines the use of the low-cost protic ionic liquid triethylammonium hydrogen sulfate ([TEA][HSO4]) to fractionate a range of South African sugarcane bagasse preparations into a cellulose-rich pulp and lignin. The study seeks to optimize pretreatment conditions and examine the necessity of applying a depithing step on bagasse prior to pretreatment.ResultsPretreatment of five bagasse preparations, namely whole, industrially depithed, laboratory depithed (short and long fiber) and pith bagasse with [TEA][HSO4]:[H2O] (4:1 w/w) solutions produced highly digestible cellulose-rich pulps, as assessed by residual lignin analysis and enzymatic hydrolysis. Pretreatment under the optimized condition of 120 °C for 4 h produced a pretreated cellulose pulp with up to 90% of the lignin removed and enabled the release of up to 69% glucose contained in the bagasse via enzymatic hydrolysis. Glucose yields from whole and depithed bagasse preparations were very similar. Significant differences in lignin recovery were obtained for laboratory depithed bagasse compared with whole and industrially depithed bagasse. The silica-rich ash components of bagasse were seen to partition mainly with the pulp, from where they could be easily recovered in the post-hydrolysis solids.ConclusionsThe five bagasse preparations were compared but did not show substantial differences in composition or cellulose digestibility after pretreatment. Evidence was presented that a depithing step appears to be unnecessary prior to ionoSolv fractionation, potentially affording significant cost and energy savings. Instead, lignin re-deposition onto the pulp surface (and, in turn, particle size and shape) appeared to be major factors affecting the conditioning of bagasse with the applied IL. We show that pith ba
  • Journal article
    Pierotti L, Schofield SJ, Collett D, Fecht D, De Hoogh K, Hansell AL, Dark J, Cullinan Pet al., 2018,

    Traffic-related air pollution and solid organ transplant failure in Great Britain: A retrospective cohort study

    , Journal of Transport and Health, Vol: 10, Pages: 124-131, ISSN: 2214-1405

    Background: Limited evidence suggests that exposure to traffic related air pollution is associated with graft failure among lung transplant recipients. We explored associations between pollution and transplant failure among lung and other solid organ transplant recipients in Great Britain through a retrospective cohort study. Methods: All patients who received a lung, heart, liver, or kidney transplant between 2000 and 2008 in Great Britain were included, as recorded in the National Health Service Blood and Transplant (NHSBT) register and followed to March 2015. Using residential addresses at time of transplant we calculated distance to nearest (major) road and modelled annual average exposures to airborne nitrogen oxides and particulate matter of diameter ≤10µm and ≤2.5µm for each transplant recipient. All-cause mortality or graft failure (kidney) during follow up was the main outcome; median follow-up was around 10 years for each organ type. We fitted Cox regression models with adjustment for age, sex, year of transplant and donor age/smoking status. Results: 780 lung, 1213 heart, 3650 liver and 11966 graft kidney transplant patients were analysed. We did not find any consistent associations between mortality or graft failure and any of the analysed air pollutants or road metrics. Although, exposure to particulate matter was associated with renal transplant failure in univariable analyses but not after adjustment for confounders. Conclusions: Our analysis does not confirm previously reported associations between traffic-related air pollution exposure and the risk of transplant failure.
  • Journal article
    Yunus IS, Wichmann J, Wördenweber R, Lauersen KJ, Kruse O, Jones PRet al., 2018,

    Synthetic metabolic pathways for photobiological conversion of CO2 into hydrocarbon fuel

    , Metabolic Engineering, Vol: 49, Pages: 201-211, ISSN: 1096-7176

    Liquid fuels sourced from fossil sources are the dominant energy form for mobile transport today. The consumption of fossil fuels is still increasing, resulting in a continued search for more sustainable methods to renew our supply of liquid fuel. Photosynthetic microorganisms naturally accumulate hydrocarbons that could serve as a replacement for fossil fuel, however productivities remain low. We report successful introduction of five synthetic metabolic pathways in two green cell factories, prokaryotic cyanobacteria and eukaryotic algae. Heterologous thioesterase expression enabled high-yield conversion of native fatty acyl-acyl carrier protein (ACP) into free fatty acids (FFA) in Synechocystis sp. PCC 6803 but not in Chlamydomonas reinhardtii where the polar lipid fraction instead was enhanced. Despite no increase in measurable FFA in Chlamydomonas, genetic recoding and over-production of the native fatty acid photodecarboxylase (FAP) resulted in increased accumulation of 7-heptadecene. Implementation of a carboxylic acid reductase (CAR) and aldehyde deformylating oxygenase (ADO) dependent synthetic pathway in Synechocystis resulted in the accumulation of fatty alcohols and a decrease in the native saturated alkanes. In contrast, the replacement of CAR and ADO with Pseudomonas mendocina UndB (so named as it is responsible for 1-undecene biosynthesis in Pseudomonas) or Chlorella variabilis FAP resulted in high-yield conversion of thioesterase-liberated FFAs into corresponding alkenes and alkanes, respectively. At best, the engineering resulted in an increase in hydrocarbon accumulation of 8- (from 1 to 8.5 mg/g cell dry weight) and 19-fold (from 4 to 77 mg/g cell dry weight) for Chlamydomonas and Synechocystis, respectively. In conclusion, reconstitution of the eukaryotic algae pathway in the prokaryotic cyanobacteria host generated the most effective system, highlighting opportunities for mix-and-match synthetic metabolism. These studies describe functioning synt
  • Journal article
    Yunus IS, Jones PR, 2018,

    Photosynthesis-dependent biosynthesis of medium chain-length fatty acids and alcohols

    , Metabolic Engineering, Vol: 49, Pages: 59-68, ISSN: 1096-7176

    Cyanobacteria can directly channel atmospheric CO2 into a wide range of versatile carbon products such as fatty acids and fatty alcohols with applications including fuel, cosmetics, and health products. Works on alcohol production in cyanobacteria have so far focused on either long (C12-C18) or short (C2-C4) chain-length products. In the present work, we report the first synthetic pathway for 1-octanol (C8) biosynthesis in Synechocystis sp. PCC 6803, employing a carboxylic acid reductase and C8-preferring fatty acyl-ACP thioesterase. The first engineered strain produced 1-octanol but exhibited poor productivity and cellular health issues. We therefore proceeded to systematically optimize the strain and cultivation conditions in order to understand what the limiting factors were. The identification of optimal promoters and ribosomal binding sites, in combination with isopropyl myristate solvent overlay, resulted in a combined (C8-OH and C10-OH) titer of more than 100 mg/L (a 25-fold improvement relative to the first engineered strain) and a restoration of cellular health. Additionally, more than 905 mg/L 1-octanol was produced when the strain expressing sfp (phosphopantetheinyl transferase) and car (carboxylic acid reductase) was fed with octanoic acid. A combination of feeding experiments and protein quantification indicated that the supply of octanoic acid from the introduced thioesterase, and possibly also native fatty acid synthesis pathway, were the main bottlenecks of the pathway.
  • Journal article
    Gschwend FJV, Brandt-Talbot A, Malaret FJ, Shinde S, Hallett JPet al., 2018,

    Rapid pretreatment of Miscanthus using the low-cost ionic liquid triethylammonium hydrogen sulfate at elevated temperatures

    , Green Chemistry, Vol: 20, Pages: 3486-3498, ISSN: 1463-9262

    Deconstruction with low-cost ionic liquids (ionoSolv) is a promising method to pre-condition lignocellulosic biomass for the production of renewable fuels, materials and chemicals. This study investigated process intensification strategies for the ionoSolv pretreatment of Miscanthus X giganteus using the low-cost ionic liquid triethylammonium hydrogen sulfate ([TEA][HSO4]) in the presence of 20 wt% water, using high temperatures and a high solid to solvent loading of 1:5 g/g. The temperatures investigated were 150, 160, 170 and 180°C. We discuss the effect of pretreatment temperature on lignin and hemicellulose removal, cellulose degradation and enzymatic saccharification yields. We report that very good fractionation can be achieved across all investigated temperatures, including an enzymatic saccharification yield exceeding 75% of the theoretical maximum after only 15 min of treatment at 180°C. We further characterised the recovered lignins which established some tunability of the hydroxyl group content, subunit composition, connectivity and molecular weight distribution in the isolated lignin while maintaining maximum saccharification yield. This drastic reduction of pretreatment time at increased biomass loading without a yield penalty is promising for the development of a commercial ionoSolv pretreatment process.
  • Report
    Pimpin L, Retat L, Fecht D, de Preux Gallone LB, Sassi F, Gulliver J, Belloni A, Ferguson B, Corbould E, Jaccard A, Webber Let al., 2018,

    Estimation of costs to the NHS and social care due to the health impacts of air pollution
  • Journal article
    Williams ML, Lott MC, Kitwiroon N, Dajnak D, Walton H, Holland M, Pye S, Fecht D, Toledano MB, Beevers SDet al., 2018,

    The Lancet countdown on health benefits from the UK Climate Change Act: a modelling study for Great Britain

    , Lancet Planetary Health, Vol: 2, Pages: e202-e213, ISSN: 2542-5196

    BACKGROUND: Climate change poses a dangerous and immediate threat to the health of populations in the UK and worldwide. We aimed to model different scenarios to assess the health co-benefits that result from mitigation actions. METHODS: In this modelling study, we combined a detailed techno-economic energy systems model (UK TIMES), air pollutant emission inventories, a sophisticated air pollution model (Community Multi-scale Air Quality), and previously published associations between concentrations and health outcomes. We used four scenarios and focused on the air pollution implications from fine particulate matter (PM2·5), nitrogen dioxide (NO2) and ozone. The four scenarios were baseline, which assumed no further climate actions beyond those already achieved and did not meet the UK's Climate Change Act (at least an 80% reduction in carbon dioxide equivalent emissions by 2050 compared with 1990) target; nuclear power, which met the Climate Change Act target with a limited increase in nuclear power; low-greenhouse gas, which met the Climate Change Act target without any policy constraint on nuclear build; and a constant scenario that held 2011 air pollutant concentrations constant until 2050. We predicted the health and economic impacts from air pollution for the scenarios until 2050, and the inequalities in exposure across different socioeconomic groups. FINDINGS: NO2 concentrations declined leading to 4 892 000 life-years saved for the nuclear power scenario and 7 178 000 life-years saved for the low-greenhouse gas scenario from 2011 to 2154. However, the associations that we used might overestimate the effects of NO2 itself. PM2·5 concentrations in Great Britain are predicted to decrease between 42% and 44% by 2050 compared with 2011 in the scenarios that met the Climate Change Act targets, especially those from road traffic and off-road machinery. These reductions in PM2·5 are tempered by a 2035 peak (and subsequent decline) in biomass (wood
  • Journal article
    Tonne C, Milà C, Fecht D, Alvarez M, Gulliver J, Smith J, Beevers S, Ross Anderson H, Kelly Fet al., 2018,

    Socioeconomic and ethnic inequalities in exposure to air and noise pollution in London

    , Environment International, Vol: 115, Pages: 170-179, ISSN: 0160-4120

    BACKGROUND: Transport-related air and noise pollution, exposures linked to adverse health outcomes, varies within cities potentially resulting in exposure inequalities. Relatively little is known regarding inequalities in personal exposure to air pollution or transport-related noise. OBJECTIVES: Our objectives were to quantify socioeconomic and ethnic inequalities in London in 1) air pollution exposure at residence compared to personal exposure; and 2) transport-related noise at residence from different sources. METHODS: We used individual-level data from the London Travel Demand Survey (n = 45,079) between 2006 and 2010. We modeled residential (CMAQ-urban) and personal (London Hybrid Exposure Model) particulate matter <2.5 μm and nitrogen dioxide (NO2), road-traffic noise at residence (TRANEX) and identified those within 50 dB noise contours of railways and Heathrow airport. We analyzed relationships between household income, area-level income deprivation and ethnicity with air and noise pollution using quantile and logistic regression. RESULTS: We observed inverse patterns in inequalities in air pollution when estimated at residence versus personal exposure with respect to household income (categorical, 8 groups). Compared to the lowest income group (<£10,000), the highest group (>£75,000) had lower residential NO2 (-1.3 (95% CI -2.1, -0.6) μg/m3 in the 95th exposure quantile) but higher personal NO2 exposure (1.9 (95% CI 1.6, 2.3) μg/m3 in the 95th quantile), which was driven largely by transport mode and duration. Inequalities in residential exposure to NO2 with respect to area-level deprivation were larger at lower exposure quantiles (e.g. estimate for NO2 5.1 (95% CI 4.6, 5.5) at quantile 0.15 versus 1.9 (95% CI 1.1, 2.6) at quantile 0.95), reflecting low-deprivation, high residential NO2 areas in the city centre. Air pollution exposure at residence consistently overestimated personal exposure; this overestimation varied with age
  • Journal article
    Fellenor JF, Barnett J, Potter C, Urquhart J, Mumford JD, Quine CPet al., 2018,

    The social amplification of risk on Twitter: the case of ash dieback disease in the United Kingdom

    , Journal of Risk Research, Vol: 21, Pages: 1163-1183, ISSN: 1466-4461

    It has long been recognised that the traditional media play a key role in representing risk and are a significant source of information which can shape how people perceive and respond to hazard events. Early work utilising the social amplification of risk framework (SARF) sought to understand the discrepancy between expert and lay perceptions of risk and patterns of risk intensification and attenuation with reference to the media. However, the advent of Web 2.0 challenges traditional models of communication. To date there has been limited consideration of social media within the SARF and its role in mediating processes of risk perception and communication. Against this backdrop, we focus on the social media platform Twitter to consider the social amplification of risk in relation to ash dieback disease (Hymenoscyphus fraxineus); a tree health issue that attracted intense media attention when it was first identified in the UK in 2012. We present an empirical analysis of 25,600 tweets in order to explore what people were saying about ash dieback on Twitter, who was talking about it and how they talked about it. Our discussion outlines the themes around which talk about ash dieback was orientated, the significance of users’ environmental ‘affiliations’ and the role of including links (URLs) to traditional media coverage. We utilise the notion of ‘piggybacking’ to demonstrate how information is customised in line with group/individual identities and interests and introduce the concept of the ‘frame fragment’ to illustrate how information is selected and moved around Twitter emphasising certain features of the messages. The paper affords a detailed consideration of the way in which people and organisations simultaneously appropriate, construct and pass on risk-relevant information. A conclusion is that social media has the potential to transform the media landscape within which the SARF was originally conceived, presenting renewe
  • Journal article
    Smith RB, Fecht D, Gulliver J, Beevers S, Dajnak D, Blangiardo M, Ghosh R, Hansell A, Kelly F, Anderson HR, Toledano MBet al., 2017,

    Impact of London's road traffic air and noise pollution on birth weight: retrospective population based cohort study

    , BMJ, Vol: 359, Pages: j5299-j5299, ISSN: 1756-1833
  • Journal article
    Parrenin F, Cavitte MGP, Blankenship DD, Chappellaz J, Fischer H, Gagliardini O, Masson-Delmotte V, Passalacqua O, Ritz C, Siegert MJ, Roberts J, Young DAet al., 2017,

    Is there 1.5 million-year old ice near Dome C, Antarctica?

    , The Cryosphere, Vol: 11, Pages: 2427-2437, ISSN: 1994-0416

    Ice sheets provide exceptional archives of past changes in polar climate, regional environment and global atmospheric composition. The oldest dated deep ice core drilled in Antarctica has been retrieved at EPICA Dome C (EDC), reaching ∼ 800 000 years. Obtaining an older paleoclimatic record from Antarctica is one of the greatest challenges of the ice core community. Here, we use internal isochrones, identified from airborne radar coupled to ice-flow modelling to estimate the age of basal ice along transects in the Dome C area. Three glaciological properties are inferred from isochrones: surface accumulation rate, geothermal flux and the exponent of the Lliboutry velocity profile. We find that old ice (> 1.5 Myr, 1.5 million years) likely exists in two regions: one ∼ 40 km south-west of Dome C along the ice divide to Vostok, close to a secondary dome that we name Little Dome C (LDC), and a second region named North Patch (NP) located 10–30 km north-east of Dome C, in a region where the geothermal flux is apparently relatively low. Our work demonstrates the value of combining radar observations with ice flow modelling to accurately represent the true nature of ice flow, and understand the formation of ice-sheet architecture, in the centre of large ice sheets.
  • Book chapter
    Gschwend FJV, Brandt-Talbot A, Chambon CL, Hallett JPet al., 2017,

    Ultra-Low Cost Ionic Liquids for the Delignification of Biomass

    , Ionic Liquids: Current State and Future Directions, Editors: Shiflett, Scurto, Publisher: American Chemical Society, Pages: 209-223, ISBN: 9780841232136

    Low-cost pretreatment of lignocellulosic biomass is an essential next step toward large-scale deployment as renewable liquid fuels, materials or chemicals. Ionic liquids (ILs) are highly effective at pretreatment, but high IL cost has hindered commercial viability. We have recently developed low-cost (ca. $1/kg) ILs, such as triethylammonium hydrogen sulphate, for pretreatment. In this chapter we discuss the fractionation of the grass Miscanthus x giganteus, wherein we deconstruct the lignocellulosic matrix into a cellulose-rich pulp, a recovered lignin fraction and an organic distillate. More than 80% of the lignin and quantitative hemicelluloses are removed during extraction. This results in 70-90% glucose release during enzymatic saccharification. The IL can also be successfully recovered and reused, with >99% IL recovery and minimal effects on efficiency of extraction. A detailed mass balance of all components and subsequent economic analysis revealed this efficient pretreatment with an ultra-low cost IL could result in an economically viable pretreatment process.
  • Journal article
    Morlighem M, Williams C, Rignot E, An L, Bamber J, Chauche N, Dowdeswell J, Dorschel B, Holland DM, Holland D, Howat I, Hubbard A, Jordan T, Millan R, Mouginot J, Noel B, OCofaigh C, Seroussi H, Siegert M, Slabon P, van den Broeke M, Weinrebe Wet al., 2017,

    BedMachine v3: Complete bed topography and ocean bathymetry mapping of Greenland from multi-beam radar sounding combined with mass conservation

    , Geophysical Research Letters, Vol: 44, Pages: 11,051-11,061, ISSN: 0094-8276

    Greenland’s bed topography is a primary control on ice flow, grounding line migration,calving dynamics, and subglacial drainage. Moreover, fjord bathymetry regulates the penetration of warmAtlantic water (AW) that rapidly melts and undercuts Greenland’s marine-terminating glaciers. Here wepresent a new compilation of Greenland bed topography that assimilates seafloor bathymetry and icethickness data through a mass conservation approach. A new 150 m horizontal resolution bed topography/bathymetric map of Greenland is constructed with seamless transitions at the ice/ocean interface, yieldingmajor improvements over previous data sets, particularly in the marine-terminating sectors of northwestand southeast Greenland. Our map reveals that the total sea level potential of the Greenland ice sheetis 7.42 ± 0.05 m, which is 7 cm greater than previous estimates. Furthermore, it explains recent calvingfront response of numerous outlet glaciers and reveals new pathways by which AW can access glacierswith marine-based basins, thereby highlighting sectors of Greenland that are most vulnerable to futureoceanic forcing.
  • Journal article
    Cai Y, Hodgson S, Blangiardo M, Gulliver J, Morley D, Vienneau D, de Hoogh K, Key T, Hveem K, Elliott P, Hansell Aet al., 2017,

    Road traffic noise and incident cardiovascular disease: a joint analysis of HUNT, EPIC-Oxford and UK Biobank

    , ICBEN 2017 Proceedings

    Aims: This study aimed to investigate the effects of long-term exposure to road traffic noise on incident CVD in three large cohorts: HUNT, EPIC-Oxford and UK Biobank. Methods: In a complete-case sample (N=361,699), 4,014 IHD and 2,109 cerebrovascular incident cases were ascertained between baseline (1993-2010) and end of follow-up (2008-2015) through medical record linkage. Annual mean road traffic noise exposure was modelled at baseline address. Individual-level covariate data were harmonised and data were pooled. Analyses used Cox proportional hazards model with adjustments for confounders, including air pollution. Results: For an interquartile range (IQR) (3.9 dBA) higher daytime noise, a non-significant association with incident IHD was seen (Hazard ratio (HR): 1.015, 95% Confidence Interval (CI): 0.989-1.042), fully adjusted. Statistically significant associations and interaction terms were seen in obese individuals (HR: 1.099, 95%CI: 1.029-1.174), and current-smokers (HR: 1.054, 95%CI: 1.007-1.103). No associations were found for ischemic or hemorrhagic stroke. Conclusions: Our study strengthens the evidence base for an effect of road traffic noise on incident IHD, whilst the association with incident stroke remains unclear.
  • Journal article
    Funke SW, Farrell PE, Piggott MD, 2017,

    Reconstructing wave profiles from inundation data

    , COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING, Vol: 322, Pages: 167-186, ISSN: 0045-7825

    This paper applies variational data assimilation to inundation problems governed by the shallow water equations with wetting and drying. The objective of the assimilation is to recover an unknown time-varying wave profile at an open ocean boundary from inundation observations. This problem is solved with derivative-based optimisation and an adjoint wetting and drying scheme to efficiently compute sensitivity information. The capabilities of this approach are demonstrated on an idealised sloping beach setup in which the profile of an incoming wave is reconstructed from wet/dry interface observations. The method is robust to noise in the observations if a regularisation term is added to the optimisation objective. Finally, the method is applied to a laboratory experiment of the Hokkaido-Nansei-Oki tsunami, where the wave profile is reconstructed with a relative L∞ error of less than 1%.
  • Journal article
    Graham F, Roberts J, Galton-Fenzi B, Young D, Blankenship D, Siegert MJet al., 2017,

    A high-resolution synthetic bed elevation grid of the Antarctic continent

    , Earth System Science Data, Vol: 9, Pages: 267-279, ISSN: 1866-3516

    Digital elevation models of Antarctic bed topography are smoothed and interpolated onto low-resolution ( > 1 km) grids as current observed topography data are generally sparsely and unevenly sampled. This issue has potential implications for numerical simulations of ice-sheet dynamics, especially in regions prone to instability where detailed knowledge of the topography, including fine-scale roughness, is required. Here, we present a high-resolution (100 m) synthetic bed elevation terrain for Antarctica, encompassing the continent, continental shelf, and seas south of 60° S. Although not identically matching observations, the synthetic bed surface – denoted as HRES – preserves topographic roughness characteristics of airborne and ground-based ice-penetrating radar data measured by the ICECAP (Investigating the Cryospheric Evolution of the Central Antarctic Plate) consortium or used to create the Bedmap1 compilation. Broad-scale ( > 5 km resolution) features of the Antarctic landscape are incorporated using a low-pass filter of the Bedmap2 bed elevation data. HRES has applicability in high-resolution ice-sheet modelling studies, including investigations of the interaction between topography, ice-sheet dynamics, and hydrology, where processes are highly sensitive to bed elevations and fine-scale roughness. The data are available for download from the Australian Antarctic Data Centre (doi:10.4225/15/57464ADE22F50).
  • Journal article
    Nowack PJ, Braesicke P, Abraham NL, Pyle JAet al., 2017,

    On the role of ozone feedback in the ENSO amplitude response under global warming

    , Geophysical Research Letters, Vol: 44, Pages: 3858-3866, ISSN: 0094-8276

    The El Niño–Southern Oscillation (ENSO) in the tropical Pacific Ocean is of key importance toglobal climate and weather. However, state-of-the-art climate models still disagree on the ENSO’s responseunder climate change. The potential role of atmospheric ozone changes in this context has not beenexplored before. Here we show that differences between typical model representations of ozone canhave a first-order impact on ENSO amplitude projections in climate sensitivity simulations. The verticaltemperature gradient of the tropical middle-to-upper troposphere adjusts to ozone changes in the uppertroposphere and lower stratosphere, modifying the Walker circulation and consequently tropical Pacificsurface temperature gradients. We show that neglecting ozone changes thus results in a significant increasein the number of extreme ENSO events in our model. Climate modeling studies of the ENSO often neglectchanges in ozone. We therefore highlight the need to understand better the coupling between ozone,the tropospheric circulation, and climate variability
  • Journal article
    Fennell PS, hallett J, Brandt-Talbot A, Gschwend Fet al., 2017,

    An economically viable ionic liquid for the fractionation of lignocellulosic biomass

    , RSC Green Chemistry, Vol: 19, Pages: 3078-3102, ISSN: 1757-7047

    Cost-effective fractionation (pretreatment) of lignocellulosic biomass is necessary to enable its large-scale use as a source of liquid fuels, bio-based materials and bio-derived chemicals. While a number of ionic liquids (ILs) have proven capable of highly effective pretreatment, their high cost presents a barrier to commercial viability. In this study, we investigate in detail the application of the low-cost (ca. $1 kg−1) ionic liquid triethylammonium hydrogen sulfate for the fractionation of the grass Miscanthus x giganteus into a cellulose rich pulp, a lignin and a distillate. We found that up to 85% of the lignin and up to 100% of the hemicellulose were solubilized into the IL solution. The hemicellulose dissolved mainly in monomeric form, and pentoses were partially converted into furfural. Up to 77% of the glucose contained in the biomass could be released by enzymatic saccharification of the pulp. The IL was successfully recovered and reused four times. A 99% IL recovery was achieved each time. Effective lignin removal and high saccharification yields were maintained during recycling, representing the first demonstration that repeated IL use is feasible due to the self-cleaning properties of the non-distillable solvent. We further demonstrate that furfural and acetic acid can be separated quantitatively from the non-volatile IL by simple distillation, providing an easily recoverable, valuable co-product stream, while IL degradation products were not detected. We further include detailed mass balances for glucose, hemicellulose and lignin, and a preliminary techno-economic estimate for the fractionation process. This is the first demonstration of an efficient and repeated lignocellulose fractionation with a truly low-cost IL, and opens a path to an economically viable IL-based pretreatment process.
  • Journal article
    Bridgestock L, Rehkamper M, van de Flierdt T, Murphy K, Khondoker R, Baker AR, Chance R, Strekopytov S, Humphreys-Williams E, Achterberg EPet al., 2017,

    The Cd isotope composition of atmospheric aerosols from the tropical Atlantic Ocean

    , Geophysical Research Letters, Vol: 44, Pages: 2932-2940, ISSN: 1944-8007

    Stable isotope compositions can potentially be used to trace atmospheric Cd inputs to the surface ocean and anthropogenic Cd emissions to the atmosphere. Both of these applications may provide valuable insights into the effects of anthropogenic activities on the cycling of Cd in the environment. However, a lack of constraints for the Cd isotope compositions of atmospheric aerosols is currently hindering such studies. Here we present stable Cd isotope data for aerosols collected over the Tropical Atlantic Ocean. The samples feature variable proportions of mineral dust-derived and anthropogenic Cd, yet exhibit similar isotope compositions, thus negating the distinction of these Cd sources by using isotopic signatures in this region. Isotopic variability between these two atmospheric Cd sources may be identified in other areas, and thus warrants further investigation. Regardless, these data provide important initial constraints on the isotope composition of atmospheric Cd inputs to the ocean.
  • Journal article
    Stucky de Quay G, Roberts GG, Watson J, Jackson CA-Let al., 2017,

    Incipient mantle plume evolution: constraints from ancient landscapes buried beneath the North Sea

    , Geochemistry, Geophysics, Geosystems, Vol: 18, Pages: 973-993, ISSN: 1525-2027

    Geological observations that constrain the history of mantle convection are sparse despite its importance in determining vertical and horizontal plate motions, plate rheology, and magmatism. We use a suite of geological and geophysical observations from the northern North Sea to constrain evolution of the incipient Paleocene-Eocene Icelandic plume. Well data and a three-dimensional seismic survey are used to reconstruct a 58–55 Ma landscape now buried ∼1.5 km beneath the seabed in the Bressay region. Geochemical analyses of cuttings from wells that intersect the landscape indicate the presence of angiosperm debris. These observations, combined with presence of coarse clastic material, interpreted beach ridges, and a large dendritic drainage network, indicate that this landscape formed subaerially. Longitudinal profiles of palaeo-rivers were extracted and inverted for an uplift rate history, indicating three distinct phases of uplift and total cumulative uplift of ∼350 m. Dinoflagellate cysts in the surrounding marine stratigraphy indicate that this terrestrial landscape formed in <3 Ma and was rapidly drowned. This uplift history is similar to that of a slightly older buried landscape in the Faeroe-Shetland basin ∼400 km to the west. These records of vertical motion are consistent with pulses of anomalously hot asthenosphere spreading out from the incipient Icelandic plume. Using simple isostatic calculations we estimate that the maximum thermal anomaly beneath Bressay was 50–100◦C. Our observations suggest that a thermal anomaly departed the Icelandic plume around 57.4±2.2 Ma at the latest, and travelled with a velocity >∼150 km/Ma.
  • Journal article
    parkinson SD, Funke SW, Hill J, Piggott MD, Allison PAet al., 2017,

    Application of the adjoint approach to optimise the initial conditions of a turbidity current with the AdjointTurbidity 1.0 model

    , Geoscientific Model Development, Vol: 10, Pages: 1051-1068, ISSN: 1991-9603

    Turbidity currents are one of the main drivers ofsediment transport from the continental shelf to the deepocean. The resulting sediment deposits can reach hundredsof kilometres into the ocean. Computer models that simulateturbidity currents and the resulting sediment deposit can helpus to understand their general behaviour. However, in orderto recreate real-world scenarios, the challenge is to find theturbidity current parameters that reproduce the observationsof sediment deposits.This paper demonstrates a solution to the inverse sedimenttransportation problem: for a known sedimentary deposit, thedeveloped model reconstructs details about the turbidity cur-rent that produced the deposit. The reconstruction is con-strained here by a shallow water sediment-laden density cur-rent model, which is discretised by the finite-element methodand an adaptive time-stepping scheme. The model is differ-entiated using the adjoint approach, and an efficient gradient-based optimisation method is applied to identify the turbidityparameters which minimise the misfit between the modelledand the observed field sediment deposits. The capabilities ofthis approach are demonstrated using measurements taken inthe Miocene Marnoso-arenacea Formation (Italy). We findthat whilst the model cannot match the deposit exactly dueto limitations in the physical processes simulated, it providesvaluable insights into the depositional processes and repre-sents a significant advance in our toolset for interpreting tur-bidity current deposits.
  • Journal article
    Green RJ, Staffell IL, 2017,

    “Prosumage” and the British electricity market

    , Economics of Energy and Environmental Policy, Vol: 6, Pages: 33-49, ISSN: 2160-5882

    Domestic electricity consumers with PV panels have become known as “prosumers”; some of them also have energy storage and we have named the combination “prosumage”. The challenges of renewable intermittency could be offset by storing power, and many engineering studies consider the role and value of storage which is properly integrated into the ‘smart grid’. Such a system with holistic optimal control may fail to materialise for regulatory, economic, or behavioural reasons. We therefore model the impact of naïve prosumage: households which use storage only to maximise self-consumption of PV, with no consideration of the wider system. We find it is neither economicfor arbitrage nor particularly beneficial for shaving peaks and filling troughs in national net demand. The extreme case of renewable self-sufficiency, becoming completely independent of the grid, is still prohibitively expensive in Britain and Germany, and even in a country like Spain with a much better solar resource.
  • Journal article
    Deaney EL, Barker S, van de Flierdt T, 2017,

    Timing and nature of AMOC recovery across Termination 2 and magnitude of deglacial CO2 change

    , Nature Communications, Vol: 8, ISSN: 2041-1723

    Large amplitude variations in atmospheric CO2were associated with glacial terminationsof the Late Pleistocene. Here we provide multiple lines of evidence suggesting that theB20 p.p.m.v. overshoot in CO2at the end of Termination 2 (T2)B129 ka was associated withan abrupt (r400 year) deepening of Atlantic Meridional Overturning Circulation (AMOC).In contrast to Termination 1 (T1), which was interrupted by the Bølling-Allerød (B-A), AMOCrecovery did not occur until the very end of T2, and was characterized by pronouncedformation of deep waters in the NW Atlantic. Considering the variable influences of oceancirculation change on atmospheric CO2, we suggest that the net change in CO2across thelast 2 terminations was approximately equal if the transient effects of deglacial oscillations inocean circulation are taken into account.
  • Journal article
    Mechleri E, Fennell PS, Mac Dowell N, 2017,

    Optimisation and evaluation of flexible operation strategies for coal- and gas-CCS power stations with a multi-period design approach

    , INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL, Vol: 59, Pages: 24-39, ISSN: 1750-5836

    Thermal power plants are increasingly required to balance power grids by compensating for the intermittent electricity supply from renewable energy resources. As CO2 capture and storage is integrated with both coal- and gas-fired power plants, it is vital that the emission mitigation technology does not compromise their ability to provide this high-value service. Therefore, developing optimal process operation strategies is vital to maximise both the value provided by and the profitability of these important assets. In this work, we present models of coal- and gas-fired power plants, integrated with a post-combustion CO2 capture process using a 30 wt% monoethanolamine (MEA) solvent. With the aim to decoupling the power and capture plants in order to facilitate profit maximising behaviour, a multi-period dynamic optimisation problem was formulated and solved using these models. Four distinct scenarios were evaluated: load following, solvent storage, exhaust gas by-pass and variable solvent regeneration (VSR). It was found that for both coal- and gas-fired power plants, the VSR strategy is consistently the most profitable option. The performance of the exhaust by-pass scenario is a strong function of the carbon prices and is only selected at very low carbon prices. The viability of the solvent storage strategy was found to be a strong function of the capital cost associated with the solvent storage infrastructure. When the cost of the solvent tanks has been paid off, then the solvent storage scenario is 3.3% and 8% more profitable than the baseline for the pulverised coal and gas-fired power plants, respectively. Sensitivity analyses showed that, for all strategies, the flexibility benefit declined with reduced carbon and fuel prices, while a “peakier” electricity market, characteristic of one with significant quantities of intermittent renewables deployment, more significantly rewarded flexible operation.
  • Journal article
    Davis T, Prentice IC, Stocker BD, Thomas RT, Whitley RJ, Wang H, Evans BJ, Gallego-Sala AV, Sykes MT, Cramer Wet al., 2017,

    Simple process-led algorithms for simulating habitats (SPLASH v.1.0): robust indices of radiation, evapotranspiration and plant-available moisture

    , Geoscientific Model Development, Vol: 10, Pages: 689-708, ISSN: 1991-9603

    Bioclimatic indices for use in studies of ecosystem function, species distribution, and vegetation dynamics under changing climate scenarios depend on estimates of surface fluxes and other quantities, such as radiation, evapotranspiration and soil moisture, for which direct observations are sparse. These quantities can be derived indirectly from meteorological variables, such as near-surface air temperature, precipitation and cloudiness. Here we present a consolidated set of simple process-led algorithms for simulating habitats (SPLASH) allowing robust approximations of key quantities at ecologically relevant timescales. We specify equations, derivations, simplifications, and assumptions for the estimation of daily and monthly quantities of top-of-the-atmosphere solar radiation, net surface radiation, photosynthetic photon flux density, evapotranspiration (potential, equilibrium, and actual), condensation, soil moisture, and runoff, based on analysis of their relationship to fundamental climatic drivers. The climatic drivers include a minimum of three meteorological inputs: precipitation, air temperature, and fraction of bright sunshine hours. Indices, such as the moisture index, the climatic water deficit, and the Priestley–Taylor coefficient, are also defined. The SPLASH code is transcribed in C++, FORTRAN, Python, and R. A total of 1 year of results are presented at the local and global scales to exemplify the spatiotemporal patterns of daily and monthly model outputs along with comparisons to other model results.
  • Journal article
    Shevchenko I, Berloff P, 2017,

    On the roles of baroclinic modes in eddy-resolving midlatitude ocean dynamics

    , Ocean Modelling, Vol: 111, Pages: 55-65, ISSN: 1463-5011

    This work concerns how different baroclinic modes interact and influence solutions of the midlatitude oceandynamics described by the eddy-resolving quasi-geostrophic model of wind-driven gyres. We developedmulti-modal energetics analysis to illuminate dynamical roles of the vertical modes, carried out a systematicanalysis of modal energetics and found that the eddy-resolving dynamics of the eastward jet extension of thewestern boundary currents, such as the Gulf Stream or Kuroshio, is dominated by the barotropic, and thefirst and second baroclinic modes, which become more energized with smaller eddy viscosity. In the absenceof high baroclinic modes, the energy input from the wind is more efficiently focused onto the lower modes,therefore, the eddy backscatter maintaining the eastward jet and its adjacent recirculation zones is thestrongest and overestimated with respect to cases including higher baroclinic modes. In the presence of highbaroclinic modes, the eddy backscatter effect on the eastward jet is much weaker. Thus, the higher baroclinicmodes play effectively the inhibiting role in the backscatter, which is opposite to what has been previouslythought. The higher baroclinic modes are less energetic and have progressively decreasing effect on the flowdynamics; nevertheless, they still play important roles in inter-mode energy transfers (by injecting energyinto the region of the most intensive eddy forcing, in the neighborhood of the eastward jet) that have to betaken into account for correct representation of the backscatter and, thus, for determining the eastward jetextension.

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