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  • Journal article
    Bushell S, Colley T, Workman M, 2015,

    A unified narrative for climate change

    , Nature Climate Change, Vol: 5, Pages: 971-973, ISSN: 1758-6798
  • Journal article
    Tsai M-Y, Hoek G, Eeftens M, de Hoogh K, Beelen R, Beregszaszi T, Cesaroni G, Cirach M, Cyrys J, De Nazelle A, de Vocht F, Ducret-Stich R, Eriksen K, Galassi C, Grazuleviciene R, Grazulevicius T, Grivas G, Gryparis A, Heinrich J, Hoffmann B, Iakovides M, Keuken M, Kraemer U, Kuenzli N, Lanki L, Madsen C, Meliefste K, Merritt A-S, Moelter A, Mosler G, Nieuwenhuijsen MJ, Pershagen G, Phuleria H, Quass U, Ranzi A, Schaffner E, Sokhi R, Stempfelet M, Stephanou E, Sugiri D, Taimisto P, Tewis M, Udvardy O, Wang M, Brunekreef Bet al., 2015,

    Spatial variation of PM elemental composition between and within 20 European study areas - Results of the ESCAPE project

    , ENVIRONMENT INTERNATIONAL, Vol: 84, Pages: 181-192, ISSN: 0160-4120
  • Journal article
    Vaissier V, Frost JM, Barnes PRF, Nelson Jet al., 2015,

    Influence of Intermolecular Interactions on the Reorganization Energy of Charge Transfer between Surface-Attached Dye Molecules

    , JOURNAL OF PHYSICAL CHEMISTRY C, Vol: 119, Pages: 24337-24341, ISSN: 1932-7447

    The parameters controlling the kinetics ofintermolecular charge transfer are traditionally estimatedfrom electronic structure calculations on the charge donorand charge acceptor in isolation. Here, we show that thisprocedure results in inaccuracies for hole transfer between apair of organic dye molecules by comparing charge-constraineddensity functional theory (DFT) calculations on a dyecation/neutral dye pair to the conventional DFT calculationson the isolated molecules. We quantify the error made in thereorganization energy of hole exchange between dye molecules(λi). We choose three indolene-based organic dyes with application to dye-sensitized solar cells, namely, D149, D102, and D131,for which experimental values of λ are available. We find that, although highly system dependent, the intermolecular interactionbetween the charge donor and acceptor can lead to a 0.25 eV change in λi, illustrating the limitations of the widely used originalmethod in predicting the rate of charge transfer.
  • Journal article
    Hausmann U, Czaja A, Marshall J, 2015,

    Estimates of air–sea feedbacks on sea surface temperature anomalies in the southern ocean

    , Journal of Climate, Vol: 29, Pages: 439-454, ISSN: 1520-0442

    Sea surface temperature (SST) air–sea feedback strengths and associated decay time scales in the Southern Ocean (SO) are estimated from observations and reanalysis datasets of SST, air–sea heat fluxes, and ocean mixed layer depths. The spatial, seasonal, and scale dependence of the air–sea heat flux feedbacks is mapped in circumpolar bands and implications for SST persistence times are explored. It is found that the damping effect of turbulent heat fluxes dominates over that due to radiative heat fluxes. The turbulent heat flux feedback acts to damp SSTs in all bands and spatial scales and in all seasons, at rates varying between 5 and 25 W m−2 K−1, while the radiative heat flux feedback has a more uniform spatial distribution with a magnitude rarely exceeding 5 W m−2 K−1. In particular, the implied net air–sea feedback (turbulent + radiative) on SST south of the polar front, and in the region of seasonal sea ice, is as weak as 5–10 W m−2 K−1 in the summertime on large spatial scales. Air–sea interaction alone thus allows SST signals induced around Antarctica in the summertime to persist for several seasons. The damping effect of mixed layer entrainment on SST anomalies averages to approximately 20 W m−2 K−1 across the ACC bands in the summer-to-winter entraining season and thereby reduces summertime SST persistence to less than half of that predicted by air–sea interaction alone (i.e., 3–6 months).
  • Journal article
    Paul M, van de Flierdt T, Rehkamper M, Khondoker R, Weiss D, Lohan MC, Homoky WBet al., 2015,

    Tracing the Agulhas leakage with lead isotopes

    , Geophysical Research Letters, Vol: 20, Pages: 8515-8521, ISSN: 1944-8007

    The transport of warm and salty waters from the Indian Ocean to the South Atlantic by the Agulhas Current constitutes a key return route of the meridional overturning circulation. Despite, the importance of the Agulhas Leakage on interoceanic exchange, its role on biogeochemical cycles is poorly documented. Here, we present the first lead (Pb) concentration and isotope data for surface seawater collected during the GEOTRACES cruise D357 in the Agulhas current system. Lead in surface waters of the Cape Basin is described by three distinct endmembers: the South African coast, open South Atlantic seawater, and Indian Ocean seawater. The latter stands out in its Pb isotopic composition and can be tracked within two distinct Agulhas rings. High Pb concentrations in the Agulhas rings further corroborate an Indian Ocean provenance of waters, and suggests that the Agulhas Leakage not only represents a major conduit for heat, but also for trace metals.
  • Journal article
    Brindley H, Osipov S, Bantges R, Smirnov A, Banks J, Levy R, Prakash PJ, Stenchikov Get al., 2015,

    An assessment of the quality of aerosol retrievals over the Red Sea and evaluation of the climatological cloud-free dust direct radiative effect in the region

    , Journal of Geophysical Research: Atmospheres, Vol: 120, Pages: 10862-10878, ISSN: 2169-897X

    Ground-based and satellite observations are used in conjunction with the Rapid Radiative Transfer Model (RRTM) to assess climatological aerosol loading and the associated cloud-free aerosol direct radiative effect (DRE) over the Red Sea. Aerosol optical depth (AOD) retrievals from the Moderate Resolution Imaging Spectroradiometer and Spinning Enhanced Visible and InfraRed Imager (SEVIRI) instruments are first evaluated via comparison with ship-based observations. Correlations are typically better than 0.9 with very small root-mean-square and bias differences. Calculations of the DRE along the ship cruises using RRTM also show good agreement with colocated estimates from the Geostationary Earth Radiation Budget instrument if the aerosol asymmetry parameter is adjusted to account for the presence of large particles. A monthly climatology of AOD over the Red Sea is then created from 5 years of SEVIRI retrievals. This shows enhanced aerosol loading and a distinct north to south gradient across the basin in the summer relative to the winter months. The climatology is used with RRTM to estimate the DRE at the top and bottom of the atmosphere and the atmospheric absorption due to dust aerosol. These climatological estimates indicate that although longwave effects can reach tens of W m−2, shortwave cooling typically dominates the net radiative effect over the Sea, being particularly pronounced in the summer, reaching 60 W m−2 at the surface. The spatial gradient in summertime AOD is reflected in the radiative effect at the surface and in associated differential heating by aerosol within the atmosphere above the Sea. This asymmetric effect is expected to exert a significant influence on the regional atmospheric and oceanic circulation.
  • Journal article
    Brindley H, Osipov S, Bantges R, Smirnov A, Banks J, Levy R, Prakash PJ, Stenchikov Get al., 2015,

    An assessment of the quality of aerosol retrievals over the Red Sea and evaluation of the climatological cloud-free dust direct radiative effect in the region

    , Journal of Geophysical Research: Atmospheres, Vol: 120, ISSN: 2169-897X

    Ground-based and satellite observations are used in conjunction with the Rapid RadiativeTransfer Model (RRTM) to assess climatological aerosol loading and the associated cloud-free aerosol directradiative effect (DRE) over the Red Sea. Aerosol optical depth (AOD) retrievals from the Moderate ResolutionImaging Spectroradiometer and Spinning Enhanced Visible and InfraRed Imager (SEVIRI) instruments are firstevaluated via comparison with ship-based observations. Correlations are typically better than 0.9 with verysmall root-mean-square and bias differences. Calculations of the DRE along the ship cruises using RRTM alsoshow good agreement with colocated estimates from the Geostationary Earth Radiation Budget instrumentif the aerosol asymmetry parameter is adjusted to account for the presence of large particles. A monthlyclimatology of AOD over the Red Sea is then created from 5 years of SEVIRI retrievals. This shows enhancedaerosol loading and a distinct north to south gradient across the basin in the summer relative to the wintermonths. The climatology is used with RRTM to estimate the DRE at the top and bottom of the atmosphereand the atmospheric absorption due to dust aerosol. These climatological estimates indicate that althoughlongwave effects can reach tens of W m 2, shortwave cooling typically dominates the net radiativeeffect over the Sea, being particularly pronounced in the summer, reaching 120 W m 2 at the surface.The spatial gradient in summertime AOD is reflected in the radiative effect at the surface and in associateddifferential heating by aerosol within the atmosphere above the Sea. This asymmetric effect is expected toexert a significant influence on the regional atmospheric and oceanic circulation.
  • Journal article
    Jimenez-Espejo FJ, Pardos-Gene M, Martinez-Ruiz F, Garcia-Alix A, van de Flierdt T, Toyofuku T, Bahr A, Kreissig Ket al., 2015,

    Geochemical evidence for intermediate water circulation in the westernmost Mediterranean over the last 20 kyr BP and its impact on the Mediterranean Outflow

    , Global and Planetary Change, Vol: 135, Pages: 38-46, ISSN: 1872-6364

    The Mediterranean Outflow (MOW) is generated by deep and intermediate waters from different basins in the Mediterranean Sea. Despite the number of studies on Mediterranean water masses, little work has been done on the source and properties of intermediate waters in the westernmost Mediterranean Sea and their links with MOW. Here we examine three marine sediment records spanning the last 20 kyr, located at key depths to trace intermediate waters along the Alboran Sea. We use a combination of redox-sensitive elements, which can serve as proxies to reconstruct variations in the water column oxygenation and the Nd isotopic composition of foraminiferal ferromanganese coatings, in order to reconstruct water mass provenance of Eastern/Western Mediterranean waters.As measured, εNd < − 9.2 and a low U/Th ratio during glacial periods can be attributed to the presence of Western Mediterranean Deep Water (WMDW) at the study sites. During deglaciation, higher Nd isotopic compositions and U/Th ratios point to an enhanced contribution of the modified Levantine Intermediate Water (LIW). The comparison between our data and other LIW and MOW records suggests that i) the lower branch of MOW is linked to WMDW during the glacial period, ii) the middle MOW branch follows LIW activity during deglaciation, while iii) the upper branch is more active during late Holocene, coinciding with LIW formation increase after sapropel deposits. This reconstruction has significant implications for an understanding of the MOW evolution.
  • Journal article
    Zhou S-X, Medlyn BE, Prentice IC, 2015,

    Long-term water stress leads to acclimation of drought sensitivity of photosynthetic capacity in xeric but not riparian Eucalyptus species

    , Annals of Botany, Vol: 117, Pages: 133-144, ISSN: 1095-8290

    Background and Aims Experimental drought is well documented to induce a decline in photosynthetic capacity. However, if given time to acclimate to low water availability, the photosynthetic responses of plants to low soil moisture content may differ from those found in short-term experiments. This study aims to test whether plants acclimate to long-term water stress by modifying the functional relationships between photosynthetic traits and water stress, and whether species of contrasting habitat differ in their degree of acclimation.Methods Three Eucalyptus taxa from xeric and riparian habitats were compared with regard to their gas exchange responses under short- and long-term drought. Photosynthetic parameters were measured after 2 and 4 months of watering treatments, namely field capacity or partial drought. At 4 months, all plants were watered to field capacity, then watering was stopped. Further measurements were made during the subsequent ‘drying-down’, continuing until stomata were closed.Key Results Two months of partial drought consistently reduced assimilation rate, stomatal sensitivity parameters (g1), apparent maximum Rubisco activity (V′cmaxVcmax′) and maximum electron transport rate (J′maxJmax′). Eucalyptus occidentalis from the xeric habitat showed the smallest decline in V′cmaxVcmax′ and J′maxJmax′; however, after 4 months, V′cmaxVcmax′ and J′maxJmax′ had recovered. Species differed in their degree of V′cmaxVcmax′ acclimation. Eucalyptus occidentalis showed significant acclimation of the pre-dawn leaf water potential at which the V′cmaxVcmax′ and ‘true’ Vcmax (accounting for mesophyll conductance) declined most steeply during drying-down.Conclusions The findings indicate carbon loss under prolonged drought could be over-estimated without accounting for acclimation. In particular, (1) species from contrasting habitats differed in th
  • Journal article
    Ferrandiz V, Sarabia LA, Ortiz MC, Cheeseman CR, Garcia-Alcocel Eet al., 2015,

    Design of bespoke lightweight cement mortars containing waste expanded polystyrene by experimental statistical methods

    , Materials & Design, Vol: 89, Pages: 901-912, ISSN: 0261-3069

    This work assesses the reuse of waste expanded polystyrene (EPS) to obtain lightweight cement mortars. The factors and interactions which affect the properties of these mortars were studied by ad-hoc designs based on the d-optimal criterion. This method allow multiple factors to be modified simultaneously, which reduces the number of experiments compared with classical design. Four factors were studied at several levels: EPS type (two levels), EPS content (two levels), admixtures mix (three levels) and cement type (three levels). Two types of aggregate were also studied. The workability, air content, compressive strength, adhesive strength, bulk density and capillary absorption were experimentally tested. The effect of factors and interactions on the properties was modelled and analysed. The results demonstrate how the factors and synergistic interactions can be manipulated to manufacture lightweight mortars which satisfy the relevant EU standards. These mortars contain up to 60% of waste EPS, low amounts of admixtures and low clinker content CEM III. Sustainable mortars containing silica sand gave flow table spread values between 168 and 180 ± 4 mm, bulk density between 1280and 1110 ± 100 kg/m³, and C90 between 0.279 and 0.025 ± 0.07 kg/m²·min⁰′⁵, making them suitable for masonry, plastering and rendering applications.1
  • Journal article
    Cole-Hunter T, Weichenthal S, Kubesch N, Foraster M, Carrasco-Turigas G, Bouso L, Martinez D, Westerdahl D, de Nazelle A, Nieuwenhuijsen Met al., 2015,

    Impact of traffic-related air pollution on acute changes in cardiac autonomic modulation during rest and physical activity: a cross-over study

    , Journal of Exposure Science and Environmental Epidemiology, Vol: 26, Pages: 133-140, ISSN: 1559-0631

    People are often exposed to traffic-related air pollution (TRAP) during physical activity (PA), but it is not clear if PA modifies the impact of TRAP on cardiac autonomic modulation. We conducted a panel study among 28 healthy adults in Barcelona, Spain to examine how PA may modify the impact of TRAP on cardiac autonomic regulation. Participants completed four 2-h exposure scenarios that included either rest or intermittent exercise in high- and low-traffic environments. Time- and frequency-domain measures of heart rate variability (HRV) were monitored during each exposure period along with continuous measures of TRAP. Linear mixed-effects models were used to estimate the impact of TRAP on HRV as well as potential effect modification by PA. Exposure to TRAP was associated with consistent decreases in HRV; however, exposure–response relationships were not always linear over the broad range of exposures. For example, each 10 μg/m3 increase in black carbon was associated with a 23% (95% CI: −31, −13) decrease in high frequency power at the low-traffic site, whereas no association was observed at the high-traffic site. PA modified the impact of TRAP on HRV at the high-traffic site and tended to weaken inverse associations with measures reflecting parasympathetic modulation (P≤0.001). Evidence of effect modification at the low-traffic site was less consistent. The strength and direction of the relationship between TRAP and HRV may vary across exposure gradients. PA may modify the impact of TRAP on HRV, particularly at higher concentrations.
  • Journal article
    Moia D, Leijtens T, Noel N, Snaith HJ, Nelson J, Barnes PRFet al., 2015,

    Dye Monolayers Used as the Hole Transporting Medium in Dye-Sensitized Solar Cells

    , ADVANCED MATERIALS, Vol: 27, Pages: 5889-5894, ISSN: 0935-9648
  • Conference paper
    Mawhood RK, Slade R, Shah N, 2015,

    Policy options to promote perennial energy crops: the limitations of the English Energy Crops Scheme and the role for agent-based modelling in policy design

    , Wellesbourne, UK, Association of Applied Biologists: Biomass and Energy Crops V, Publisher: Association of Applied Biologists, Pages: 143-153, ISSN: 0265-1491

    The UK government’s bioenergy strategy anticipates the cultivation of between 300,000 and 900,000 ha of energy crops by 2030. Yet policy incentives to promote uptake of perennial energy crops (PECs), notably the English Energy Crops Scheme (ECS), have had little impact. Less than 10,000 ha of PECs were being grown in 2013. To investigate the barriers to deployment a critical literature review and stakeholder interviews were conducted. These identified numerous substantial obstacles regarding PEC economics, alignment with existing institutions and factors affecting risk perception. Many of these are interdependent and involve a broad range of stakeholders. Agent-based modelling is proposed as an approach to explore the cumulative impacts of individual stakeholders’ behaviours under alternative policy and market conditions.
  • Journal article
    Ukkola AM, Prentice IC, Keenan TF, van Dijk AIJM, Viney NR, Myneni RB, Bi Jet al., 2015,

    Reduced streamflow in water-stressed climates consistent with CO2 effects on vegetation

    , Nature Climate Change, Vol: 6, Pages: 75-78, ISSN: 1758-6798

    Global environmental change has implications for the spatial and temporal distribution of water resources, but quantifying its effects remains a challenge. The impact of vegetation responses to increasing atmospheric CO2 concentrations on the hydrologic cycle is particularly poorly constrained1, 2, 3. Here we combine remotely sensed normalized difference vegetation index (NDVI) data and long-term water-balance evapotranspiration (ET) measurements from 190 unimpaired river basins across Australia during 1982–2010 to show that the precipitation threshold for water limitation of vegetation cover has significantly declined during the past three decades, whereas sub-humid and semi-arid basins are not only ‘greening’ but also consuming more water, leading to significant (24–28%) reductions in streamflow. In contrast, wet and arid basins show nonsignificant changes in NDVI and reductions in ET. These observations are consistent with expected effects of elevated CO2 on vegetation. They suggest that projected future decreases in precipitation4 are likely to be compounded by increased vegetation water use, further reducing streamflow in water-stressed regions.
  • Journal article
    van Sebille E, Waterman S, Barthel A, Lumpkin R, Keating SR, Fogwill C, Turney Cet al., 2015,

    Pairwise surface drifter separation in the Western Pacific Sector of the Southern Ocean

    , Journal of Geophysical Research: Oceans, Vol: 120, Pages: 6769-6781, ISSN: 2169-9275

    The Southern Ocean plays a critical role in global climate, yet the mixing properties of the circulation in this part of the ocean remain poorly understood. Here, dispersion in the vicinity of the Southern Antarctic Circumpolar Current Front, one of the branches of the Antarctic Circumpolar Current, is studied using ten pairs of surface drifters deployed systematically across the frontal jet and its flanks. Drifter pairs were deployed with an initial separation of 13m and report their position every hour. The separation of the pairs over seven months, in terms of their Finite Scale Lyaponuv Exponents (FSLE), dispersion, and diffusivity, is characterized and related to expected behavior from Quasi-geostrophic (QG) and Surface Quasi-geostrophic (SQG) theories. The FSLE analysis reveals two submesoscale regimes, with SQG-like behavior at scales below 3.2km and mixed QG/SQG behavior at scales between 3.2km and 73km. The dispersion analysis, however, suggests QG-like behavior for the smallest scales. Both dispersion and diffusivity appear isotropic for scales up to 500km. Finally, there is no clear indication of a cross-jet variation of drifter dispersion.
  • Journal article
    Yu W, Graham N, Yang Y, Zhou Z, Campos LCet al., 2015,

    Effect of sludge retention on UF membrane fouling: The significance of sludge crystallization and EPS increase

    , WATER RESEARCH, Vol: 83, Pages: 319-328, ISSN: 0043-1354
  • Journal article
    Yu W, Graham NJD, 2015,

    Performance of an integrated granular media - Ultrafiltration membrane process for drinking water treatment

    , JOURNAL OF MEMBRANE SCIENCE, Vol: 492, Pages: 164-172, ISSN: 0376-7388
  • Report
    MacLean K, Gross R, Hannon M, Rhodes AR, Parrish Bet al., 2015,

    Energy system crossroads - time for decisions:UK 2030 low carbon scenarios and pathways - key decision points for a decarbonised energy system

    , ICEPT/WP/2015/019
  • Journal article
    Gonzalez B, Blamey J, Al-Jeboori MJ, Florin NH, Clough PT, Fennell PSet al., 2015,

    Additive effects of steam addition and HBr doping for CaO-based sorbents for CO2 capture

    , Chemical Engineering and Processing: Process Intensification, Vol: 103, Pages: 21-26, ISSN: 1873-3204

    Calcium looping is a developing CO2 capture and storage technology that employs the reversible carbonation of CaO (potentially derived from natural limestone). The CO2 uptake potential of CaO particles reduces upon repeated reaction, largely through loss of reactive surface area and densification of particles. Doping of particles has previously been found to reduce the rate of decay of CO2 uptake, as has the introduction of steam into calcination and carbonation stages of the reaction. Here, the synergistic effects of steam and doping, using an HBr solution, of 5 natural limestones have been investigated. The enhancement to the CO2 uptake was found to be additive, with CO2 uptake after 13 cycles found to be up to 3 times higher for HBr-doped limestones subjected to cycles of carbonation and calcination in the presence of 10% steam, in comparison to natural limestone cycled in the absence of steam. A qualitative discussion of kinetic data is also presented.
  • Journal article
    Moulds S, Buytaert W, Mijic A, 2015,

    An open and extensible framework for spatially explicit land use change modelling: the lulcc R package

    , Geoscientific Model Development, Vol: 8, Pages: 3215-3229, ISSN: 1991-9603

    We present the lulcc software package, an object-oriented framework for land use change modelling written in the R programming language. The contribution of the work is to resolve the following limitations associated with the current land use change modelling paradigm: (1) the source code for model implementations is frequently unavailable, severely compromising the reproducibility of scientific results and making it impossible for members of the community to improve or adapt models for their own purposes; (2) ensemble experiments to capture model structural uncertainty are difficult because of fundamental differences between implementations of alternative models; and (3) additional software is required because existing applications frequently perform only the spatial allocation of change. The package includes a stochastic ordered allocation procedure as well as an implementation of the CLUE-S algorithm. We demonstrate its functionality by simulating land use change at the Plum Island Ecosystems site, using a data set included with the package. It is envisaged that lulcc will enable future model development and comparison within an open environment.
  • Journal article
    Parfitt R, Czaja A, 2015,

    On the contribution of synoptic transients to the mean atmospheric state in the Gulf Stream region

    , Quarterly Journal of the Royal Meteorological Society, Vol: 142, Pages: 1554-1561, ISSN: 1477-870X

    A new decomposition of the time mean sea level pressure, precipitation, meridional velocity (v) and pressure vertical velocity (ω) is applied to ERA-Interim reanalysis data over the North Atlantic ocean for the December-February 1979–2011 time period. The decomposition suggests that the atmosphere over the Gulf Stream is dominated by a continuous series of synoptic systems, or baroclinic waves, propagating across the region. The time mean value of precipitation, meridional velocity and ω (the latter being taken as a proxy for upward and downward motion) is accordingly set by the propagating waves. The result is particularly striking for ω (v) considering that ascent and descent (poleward and equatorward flow) could reasonably be expected to cancel out in such a series of waves.These results shed a new light on analyses of the storm track heat budget in which the residual between diabatic heating and “transient” eddy heat fluxes (singled out through band pass time filtering or spatial Fourier analysis) is interpreted as a Rossby wave source. This interpretation is questioned because, as a consequence of the filtering used, these studies prevent any direct contribution of the “transients” to the time mean ω or meridional velocity, attributing entirely both fields to the circulation associated with the thermally forced Rossby wave. The fact that “transients” directly contribute to the observed time mean ω over the Gulf Stream might also explain the discrepancy between the observed and predicted response of the vertical motion field to heating in midlatitudes.
  • Journal article
    Blamey J, Al-Jeboori MJ, Manovic V, Fennell PS, Anthony EJet al., 2015,

    CO2 capture by calcium aluminate pellets in a small fluidized bed

    , Fuel Processing Technology, Vol: 142, Pages: 100-106, ISSN: 1873-7188

    Synthetic pellets made using calcium aluminate cement and quicklime have been examined in a small fluidized bed reactor to determine their performance in cyclic CO2 capture for up to 20 calcination/capture cycles. Two batches were examined one a “fresh” batch, and the second an “aged” batch of pellets and their performance was compared with the original parent limestone. Carbonation was carried out at 650 °C and calcination at 900 °C, both with 15% CO2, balance N2, as a synthetic flue gas. Experiments were also performed with and without steam in the flue gas and showed that steam always improved capture performance. In addition, there was no major attrition associated with the pellets, and pellets tended to perform better in terms of carbon capture than the parent limestone.
  • Journal article
    Yi N, Unruangsri J, Shaw J, Williams CKet al., 2015,

    Carbon dioxide capture and utilization: using dinuclear catalysts to prepare polycarbonates.

    , Faraday Discussions, Vol: 183, Pages: 67-82, ISSN: 1364-5498

    The copolymerization of epoxides, including cyclohexene oxide and vinyl-cyclohexene oxide with carbon dioxide are presented. These processes are catalyzed using a homogeneous di-zinc complex that shows good activity and very high selectivities for polycarbonate polyol formation. The polymerizations are investigated in the presence of different amounts of exogenous reagents, including water, diols and diamines, as models for common contaminants in any carbon dioxide capture and utilization scenario.
  • Journal article
    Nerini D, Zulkafli Z, Wang L-P, Onof C, Buytaert W, Lavado-Casimiro W, Guyot J-Let al., 2015,

    A Comparative Analysis of TRMM-Rain Gauge Data Merging Techniques at the Daily Time Scale for Distributed Rainfall-Runoff Modeling Applications

    , Journal of Hydrometeorology, Vol: 16, Pages: 2153-2168, ISSN: 1525-755X

    This study compares two nonparametric rainfall data merging methods—the mean bias correction and double-kernel smoothing—with two geostatistical methods—kriging with external drift and Bayesian combination—for optimizing the hydrometeorological performance of a satellite-based precipitation product over a mesoscale tropical Andean watershed in Peru. The analysis is conducted using 11 years of daily time series from the Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA) research product (also TRMM 3B42) and 173 rain gauges from the national weather station network. The results are assessed using 1) a cross-validation procedure and 2) a catchment water balance analysis and hydrological modeling. It is found that the double-kernel smoothing method delivered the most consistent improvement over the original satellite product in both the cross-validation and hydrological evaluation. The mean bias correction also improved hydrological performance scores, particularly at the subbasin scale where the rain gauge density is higher. Given the spatial heterogeneity of the climate, the size of the modeled catchment, and the sparsity of data, it is concluded that nonparametric merging methods can perform as well as or better than more complex geostatistical methods, whose assumptions may not hold under the studied conditions. Based on these results, a systematic approach to the selection of a satellite–rain gauge data merging technique is proposed that is based on data characteristics. Finally, the underperformance of an ordinary kriging interpolation of the rain gauge data, compared to TMPA and other merged products, supports the use of satellite-based products over gridded rain gauge products that utilize sparse data for hydrological modeling at large scales.
  • Journal article
    Al-Menhali A, Niu B, Krevor S, 2015,

    Capillarity and wetting of carbon dioxide and brine during drainage in Berea sandstone at reservoir conditions

    , Water Resources Research, Vol: 51, Pages: 7895-7914, ISSN: 0043-1397

    The wettability of CO2-brine-rock systems will have a major impact on the management of carbon sequestration in subsurface geological formations. Recent contact angle measurement studies have reported sensitivity in wetting behaviour of this system to pressure, temperature and brine salinity. We report observations of the impact of reservoir conditions on the capillary pressure characteristic curve and and relative permeability of a single Berea sandstone during drainage - CO2 displacing brine - through effects on the wetting state. Eight reservoir condition drainage capillary pressure characteristic curves were measured using CO2 and brine in a single fired Berea sandstone at pressures (5 to 20 MPa), temperatures (25 to 50°C) and ionic strengths (0 to 5 mol kg−1 NaCl). A ninth measurement using a N2-water system provided a benchmark for capillarity with a strongly water wet system. The capillary pressure curves from each of the tests were found to be similar to the N2-water curve when scaled by the interfacial tension. Reservoir conditions were not found to have a significant impact on the capillary strength of the CO2-brine system during drainage through a variation in the wetting state. Two steady-state relative permeability measurements with CO2 and brine and one with N2 and brine similarly show little variation between conditions, consistent with the observation that the CO2-brine-sandstone system is water wetting and multiphase flow properties invariant across a wide range of reservoir conditions.
  • Journal article
    Alexander JS, McNamara J, Rowcliffe JM, Oppong J, Milner-Gulland EJet al., 2015,

    The role of bushmeat in a West African agricultural landscape

    , ORYX, Vol: 49, Pages: 643-651, ISSN: 0030-6053
  • Journal article
    Cole-Hunter T, Donaire-Gonzalez D, Curto A, Ambros A, Valentin A, Garcia-Aymerich J, Martinez D, Braun LM, Mendez M, Jerrett M, Rodriguez D, de Nazelle A, Nieuwenhuijsen Met al., 2015,

    Objective correlates and determinants of bicycle commuting propensity in an urban environment

    , Transportation Research Part D: Transport and Environment, Vol: 40, Pages: 132-143, ISSN: 1879-2340

    ObjectiveBicycle use for commuting is being encouraged not only to address physical inactivity, but also vehicular congestion, air pollution and climate change. The current study aimed to ascertain the urban environmental correlates and determinants of bicycle use for commuting (bicycle commuting) among the working or studying population in Barcelona, Spain.MethodsAdults (n = 769; 52% females) recruited whilst commuting within Barcelona (Spain) responded to a comprehensive telephone survey concerning their travel behaviour. Based upon responses collected from June 2011 to May 2012, participants were categorised into four groups: frequent bicyclists, infrequent bicyclists, willing non-bicyclists, and unwilling non-bicyclists. The determinants of frequency and willingness (propensity) to commute by bicycle were assessed by multinomial logistic regression models adjusted for potential confounders and covariates.ResultsThe number of public bicycle stations surrounding the home address and amount of greenness surrounding the work/study address were significant positive determinants of bicycle commuting propensity. On the other hand, the number of public transport stations surrounding the home address and elevation of the work/study address were significant negative determinants of bicycle commuting propensity. Individual age, education level, gender, nationality, physical activity level and commute distance significantly affected this propensity.ConclusionGreater availability of public bicycle stations and higher levels of urban greenness may increase bicycle use by adults commuting within a city such as Barcelona, Spain. Electrically-assisted public bicycles may address the challenge of elevation, making this system a more competitive mode against traditional motorised public transport.
  • Journal article
    Castelltort S, Whittaker AC, Verges J, 2015,

    Tectonics, sedimentation and surface processes: from the erosional engine to basin deposition

    , Earth Surface Processes and Landforms, Vol: 40, Pages: 1839-1846, ISSN: 1096-9837
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