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An atmospheric chemistry transport model (FRAME) is used here to calculate annual UK N deposition for the years 1990–2017, at a 1 km × 1 km resolution. Reactive nitrogen (N) deposition is a threat that can lead to adverse effects on the environment and human health. In Europe, substantial reductions in N deposition from nitrogen oxide emissions have been achieved in recent decades. This paper quantifies reductions in UK N deposition following the N emissions peak in 1990. In the UK, estimates of N deposition are typically available at a coarse spatial resolution (typically 5 km × 5 km grid resolution), and it is often difficult to compare estimates between years due to methodological changes in emission estimates. Through efforts to reduce emissions of N from industry, traffic, and agriculture, this study predicts that UK N deposition has reduced from 465 kt N in 1990 to 278 kt N in 2017. However, as part of this overall reduction, there are non-uniform changes for wet and dry deposition of reduced N (NHx) and oxidised N (NOy). In 2017, it is estimated 59 % of all N deposition is in the form of reduced N, a change from 35 % in 1990. This dataset uses 28 years of emissions data from 1990 to 2017 to produce the first long-term dataset of 28 years of N deposition at 1 km × 1 km resolution in the UK. Full data are available at 10.5285/9b203324-6b37-4e91-b028-e073b197fb9f (Tomlinson et al., 2020). [ABSTRACT FROM AUTHOR]

Many coastal sand dune systems in the UK and other parts of the world have experienced a decline in bare sand extent and dune mobility over the past 70 years, accompanied by increased coverage of coarse grass, scrub and woodland vegetation. This has raised concerns amongst nature conservationists about the survival of dune specialist species. Opinions are divided, however, regarding what management interventions should be made to counteract these trends. This paper reviews the factors which have contributed to progressive dune system stabilization at Sandscale Haws, located on the Irish Sea coast in Northwest England, considers the implications for the site of UKCP18 future climate change projections, and discusses the options and plans for future adaptive management. Analaysis of aerial photographs indicated a large reduction in bare sand area between 1946 and 1988 (from >34% to 9% of the dune system), since when there has been a further decline to 1.7%. Consideration of the evidence suggests that a trend towards a warmer, slightly wetter and less windy climate has been the main driver of stabilization, although atmospheric nitrogen deposition, increasing atmospheric CO2 concentrations, reduced grazing intensity, reduced human disturbance from the mid-1980s onwards and a tendency for shoreline progradation on the west-facing coast have played contributing roles. Some species characteristic of open habitats can still be found in good numbers in parts of the dune system, but without increased management it is likely they will decline further and some may become locally extinct. Since the site is of national and international importance for a number of nationally scarce plant and animal species it is considered that there is both a legal and an ethical duty to attempt to maintain suitable habitat for their survival. As a National Nature Reserve Sandscale Haws provides a suitable 'natural laboratory' within which to research the effectiveness of different intervention methods. A number of small-scale dune rejuvenation methods have been trialled since 2015, and options for larger scale interventions, including turf stripping and possible dune notching, are currently being evaluated as part of the nation-wide Dynamic Dunescapes project. [ABSTRACT FROM AUTHOR]

Atmospheric nitrogen pollution has severe impacts on biodiversity, but approaches to value them are limited. This paper develops a spatially explicit methodology to value the benefits from improvements in biodiversity resulting from current policy initiatives to reduce nitrogen emissions. Using the UK as a case study, we quantify nitrogen impacts on plant diversity in four habitats: heathland, acid grassland, dunes and bogs, at fine spatial resolution. Focusing on non-use values for biodiversity we apply value-transfer based on household's willingness to pay to avoid changes in plant species richness, and calculate the benefit of projected emission declines of 37% for nitrogen dioxide (NO 2 ) and 6% for ammonia (NH 3 ) over the scenario period 2007–2020. The annualised benefit resulting from these pollutant declines is £32.7 m (£4.4 m to £109.7 m, 95% Confidence Interval), with the greatest benefit accruing from heathland and acid grassland due to their large area. We also calculate damage costs per unit of NO 2 and NH 3 emitted, to quantify some of the environmental impacts of air pollution for use alongside damage costs for human health in policy appraisal. The benefit is £103 (£33 to £237) per tonne of NO 2 saved, and £414 (£139 to £1022) per tonne of NH 3 saved. [ABSTRACT FROM AUTHOR]

The accumulations of waste plastics and municipal solid wastes from the resident groups and industrial companies have been causing serious environmental issues in the UK, due to difficulties in logistics, sorting, and reuse. In this sense, this paper is stimulated to develop novel approaches to convert some wastes into eco-friendly infrastructural materials, which provides a new way of waste reduction and reuse and extending the service life of asphalt pavement. This study aims to characterise the healing performance of waste-derived bitumen before and after pressure ageing vessel (PAV) ageing based on the crack length. One waste-derived bitumen was fabricated by blending the bio-oil pyrolysed from the organic fraction of municipal solid waste (5 wt%) with a control bitumen (X70) using a high shear mixer at a speed of 150 revolutions per minute (RPM) for 30 min at 150 °C under nitrogen atmosphere. A second waste-derived bitumen was fabricated using the low-density polyethene (LDPE) and mixed with the control bitumen at a concentration of 6 wt% at a speed of 900RPM for 90 min at 180 °C under nitrogen atmosphere. Crack length-based healing index and Ramberg-Osgood model were employed to characterise the healing rate and healing capability of the bitumen, respectively. Material properties (e.g., relaxation modulus and surface energy) of the bitumen used in the healing models were calibrated by linear amplitude sweep test (10 Hz and 20 °C), frequency sweep test (10 Hz, 10–70 °C), and time sweep fatigue-healing test (10 Hz and 20 °C) at a controlled strain level of 5% with different rest durations. Advancing contact angles used in the healing models of the bitumen were measured by a sessile drop tensiometer based on the tilting cradle method. Results show that the bio-oil productively promotes the healing potential and capability of the unaged bitumen, and the LDPE slightly strengthens them. The PAV ageing process evaporates most of the modifier bio-oil; hence, the PAV-aged bio-oil modified bitumen does not show better healing performance than that of the PAV-aged control bitumen. The PAV-aged LDPE modified bitumen has much better healing performance than those of the PAV-aged control bitumen and the PAV-aged bio-oil modified bitumen. The short-term healing rate and healing potential dominate the healing behaviours of the bitumen. The unaged bio-oil modified bitumen heals the fastest (having the highest short-term healing rate) and most (having the highest healing potential), followed by the unaged LDPE modified bitumen, and the unaged control bitumen heals the least and slowest. The PAV-aged LDPE modified bitumen heals the fastest and most, followed by the PAV-aged bio-oil modified bitumen and the PAV-aged control bitumen. The fundamental reason for LDPE's enhancement to bitumen's healing is that the LDPE increased the deformation recovery ability of the bitumen, leading to a higher wetting rate of the cracked surfaces and thus a higher short-term healing rate. However, the LDPE in bitumen cannot accelerate the molecular diffusion to increase the intrinsic healing or the long-term healing rate. • Two waste materials were firstly used to enhance healing ability of bitumen. • Healing properties of bitumen was characterised based on crack length. • Healing rate and potential was modelled using Ramberg-Osgood Equation. • Bio-oil productively promotes healing performance of unaged bitumen. • LDPE strengthens healing performances of unaged and PAV-aged bitumen. [ABSTRACT FROM AUTHOR]

The iron and steel industry has a long tradition of bulk reuse of slags for a range of construction applications. Growing interest in recent years has seen slag resource recovery options extend to critical raw material recovery and atmospheric carbon capture. Full scale deployment of such technologies is currently limited in part by absent or partial inventories of slag deposit locations, data on composition, and volume estimates in many jurisdictions. This paper integrates a range of spatial information to compile a database of iron and steel slag deposits in mainland United Kingdom (UK) for the first time and evaluate the associated resource potential. Over 190 million tonnes of legacy iron and steel slag are present across current and former iron and steel working regions of the UK, with particular concentrations in the north west and north east of England, and central Scotland. While significant potential stockpiles of blast furnace and basic oxygen furnace slag could provide up to 0.9 million tonnes of vanadium and a cumulative carbon dioxide capture potential of 57–138 million tonnes, major management challenges for resource recovery are apparent. Over one third are located in close proximity to designated conservation areas which may limit resource recovery. Furthermore, land use analyses show that many of the sites have already been redeveloped for housing (nearly 30% urban cover). Deposits from recent decades in current or recently closed steel-working areas may have the greatest potential for resource recovery where such ambitions could be coupled with site restoration and regeneration efforts. Unlabelled Image • Iron and steel-making slags have considerable resource recovery potential. • The extent of legacy iron and steel slag deposits was previously not well quantified. • A national database of slag deposits was created and analysed for mainland UK sites. • Carbon capture potential and critical raw materials (CRM) recovery potential estimated. • Current land use and conservation designations may limit resource recovery viability. [ABSTRACT FROM AUTHOR]

Plant growth in nitrogen (N)-limited, unfertilised terrestrial ecosystems should respond to additional N inputs from atmospheric deposition (Ndep). We investigated this for sites in Great Britain (GB) by compiling 796 estimates of net primary productivity (NPP) from measured biomass production over the period 1932–2014, although the great majority were for 1990 onwards. The sites were largely vegetated with shrubs, grass and bracken, and had a wide range of Ndep (0.5–3.3 gN m−2 a−1 in 2000). The measured NPP estimates were compared with calculated values from the biogeochemical ecosystem model N14CP, which predicts that NPP depends strongly upon Ndep. The measured and modelled average total NPP values (gC m−2 a−1) from all data were 387 (standard deviation, SD = 193) and 377 (SD = 72) respectively. Measured and modelled averages for vegetation classes followed the sequence: broadleaved trees ~ needle-leaved trees > herbs (rough grassland + bracken) ~ shrubs. After averaging measured values for sites in individual model grid cells (5 km × 5 km) with 10 or more replicates, the measured and modelled NPP values were correlated (n = 26, r2 = 0.22, p = 0.011), with a slope close to unity. Significant linear relationships were found between measured ln NPP and cumulative Ndep for both herbs (n = 298, p = 0.021) and shrubs (n = 473, p = 0.006), with slopes comparable to those predicted with the model. The results suggest that semi-natural NPP in GB depends positively upon Ndep, in a manner that agrees quantitatively with N14CP predictions. Calculations with the model, using modelled temporal variation in Ndep, indicate that fertilisation by Ndep caused average increases in semi-natural NPP over the period 1800 to 2010 of 30% for shrubs, 71% for herbs, and 91% for broadleaved trees. Combined with previous published results for forests, our findings suggest a general and widespread vegetation response to fertilisation by Ndep. [ABSTRACT FROM AUTHOR]