Helen ApSimon

Dispersion, deposition and impacts of atmospheric ammonia: quantifying local budgets and spatial variability

Ammonia is a reactive pollutant emitted primarily by agricultural sources near ground level in the rural environment. The consequence of these factors is that, in addition to the effects of long-range pollutant transport, ammonia has major effects at a local scale, with emission and receptor areas often closely located in the rural landscape. There is a substantial local spatial variability that needs to be considered in effects assessments, while variations in local deposition may affect the amount of ammonia available for impacts further afield. The wide-ranging UK programme ADEPT (Ammonia Distribution and Effects ProjecT) has addressed these issues through a combination of measurement and modelling activities concerning the distribution of emissions, atmospheric transport, deposition and effects assessment. The results are illustrated here by summarizing the findings of a joint experiment at Burrington Moor, Devon, and wider modelling contrasting the variability at a field scale with 5 km resolution estimates for the UK. The fraction of emitted NH3 deposited locally is shown to depend critically on the downwind land-cover, with fluxes being dependent on interactions with the ammonia compensation point. This will restrict deposition back to agricultural land, but may mean that non-conservation woodlands could be of benefit to recapture a significant fraction of emissions. The generalized models demonstrate the high spatial variability of ammonia impacts, with a case study being used to show the consequences at a field scale. In source regions substantial variability occurs at sub-1 km levels and this will have major consequences for the emission reduction targets needed to protect ecosystems.

From acid rain to climate change

Updated air pollution science and policies address human health, ecosystem effects, and climate change in Europe. The Convention on Long-Range Transboundary Air Pollution (CLRTAP) under the United Nations Economic Commission for Europe (UNECE) was established in 1979 to control damage to ecosystems and cultural heritage from acid rain, initially in Europe (1). Extended by eight protocols, most recently the Gothenburg Protocol (GP) signed in 1999, it has been key for developing cross-border air pollution control strategies over the UNECE region, which includes the United States and Canada. We describe how recent amendments to the GP reflect improved scientific knowledge on pollution, environmental relations, and links between regional air pollution and global climate change.

Validity and uncertainty in the calculation of an emission inventory for ammonia arising from agriculture in Great Britain

Emissions of ammonia have received increasing attention recently, following concern about the environmental consequences, especially in The Netherlands where levels are high due to intensive livestock farming. Direct local effects and more widespread consequences for a range of ecosystems have been attributed to ammonia emissions. As the most prevalent alkaline gas in the atmosphere, ammonia interacts with acidic species, changing their characteristics, chemical and physical behaviour, and enhancing their potential for acidification of soils. Ammonia also forms an important component of the nitrogen cycle and of nitrogen deposition. In the UK, as in many other European countries, there has been a considerable increase in the emission of ammonia within the last 30 years, estimated at about 50%. This results mainly from increases in agricultural production based on the steadily rising number of livestock and increasing fertilizer consumption. This paper discusses the various sources to emissions of ammonia from agricultural sources in the United Kingdom, and some of the uncertainties involved in constructing a national emissions inventory.

Mitigating Diffuse Phosphorus Transfer from Agriculture According to Cost and Efficiency

Potential options for mitigating phosphorus (P) transfer from agriculture to water in England and Wales (E&W) were collated across a range of farm systems to assess their potential effectiveness in reducing mass of P transferred and potential cost (pounds sterling [ pound]) to the farming industry. A simple model framework (called PEASE) incorporating a number of assumptions was used to identify 15 methods for mitigating inputs of P to agricultural systems, 19 methods for preventing mobilization of P, and six methods for controlling the transport of P to streams. The scope for largest reductions in P inputs was to grassland and horticulture. Potential reductions in P mobilization were up to 1.2 kg P ha(-1). Reductions in P transfer associated with transport mitigation were larger than those associated with input and mobilization methods (up to 2.2 kg P ha(-1)). The largest estimated reductions were achieved by installing buffer zones and constructed wetlands, the former being very cost effective ( pound3-5 kg(-1) P saved). Plots of cost curves helped identify where the combined and cumulative P transfer reductions were attainable; these were approximately 0.2 kg ha(-1) for uplands, 0.6 kg ha(-1) for outdoor pigs, 0.9 kg ha(-1) for intensive dairy, and 2.2 kg ha(-1) for arable examples. We concluded that established catchment-scale evidence for mitigation is sparse, especially for specific farm systems in E&W. Sensitivities and uncertainties in the approach, especially associated with expert coefficients, are noted. This approach is nonetheless considered useful for prioritizing where and how best options might be most effectively targeted for least cost but greatest benefit.

Modelling future impacts of air pollution using the multi-scale UK Integrated Assessment Model (UKIAM).

Integrated assessment modelling has evolved to support policy development in relation to air pollutants and greenhouse gases by providing integrated simulation tools able to produce quick and realistic representations of emission scenarios and their environmental impacts without the need to re-run complex atmospheric dispersion models. The UK Integrated Assessment Model (UKIAM) has been developed to investigate strategies for reducing UK emissions by bringing together information on projected UK emissions of SO2, NOx, NH3, PM10 and PM2.5, atmospheric dispersion, criteria for protection of ecosystems, urban air quality and human health, and data on potential abatement measures to reduce emissions, which may subsequently be linked to associated analyses of costs and benefits. We describe the multi-scale model structure ranging from continental to roadside, UK emission sources, atmospheric dispersion of emissions, implementation of abatement measures, integration with European-scale modelling, and environmental impacts. The model generates outputs from a national perspective which are used to evaluate alternative strategies in relation to emissions, deposition patterns, air quality metrics and ecosystem critical load exceedance. We present a selection of scenarios in relation to the 2020 Business-As-Usual projections and identify potential further reductions beyond those currently being planned.

Synergies in addressing air quality and climate change

Air quality is a serious concern for the protection of human health and our natural environment. The pollutants contributing the most to both local and transboundary air pollution problems are SO2, NOx, NH3, volatile organic compounds (VOCs), and fine particulate matter (PM), and mostly originate from the same sources as greenhouse gases. There are thus strong interactions between strategies designed to improve air quality and those addressing climate change. This article examines these interactions, and the benefits of combined strategies with greater attention to the overall environmental impacts, and finding the ‘win—win’ solutions. Illustrations are provided from the development of policy in Europe under the UN ECE Convention on Long-Range Transboundary Air Pollution, which is now inextricably linked with strategies to control greenhouse gases.

Modelling Atmospheric Dispersal of the Chernobyl Release Across Europe

At the time of the Chernobyl accident little was known about the magnitude and time pattern of the release from the damaged reactor. This paper describes the detective work done in the weeks following the accident to assess the release and its dispersal across Europe; also calculations done since the USSR presentations in Vienna at the end of August 1986 and some estimates of longer term collective dose commitment. To conclude some general remarks are made about the implications of the Chernobyl accident for technical support in emergency procedures for any future nuclear accident.

Illustrative national scale scenarios of environmental and human health impacts of Carbon Capture and Storage.

Integrated Assessment, and the development of strategies to reduce the impacts of air pollution, has tended to focus only upon the direct emissions from different sources, with the indirect emissions associated with the full life-cycle of a technology often overlooked. Carbon Capture and Storage (CCS) reflects a number of new technologies designed to reduce CO2 emissions, but which may have much broader environmental implications than greenhouse gas emissions. This paper considers a wider range of pollutants from a full life-cycle perspective, illustrating a methodology for assessing environmental impacts using source-apportioned effects based impact factors calculated by the national scale UK Integrated Assessment Model (UKIAM). Contrasting illustrative scenarios for the deployment of CCS towards 2050 are presented which compare the life-cycle effects of air pollutant emissions upon human health and ecosystems of business-as-usual, deployment of CCS and widespread uptake of IGCC for power generation. Together with estimation of the transboundary impacts we discuss the benefits of an effects based approach to such assessments in relation to emissions based techniques.

Health and environmental co-benefits and conflicts of actions to meet UK carbon targets

Many actions to reduce GHG emissions have wider impacts on health, the economy, and the environment, beyond their role in mitigating climate change. These ancillary impacts can be positive (co-benefits) or negative (conflicts). This article presents the first quantitative review of the wider impacts on health and the environment likely to arise from action to meet the UKs legally-binding carbon budgets. Impacts were assessed for climate measures directed at power generation, energy use in buildings, and industry, transport, and agriculture. The study considered a wide range of health and environmental impacts including air pollution, noise, the upstream impacts of fuel extraction, and the lifestyle benefits of active travel. It was not possible to quantify all impacts, but for those that were monetized the co-benefits of climate action (i.e. excluding climate benefits) significantly outweigh the negative impacts, with a net present value of more than £85 billion from 2008 to 2030. Substantial benefits arise from reduced congestion, pollution, noise, and road accidents as a result of avoided journeys. There is also a large health benefit as a result of increased exercise from walking and cycling instead of driving. Awareness of these benefits could strengthen the case for more ambitious climate mitigation action. Policy relevance This article demonstrates that actions to mitigate GHG emissions have significant wider benefits for health and the environment. Including these impacts in cost–benefit analysis would strengthen the case for the UK (and similar countries) to set ambitious emissions reduction targets. Understanding co-benefits and trade-offs will also improve coordination across policy areas and cut costs. In addition, co-benefits such as air quality improvements are often immediate and local, whereas climate benefits may occur on a longer timescale and mainly in a distant region, as well as being harder to demonstrate. Dissemination of the benefits, along with better anticipation of trade-offs, could therefore boost public support for climate action.

Investigating the sensitivity of health benefits to focussed PM2.5 emission abatement strategies

Modelling, pollution monitoring and epidemiological studies all have a role to play in developing effective policies to improve air quality and human health. Epidemiological studies have shown that of particular importance are the effects of fine particulate matter, PM10 and PM2.5 which can penetrate into human lungs. At present it is not clear which components of PM are responsible for health effects although toxicological studies have identified several potential factors. Hence, based on WHO guidance, current legislation has focused on the total mass, with the EC setting limit values on total PM10, followed by target reductions for population exposure to PM2.5 in urban agglomerations. Trends in measured concentrations at selected urban monitoring stations are required as evidence for achievement of these reductions. This paper addresses these issues at the borough level in London using the integrated assessment model UKIAM, developed originally for application at the national scale, with illustrations comparing abatement of two contrasting sources - domestic combustion and road transport. The former, dominated by natural gas generating NOX emissions, contributes to longer range secondary PM formation extending beyond the city. The latter is an important source of black carbon as a primary pollutant causing local exposure, as well as NOX. WHO data is used in relation to impacts of particle concentrations by mass, and response functions for black carbon are taken from the literature. The results show that from a city perspective there are enhanced benefits from reducing the road transport emissions, especially with regard to potential toxicity of black carbon. The scenarios modelled also highlight the spatial variations of benefits across London, and illustrate deviations from trends as represented by limited monitoring data from the different boroughs, together with the influence upon exposure of mobile population within the city. We use integrated assessment modelling to focus strategies to benefit human health.We quantify the variable potential for health benefits in different London boroughs.We highlight the greatly increased health benefits of focussing upon black carbon.We discuss the uncertainties in reported health impacts of fine particulate matter.We suggest greater possible benefit under the EC Directive by reducing BC emissions.