Estimating nitrogen fluxes at the European scale by upscaling INTEGRATOR model outputs from selected sites

A comparison was made between upscaled model results of nitrogen (N) fluxes to air and water from 450 sites within the EU-27 and results derived for the entire EU-27 area using the model INTEGRATOR. The 450 sites were selected using stratified random sampling, dividing the EU-27 into 150 strata and selecting three sites at random within each stratum. The strata were based on important environmental factors influencing N fluxes. Hierarchical divisive cluster analysis was used to reduce the numerous combinations of environmental factors to the required total of 150, such that the heterogeneity of environmental factors within strata was as small as possible. Modelled NH<sub>3</sub>, N<sub>2</sub>O and NO<sub>x</sub> emissions and N leaching/runoff obtained were scaled up from the 450 sites to the entire EU-27 and were within 10% of results obtained by running the model for the whole of the EU-27 using about 36 500 sites. This implies that a reliable estimate of N fluxes for EU-27 can be made by upscaling results of the 450 selected sites suggesting that dramatic reduction in computation time can be achieved without substantial deterioration of result

Uncertainties in model predictions of nitrogen fluxes from agro-ecosystems in Europe

To assess the responses of nitrogen and greenhouse gas emissions to pan-European changes in land cover, land management and climate, an integrated dynamic model, INTEGRATOR, has been developed. This model includes both simple process-based descriptions and empirical relationships and uses detailed GIS-based environmental and farming data in combination with various downscaling methods. This paper analyses the propagation of uncertainties in model inputs and parameters to outputs of INTEGRATOR, using a Monte Carlo analysis. Uncertain model inputs and parameters were represented by probability distributions, while spatial correlation in these uncertainties was taken into account by assigning correlation coefficients at various spatial scales. The uncertainty propagation was analysed for the emissions of NH<sub>3</sub>, N<sub>2</sub>O and NO<sub>x</sub>, N leaching to groundwater and N runoff to surface water for the entire EU27 and for individual countries. Results show large uncertainties for N leaching and runoff (relative errors of ∼ 19% for Europe as a whole), and smaller uncertainties for emission of N<sub>2</sub>O, NH<sub>3</sub> and NO<sub>x</sub> (relative errors of ∼ 12%). Uncertainties for Europe as a whole were much smaller compared to uncertainties at country level, because errors partly cancelled out due to spatial aggregation

Linking monitoring and modelling: can long-term datasets be used more effectively as a basis for large-scale prediction?

Data from long-term monitoring sites are vital for biogeochemical process understanding, and for model development. Implicitly or explicitly, information provided by both monitoring and modelling must be extrapolated in order to have wider scientific and policy utility. In many cases, large-scale modelling utilises little of the data available from long-term monitoring, instead relying on simplified models and limited, often highly uncertain, data for parameterisation. Here, we propose a new approach whereby outputs from model applications to long-term monitoring sites are upscaled to the wider landscape using a simple statistical method. For the 22 lakes and streams of the UK Acid Waters Monitoring Network (AWMN), standardised concentrations (Z scores) for Acid Neutralising Capacity (ANC), dissolved organic carbon, nitrate and sulphate show high temporal coherence among sites. This coherence permits annual mean solute concentrations at a new site to be predicted by back-transforming Z scores derived from observations or model applications at other sites. The approach requires limited observational data for the new site, such as annual mean estimates from two synoptic surveys. Several illustrative applications of the method suggest that it is effective at predicting long-term ANC change in upland surface waters, and may have wider application. Because it is possible to parameterise and constrain more sophisticated models with data from intensively monitored sites, the extrapolation of model outputs to policy relevant scales using this approach could provide a more robust, and less computationally demanding, alternative to the application of simple generalised models using extrapolated input data

Critical loads of cadmium, lead and mercury and their exceedances in Europe

In this chapter information is summarized on the assessment of the risk of impacts of cadmium, lead and mercury emissions and related depositions of these metals, with an emphasis on natural areas in Europe. Depositions are compared to critical loads to identify areas in Europe where critical loads are exceeded. Critical loads of cadmium, lead and mercury were based on (i) computations by 18 Parties to the Convention on Long-range Transboundary Air Pollution (LRTAP) and (ii) computations from available data on soil chemistry, meteorology and land cover for the other Parties. Two target years are considered, i.e. 2010 and 2020. Emissions for these years have been assessed in support of the negotiations for the review and possible revision of the Heavy metal protocol (Aarhus 1998). The relationship between emissions, depositions and critical load exceedances is analysed assuming the implementation of abatement techniques under Current LEgislation in 2010 (CLE2010) and in 2020 under Full Implementation of the Aarhus protocol (FI2020). Comparing the critical loads to atmospheric depositions in these years, shows that cadmium deposition is not a widespread risk in either years, that the computed risk of lead deposition affects about 22 and 16¿% of natural European area in 2010 and 2020, respectively, and that mercury deposition is computed to affect an area of more than 74¿% in both years

European Critical Loads of Cadmium, Lead and Mercury and their Exceedances

Critical loads of cadmium, lead and mercury were computed by 18 countries of the LRTAP Convention. These national data were collated into a single database for the purpose of identifying sensitive areas in Europe. Computing exceedances, i.e. comparing the critical loads to atmospheric deposition, shows that cadmium was not a widespread risk in 2000, that the risk from lead deposition has decreased since 1990 but was still widespread in 2000, and that the risk from mercury remains high without much change from 1990 to 2000 in most of the countries

Intensive monitoring of forest ecosystems in Europe; 1 objectives, set-up and evaluation strategy

In order to contribute to a better understanding of the impact of air pollution and other environmental factors on forest ecosystems, a Pan-European Programme for Intensive and Continuous Monitoring of Forest Ecosystems has been implemented in 1994. Results of the Programme must contribute to a European wide overview of impacts of air pollution and the further development of its control strategies, being described in air pollution protocols. Objectives of the Intensive Monitoring Programme related toair pollution are the assessment of: (i) responses of forest ecosystems to changes in air pollution; (ii) differences between present loads and critical loads (long-term sustainable inputs) of atmospheric deposition; and (iii) impacts of future scenariosof atmospheric deposition on the ecosystem condition. Furthermore, the Intensive Monitoring Programme contributes to the assessment of `criteria and indicators for sustainable forest management', such as the maintenance of forests as a net carbon sink toreduce the build up of atmospheric greenhouse gasses and the maintenance of species diversity of ground vegetation. The Intensive Monitoring Programme, which is carried out on approximately 860 selected plots, comprises monitoring of crown condition, forest growth and the chemical status of soil and foliage at all plots and monitoring of deposition, meteorology, soil solution and ground vegetation in a subset of the plots. In order to meet the major objectives of the Intensive Monitoring Programme, studies have been or are presently carried out with respect to the assessment of: (i) correlations between site and stress factors and the "forest ecosystem condition"; (ii) trends in stress factors and/or ecosystem conditions; (iii) critical loads, by evaluating the fate of atmospheric pollutants in the ecosystem with input-output budgets; and (iv) large-scale and long-term impacts of climate and deposition on forests and vice versa. Examples of those studies are given and the potential of the Programme tofulfil the objectives is evaluated