Sanna Syri

Low-CO2 energy pathways and regional air pollution in Europe

Abstract This paper compares three scenarios of energy demand in the European Union until 2010 and analyses their effects on carbon emissions as well as their impacts on the precursor emissions for acidification and ground-level ozone. The analysis links the results of energy model PRIMES with the integrated environmental assessment model RAINS. Important synergies between climate change policies and policies to control regional air pollution have been identified. Mitigation of acidification and ozone according to the current EU strategy will be easier and cheaper if the Kyoto targets for the reduction of the emissions of greenhouse gases (GHG) are to be met. In case when the Kyoto target needs to be achieved by individual EU member countries without trading in CO2 emission rights, the costs of controlling the pollutants contributing to acidification and ground-level ozone can be up to 10% lower than for the baseline scenario which does not assume any climate change policies. Although lower, the effects are also important if trading in carbon emission rights is allowed. These cost savings compensate up to 20% of higher costs of energy supplies in the EU and associated with them welfare losses caused by the necessity to meet the carbon constraint.

Recovery from acidification of Finnish lakes: regional patterns and relations to emission reduction policy

The regional-scale response of Finnish headwater lakes to changes in acidifying deposition loads was studied using data from a national deposition monitoring network (19 stations), acidification monitoring lakes (163 lakes) and results of a statistically based national lake survey (873 lakes). Data from 1990 to 1999 were used for statistical trend analysis. A deposition model was used to assess changes in S and N deposition for the year 2010, assuming emission reductions according to two international agreements. The deposition of sulfate and H(+) showed statistically significant (Kendall-tau, P<0.05) decreasing trends at nearly all deposition stations. For N compounds, nearly all slopes were negative, but rarely statistically significant. Sulfate concentrations have declined in all types of small lakes throughout Finland in the 1990s (significant decline in 64-85% of the lakes in three different lake regions), indicating a clear response to S emission reductions and declined sulfate deposition. Base cation concentrations decreased in both deposition and lake water, especially in southern Finland, but to a lesser extent than sulfate concentrations. The median slope of the trend for Gran alkalinity in lakes ranged between 0.98 and 2.1 microeq l(-1) a(-1). Some 1400 (27%) of Finnish headwater lakes of size 4-100 ha were estimated to show statistically significant increases in Gran alkalinity (recovery). No large changes were observed in the lake water TOC concentrations. The reduction in S deposition is the main driving factor for the lake acidification recovery process in Finland. Deposition model calculations showed that further large reductions in S deposition beyond the 1999 level are not likely to occur by the year 2010, particularly for southeastern Finland. The mean estimated S deposition change by 2010 for the three lake regions in Finland was only between -0.9 and -6.6% for the two policy scenarios (UN/ECE Gothenburg protocol, EU NEC-directive), respectively. A slower acidification recovery of the lake ecosystems is, therefore, anticipated in the future.

Application of nitrogen transfer matrices for integrated assessment

Abstract Linear transfer matrices for nitrogen compounds were constructed from the results of the regional air quality model of the Finnish Meteorological Institute (FMI-RM). The matrices are implemented into the integrated assessment model DAIQUIRI used at the Finnish Environment Institute. The deposition fields of oxidised and reduced nitrogen calculated with both models for year 1990 are compared with each other and against measured deposition. Both models give higher depositions than the measurements, and DAIQUIRI often more than FMI-RM. DAIQUIRI currently tends to overestimate nearby deposition of oxidised and reduced nitrogen in areas where land use types other than forest dominate.

Estimating long-term population exposure to ozone in urban areas of Europe

Tropospheric ozone concentrations regarded as harmful for human health are frequently encountered in Central Europe in summertime. Although ozone formation generally results from precursors transported over long distances, in urban areas local effects, such as reactions due to nearby emission sources, play a major role in determining ozone concentrations. Europe-wide mapping and modeling of population exposure to high ozone concentrations is subject to many uncertainties, because small-scale phenomena in urban areas can significantly change ozone levels from those of the surroundings. Currently the integrated assessment modeling of European ozone control strategies is done utilizing the results of large-scale models intended for estimating the rural background ozone levels. This paper presents an initial study on how much local nitrogen oxide (NOx) concentrations can explain variations between large-scale ozone model results and urban ozone measurements, on one hand, and between urban and nearby rural measurements, on the other. The impact of urban NOx concentrations on ozone levels was derived from chemical equations describing the ozone balance. The study investigated the applicability of the method for improving the accuracy of modeled population exposure, which is needed for efficient control strategy development. The method was tested with NOx and ozone measurements from both urban and rural areas in Switzerland and with the ozone predictions of the large-scale photochemical model currently used in designing Europe-wide control strategies for ground-level ozone. The results suggest that urban NOx levels are a significant explanatory factor in differences between urban and nearby rural ozone concentrations and that the phenomenon could be satisfactorily represented with this kind of method. Further research efforts should comprise testing of the method in more locations and analyzing the performance of more widely applicable ways of deriving the initial parameters.

Regional nitrogen deposition model for integrated assessment of acidification and eutrophication

Abstract To complement the continent-scale integrated assessment of emission abatement strategies with regional studies, tools with high resolution are needed. For this purpose, the regional nitrogen transport and deposition model DAIQUIRI using linear transfer matrices, i.e. source-receptor relationships, was developed at the Finnish Environment Institute. The model is based on results of a regional dispersion and deposition model of the Finnish Meteorological Institute (FMI-RM). This paper describes the second phase of model development and validation. The transfer matrices constructed for years 1993 and 1995 were used for generating deposition fields, which were then compared with the results of FMI-RM and continent-scale EMEP model, and with measurements. In addition, the model performance in applications was evaluated: the impacts of regional deposition modelling on exceedances of ecosystem critical loads for acidification were calculated and compared with those using the EMEP model. Both regional models gave comparable results, although some differences existed especially for areas where other land-use types than forest dominate. Also the comparison with measurements showed that estimation of deposition for coastal and sea areas is fraught with uncertainties. For reduced nitrogen, the resolution of the models was insufficient to describe the fine-resolution deposition pattern close to emissions. The comparison with results of the EMEP model, however, showed the ability of regional models to represent the spatial deposition pattern in more detail in areas near emissions. The use of regional modelling resulted in larger estimates of areas at risk of acidification than when using only the continent-scale EMEP model.

From emissions in Europe to critical load exceedances in Finland — uncertainty analysis of acidification integrated assessment

Abstract This paper evaluates the uncertainties in integrated assessment modeling of acidification, relates the findings to European emission reduction strategies and draws conclusions about further research priorities. The paper presents a mathematical and literature analysis of the uncertainties in the ecosystem areas at risk of acidification in Finland inherent in the integrated assessment of air pollution used in the development of European emission abatement agreements. Owing to the need for relatively simple models, integrated assessment is uncertainty prone. Uncertainties in national inventories of acidifying emissions in European countries and their spatial locations, in the atmospheric transport of the pollutants and in the critical loads, characterizing the ecosystems’ sensitivity, were taken into account. The relative contributions of the uncertainties in the individual modules of the integrated assessment modeling to the overall uncertainty of ecosystem protection levels were calculated for 1990 and 2010, assuming the implementation of the recent UN/ECE Gothenburg Protocol curbing long-range transboundary air pollution. The robustness of the acidification risk estimates was shown to improve significantly from 1990 to 2010, which is due to the anticipated large overall decrease in deposition levels. For most parts of Finland uncertainties in the critical loads were found to dominate the total uncertainty of integrated assessment modeling of acidification. Thus further research efforts to reduce uncertainties should be mainly focused on a more precise description of ecosystem processes. In Southern Finland and in areas close to Russian emission sources also the uncertainties in emission inventories and in the atmospheric transport and deposition modeling were shown to be significant, which emphasizes the need for high-resolution modeling when developing protection strategies for natural areas in the vicinity of significant emissions. Using a 95% confidence level, a probabilistic impact assessment of emission reduction alternatives indicates a considerably more pessimistic ecosystem protection level than the deterministic approach used in European decision-making.

Sensitivity of soil acidification model to deposition and forest growth.

We report an investigation concerning the impacts of acid deposition and forest growth scenarios on simulated soil effective base saturation for a forested catchment in eastern Finland. These forests have not been managed during the last 150 yr and the area receives low levels of acidifying deposition. The fluxes of sulphur, nitrogen and base cations were assessed with models simulating historic and future deposition, stand uptake and leaching. We tested the effects of calibrating the modelled deposition time series to high and low estimates of current levels of deposition. The highest future soil base saturation was predicted when using the year with the lowest observed sulphur and nitrogen deposition (1993) as representative of the present deposition. The lowest historical and future soil base saturation resulted for using the year with the highest observed deposition of sulphur and nitrogen (1988). All scenarios concerning nutrient uptake, emission reduction levels and timing of the reductions resulted in simulated future soil base saturation values located between those predicted with the high and low observed present deposition. The standard deviation in the soil base saturation introduced by varying the present forest biomass and growth was smaller than that produced by varying the present deposition values.

Integrated assessment modeling of air pollution in four european countries

The integrated assessment modeling on acid rain has incorporated several related effects and pollutants into a multi-pollutant/multi-effect approach, resulting in complex integrated models and policy assessments. The development and implementation of effects-oriented cost-effective emission reduction strategies in Europe are based on integrated assessment models. The project on national integrated assessment modeling in Finland, Denmark, Spain and Sweden aimed to support the national evaluation of European emission reduction strategies. The tasks covered the comparison of inventories and projections for emissions of sulfur, nitrogen oxides, ammonia and volatile organic compounds, assessment of control techniques and related costs, concentration and deposition scenarios to estimate environmental effects of acidification, eutrophication and ground-level ozone and their temporal aspects, uncertainty analyses on both individual modules and whole integrated models, and dissemination of results to stakeholders. The integrated assessment modeling provided a consistent framework for the harmonization of input data and in-depth scientific research tasks on emissions, pollutant loading and impacts including comprehensive uncertainty analyses, and facilitated the dissemination of knowledge to policy-makers.

Assessing the effects of domestic and international energy scenarios and emission reduction strategies on acidification in Finland

An integrated model system was developed and used to assess the effects of alternative energy production scenarios and reduction policies on acidification of lakes and forest soils in Finland. The analysis covered different energy scenarios and resulting emissions of sulfur oxides and nitrogen oxides in Finland, as well as ammonia emissions with various control requirements. In addition, emission reduction scenarios of varied ambition levels in the bordering areas of Finland and in other parts of Europe were included in the analysis. The impacts of the different scenarios were quantified with exceedances of critical loads for acidification and with the total areas where the critical loads are exceeded. The possibilities for reducing the areas with critical load exceedances with national or bilateral measures were investigated. The differences in areas at risk, if depositions from domestic and nearby sources are estimated with a regional model and point-source databases or with a continental scale model and coarser-scale emission data, were analyzed. The reasons for the differences and the implications for national-level assessment are discussed.