Long-range Transboundary Air Pollution Convention Research Articles

Validation of ozone response functions for annual Mediterranean pasture species using close-to-field-conditions experiments.

Ozone (O3) critical levels have been established under the Long-Range Transboundary Air Pollution Convention to assess the risk of O3 effects in European vegetation. A recent review study has led to the development of O3 critical levels for annual Mediterranean pasture species using plants growing in well-watered pots at a coastal site and under low levels of competition. However, uncertainties remain in the extrapolation of the O3 sensitivity of these species under natural conditions. The response of two O3-sensitive annual Mediterranean pasture Trifolium species at the coastal site was compared with the response of the same species growing at a continental site, in natural soil and subject to water-stress and inter-specific competition, representing more closely their natural habitat. The slopes of exposure- and dose-response relationships derived for the two sites showed differences in the response to O3 between sites attributed to differences in environmental growing conditions, growing medium and the level of inter-specific competition, but the effect of the individual factors could not be assessed separately. Dose-based O3 indices partially explained differences due to environmental growing conditions between sites. The slopes showed that plants were more sensitive to O3 at the continental site, but homogeneity of slopes tests revealed that results from both experimental sites may be combined. Although more experimental data considering complex inter-specific competition situations and the effect of important interactive factors such as nitrogen would be needed, these results confirm the validity of applying the current flux-based O3 critical level under close to natural growing conditions. The AOT40-based O3 critical level derived at the coastal site was also considered a suitable risk indicator in close to natural growing conditions in the absence of soil moisture limitations on plant growth.

Measuring the Impact of Multiple Air Pollution Agreements on Global CO2Emissions

This paper studies the effect on CO 2 emissions of the various agreements that follow the Long-Range Transboundary Air Pollution Convention and are related to acid rain problems. The analysis is based on a panel dataset of 150 countries over the period 1970–2008 and deals with the problems linked to the analysis of multiple agreements (e.g., time and membership overlap). We show that ratifying an additional treaty has a significant and negative impact on the level of CO 2 emissions, even if it is not targeted toward CO 2 . (JEL Q53, Q54)

Flux-based ozone risk assessment for adult beech forests

Tropospheric ozone (O3) is a critical threat to forest ecosystems. A stomatal flux-based risk evaluation methodology at the leaf level was established recently in the context of the Convention on Long-Range Transboundary Air Pollution (LRTAP). This study demonstrates improvement and validation of the stomatal flux-effect approach for adult beech with results from the 8-year free-air O3 enrichment experiment at “Kranzberger Forst” (Germany). The risk assessment module of the SVAT model FO3REST, being under development for local scale O3-risk assessment of adult beech stands, was parameterized according to the LRTAP Convention’s Mapping Manual. Mean maximum stomatal conductance for water vapour of 245 mmol H2O m−2 PLA s−1, as suggested in the LRTAP Convention’s Mapping Manual for beech, was affirmed by assessment at “Kranzberger Forst”, resulting in 162 mmol O3 m−2 PLA s−1 upon recommended adjustment of the O3/water vapour diffusivity ratio to 0.663. Based on this ratio, a provisional corrected flux-effect function was deduced. Modelled Phytotoxic O3 Doses (POD 1) and potential O3-caused losses in biomass formation estimated with a site-specific stomatal conductance algorithm differed slightly only from estimates by the original LRTAP parameterisation. Analysis-derived POD 1 target value within the meaning of Article 2 of the European Council Directive 2008/50/EC of 10 mmol O3 m−2 corresponded to potential loss in biomass formation of about 10 % in ambient air relative to “pre-industrial” conditions. However, exceedance occurred by about a factor of two during the study period, indicating high risk at “Kranzberger Forst” under ambient air. Assessment for doubled O3 exposure indicated potential underestimation even of the O3 risk because modelled losses in biomass formation are in the lower range of the standard deviation of the observed ones.

Twenty-five years of continuous sulphur dioxide emission reduction in Europe

Abstract. During the last twenty-five years European emission data have been compiled and reported under the Cooperative Programme for Monitoring and Evaluation of the Long-range Transmission of Air Pollutants in Europe (EMEP) as part of the work under the UNECE Convention on Long-range Transboundary Air Pollution (LRTAP). This paper presents emission trends of SO2 reported to EMEP and validated within the programme for the period 1980–2004. These European anthropogenic sulphur emissions have been steadily decreasing over the last twenty-five years, amounting from about 55 Tg SO2 in 1980 to 15 Tg SO2 in 2004. The uncertainty in sulphur emission estimates for individual countries and years are documented to range between 3% and 25%. The relative contribution of European emissions to global anthropogenic sulphur emissions has been halved during this period. Based on annual emission reports from European countries, three emission reduction regimes have been identified. The period 1980–1989 is characterized by low annual emission reductions (below 5% reduction per year and 20% for the whole period) and is dominated by emission reductions in Western Europe. The period 1990–1999 is characterised by high annual emission reductions (up to 11% reduction per year and 54% for the whole period), most pronounced in Central and Eastern Europe. The annual emission reductions in the period 2000–2004 are medium to low (below 6% reduction per year and 17% for the whole period) and reflect the unified Europe, with equally large reductions in both East and West. The sulphur emission reduction has been largest in the sector Combustion in energy and transformation industries, but substantial decreases are also seen in the Non-industrial combustion plants together with the sectors Industrial combustion and Industrial production processes. The majority of European countries have reduced their emissions by more than 60% between 1990 and 2004, and one quarter have already achieved sulphur emission reductions higher than 80%. At European level, the total sulphur target for 2010 set in the Gothenburg Protocol (16 Tg) has apparently already been met by 2004. However, still half of the Parties to the Gothenburg Protocol have to reduce further their sulphur emissions in order to attain their individual country total emission targets for 2010. It is also noteworthy that, contrasting the Gothenburg Protocol requirements, a growing number of countries have recently been reporting increasing sulphur emissions, while others report only minor further decreases. The emission trends presented here are supported by different studies of air concentrations and depositions carried out within and outside the framework of the LRTAP Convention.

Regional scale evidence for improvements in surface water chemistry 1990–2001

The main aim of the international UNECE monitoring program ICP Waters under the Convention of Long-range Transboundary Air Pollution (CLRTAP) is to assess, on a regional basis, the degree and geographical extent of the impact of atmospheric pollution, in particular acidification, on surface waters. Regional trends are calculated for 12 geographical regions in Europe and North America, comprising 189 surface waters sites. From 1990–2001 sulphate concentrations decreased in all but one of the investigated regions. Nitrate increased in only one region, and decreased in three North American regions. Improvements in alkalinity and pH are widely observed. Results from the ICP Waters programme clearly show widespread improvement in surface water acid-base chemistry, in response to emissions controls programs and decreasing acidic deposition. Limited site-specific biological data suggest that continued improvement in the chemical status of acid-sensitive lakes and streams will lead to biological recovery in the future.

Atmospheric Deposition of Trace Elements in Romania Studied by the Moss Biomonitoring Technique

The first systematic study in Romania of atmospheric pollution from heavy metals and other toxic elements based on moss analysis was undertaken as a Romanian-Russian-Norwegian collaboration, primarily in order to assess the general state of heavy metal pollution in Romania. An additional goal was to contribute to the European heavy metals in mosses survey, conducted under the auspices UNECE ICP Vegetation 1 which reports to the Working Group of Effects of the Long-range Transboundary Air Pollution Convention. Samples of the moss species Hypnum cupressiforme, Hylo- comium splendens and Brachytechium salebrosum and B. rutabulum were collected during the period 1995-2001. A total of 40 elements were determined using NAA and AAS. The total concentrations of arsenic, cadmium, copper, nickel, vanadium and zinc are presented in the form of contour maps. Generally, the observed concentrations in Romania are markedly higher than those observed in most other countries of Europe using the moss technique. Ke yw ords: atomic absorption spectrometry, heavy metal pollution, moss biomonitoring technique, neutron activation analysis, trace elements.

Dynamics of understory vegetation in boreal forests: experiences from Swedish integrated monitoring sites

This study reports results from a first analysis of vegetation dynamics in permanent plots in Swedish boreal forests. The plots are a part of the international cooperative programme on integrated monitoring of air pollution effects on ecosystems (ICP IM), which is part of the long-range transboundary air pollution convention (LRTAP) of the united nation’s economic commission for Europe. In Sweden, there are four ICP IM monitoring sites, established 1982–1999. Vegetation measurements are made about every second year to be able to detect and follow possible changes in species composition. Ellenberg indices for light, moisture, pH and nitrogen were used as indirect metrics of environmental conditions. Vegetational gradients were explored by multivariate ordination methods. All gradients were short, less than 1.5 units in detrended correspondence analyses. Despite the short gradients, all sites showed spatial variation that could be related to different Ellenberg indices. A temporal trend in species composition was detected only at one site. At this site time accounted for 8% of the variation in the data set and a spatial variable accounted for 13%. Correlations between ordination plot scores and Ellenberg indices indicated that the temporal trend was partly caused by increasing light regime and decreasing soil moisture.

Element removal in harvested tree biomass: scenarios for critical loads in Wallonia, south Belgium

The critical load concept is nowwidely used as a tool for developing emissioncontrol policies in Europe. As a signatorycountry of the Convention of Long-RangeTransboundary Air Pollution, critical loads foracidity, nutrient nitrogen, nitrogen and sulphurhave been calculated for the Flemish and Walloonregions in Belgium. This paper describes themethodology used for estimating critical loadsfor forest soils in the Walloon region accordingto the Steady-State Mass Balance equations. As anexample the methodology was applied to thecatchment `Waroneu', situated in a sensitive areaof the Haute Ardenne. Main input parameters tothe equations were derived from precipitation andrunoff data of the catchment study. Improvedestimates of nitrogen uptake (Nu) and base cationuptake (BCu) were obtained by intensive samplingof Picea abies and Quercus roburtrees. Nutrient contents (Ca, Mg, K, N) andnutrient to nitrogen ratios of Picea abiesreflected the poor soil quality at a site withhigh N deposition. Quercus robur nutrientcontents increased from stem to higher orderbranches with a high proportion of nutrientslocated in the bark. However the simulation ofstem only harvesting had a minor effect oncritical loads. Measured wood densities werelower than reported literature values with a maineffect on Nu and BCu estimates. The use ofrecommended default values and/or data derivedfrom the experimental site resulted in a widerange of critical loads, some of which werelargely overestimated. Results demonstrated theimportance of site specific data for criticalload calculations.

The critical load concept for emission abatement strategies in Europe: a review

Critical loads studies (critical load is ‘a quantitative estimate of an exposure to one or more pollutants below which no harmful effects may occur’) have been used as the basis for assessing European strategies for reduction of sulphur emissions within the United Nations (UN) Economic Commission for Europe (ECE) Convention on Long-Range Transboundary Air Pollution (LRTAP). It is expected that the critical loads method will be applied to future international agreements under the Convention. Mapping of European critical loads conducted for the LRTAP Convention have progressed notably in recent years.The concept of designing pollution control measures with the aim of protecting the most sensitive ecosystems, led to the creation of the Task Force on Mapping and Coordination Centre for Effects to implement these concepts on a European scale together with the corresponding National Focal Centres. The Russian National Focal Centre is used to illustrate how critical load data can be applied at the scale of a large country.The policy implications resulting from the methods described in this review would support the development of an acidification protocol. While this has been suggested in the past, it is only now that scientific knowledge has advanced sufficiently to consider the feasibility of such a policy.