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- de Vries, Wim; Forsius, Martin; Lorenz, Martin; Lundin, Lars; Haußmann, Thomas; Augustin, Sabine; Ferretti, Marco; Kleemola, Sirpa; Vel, Evert,
(författare)
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Cause-effect Relationships of Forest Ecosystems
- 2002
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- For more than 20 years the Convention on Long-range Transboundary Air Pollution (CLRTAP) has been striving to control air pollutant emission in Europe and North America. Its Working Group onEffects (WGE) has been responsible for the scientific underpinning. The International CooperativeProgrammes (ICPs) identify air pollution effects on the environment through monitoring, modellingand scientific review. The scientific network of the ICPs and the monitoring and modelling resultshave been promoting the development of the Convention and are an essential component for itssuccess in the future.The International Cooperative Programme on Assessment and Monitoring of Air Pollution Effectson Forests (ICP Forests) collects in close cooperation with the European Commission data anddetermines cause effect relationships of changes in forests due to air pollution and other stresses bymeans of monitoring both at the large scale and at the scale of ecosystems. The International CooperativeProgramme on Integrated Monitoring of Air Pollution Effects on Ecosystems (ICP IM)determines and predicts the state of ecosystems or catchments and their changes from a long-termperspective with respect to the regional variation and impact of air pollutants.Both ICPs have been co-operating closely for a number of years now although the objects understudy are different at first sight. ICP IM is focusing on catchments in undisturbed ecosystems whileICP Forests monitors forest ecosystems which are managed regularly. As most ICP IM sites arewithin forest areas and as many countries have linked their plots of both programmes within onemonitoring system, it is common agreement to intensify the co-operation. One result of this intensiveco-operation is the harmonisation of assessment methods. As the next level of cooperation, thisreport reviews the outstanding data and information gathered by both programmes and presents forvarious areas of research the main findings. In addition results and information were contributed bya large number of participating countries. All support received from the countries in the preparationof the report is gratefully acknowledged.It is expected that this report will intensify the co-operation between the National Focal Centres(NFCs) in all participating countries and help to intensify the work in those areas which will be ofhighest priority for the two programmes in future.
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| 2. |
- Meili, M, et al.
(författare)
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Critical levels of atmospheric pollution: criteria and concepts for operational modelling of mercury in forests and lake ecosystems.
- 2003
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Ingår i: Science of the Total Environment. - 1879-1026. ; 304:1-4, s. 83-106
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Tidskriftsartikel (refereegranskat)abstract
- Mercury (Hg) is regarded as a major environmental concern in many regions, traditionally because of high concentrations in freshwater fish, and now also because of potential toxic effects on soil microflora. The predominant source of Hg in most watersheds is atmospheric deposition, which has increased 2- to >20-fold over the past centuries. A promising approach for supporting current European efforts to limit transboundary air pollution is the development of emission-exposure-effect relationships, with the aim of determining the critical level of atmospheric pollution (CLAP, cf. critical load) causing harm or concern in sensitive elements of the environment. This requires a quantification of slow ecosystem dynamics from short-term collections of data. Aiming at an operational tool for assessing the past and future metal contamination of terrestrial and aquatic ecosystems, we present a simple and flexible modelling concept, including ways of minimizing requirements for computation and data collection, focusing on the exposure of biota in forest soils and lakes to Hg. Issues related to the complexity of Hg biogeochemistry are addressed by (1) a model design that allows independent validation of each model unit with readily available data, (2) a process- and scale-independent model formulation based on concentration ratios and transfer factors without requiring loads and mass balance, and (3) an equilibration concept that accounts for relevant dynamics in ecosystems without long-term data collection or advanced calculations. Based on data accumulated in Sweden over the past decades, we present a model to determine the CLAP-Hg from standardized values of region- or site-specific synoptic concentrations in four key matrices of boreal watersheds: precipitation (atmospheric source), large lacustrine fish (aquatic receptor and vector), organic soil layers (terrestrial receptor proxy and temporary reservoir), as well as new and old lake sediments (archives of response dynamics). Key dynamics in watersheds are accounted for by quantifying current states of equilibration in both soils and lakes based on comparison of contamination factors in sediment cores. Future steady-state concentrations in soils and fish in single watersheds or entire regions are then determined by corresponding projection of survey data. A regional-scale application to southern Sweden suggests that the response of environmental Hg levels to changes in atmospheric Hg pollution is delayed by centuries and initially not proportional among receptors (atmosphere>>soils≠sediments>fish; clearwater lakes>>humic lakes). This has implications for the interpretation of common survey data as well as for the implementation of pollution control strategies. Near Hg emission sources, the pollution of organic soils and clearwater lakes deserves attention. Critical receptors, however, even in remote areas, are humic waters, in which biotic Hg levels are naturally high, most likely to increase further, and at high long-term risk of exceeding the current levels of concern: 0.5 mg (kg fw)−1 in freshwater fish, and 0.5 mg (kg dw)−1 in soil organic matter. If environmental Hg concentrations are to be reduced and kept below these critical limits, virtually no man-made atmospheric Hg emissions can be permitted.
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