Contract EVK1-1999-00087 - RECOVER:2010

Part of the 'Sustainable Management and Quality of Water'

Ecosystem Functioning

Directorate General Research

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Acidification is a widespread regional water pollution problem in nearly 90,000-km2 area of southern Norway. Acid deposition peaked in the late 1970's and since then S deposition has declined by nearly 50%. The chemistry of lakes, rivers and streams monitored since the 1970's shows that conditions have improved since 1980, slowly at first and more markedly during the 1990's (Skjelkvåle et al., 1998). Concentrations of sulphate have decreased, accompanied by decreases in base cations, and increase of ANC and pH. The rate, timing and degree of recovery differ from site-to-site and between different regions in Norway. Some lakes in southeastern Norway have also have experienced an increase in TOC during the 1990's, the reason for which is unknown. This confuses the picture of response to decreased S deposition. As sulphate declines, nitrate has become of increasing importance and there is risk that recovery of these waters following reduced S deposition may be offset by future increases in nitrate. The long-term records from monitoring sites in Norway show trends of increasing NO3 concentrations at some sites, but not at others. The risk of N saturation and increased NO3 in runoff is not known. Norwegian data for RECOVER:2010 will come from the ongoing national monitoring program (SFT, 1998) as well as from whole-ecosystem manipulation experiments with decreased acid deposition (Wright et al., 1993). Norwegian lake survey data also collected under the auspices of the national monitoring programme will also be used in RECOVER 2010 (Skjelkvåle et al., 1998). About 100 lakes located throughout Norway are sampled annually since 1986 and measured for water chemistry. These lakes are a sub set of the national lake surveys conducted in 1986 and 1995. Thus the trends revealed from the 100 lake dataset can be extrapolated to the entire population of lakes in Norway. Data from large-scale manipulation experiments with reduced acid deposition will also be used to evaluate recovery. These include data from the roof experiments of the RAIN project at Risdalsheia, Norway (Wright et al., 1993), Gårdsjön, Sweden (Hultberg and Skeffington, 1998), Solling, Germany (Bredemeier et al. 1995), and Klosterhede, Denmark (Beier et al. 1998 FEM). Data from these sites include input (precipitation and throughfall), outputs (soil solution and runoff), as well as soil chemistry and detailed information on soil and vegetation process. In addition process-oriented models such as MAGIC have been applied at the sites. These applications are robust tests of the models and reveal strengths and shortcomings. Indeed the aspects of the measured response to reduced deposition not explained by the models points the way to processes inadequately understood or described in the models. As part of RECOVER:2010 the data from these experiments will be augmented and updated by resampling the soils to detect changes in pools of sulphur, nitrogen, carbon and base cations.

Results from Scandinavia 

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Upland Uk
Southern Norway
Czech Republic