PREDICTING RECOVERY IN ACIDIFIED FRESHWATERS BY THE YEAR 2010, AND BEYOND

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• Upland UK
• Germany
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Sulphur and nitrogen fluxes and budgets in the Bohemian Forest and Tatra Mountains during the Industrial Revolution (1850-2000)

J. Kopacek¹, J. Veselý ²and E Stuchlík^3
1Hydrobiological Institute, AS CR, and Faculty of Biological Sciences, USB, Na sádkách 7,370 05 Èeské Budejovice, Czech Republic
²Czech Geological Survey, Geologická 6, 152 00 Praha 5
³Department of Hydrobiology, Charles University, Vinicná 7, 120 44 Praha 2, Czech Republic

Full Reference
Kopácek, J., Vesely, J. and Stuchlik, E. (2001). Sulphur and nitrogen fluxes and budgets in the Bohemian Forest and Tatra Mountains during the Industrial Revolution (1850 to 2000). Hydrology and Earth System Sciences Vol. 5, No. 3, 391-405

Summary of Research

In this paper major fluxes of S and N compounds in two central European mountain areas (Bohemian forest and Tatra Mountains) are estimated for the whole industrial period. First, historical (1850-2000) emission rates of S and N in the area of the Czech Republic and Slovakia are reconstructed. Second, historical trends in S and N deposition in the mountains are estimated using relationships between emissions rates and measured deposition. Third, S and N outputs from catchment-lake processes are estimated using historical and recent water chemistry records. Finally, the input-output fluxes are used to estimate possible changes in soil storage of S and N over the 1930-2000 period.

Site Description

Two lakes (Cerne and Certovo) were studies in the Bohemian Forest. These lakes are are situated in steep, forested catchments, planted predominantly with Norway spruce and sparce beech. Soils are mostly acidic podzols in different stages of developement. Three lakes (Wielki Staw; Morskie Oko, Vysné Wahlenbergovo were studies in the Tatra Mountains. Wielki Staw and Vysné Wahlenbergovo are situated in the alpine zone, while Morskie Oko is below the local tree line with 80% of the catchment in the alpine zone. Bedrock is mostly composed of granodiorite. SOils above the tree line are generally underdeveloped alpine podzols. Details of morphological and chemical parameters of the Bohemian Forest and Tatra Mounatins catchment-lake ecosystems are shown in Table 1. The chemical composition of the lake water are also presented in Table 1 from a survey conducted in September-October 2000.
















Major fluxes in sulphur and dissolved inorganic nitrogen were estimated in Central European mountain ecosystems of the Bohemian Forest (forest lakes) and Tatra Mountains (alpine lakes) over the industrial period. Sulphur outputs from these ecosystems were comparable to inputs during a period of relatively stable atmospheric deposition (10-35 mmol m^-2 yr^-1) around the 1930s. Atmospheric inputs of sulphur increased by three- to four-fold between the 1950s and 1980s to ~140 and ~60 mmol m^-2 yr^-1 in the Bohemian Forest and Tatra Mountains, respectively Figure 1). Sulphur outputs were lower than inputs due to accumulation in soils, which was higher in forest soils than in the sparser alpine soils and represented 0.8-1.6 and 0.2-0.3 mol m^-2, respectively, for the whole 1930-2000 period. In the 1990s, atmospheric inputs of sulphur decreased by 80% and 50% in the Bohemian Forest and Tatra Mountrains, respectively, and sulphur outputs exceeded inputs. Catchment soils became pronounced sources of sulphur with output fluxes averaging between 15 and 31 mmol m^-2yr^-1. Higher sulphur accumulation in the forest soils has delayed (by several decades) recovery of forest lakes from acidification compared to alpine lakes.












Dissolved inorganic nitrogen was efficiently retained in the ecosystems and nitrate export was negligible (0-7 mmol m^-2 yr^-1). By the 1980s, nitrogen deposition increased to ~160 and ~80 mmol m^-2 yr^-1 in the Bohemian Forest and Tatra Mountains, respectively, and nitrogen output increased to 120 and 60 mmol m^-2 yr^-1 (Figure 2). Moreover, assimilation of nitrogen in soils declined from ~40 to 10-20 mmol m^-2 yr^-1 in the alpine soils and even more in the Bohemian Forest, where one of the catchments has even become a net source of nitrogen. In the 1990s, nitrogen deposition decreased by ~30% and DIN output decreased to <70 and 35 mmol m^-2 yr^-1 in the Bohemian Forest and Tatra Mountains, respectively. New steady-state conditions, with negligible nitrogen export, could be reached in future but at lower nitrogen depositions than in the 1930s.

Estimated deposition of dissolved inorganic nitrogen was 53-75 mmol m^-2 yr^-1 in the Bohemian Forest and 35-45 mmol m^-2 yr^-1 in the Tatra Mountains in the 1880-1950 period, i.e. below the empirically derived threshold of ~70 mmol m^-2 yr^-1, above which nitrogen leaching often occurs.

Trends in the atmospheric input of DIN and its output from catchment-lake ecosystems of the Bohemian forest and Tatra mountains are shown in the upper part of Figure 3. Ratios of N ouput to N input paralleled the increase and decrease in deposition rate and did not exceed 1 in any lake after the deposition declined (lower part of Figure 3). This contrasts with S trends in the two regions.