Modelling long-term changes in stream water and soil chemistry in catchments with contrasting vulnerability to acidification (Lysina and Pluhuv Bor, Czech Republic)

Abstract

In two Czech catchments covered by Norway spruce forests, the MAGIC model was used to simulate annual stream water and soil chemistry for the period 18512030. These two sites represent geochemical end-members of ecosystem sensitivity to acidification (acid-sensitive granitic Lysina catchment vs. acid-resistant serpentinitic Pluhuv Bor catchment). Although the total deposition of sulphur to the catchments declined by 75% between 1990 and 2002, the recovery of stream water pH was relatively small over this period. At Lysina, the annual discharge-weighted mean pH of stream water increased only from 3.92 to 4.01, although SO 4 concentration declined very sharply from 570 meq L 1 in 1990 to 150 meq L 1 in 2002. Stream water buffering was caused mainly by dissociation of organic acids. At Pluhuv Bor, the annual mean pH varied inversely with the annual discharge. Stream water concentrations of SO 4 declined dramatically at Pluhuv Bor, from 1040 meq L 1 in 1992 to 220 meq L 1 in 2002. Using atmospheric deposition as specified in the Gothenburg Protocol, the model predicts that, at Lysina, stream water pH will increase to 4.3 and soil base saturation will increase to 6.0% by 2030 (from 5.6% in 2002); corresponding pre-industrial stream water pH was simulated to be 5.5 and soil base saturation to be 25%. At Pluhuv Bor, the pre-industrial pH was estimated to be 7.2 and the corresponding base saturation was 94%. Large anthropogenic acidification in the 20 th century caused only a small decline in pH (to 6.9) and base saturation (to 88%). Simulations in accordance with the Gothenburg Protocol predict that the pH should increase by 0.2 pH units and the base saturation by 1% by 2030. Under this protocol, critical loads of atmospheric deposition for SO 4 and NO 3 will not be exceeded at Pluhuv Bor but will be exceeded at Lysina.

Depth profiles of potassium and its isotope ratio (40K/K) in several forest soils

“…13 Under a thin (a few cm) organic layer, the soil shows clayey texture of grey in color down to a certain depth (~50 cm), and below this depth fragile dark green fragments appeared as a predominant phase. In contrast, the soils from Lysina and Nacetin showed highest value of It is now speculated that there might be potential factors influencing variability of 40 K isotope ratio in soil.…”

Long-term changes in aluminum fractions of drainage waters in two forest catchments with contrasting lithology

“…Bulk precipitation and throughfall have been collected at several sites ( Fig. 1) monthly since the beginning of 1990s [10]. Stream water discharge have been monitored continuously using V-notch weirs and mechanical water level recorders since September 1989 at Lysina and since November 1991 at Pluhův Bor [21].…”

“…In the early 1990s, runoff from Lysina was acidic and high in Al concentrations [2]. Long-term changes in Al concentrations have been simulated by the MAGIC model in both catchments [10]. A combination of a MAGIC model with a model that predicts short-term transient changes in hydrochemistry during hydrologic events (pBDM) showed that Al mobilization was highly variable at Lysina due to historic changes in acidic inputs [16].…”

“…Furthermore, dry deposition of acidic substances onto the canopy of coniferous spruce trees substantially increases acid inputs to the soil in comparison to the canopy of decidous beech [8]. Another important factor controlling the effects of acidic deposition on water quality is the bedrock type [9,10].…”

Predicting long-term recovery of a strongly acidified stream using MAGIC and climate models (Litavka, Czech Republic)

“…Large reductions in S and N inputs in the 1980s and 1990s have resulted in significant reversal of acidification in some of these fresh waters . Dynamic models have been successfully applied to many catchments in the region (Majer et al, 2003;Hruška and Krám, 2003;Kopáček et al, 2004a) and have proven to be robust in predicting changes in soil and water chemistry in response to the decreased deposition. Future predictions based on expected atmospheric emission reductions required under European Union agreements (Gothenburg Protocol -UN-ECE, 1999), however, show that recovery of these ecosystems is complicated by continued leaching of sulphate (SO 4 ), and in some cases nitrate (NO 3 ), from soils exposed to long-term deposition of these compounds (Kopáček et al, 2002;Hruška et al, 2002).…”