Modeling anticipated climate change impact on biogeochemical cycles of an acidified headwater catchment

Abstract

Abstract The aim of this study was to estimate future water balance and streamwater chemistry changes, according to different climate change scenario, in a forested acid-sensitive catchment. The investigated Czech catchment was affected by large anthropogenic acidification in the 20th century. Runoff for the year 2070 and streamwater chemistry for the period 1860–2070 were simulated by the models Brook90 and MAGIC, respectively. The runoff would change from 450 mm a−1 (1990–2006) to 320–402 mm a−1 for the year 2070 according to Brook90 simulations with bias-corrected regional climate model (RCAO) data with A2 emission scenario. Future streamwater SO 4 2 - concentration would maintain at the current level of approximately 90 μeq L−1 (2008–2009) in the case of minimum or no change in runoff, or would increase by 10–30% as a result of projected runoff decrease. The runoff change would increase the concentration of base cations of a similar magnitude compared to the measured 160 μeq L−1 (2008–2009). According to both scenarios, the effect of climate change on pH would be small and would lead to slight re-acidification of streamwater compared to the measured 4.2 (2008–2009). The climate change influence to streamwater chemistry would be small compared to the influence of atmospheric acid deposition. The environmental condition of the stream will probably remain unsatisfactory until the 2070s.