Modelling Long-Term Acidification: A Comparison with Diatom Reconstructions and the Implications for Reversibility

A model of long term acidification (MAGIC) is applied to a range of catchments in Scotland that are subject to different pollution inputs and land uses. The simulated historical trends in pH are compared with data from palaeolimnological reconstructions undertaken at the same sites. Both techniques produce similar historical acidification trends and, with some exceptions, closely match observed present day pH. The MAGIC model results indicate that pollution inputs and land-use, particularly afforestation, have significant effects on surface water acidification. Moreover, the model indicates that reversibility may be occurring at several sites. Reversibility of acidification is further explored by using the model in predictive mode under several scenarios for reduction deposition.