Reversibility of acidification: Soils and surface waters

Recent declining levels of acid deposition in both North America and Europe have initiated reversal of acidification and recovery of impacted ecosystems. The reversibility of acidification has also been investigated by means of large-scale experiments with whole ecosystems. Predictive models can account for much of this empirical and experimental data, at least at coarse spatial and temporal scales. Discrepancies between observed and predicted effects are due in part to the increasingly important role of nitrogen in soil and water acidification. "Nitrogen saturation" threatens to offset the incipient recovery due to reductions in SO2 emissions. Possible ecosystem impacts of future climate change add further uncertainty to predictions of long-term acidifications trends