Abstract: Over the past two decades, substantial reductions in the deposition of
acidifying substances (primarily sulphur) have occurred in most parts of Europe and,
following recent agreements, this trend is likely to continue. The question arises as to
how have sensitive ecosystems reacted, and will react in the future, to these reduced
inputs of acidity? In this paper, the SMART dynamic acidification model predicts the
possible recovery of 36 acid-sensitive Finnish headwater lakes, for which both catchment
soil and water quality measurements were available. The model was calibrated to
measurements by adjusting poorly known parameters; it was then used to simulate soil and
water chemistry until 2030 under the ‘current legislation scenario’ resulting from
implementing current European emission reduction agreements. Whereas most of the catchment
soils show very little change in base saturation, the positive trends in lake ANC and
the negative trends in lake sulphate concentrations, observed over the past decade,
continue into the future, albeit at a slower pace. The model predicts that, during
2010–30, all lakes will have reached a positive ANC, a pre-requisite for the recovery
of fish populations.
Keywords: acidification, lake, catchment, recovery, SMART model, Finland |