Chemical and biological recovery in acid-sensitive waters: trends and prognosis (ICP Waters report 119/2015)

We present a trend analysis of surface water chemistry in in acid-sensitive lakes and rivers in Europe and North America, for the period 2000 to 2011, combined with a prognosis for water chemistry in Europe in 2020. Also, trends in freshwater biology in acidified surface waters in Europe are presented. Declining emissions and deposition of sulphur between 2000 and 2011 have lowered sulphate concentrations in surface waters. The clearest indication that water chemistry is getting less hostile to acid sensitive organisms is increased pH. Several examples of partial biological recovery are presented, but also examples where communities of aquatic invertebrates show few signs of recovery. We expect that climate variability will confound effects of reduced sulphur emissions on chemical and biological recovery in the next decades.