Trends in the hydrochemistry of acid-sensitive surface waters in the UK 1988-2008

► Hydrochemical trends (1988-2007) in acidified UK lakes and streams are reviewed. ► Concentrations of non-marine sulphate (xSO4) showed coherent national declines. ► Acid Neutralising Capacity (ANC) increased proportionally to reductions in xSO4. ► Increases in organic acids dominated the ANC response in the least acidified sites.