Influence of air pollution on the hydrochemistry of small Irish lakes

A re-survey of remote, acid-sensitive lakes in Ireland (n = 142) was carried out during spring 2007 and 2008 to assess the changes in water chemistry (since 1997) as a result of greater than 50% reductions in sulphur dioxide emissions in Europe. Despite their location on the western periphery of Europe and the dominant influence from Atlantic clean air masses, small Irish lakes have shown a significant chemical response to reductions in air pollution. Observed changes include decreases in sulphate, base cations, and aluminium concentration with increases in alkalinity and acid neutralizing capacity. However, pH has not changed owing to increases in dissolved organic carbon (organic acids) in most lakes. Trace metal concentrations were low, within the natural background range for surface waters. Nonetheless, redundancy analysis suggested many metals may be influenced directly through atmospheric pollution (e.g., Pb, Hg) or indirectly through leaching from acidification (e.g., Al, Zn).;Keywords: Lakes, water chemistry, acid deposition, survey, acidification, trace metals...