Results from the Italian Participation in the International Co-operative programme on Assessment and Monitoring of Acidification of Rivers and Lakes (ICP Waters)

This paper describes the research activity carried out by the Istituto Italiano di Idrobiologia of the CNR, on behalf of the Ministero dell'Ambiente, Servizio Inquinamento Atmosferico e Acustico, in the context of the Italian participation in the International Cooperative Programme on Assessment and Monitoring of Acidification of Rivers and Lakes (ICP Waters). Atmospheric deposition chemistry shows that nitrate increased and sulphate decreased in the 70's and 80's, while acidity started to decrease in the early 90's. The studied rivers and lakes show variations in sulphate and nitrate in agreement with those of atmospheric deposition. Alkalinity is mainly determined by watershed geo-lithology and is always present in the studied lakes and streams; the lowest values of 0-10 ?eq l-1 are measured in the high altitude Lake Paione Superiore, which however shows an increasing trend of alkalinity and pH.