Distribuzione lungo un gradiente di acidità delle diatomee nei sedimenti dei laghi alpini nella Val d'Ossola (Alpi Centrali)

Diatom assemblages were analysed from the sediment of 15 high mountain lakes in the Ossola Valley (Central Alps, ltaly), considering the top 0.5 cm (present-day) and the bottorn 2 cm (pre-industrial time) of short sediment cores. In most lakes, acidophylous and acidobiontic diatoms were more abundant in the top than in the bottom sample, and diatom-inferred pH were lower in the former than in the latter, indicating lake acidification especially marked in lakes with circumneutral pH values.