Trends in the chemistry of atmospheric deposition and surface waters in the Lake Maggiore catchment

Abstract

The Lake Maggiore catchment is the area of Italy most affected by acid deposition. Trend analysis was performed on long-term (15-30 years) series of chemical analyses of atmospheric deposition, four small rivers draining forested catchments and four high mountain lakes. An improvement in the quality of atmospheric deposition was detected, due to decreasing sulphate concentration and increasing pH. Similar trends were also found in high mountain lakes and in small rivers. Atmospheric deposition, however, is still providing a large and steady flux of nitrogen compounds (nitrate and ammonium) which is causing increasing nitrogen saturation in forest ecosystems and increasing nitrate levels in rivers. Besides atmospheric deposition, an important factor controlling water acidification and recovery is the weathering of rocks and soils which may be influenced by climate warming. A further factor is the episodic deposition of Saharan calcareous dust which contributes significantly to base cation deposition.

Climate control on sulphate and nitrate concentrations in alpine streams of Northern Italy along a nitrogen saturation gradient

“…An increasing trend of NO 3 levels in surface waters has been observed in several rivers and lakes in the alpine and subalpine areas of Northern Italy and N saturation has been suggested as the main reason for these trends Rogora et al, 2001). The lack of a significant seasonality in NO 3 levels, and hence of a reduced N retention capacity even in the growing season, confirmed this hypothesis for the Cannobino and the S. Bernardino.…”

Recovery from acidification in European surface waters

“…Site trends are considered individually, but an attempt is made to identify general patterns of chemical change at the European scale and the extent to which systematic differences arise between trends in a total of six regions (primarily individual countries). The European-scale assessment presented here is also supported by more detailed analyses of trends in each individual region by , Rogora et al (2001), Moldan et al (2001), Skjelkvåle et al (2001), and Kopácek et al (2001).…”

Assessment of recovery of European surface waters from acidification 1970-2000: An introduction to the Special Issue

“…The timing of peak deposition flux is consistent across Soulsby et al (2001), in Northern Italy by Rogora et al (2001), in Scandinavia by and in the Bohemian Forest and Tatra Mountains by Kopácek et al (2001). Changes in other environmental drivers that confound the long-term trend in response to decreased acid deposition are also important and must be considered in the assessment of recovery in response to reductions in acidic deposition.…”

“…Changes in other environmental drivers that confound the long-term trend in response to decreased acid deposition are also important and must be considered in the assessment of recovery in response to reductions in acidic deposition. In this volume, meteorological influences, and in particular the North Atlantic Oscillation, are considered in detail by Evans and Monteith (2001) and Wright and Jenkins (2001); deposition of sea-salt and dust is assessed by Helliwell et al (2001), Neal et al (2001), Wright and Jenkins (2001) and Rogora et al (2001) and interactions with land use change is assessed by Helliwell et al (2001) and Neal et al (2001).…”