This lecture focuses on the long-term variations in atmospheric deposition in Italy and its environmental impact on freshwater, soil and vegetation. The longest data records are available from Verbania Pallanza, the location of the CNR's Institute of Ecosystem Study in the subalpine area of North-Western Italy. Sampling is performed on a weekly or event basis, both with bulk and wet-only samplers; the amount of deposition is measured by calibrated gauges, and chemical analyses performed using updated equipment and widely accepted analytical methods. A strict program of internal and external QA/QC is followed, including participation in international interlaboratory exercises. The 1975-76 data showed acid atmospheric deposition, with mean volume-weighted pH between 4.3 and 4.5, and sulphate, nitrate and ammonium as the main ions. In the '80s and '90s, as a result of a European policy to reduce SOx emissions, sulphate concentrations decreased by about 70%, with a concurrent decrease in acidity (pH between 5.0 and 5.5). Nevertheless, both ammonium and nitrate concentrations remained very high and, due also to the high volume of precipitation, the deposition of nitrogen in the area was recorded as being among the highest in Europe. The study was extended in the '80s to include stations in the subalpine and alpine area, focusing on the role of the Alps in generating orographic precipitation and in the deposition of pollutants. Nitrogen deposition in this area shows a north-south gradient from the mountains to the Po Plain, one of the areas with the greatest concentration of industry and intensive agriculture in Europe (from 15 to 25 kg N ha-1 y-1 as inorganic N). This huge flux of nitrogen is causing N saturation of terrestrial catchments and nitrate enrichment of surface water.In the '90s an Italian network was developed under the UN-ECEICPForest program, and managed in Italy by the National Forest Service through the CONECOFOR program. It includes 20 remote forest sites spanning a wide range of geographical and catchment (latitude, altitude, slope, area, land cover) characteristics. N deposition is measured both in open field and in the forest, as throughfall and stemflow samples. The % N retention for a few forested catchments was calculated for a pluriannual period, and the trend analyzed in relation to changes in N deposition. We focused in particular on the most recent period (2004-2007), when a slight decrease in the annual average N deposition was observed due to a reduction in the amount of precipitation (about 1300 mm compared to the mean historical value of 1650 mm in the study area). The interdisciplinary study also considered the effects of nitrogen deposition on forest health, finding a significant relationship between defoliation and N deposition, though all of the variability in defoliation was accounted for by site and soil characteristics, which are however partly related to N deposition.
Long-term evolution of N deposition in Italy and effects on surface waters
Mosello;Rosario
2011
Abstract
This lecture focuses on the long-term variations in atmospheric deposition in Italy and its environmental impact on freshwater, soil and vegetation. The longest data records are available from Verbania Pallanza, the location of the CNR's Institute of Ecosystem Study in the subalpine area of North-Western Italy. Sampling is performed on a weekly or event basis, both with bulk and wet-only samplers; the amount of deposition is measured by calibrated gauges, and chemical analyses performed using updated equipment and widely accepted analytical methods. A strict program of internal and external QA/QC is followed, including participation in international interlaboratory exercises. The 1975-76 data showed acid atmospheric deposition, with mean volume-weighted pH between 4.3 and 4.5, and sulphate, nitrate and ammonium as the main ions. In the '80s and '90s, as a result of a European policy to reduce SOx emissions, sulphate concentrations decreased by about 70%, with a concurrent decrease in acidity (pH between 5.0 and 5.5). Nevertheless, both ammonium and nitrate concentrations remained very high and, due also to the high volume of precipitation, the deposition of nitrogen in the area was recorded as being among the highest in Europe. The study was extended in the '80s to include stations in the subalpine and alpine area, focusing on the role of the Alps in generating orographic precipitation and in the deposition of pollutants. Nitrogen deposition in this area shows a north-south gradient from the mountains to the Po Plain, one of the areas with the greatest concentration of industry and intensive agriculture in Europe (from 15 to 25 kg N ha-1 y-1 as inorganic N). This huge flux of nitrogen is causing N saturation of terrestrial catchments and nitrate enrichment of surface water.In the '90s an Italian network was developed under the UN-ECEICPForest program, and managed in Italy by the National Forest Service through the CONECOFOR program. It includes 20 remote forest sites spanning a wide range of geographical and catchment (latitude, altitude, slope, area, land cover) characteristics. N deposition is measured both in open field and in the forest, as throughfall and stemflow samples. The % N retention for a few forested catchments was calculated for a pluriannual period, and the trend analyzed in relation to changes in N deposition. We focused in particular on the most recent period (2004-2007), when a slight decrease in the annual average N deposition was observed due to a reduction in the amount of precipitation (about 1300 mm compared to the mean historical value of 1650 mm in the study area). The interdisciplinary study also considered the effects of nitrogen deposition on forest health, finding a significant relationship between defoliation and N deposition, though all of the variability in defoliation was accounted for by site and soil characteristics, which are however partly related to N deposition.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
