| Abstract | Several research programs monitoring atmospheric deposition have been launched in the Alpine countries in the last few decades. This paper uses data from previous and ongoing projects to: (i)
investigate geographical variability in wet deposition chemistry over the Alps; (ii) assess temporal trends of the major chemical variables in response to changes in the atmospheric emission of pollutants; (iii) discuss the potential relationship between the status of atmospheric deposition and its effects on forest ecosystems in the alpine and subalpine area, focusing particularly on nitrogen input. We also present results of studies performed at a local level on specific topics such as long-term changes in lead deposition and the role of occult deposition in total nitrogen input. The analysis performed here highlights the marked geographical variability of atmospheric deposition in the Alpine region. Apart from some evidence of geographically limited effects, due to local sources, no obvious gradients were identified in the major ion deposition. The highest ionic loads were recorded in areas in the foothills of the Alps, such as the pre-alpine area in North-Western Italy and the area of Canton Ticino, Switzerland. Trend analysis shows a widespread decrease in the acidity of precipitation in the last 15-20 years as a consequence of the reduced emission of S compounds. On the other hand, nitrate concentrations in rain have not changed so much, and ammonium has decreased significantly only at the Austrian sampling sites. The deposition of N is still well above the estimated critical loads of nutrient N at some forest sites in the alpine and subalpine areas, thus confirming the critical situation of both terrestrial and aquatic ecosystems regarding N inputs. Existing data highlights the importance of continuously monitoring atmospheric deposition chemistry in the Alpine area, taking account of acidifying elements, nutrients and other pollutants such as heavy metals and organic compounds. There is also a need for unifying sampling and analytical methods in order to obtain comparable data from the different regions of the Alps. |
| Text | 42134 2006 Precipitation chemistry wet deposition forest nitrogen trend. AN OVERVIEW OF ATMOSPHERIC DEPOSITION CHEMISTRY OVER THE ALPS PRESENT STATUS AND LONG TERM TRENDS ROGORA M., MOSELLO R., BALESTRINI R., ET AL. CNR Institute of Ecosystem Study, Largo Tonolli 50, 28922 Verbania Pallanza, Italy Cantonal Agency for Water Protection and Treatment, UPDA SPAAS, 6501 Bellinzona, Cantone Ticino, Switzerland Department of Hydrobiology Applied to Water Pollution, CNR Water Research Institute, 20047 Brugherio, Milan, Italy WSL, Swiss Federal Institute for Forest, Snow and Landscape Research, 8903 Birmensdorf, Switzerland Institute of Analytical Chemistry IAC , Vienna University of Technology, 1060 Vienna, Austria Institute of Meteorology and Geophysics, University of Innsbruck, 6020 Innsbruck, Austria 7Office National des Fore ts, 77300 Fontainebleau, France Laboratoire des Me´canismes et Transferts en Ge´ologie LMTG , UMR 5563, CNRS/IRD/UPS, 38, rue des 36 Ponts, 31400 Toulouse, France Several research programs monitoring atmospheric deposition have been launched in the Alpine countries in the last few decades. This paper uses data from previous and ongoing projects to i investigate geographical variability in wet deposition chemistry over the Alps; ii assess temporal trends of the major chemical variables in response to changes in the atmospheric emission of pollutants; iii discuss the potential relationship between the status of atmospheric deposition and its effects on forest ecosystems in the alpine and subalpine area, focusing particularly on nitrogen input. We also present results of studies performed at a local level on specific topics such as long term changes in lead deposition and the role of occult deposition in total nitrogen input. The analysis performed here highlights the marked geographical variability of atmospheric deposition in the Alpine region. Apart from some evidence of geographically limited effects, due to local sources, no obvious gradients were identified in the major ion deposition. The highest ionic loads were recorded in areas in the foothills of the Alps, such as the pre alpine area in North Western Italy and the area of Canton Ticino, Switzerland. Trend analysis shows a widespread decrease in the acidity of precipitation in the last 15 20 years as a consequence of the reduced emission of S compounds. On the other hand, nitrate concentrations in rain have not changed so much, and ammonium has decreased significantly only at the Austrian sampling sites. The deposition of N is still well above the estimated critical loads of nutrient N at some forest sites in the alpine and subalpine areas, thus confirming the critical situation of both terrestrial and aquatic ecosystems regarding N inputs. Existing data highlights the importance of continuously monitoring atmospheric deposition chemistry in the Alpine area, taking account of acidifying elements, nutrients and other pollutants such as heavy metals and organic compounds. There is also a need for unifying sampling and analytical methods in order to obtain comparable data from the different regions of the Alps. 526 An overview of atmospheric deposition chemistry over the Alps present status and long term trends Rogora2006Hidro.pdf Articolo in rivista Kluwer Academic Publishers 0018 8158 Hydrobiologia The Hague. Print Hydrobiologia The Hague. Print Hydrobiologia The Hague. Print Hydrobiologia. The Hague. Print Hydrobiologia Dordrecht The Hague. Print Hydrobiologia Boston The Hague. Print Hydrobiologia London The Hague. Print raffaella.balestrini BALESTRINI RAFFAELLA michela.rogora ROGORA MICHELA rosario.mosello MOSELLO ROSARIO TA.P04.016.001 Caratteristiche ecologiche di comunita acquatiche in ambienti fluviali e lagunari |
