Mountain ecosystems, in particular the alpine tundra, located above treeline, are highly vulnerable to changes in climate, pollutants and nutrient input. Short growing season, extremely low air temperatures, and often snow-covered soils, all contribute in reducing the ability of these ecosystems to face alterations that affect their physical structure and biological communities. Results from a number of studies have suggested that high elevation ecosystems are more susceptible to ecological impacts from N deposition than forest or grassland ecosystems at lower altitudes. In these areas, small increases in inorganic N deposition could cause a shift from conditions of N limitation to "N saturation". The general aim of the project is to integrate the role of atmospheric deposition in the long-term monitoring of biogeochemical cycles in the LTER (Long-Term Ecological Researches) station Angelo Mosso, located at 2901 m s.l.m. close to the Monte Rosa Massif (4634 m) in NW-Italy. We will compute the total atmospheric fluxes, by monitoring the snowpack, the summer precipitation and the dry deposition. The high-elevation snowpacks collect both wet and dry deposition and may accumulate two to three times the annual precipitation measured at lower elevations where regular monitoring is more easily accomplished. Although the snowfall provides most of the annual precipitation in the study headwater basin, it is crucial to quantify the contribution of summer precipitation, that often is richer of both airborne pollutants and nutrients than the colder period. In addition, we will measure the dry component by using a passive sampler with a marble dust-collecting insert that provides greater surface area for better particulate trapping during periods of high wind very frequent at the studied catchment. Problems associated with measuring and modeling dry deposition flux limit the availability of estimates of its contribution to total deposition, particularly at remote sites. The role of dry deposition as a key source of carbon and nitrogen for remote alpine lakes and soils is recently recognized. In order to further improve the understanding of biogeochemical cycling in seasonally snow covered systems we will investigate the interannual variability of inorganic and organic N and C forms in soils and waters in response to atmospheric deposition fluxes along with climatic factors - e.g. the Snow Cover Duration - and pedoclimatic conditions. Furthermore, we aim to investigate the sources and processing of atmospheric nitrogen species as well as their geographic origin by using the isotopic techniques (N-isotopes and ?2H and ?18O water molecule) and the backward trajectories analysis. The main element of novelty of this project is the integrated approach, which will allow to follow the dynamic of N and C compounds in different environmental matrices, such as atmospheric depositions, snowpack, soil and surface waters. By integrating the role of each compartments as a temporary or permanent sink or as a source for nutrients, the project will investigate the ecosystem services provided by each of them (e.g. N removal via denitrification, C sequestration) and provide useful indications for a management of high elevation ecosystems, aware of global changes.
Atmospheric deposition, soils and surface waters at an alpine tundra catchment in NW Italian Alps: implications for N and C biogeochemical cycles
Raffaella Balestrini
2018
Abstract
Mountain ecosystems, in particular the alpine tundra, located above treeline, are highly vulnerable to changes in climate, pollutants and nutrient input. Short growing season, extremely low air temperatures, and often snow-covered soils, all contribute in reducing the ability of these ecosystems to face alterations that affect their physical structure and biological communities. Results from a number of studies have suggested that high elevation ecosystems are more susceptible to ecological impacts from N deposition than forest or grassland ecosystems at lower altitudes. In these areas, small increases in inorganic N deposition could cause a shift from conditions of N limitation to "N saturation". The general aim of the project is to integrate the role of atmospheric deposition in the long-term monitoring of biogeochemical cycles in the LTER (Long-Term Ecological Researches) station Angelo Mosso, located at 2901 m s.l.m. close to the Monte Rosa Massif (4634 m) in NW-Italy. We will compute the total atmospheric fluxes, by monitoring the snowpack, the summer precipitation and the dry deposition. The high-elevation snowpacks collect both wet and dry deposition and may accumulate two to three times the annual precipitation measured at lower elevations where regular monitoring is more easily accomplished. Although the snowfall provides most of the annual precipitation in the study headwater basin, it is crucial to quantify the contribution of summer precipitation, that often is richer of both airborne pollutants and nutrients than the colder period. In addition, we will measure the dry component by using a passive sampler with a marble dust-collecting insert that provides greater surface area for better particulate trapping during periods of high wind very frequent at the studied catchment. Problems associated with measuring and modeling dry deposition flux limit the availability of estimates of its contribution to total deposition, particularly at remote sites. The role of dry deposition as a key source of carbon and nitrogen for remote alpine lakes and soils is recently recognized. In order to further improve the understanding of biogeochemical cycling in seasonally snow covered systems we will investigate the interannual variability of inorganic and organic N and C forms in soils and waters in response to atmospheric deposition fluxes along with climatic factors - e.g. the Snow Cover Duration - and pedoclimatic conditions. Furthermore, we aim to investigate the sources and processing of atmospheric nitrogen species as well as their geographic origin by using the isotopic techniques (N-isotopes and ?2H and ?18O water molecule) and the backward trajectories analysis. The main element of novelty of this project is the integrated approach, which will allow to follow the dynamic of N and C compounds in different environmental matrices, such as atmospheric depositions, snowpack, soil and surface waters. By integrating the role of each compartments as a temporary or permanent sink or as a source for nutrients, the project will investigate the ecosystem services provided by each of them (e.g. N removal via denitrification, C sequestration) and provide useful indications for a management of high elevation ecosystems, aware of global changes.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
