A study from ZAMG, TU Wien, University of Graz and IIASA showed a distinct reduction of Sulfate and Nitrate ion deposition in snowpack samples over the last 30 years (1983-2014). The total ion concentration declined by 25% whereas single ions such as Nitrate and Sulfate decreased much more by 30% and even 70%, respectively. Dissolved ions are stored in the snowpack and released during snow melt. The rapid release of these pollutants acidifies the meltwater and can induce an “acid shock” in surrounding ecosystems like streams, rivers and soils. The reduction of the deposition of acidifying ions, such as Sulfate and Nitrate, reflects the successful emission reductions of their precursor gases SO2 and NOx, mainly originating from anthropogenic sources like traffic and industry.
Both ions show a clear seasonality with elevated spring concentrations compared to fall snow, reflecting the beginning of vertical mixing in the atmosphere in spring.
Nitrate in the snowpack at Sonnblick.
Sulfate in the snowpack at Sonnblick.
Density and temperature measurements in a snow pit with a Sahara dust layer at 120 cm (photo: A. Neureiter).