Nitrogen budget of Lago Maggiore: the relative importance of atmospheric deposition and catchment sources

  • Rosario MOSELLO | r.mosello@iii.to.cnr.it
  • Alberto BARBIERI
  • Maria Cristina BRIZZIO
  • Alcide CALDERONI
  • Aldo MARCHETTO
  • Stefania PASSERA
  • Michela ROGORA
  • Gabriele TARTARI

Abstract

Hydrological and chemical data of 1996 and 1997 are used to evaluate the relative contributions of atmospheric deposition and urban/industrial wastewaters to the nitrogen budget of Lago Maggiore. The atmospheric load of nitrogen was about 80% of the total input to the lake, with negligible variations in dry (1997) and wet (1996) years. A comparison of the two study years with the yearly N budgets evaluated from 1978 to 1998, showed that the N load was higher with increasing amounts of precipitation/water inflow. Soils and vegetation act as N sinks; the % retention varies between 40-60% for the forested catchments with low population density in the central-northern part of the basin, to values close to zero or even negative in the south, indicating a net leaching from the soils. The Traaen & Stoddard (1995) approach revealed that all the catchments of the major inflowing rivers were oversaturated with nitrogen. The long-term trend of nitrogen concentrations in Lago Maggiore (1955-99) is analogous to the trend for atmospheric deposition (1975-99), which is related to emissions of nitrogen oxides and ammonia in the atmosphere. The relationships between the present N load and in-lake concentrations are discussed using a budget model, which is also used to infer the pristine load of N. The close relationships between N trends in lakes Maggiore, Como and Iseo, and the geographical and anthropogenic features common to their catchments, suggest that the results obtained for Lago Maggiore can be extended to a wider area.

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Published
2001-02-01
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Original Articles
Keywords:
Lago Maggiore, nitrogen budget, atmospheric deposition, river water, catchment
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How to Cite
1.
MOSELLO R, BARBIERI A, BRIZZIO MC, CALDERONI A, MARCHETTO A, PASSERA S, ROGORA M, TARTARI G. Nitrogen budget of Lago Maggiore: the relative importance of atmospheric deposition and catchment sources. J Limnol [Internet]. 2001Feb.1 [cited 2020Aug.12];60(1):27-0. Available from: https://www.jlimnol.it/index.php/jlimnol/article/view/jlimnol.2001.27

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