Open AccessNitrogen budget of Lago Maggiore: the relative importance of atmospheric deposition and catchment sources
Author(s) -
Rosario Mosello,
Alberto Barbieri,
Maria Cristina Brizzio,
A. Calderoni,
Aldo Marchetto,
Stefania Passera,
Michela Rogora,
Gabriele Tartari
Publication year - 2001
Publication title -
journal of limnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.465
H-Index - 44
eISSN - 1723-8633
pISSN - 1129-5767
DOI - 10.4081/jlimnol.2001.27
Subject(s) - hydrology (agriculture) , environmental science , drainage basin , precipitation , nitrogen , soil water , deposition (geology) , leaching (pedology) , vegetation (pathology) , population , atmospheric sciences , physical geography , structural basin , geography , soil science , geology , chemistry , geomorphology , meteorology , geotechnical engineering , cartography , organic chemistry , medicine , demography , pathology , sociology
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