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标题：Nitrogen budget of Lago Maggiore: the relative importance of atmospheric deposition and catchment sources
其他标题：Nitrogen budget of Lago Maggiore: the relative importance of atmospheric deposition and catchment sources
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作者：Rosario MOSELLO ; Alberto BARBIERI ; Maria Cristina BRIZZIO 等
期刊名称：Journal of limnology
印刷版ISSN：1129-5767
电子版ISSN：1723-8633
出版年度：2001
卷号：60
期号：1
页码：27-40
DOI：10.4081/jlimnol.2001.27
出版社：Istituto italiano di idrobiologia
摘要：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.
关键词：Lago Maggiore; nitrogen budget; atmospheric deposition; river water; catchment