Atmospheric deposition of nitrogen, runoff of organic nitrogen, and critical loads for soils and waters Wright, Richard F; Raastad, Inger Aandahl; Kaste, Oeyvind 54 ENVIRONMENTAL SCIENCES; NORWAY; ACID RAIN; LAKES; NITROGEN; WATER; SOIL CHEMISTRY; CARBON; ORGANIC COMPOUNDS; ENVIRONMENT This report tests the hypothesis that increased deposition of inorganic nitrogen compounds leads to increased leaching and runoff of organic nitrogen and thus a higher critical load. The authors use mainly Norwegian data from input-output fluxes at small catchments, national lake surveys, and large-scale experiments with nitrogen deposition to whole catchments. Concentrations of organic nitrogen are not significantly related to nitrogen deposition. Much of the variance in organic nitrogen levels are explained by total organic carbon concentrations. For the small catchments, there is a significant relationship between the carbon/nitrogen (C/N) ratio in dissolved organic matter and the nitrogen deposition. The sites with high nitrogen deposition have low C/N ratio. Chronically high nitrogen deposition and long-term accumulation of nitrogen in soils and biomass may have led to organic matter more enriched in nitrogen relative to pristine sites. Time trend data from manipulated catchments do not show changes in organic-N leaching over 4 to 10 years. Although organic-N levels may have increased as a result of nitrogen deposition, the resultant effect on estimate of critical load for nitrogen for freshwater is minor. For practical purposes, organic nitrogen outputs can be neglected in estimating and mapping critical loads for nitrogen in Norway. 23 refs., 11 figs., 4 tabs. Norsk Inst. for Vannforskning, Oslo (Norway) OSTI as DE98777245 Norway 1998-12-31 English Technical Report Other Information: PBD: 1997 Medium: ED; Size: 30 p. https://doi.org/ ON: DE98777245; ISBN 82-577-3145-5 [] NIVA-O-3592/97 Other: ON: DE98777245; ISBN 82-577-3145-5; TRN: NO9805321 NW; SCA: 540320; PA: NW-98:005321; EDB-98:102773; SN: 98002004251 2010-04-23 645455 https://www.osti.gov/etdeweb/servlets/purl/645455