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- Title
Trends in concentrations and export of nitrogen in boreal forest streams.
- Authors
Sarkkola, Sakari; Nieminen, Mika; Koivusalo, Harri; Laurén, Ari; Kortelainen, Pirkko; Mattsson, Tuija; Palviainen, Marjo; Piirainen, Sirpa; Starr, Mike; Finér, Leena
- Abstract
Temporal trends in inorganic and organic nitrogen (N) export in the stream water between 1979 and 2006 were studied in eight forested headwater catchments in eastern Finland, where an increasing air-temperature trend and a decreasing N-deposition trend has been observed since the 1980s. The Seasonal Kendall test was conducted to study if the stream water N concentrations have changed concurrently and a mixed model regression analysis was used to study which catchment characteristics and hydrometeorological variables were related to the variation in stream water N. The annual concentrations of total organic N (TON) increased at two catchments and the concentrations of nitrate (NO3-N) and ammonium (NH4-N) decreased at three and four catchments, respectively. The main factor explaining variation in concentrations and export of N was percentage of peatlands in a catchment. The NH4-N concentrations were also related to the N deposition, and the exports of NO3, NH4 , and TON to precipitation. Quantitative changes in both the N concentrations and exports were small. The results suggested relatively small changes in the N concentrations and exports between 1979 and 2006, most probably because the effects of increased air and stream water temperatures largely have been concealed behind the concurrent decrease in N deposition.
- Subjects
TRENDS; EXPORTS; NITROGEN; TAIGAS; REGRESSION analysis; PEATLANDS; TEMPERATURE
- Publication
Boreal Environment Research, 2012, Vol 17, Issue 2, p85
- ISSN
1239-6095
- Publication type
Article