caa a22 4500 445384255 CHVBK 20180317143027.0 cr unu---uuuuu 170323e20110301xx s 000 0 eng 10.1007/s10021-011-9422-1 doi (NATIONALLICENCE)springer-10.1007/s10021-011-9422-1 Stream Nitrate Responds Rapidly to Decreasing Nitrate Deposition [Elektronische Daten] [Dolly Kothawala, Shaun Watmough, Martyn Futter, Leiming Zhang, Peter Dillon] Ecosystem acidification and eutrophication resulting from increased deposition of dissolved inorganic nitrogen (DIN) are issues of increasing global concern. Consequently, costly policy decisions are being implemented to decrease nitrogen oxide (NOx) emissions. Although declining DIN deposition along with rapid declines of DIN in surface waters have been reported in parts of Europe, the same observation is just emerging in North America. Here we find a significant decline in bulk deposition NO3 − during the later part of a 28-year record in southcentral Ontario, Canada. Despite high N retention and substantial inter-annual variability in the long-term record due to periods of drought, we find significant declines in annual NO3 − concentrations and export at six out of 11 streams that drain upland-dominated catchments. In contrast, five streams draining primarily wetland-dominated catchments with lower levels of NO3 − show no decreasing trend in NO3 − concentration or export. The rapid response in stream NO3 − to declining atmospheric inputs was observed at sites with historically moderate inputs of DIN (~870mgm−2 y−1) in bulk deposition. Topographic features such as slope, and related catchment features including wetland cover, appear to influence which catchments will respond positively to declining DIN deposition. These findings force us to revise our original conceptualization of the N saturation status of these catchments. Springer Science+Business Media, LLC, 2011 nitrate deposition nationallicence stream nitrate nationallicence long-term trends nationallicence forest catchments nationallicence nitrogen saturation nationallicence nitrogen cycling nationallicence biogeochemical cycles nationallicence Kothawala Dolly Chemistry Department, Trent University, 1600 West Bank Drive, K9J 7B8, Peterborough, Ontario, Canada aut Watmough Shaun Environmental Resource Studies Program, Trent University, 1600 West Bank Drive, K9J 7B8, Peterborough, Ontario, Canada aut Futter Martyn Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, 75007, Uppsala, Sweden aut Zhang Leiming Air Quality Research Division, Science and Technology Branch, Environment Canada, 4905 Dufferin St., M3H 5T4, Toronto, Ontario, Canada aut Dillon Peter Chemistry Department, Trent University, 1600 West Bank Drive, K9J 7B8, Peterborough, Ontario, Canada aut Ecosystems Springer-Verlag 14/2(2011-03-01), 274-286 1432-9840 14:2<274 2011 14 10021 https://doi.org/10.1007/s10021-011-9422-1 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10021-011-9422-1 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Kothawala Dolly Chemistry Department, Trent University, 1600 West Bank Drive, K9J 7B8, Peterborough, Ontario, Canada aut NATIONALLICENCE 700 1- Watmough Shaun Environmental Resource Studies Program, Trent University, 1600 West Bank Drive, K9J 7B8, Peterborough, Ontario, Canada aut NATIONALLICENCE 700 1- Futter Martyn Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, 75007, Uppsala, Sweden aut NATIONALLICENCE 700 1- Zhang Leiming Air Quality Research Division, Science and Technology Branch, Environment Canada, 4905 Dufferin St., M3H 5T4, Toronto, Ontario, Canada aut NATIONALLICENCE 700 1- Dillon Peter Chemistry Department, Trent University, 1600 West Bank Drive, K9J 7B8, Peterborough, Ontario, Canada aut NATIONALLICENCE 773 0- Ecosystems Springer-Verlag 14/2(2011-03-01), 274-286 1432-9840 14:2<274 2011 14 10021 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer