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Article: Variations of the nitrate isotopic composition in the St. Lawrence River caused by seasonal changes in atmospheric nitrogen inputs
Title | Variations of the nitrate isotopic composition in the St. Lawrence River caused by seasonal changes in atmospheric nitrogen inputs |
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Authors | |
Keywords | Eutrophication Time series Isotope Nitrogen Hydrology St. Lawrence |
Issue Date | 2013 |
Citation | Biogeochemistry, 2013, v. 115, n. 1-3, p. 287-298 How to Cite? |
Abstract | We present 42 dual-isotope nitrate analyses of fresh water samples collected in the St. Lawrence River between June 2006 and July 2008. Measured δ15N-NO3 - and δ18O-NO3 - values correlate negatively, while δ18O-NO3 - displays no negative correlation with nitrate concentration. This suggests that nitrate uptake and/or elimination by denitrification is not the main driver of observed variations in nitrate concentration and isotopic signature in the St. Lawrence River. In addition, δ18O-NO3 - is negatively correlated with the seasonally variable δ18O of ambient water, indicating that the variation in the isotopic signature of nitrate is barely modulated by in-stream nitrate regeneration (nitrification). It rather is constrained by along-river changes in the external sources of nitrate. Given the distinct nitrogen (N) and oxygen (O) isotopic signature of atmospheric nitrate, we argue that observed seasonal variations of δ15N-NO3 - and δ18O-NO3 - in the St. Lawrence River are due to variable contributions of snowmelt-derived water. Based on a N and O isotope mass balance, we show that total nitrate loading in the St. Lawrence River is dominated by a N input from the Great Lakes (47 ± 28 %) and from nitrate regeneration of both internal and external N (48 ± 22 %). While temporal nitrate N and O isotope dynamics in the St. Lawrence River are mainly influenced by the atmospheric N input fluctuations, with an increase in atmospheric loading during spring, atmospheric N plays overall a rather insignificant role with regards to the N budget (5 ± 4 %). © 2013 Springer Science+Business Media Dordrecht. |
Persistent Identifier | http://hdl.handle.net/10722/210581 |
ISSN | 2023 Impact Factor: 3.9 2023 SCImago Journal Rankings: 1.392 |
ISI Accession Number ID |
DC Field | Value | Language |
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dc.contributor.author | Thibodeau, Benoit | - |
dc.contributor.author | Hélie, Jean François | - |
dc.contributor.author | Lehmann, Moritz F. | - |
dc.date.accessioned | 2015-06-19T01:49:27Z | - |
dc.date.available | 2015-06-19T01:49:27Z | - |
dc.date.issued | 2013 | - |
dc.identifier.citation | Biogeochemistry, 2013, v. 115, n. 1-3, p. 287-298 | - |
dc.identifier.issn | 0168-2563 | - |
dc.identifier.uri | http://hdl.handle.net/10722/210581 | - |
dc.description.abstract | We present 42 dual-isotope nitrate analyses of fresh water samples collected in the St. Lawrence River between June 2006 and July 2008. Measured δ15N-NO3 - and δ18O-NO3 - values correlate negatively, while δ18O-NO3 - displays no negative correlation with nitrate concentration. This suggests that nitrate uptake and/or elimination by denitrification is not the main driver of observed variations in nitrate concentration and isotopic signature in the St. Lawrence River. In addition, δ18O-NO3 - is negatively correlated with the seasonally variable δ18O of ambient water, indicating that the variation in the isotopic signature of nitrate is barely modulated by in-stream nitrate regeneration (nitrification). It rather is constrained by along-river changes in the external sources of nitrate. Given the distinct nitrogen (N) and oxygen (O) isotopic signature of atmospheric nitrate, we argue that observed seasonal variations of δ15N-NO3 - and δ18O-NO3 - in the St. Lawrence River are due to variable contributions of snowmelt-derived water. Based on a N and O isotope mass balance, we show that total nitrate loading in the St. Lawrence River is dominated by a N input from the Great Lakes (47 ± 28 %) and from nitrate regeneration of both internal and external N (48 ± 22 %). While temporal nitrate N and O isotope dynamics in the St. Lawrence River are mainly influenced by the atmospheric N input fluctuations, with an increase in atmospheric loading during spring, atmospheric N plays overall a rather insignificant role with regards to the N budget (5 ± 4 %). © 2013 Springer Science+Business Media Dordrecht. | - |
dc.language | eng | - |
dc.relation.ispartof | Biogeochemistry | - |
dc.subject | Eutrophication | - |
dc.subject | Time series | - |
dc.subject | Isotope | - |
dc.subject | Nitrogen | - |
dc.subject | Hydrology | - |
dc.subject | St. Lawrence | - |
dc.title | Variations of the nitrate isotopic composition in the St. Lawrence River caused by seasonal changes in atmospheric nitrogen inputs | - |
dc.type | Article | - |
dc.description.nature | link_to_subscribed_fulltext | - |
dc.identifier.doi | 10.1007/s10533-013-9834-4 | - |
dc.identifier.scopus | eid_2-s2.0-84884904563 | - |
dc.identifier.volume | 115 | - |
dc.identifier.issue | 1-3 | - |
dc.identifier.spage | 287 | - |
dc.identifier.epage | 298 | - |
dc.identifier.eissn | 1573-515X | - |
dc.identifier.isi | WOS:000325116700018 | - |
dc.identifier.issnl | 0168-2563 | - |