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Insights into anthropogenic nitrogen deposition to the North Atlantic investigated using the isotopic composition of aerosol and rainwater nitrate
Author(s) -
Gobel Amy R.,
Altieri Katye E.,
Peters Andrew J.,
Hastings Meredith G.,
Sigman Daniel M.
Publication year - 2013
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2013gl058167
Subject(s) - rainwater harvesting , nitrate , deposition (geology) , aerosol , environmental science , nitrogen , environmental chemistry , oceanography , atmospheric sciences , geology , chemistry , meteorology , geography , ecology , geomorphology , organic chemistry , sediment , biology
Identifying the dominant sources of atmospheric reactive nitrogen (N r ) is critical for determining the influence of anthropogenic emissions on N r deposition, especially in marine ecosystems. To test the influence of anthropogenic versus marine air masses, samples were collected in Bermuda, where seasonal atmospheric circulation patterns lead to greater continental transport during the cool season. The 15 N/ 14 N of aerosol nitrate (NO 3 – ) indicates changes in N r sources and its 18 O/ 16 O indicates a seasonal shift in the relative strength of pathways of NO 3 – formation. The aerosol δ 15 N‐NO 3 – was consistently lower than or equal to the rainwater from the same sampling period, the opposite trend of that observed in polluted systems. We propose that this is due to HNO 3(g) uptake onto aerosol particles with a kinetic isotope effect, lowering the aerosol δ 15 N‐NO 3 – relative to residual HNO 3(g) . The aerosol δ 18 O‐NO 3 – was higher than that in rainwater during the cool season, but was not different during the warm season, which we tentatively attribute to the increased importance of heterogeneous halogen chemistry on the formation of NO 3 – during the cool season.