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Tracing the sources and formation pathways of atmospheric particulate nitrate over the Pacific Ocean using stable isotopes
https://orcid.org/0000-0002-2819-6338
https://orcid.org/0000-0002-4438-5462
https://orcid.org/0000-0001-9853-8631
Abstract This paper presents isotopic compositions (δ15N and Δ17O values) of atmospheric particulate nitrate (p-NO3 −) collected over the Pacific Ocean between 40°S and 68°N on two cruises using the Research Vessel Hakuho Maru. Six marine regions over the Pacific Ocean were categorized using backward trajectory analysis, and various ion concentrations were employed to assess the dominance of anthropogenic or non-anthropogenic sources. The δ15N(p-NO3 −) values ranged from −15.4‰ to 2.5‰ over the Pacific Ocean between 40°S and 68°N. The range of the source δ15N(NOx) values were calculated for each sample based on isotopic exchange/fractionation during oxidation from NOx (NO and NO2) to HNO3, and a range of −14.1 to 6.9‰ was yielded over the Pacific Ocean. Compared to other regions, extremely low δ15N(NOx) values of −14.1‰ to −7.3‰ were found over the equatorial Pacific, and such values cannot be matched using conventional NOx apportionment. Emissions of specific oceanic nitrogen emissions of NH3 and alkyl nitrate are thus proposed for the equatorial Pacific. Results demonstrate the importance of the nitrogen recycling process between the ocean and lower atmosphere in the equatorial Pacific. Δ17O(p-NO3 −) values and light flux were found to be generally well-correlated in most Pacific Ocean regions, and this result is consistent with the importance of photolysis for OH radical concentrations relative to the contribution of O3 in producing HNO3 from NOx. In contrast, Δ17O(p-NO3 −) values for the eastern North Pacific region were higher than in other regions with similar light fluxes, which implies a contribution from halogens to p-NO3 − formation.
Highlights We present data sets of δ15N and Δ17O of atmospheric p-NO3 − over Pacific Ocean. The low δ15N in equatorial Pacific suggest N recycle between marine and atmosphere. The high Δ17O indicate NO3 − formation by halogen in the central North Pacific.
Tracing the sources and formation pathways of atmospheric particulate nitrate over the Pacific Ocean using stable isotopes
https://orcid.org/0000-0002-2819-6338
https://orcid.org/0000-0002-4438-5462
https://orcid.org/0000-0001-9853-8631
Abstract This paper presents isotopic compositions (δ15N and Δ17O values) of atmospheric particulate nitrate (p-NO3 −) collected over the Pacific Ocean between 40°S and 68°N on two cruises using the Research Vessel Hakuho Maru. Six marine regions over the Pacific Ocean were categorized using backward trajectory analysis, and various ion concentrations were employed to assess the dominance of anthropogenic or non-anthropogenic sources. The δ15N(p-NO3 −) values ranged from −15.4‰ to 2.5‰ over the Pacific Ocean between 40°S and 68°N. The range of the source δ15N(NOx) values were calculated for each sample based on isotopic exchange/fractionation during oxidation from NOx (NO and NO2) to HNO3, and a range of −14.1 to 6.9‰ was yielded over the Pacific Ocean. Compared to other regions, extremely low δ15N(NOx) values of −14.1‰ to −7.3‰ were found over the equatorial Pacific, and such values cannot be matched using conventional NOx apportionment. Emissions of specific oceanic nitrogen emissions of NH3 and alkyl nitrate are thus proposed for the equatorial Pacific. Results demonstrate the importance of the nitrogen recycling process between the ocean and lower atmosphere in the equatorial Pacific. Δ17O(p-NO3 −) values and light flux were found to be generally well-correlated in most Pacific Ocean regions, and this result is consistent with the importance of photolysis for OH radical concentrations relative to the contribution of O3 in producing HNO3 from NOx. In contrast, Δ17O(p-NO3 −) values for the eastern North Pacific region were higher than in other regions with similar light fluxes, which implies a contribution from halogens to p-NO3 − formation.
Highlights We present data sets of δ15N and Δ17O of atmospheric p-NO3 − over Pacific Ocean. The low δ15N in equatorial Pacific suggest N recycle between marine and atmosphere. The high Δ17O indicate NO3 − formation by halogen in the central North Pacific.
Tracing the sources and formation pathways of atmospheric particulate nitrate over the Pacific Ocean using stable isotopes
https://orcid.org/0000-0002-2819-6338
https://orcid.org/0000-0002-4438-5462
https://orcid.org/0000-0001-9853-8631
Abstract This paper presents isotopic compositions (δ15N and Δ17O values) of atmospheric particulate nitrate (p-NO3 −) collected over the Pacific Ocean between 40°S and 68°N on two cruises using the Research Vessel Hakuho Maru. Six marine regions over the Pacific Ocean were categorized using backward trajectory analysis, and various ion concentrations were employed to assess the dominance of anthropogenic or non-anthropogenic sources. The δ15N(p-NO3 −) values ranged from −15.4‰ to 2.5‰ over the Pacific Ocean between 40°S and 68°N. The range of the source δ15N(NOx) values were calculated for each sample based on isotopic exchange/fractionation during oxidation from NOx (NO and NO2) to HNO3, and a range of −14.1 to 6.9‰ was yielded over the Pacific Ocean. Compared to other regions, extremely low δ15N(NOx) values of −14.1‰ to −7.3‰ were found over the equatorial Pacific, and such values cannot be matched using conventional NOx apportionment. Emissions of specific oceanic nitrogen emissions of NH3 and alkyl nitrate are thus proposed for the equatorial Pacific. Results demonstrate the importance of the nitrogen recycling process between the ocean and lower atmosphere in the equatorial Pacific. Δ17O(p-NO3 −) values and light flux were found to be generally well-correlated in most Pacific Ocean regions, and this result is consistent with the importance of photolysis for OH radical concentrations relative to the contribution of O3 in producing HNO3 from NOx. In contrast, Δ17O(p-NO3 −) values for the eastern North Pacific region were higher than in other regions with similar light fluxes, which implies a contribution from halogens to p-NO3 − formation.
Highlights We present data sets of δ15N and Δ17O of atmospheric p-NO3 − over Pacific Ocean. The low δ15N in equatorial Pacific suggest N recycle between marine and atmosphere. The high Δ17O indicate NO3 − formation by halogen in the central North Pacific.
Tracing the sources and formation pathways of atmospheric particulate nitrate over the Pacific Ocean using stable isotopes
Kamezaki, Kazuki (author) / Hattori, Shohei (author) / Iwamoto, Yoko (author) / Ishino, Sakiko (author) / Furutani, Hiroshi (author) / Miki, Yusuke (author) / Uematsu, Mitsuo (author) / Miura, Kazuhiko (author) / Yoshida, Naohiro (author)
Atmospheric Environment ; 209 ; 152-166
2019-04-13
15 pages
Article (Journal)
Electronic Resource
English
Tracing potential water sources of the Nagqu River using stable isotopes
| Elsevier | 2021