Glacial/interglacial changes in the isotopes of nitrate from the Greenland Ice Sheet Project 2 (GISP2) ice core

Hastings, Meredith G.; Sigman, Daniel M.; Steig, Eric J.

doi:10.1029/2005gb002502

Cited by 51 publications

(58 citation statements)

References 88 publications

(175 reference statements)

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“…Freyer et al (1996) showed that nitrogen isotope composition in Antarctic NO − 3 was closely related to snow accumulation rate, with lower 15 N at higher accumulation sites. This result was later confirmed for Greenland ice (Hastings et al, 2005). For high accumulation sites, Hastings et al (2004) concluded that 15 N and 18 O of NO − 3 are related to atmospheric sources/processes, in particular NO x oxidation chemistry, rather than post depositional effects, a result also suggested by other studies (Alexander et al, 2004;Heaton et al, 2004).…”

Section: Sources Of Snowpack Nitratesupporting

confidence: 69%

An overview of snow photochemistry: evidence, mechanisms and impacts

et al. 2007

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Abstract. It has been shown that sunlit snow and ice plays an important role in processing atmospheric species. Photochemical production of a variety of chemicals has recently been reported to occur in snow/ice and the release of these photochemically generated species may significantly impact the chemistry of the overlying atmosphere. Nitrogen oxide and oxidant precursor fluxes have been measured in a number of snow covered environments, where in some cases the emissions significantly impact the overlying boundary layer. For example, photochemical ozone production (such as that occurring in polluted mid-latitudes) of 3-4 ppbv/day has been observed at South Pole, due to high OH and NO levels present in a relatively shallow boundary layer. Field and laboratory experiments have determined that the origin of the observed NO x flux is the photochemistry of nitrate within the snowpack, however some details of the mechanism have not yet been elucidated. A variety of low molecular weight organic compounds have been shown to be emitted from sunlit snowpacks, the source of which has been proposed to be either direct or indirect photo-oxidation of natural organic materials present in the snow. Although myriad studies have observed active processing of species within irradiated snowpacks, the fundamental chemistry occurring remains poorly understood. Here we consider the nature of snow at a fundamental, physical level; photochemical processes within snow and the caveats needed for comparison to atmospheric photochemistry; our current understanding of nitrogen, oxidant, halogen and organic photochemistry within snow; the current limitations faced by the field and implications for the future.

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Section: Sources Of Snowpack Nitratesupporting

confidence: 69%

An overview of snow photochemistry: evidence, mechanisms and impacts

et al. 2007

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“…Profiles of nitrogen (oxygen) stable isotopes of NO Hastings et al, 2005;Jarvis et al, 2009) is discouraged, due to its sensitivity to post-depositional fractionation.…”

Section: Discussionmentioning

confidence: 99%

Photolysis imprint in the nitrate stable isotope signal in snow and atmosphere of East Antarctica and implications for reactive nitrogen cycling

et al. 2009

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) is small, potentially allowing reconstruction of past shifts in tropospheric oxidation pathways from ice cores. Assuming a Rayleigh-type process we find fractionation constants ε of −60±15‰, 8±2‰ and 1±1‰, for δ 15 N, δ 18 O and 17 O, respectively. A photolysis model yields an upper limit for the photolytic fractionation constant 15 ε of δ 15 N, consistent with lab and field measurements, and demonstrates a high sensitivity of 15 ε to the incident actinic flux spectrum. The photolytic 15 ε is process-specific and therefore applies to any snow covered location. Previously published 15 ε values are not representative for conditions at the Earth surface, but apply only to the UV lamp used in the reported experiment (Blunier et al., 2005;Jacobi et al., 2006). Depletion of oxygen stable isotopes is attributed to photolysis followed by isotopic exchange with water and hydroxyl radicals. Conversely, 15 N enrichment of the NO

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“…On the basis of our new measurements, our goal is threefold: to show how isotopic measurements of nitrate can be used to study atmospheric processes operating on NO x , ozone and related trace gases, to assess the most likely controls over δ 15 N and Δ 17 O of nitrate, and in this regard to critically review current assumptions, and to identify most pressing needs in this research field. This has important implications in terms of interpreting the message carried by stable isotope ratios of ice‐core nitrate [ Alexander et al , 2004], in particular its δ 15 N signature [ Freyer et al , 1996; Hastings et al , 2005].…”

Section: Introductionmentioning

confidence: 99%

Comprehensive isotopic composition of atmospheric nitrate in the Atlantic Ocean boundary layer from 65°S to 79°N

Morin¹,

Savarino²,

Frey³

et al. 2009

J. Geophys. Res.

194

305

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International audienceThe comprehensive isotopic composition of atmospheric nitrate (i.e., the simultaneous measurement of all its stable isotope ratios: 15N/14N, 17O/16O and 18O/16O) has been determined for aerosol samples collected in the marine boundary layer (MBL) over the Atlantic Ocean from 65°S (Weddell Sea) to 79°N (Svalbard), along a ship-borne latitudinal transect. In nonpolar areas, the δ 15N of nitrate mostly deriving from anthropogenically emitted NO x is found to be significantly different (from 0 to 6‰) from nitrate sampled in locations influenced by natural NO x sources (−4 ± 2)‰. The effects on δ 15N(NO3 −) of different NO x sources and nitrate removal processes associated with its atmospheric transport are discussed. Measurements of the oxygen isotope anomaly (Δ17O = δ 17O − 0.52 × δ 18O) of nitrate suggest that nocturnal processes involving the nitrate radical play a major role in terms of NO x sinks. Different Δ17O between aerosol size fractions indicate different proportions between nitrate formation pathways as a function of the size and composition of the particles. Extremely low δ 15N values (down to −40‰) are found in air masses exposed to snow-covered areas, showing that snowpack emissions of NO x from upwind regions can have a significant impact on the local surface budget of reactive nitrogen, in conjunction with interactions with active halogen chemistry. The implications of the results are discussed in light of the potential use of the stable isotopic composition of nitrate to infer atmospherically relevant information from nitrate preserved in ice cores

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Glacial/interglacial changes in the isotopes of nitrate from the Greenland Ice Sheet Project 2 (GISP2) ice core

Cited by 51 publications

References 88 publications

An overview of snow photochemistry: evidence, mechanisms and impacts

An overview of snow photochemistry: evidence, mechanisms and impacts

Photolysis imprint in the nitrate stable isotope signal in snow and atmosphere of East Antarctica and implications for reactive nitrogen cycling

Comprehensive isotopic composition of atmospheric nitrate in the Atlantic Ocean boundary layer from 65°S to 79°N

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