Quantitative constraints on the 17O-excess (Δ17O) signature of surface ozone: Ambient measurements from 50°N to 50°S using the nitrite-coated filter technique

Vicars, W. C.; Savarino, Joël

doi:10.1016/j.gca.2014.03.023

Cited by 113 publications

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“…Relations between δ 18 O and Δ 17 O for collected NO 3 − sorted by season displayed with the high δ 18 O‐Δ 17 O end‐member, O 3(term.) /XO (indicated by the black rectangle; δ 18 O = 95–115‰; Johnston & Thiemens, ; and Δ 17 O = 39.3‰; Vicars & Savarino, ) and its mixing relations with other important tropospheric O bearing atmospheric molecules including RO 2 /HO 2 (δ 18 O ~ 23.5‰ and Δ 17 O ~ 0‰), H 2 O (δ 18 O = −40‰ and Δ 17 O = 0‰, and OH (δ 18 O = −80‰ and Δ 17 O = 0‰; Michalski et al, ).…”

Section: Resultsmentioning

confidence: 99%

“…To further constrain NO 3 − oxidation pathways, we considered δ 18 O‐Δ 17 O relations for major tropospheric O bearing molecules incorporated into NO 3 − (Figure ; Fibiger et al, ; Michalski et al, ). Here we assume that the O isotopic composition of NO 3 − is derived from a mixture between a high δ 18 O‐Δ 17 O end‐member, O 3(terminal) and XO (δ 18 O = 95–115‰; Johnston & Thiemens, ), Δ 17 O =39.3±2.0‰ (Vicars & Savarino, ), and various low δ 18 O‐Δ 17 O end‐members including O 2 /RO 2 /HO 2 (δ 18 O = 23.5‰, Δ 17 O = 0‰; Kroopnick & Craig, ), H 2 O (δ 18 O = −27.5±20‰, Δ 17 O = 0‰) and OH (δ 18 O = ‐70±20‰, Δ 17 O = 0‰) (Michalski et al, ). We note that OH may not attain complete isotopic equilibrium with H 2 O vapor in polar regions because of low water mixing ratios (Morin et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…Gas‐phase oxidation via OH will result in a Δ 17 O(SO 4 2‐ ) of 0‰ when isotopic equilibrium with H 2 O is reached. Previous works have shown that the Δ 17 O signature of O 3(bulk) (26‰; Vicars & Savarino, ) and hydrogen peroxide (~1.7‰; Lyons, ; Savarino & Thiemens, ) are partially transferred into SO 4 2− based on O mass balance resulting in Δ 17 O(SO 4 2− ) values near 6.5‰ and 0.8‰, respectively. However, we note that if O atom transfer occurs from O 3(term) as indicated by ab initio results (Liu et al, ), then the S (IV) (=SO 2 ·H 2 O + HSO 3 − + SO 3 2− ) + O 3 oxidation pathway could have a Δ 17 O as high as 9.3–10.6‰ (Table ).…”

Section: Introductionmentioning

confidence: 99%

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Assessing the Seasonal Dynamics of Nitrate and Sulfate Aerosols at the South Pole Utilizing Stable Isotopes

et al. 2019

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Atmospheric nitrate (NO3− = particulate NO3− + gas‐phase nitric acid [HNO3]) and sulfate (SO42−) are key molecules that play important roles in numerous atmospheric processes. Here, the seasonal cycles of NO3− and total suspended particulate sulfate (SO42−(TSP)) were evaluated at the South Pole from aerosol samples collected weekly for approximately 10 months (26 January to 25 October) in 2002 and analyzed for their concentration and isotopic compositions. Aerosol NO3− was largely affected by snowpack emissions in which [NO3−] and δ15N(NO3−) were highest (49.3 ± 21.4 ng/m3, n = 8) and lowest (−47.0 ± 11.7‰, n = 5), respectively, during periods of sunlight in the interior of Antarctica. The seasonal cycle of Δ17O(NO3−) reflected tropospheric chemistry year‐round with lower values observed during sunlight periods and higher values observed during dark periods, reflecting shifts from HOx‐ to O3‐dominated oxidation chemistry. SO42−(TSP) concentrations were highest during austral summer and fall (86.7 ± 73.7 ng/m3, n = 18) and are indicated to be derived from dimethyl sulfide (DMS) emissions, as δ34S(SO42−)(TSP) values (18.5 ± 1.0‰, n = 10) were similar to literature δ34S(DMS) values. The seasonal cycle of Δ17O(SO42−)(TSP) exhibited minima during austral summer (0.9 ± 0.1‰, n = 5) and maxima during austral fall (1.3 ± 0.3‰, n = 6) and austral spring (1.6 ± 0.1‰, n = 5), indicating a shift from HOx‐ to O3‐dominated chemistry in the atmospheric derived SO42− component. Overall, the budgets of NO3− and SO42−(TSP) at the South Pole were complex functions of transport, localized chemistry, biological activity, and meteorological conditions, and these results will be important for interpretations of oxyanions in ice core records in the interior of Antarctica.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Assessing the Seasonal Dynamics of Nitrate and Sulfate Aerosols at the South Pole Utilizing Stable Isotopes

et al. 2019

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“…SO 2 has 17 O = 0 ‰ due to the rapid isotopic exchange with abundant vapor water whose 17 O is near 0 ‰ (Holt et al, 1981). S(IV) oxidation by H 2 O 2 and O 3 leads to 17 O(SO 2− 4 ) = 0.7 and 6.5 ‰, respectively, on the basis of 17 O(H 2 O 2 ) = 1.4 ‰ (Savarino and Thiemens, 1999) and assuming 17 O(O 3 ) = 26 ‰ (Vicars and Savarino, 2014;Ishino et al, 2017 (Dubey et al, 1997;Luz and Barkan, 2005;Lee et al, 2002;Bao et al, 2000). Sulfate produced by NO 2 oxidation is suggested to occur either via a radical chain mechanism (Shen and Rochelle, 1998), via oxygen-atom transfer from OH − (Clifton et al, 1988), or from O 2 based on experimental results of He et al (2014) (Fu, 2014).…”

Section: Introductionmentioning

confidence: 99%

Isotopic constraints on heterogeneous sulfate production in Beijing haze

et al. 2018

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Abstract. Discerning mechanisms of sulfate formation during fine-particle pollution (referred to as haze hereafter) in Beijing is important for understanding the rapid evolution of haze and for developing cost-effective air pollution mitigation strategies. Here we present observations of the oxygen-17 excess of PM 2.5 sulfate ( 17 O(SO 2− 4 )) collected in Beijing haze from October 2014 to January 2015 to constrain possible sulfate formation pathways. Throughout the sampling campaign, the 12-hourly averaged PM 2.5 concentrations ranged from 16 to 323 µg m −3 with a mean of (141 ± 88 (1σ )) µg m −3 , with SO Our estimate suggested that in-cloud reactions dominated sulfate production on polluted days (PDs, PM 2.5 ≥ 75 µg m −3 ) of Case II in October 2014 due to the relatively high cloud liquid water content, with a fractional contribution of up to 68 %. During PDs of Cases I and III-V, heterogeneous sulfate production (P het ) was estimated to contribute 41-54 % to total sulfate formation with a mean of (48 ± 5) %. For the specific mechanisms of heterogeneous oxidation of SO 2 , chemical reaction kinetics calculations suggested S(IV) (= SO 2 q H 2 O + HSO − 3 + SO 2− 3 ) oxidation by H 2 O 2 in aerosol water accounted for 5-13 % of P het . The relative importance of heterogeneous sulfate production by other mechanisms was constrained by our observed 17 O(SO 2− 4 ). Heterogeneous sulfate production via S(IV) oxidation by O 3 was estimated to contribute 21-22 % of P het on average. Heterogeneous sulfate production pathways that result in zero-17 O(SO 2− 4 ), such as S(IV) oxidation by NO 2 in aerosol water and/or by O 2 via a radical chain mechanism, contributed the remaining 66-73 % of P het . The assumption about the thermodynamic state of aerosols (stable or metastable) was found to significantly influence the calculated aerosol pH (7.6 ± 0.1 or 4.7 ± 1.1, respectively), and thus influence the relative importance of heterogeneous sulfate production via S(IV) oxidation by NO 2 and by O 2 . Our local atmospheric conditions-based calculations suggest sulfate formation via NO 2 oxidation can be the dominant pathway in aerosols at high-pH conditions calculated assuming stable state while S(IV) oxidation by O 2 can be the dominant pathway providing that highly acidic aerosols (pH ≤ 3) exist. Our local atmospheric-conditions-based calculations illustrate the utility of 17 O(SO 2− 4 ) for quantifying sulfate forPublished by Copernicus Publications on behalf of the European Geosciences Union. 5516 P. He et al.: Isotopic constraints on heterogeneous sulfate production in Beijing haze mation pathways, but this estimate may be further improved with future regional modeling work.

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“…The most current estimate of the fractionation of OH in equilibrium with water is ~ −40‰ [ Michalski et al ., ], and in this case, OH at Summit would be expected to have a δ 18 O of ~ −50‰. The isotopic composition of O 3 is unique among oxidants, with typical Δ 17 O of ~26‰ and δ 18 O of ~115‰ [ Vicars and Savarino , ]. As demonstrated by Vicars and Savarino [, and references therein], these values reflect the properties of bulk O 3 , while the reactions that produce NO 3 − interact with the terminal oxygen atoms of O 3 , such that the isotopic composition transferred to NO 3 − is ~40‰ for Δ 17 O and ~128‰ for δ 18 O.…”

Section: Introductionmentioning

confidence: 99%

Analysis of nitrate in the snow and atmosphere at Summit, Greenland: Chemistry and transport

et al. 2016

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International audienceAs a major sink of atmospheric nitrogen oxides (NO_x= NO + NO₂), nitrate (NO₃^-) in polar snow can reflect the long-range transport of NO_x and related species (e.g., PAN). On the other hand, because NO₃^- in snow can be photolyzed, potentially producing gas-phase NO_x locally, NO₃^- in snow (and thus, ice) may reflect local processes. Here we investigate the relationship between local atmospheric composition at Summit, Greenland (72°35’N, 38°25’W) and the isotopic composition of NO₃^- to determine the degree to which local processes influence atmospheric and snow NO₃^-. Based on snow and atmospheric observations during May-June 2010 and 2011, we find no connection between the local atmospheric concentrations of a suite of gases (BrO, NO, NO_y, HNO₃ and nitrite (NO₂^-)) and the NO₃^- isotopic composition or concentration in snow. This suggests that 1) the snow NO₃^- at Summit is primarily derived from long-range transport and 2) this NO₃^- is largely preserved in the snow. Additionally, three isotopically distinct NO₃^- sources were found to be contributing to the NO₃^- in the snow at Summit during both 2010 and 2011. Through the complete isotopic composition of NO₃^-, we suggest that these sources are local anthropogenic particulate NO₃^- from station activities (δ¹⁵N = 16‰, Δ¹⁷O = 4‰ and δ¹⁸O = 23‰), NO₃^- formed from mid-latitude NO_x (δ¹⁵N = -10‰, Δ¹⁷O = 29‰, δ¹⁸O = 78‰) and a NO₃^- source that is possibly influenced or derived from stratospheric ozone NO₃^- (δ¹⁵N = 5‰, Δ¹⁷O = 39‰, δ¹⁸O = 100‰)

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Quantitative constraints on the 17O-excess (Δ17O) signature of surface ozone: Ambient measurements from 50°N to 50°S using the nitrite-coated filter technique

Cited by 113 publications

References 104 publications

Assessing the Seasonal Dynamics of Nitrate and Sulfate Aerosols at the South Pole Utilizing Stable Isotopes

Assessing the Seasonal Dynamics of Nitrate and Sulfate Aerosols at the South Pole Utilizing Stable Isotopes

Isotopic constraints on heterogeneous sulfate production in Beijing haze

Analysis of nitrate in the snow and atmosphere at Summit, Greenland: Chemistry and transport

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