Tracing the sources and formation pathways of atmospheric particulate nitrate over the Pacific Ocean using stable isotopes
Tracing the sources and formation pathways of atmospheric particulate nitrate over the Pacific Ocean using stable isotopes
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DOI：
10.1016/j.atmosenv.2019.04.026
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发表时间：
2019-07
影响因子：
5
通讯作者：
Kazuki Kamezaki;S. Hattori;Yoko Iwamoto;S. Ishino;H. Furutani;Yusuke Miki;M. Uematsu;K. Miura
中科院分区：
文献类型：
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作者：
Kazuki Kamezaki;S. Hattori;Yoko Iwamoto;S. Ishino;H. Furutani;Yusuke Miki;M. Uematsu;K. Miura
本文介绍了两个航次在S 40°和68°N之间的太平洋大气颗粒物硝酸盐(p-NO_3-−)的同位素组成(15N和17O值)。利用后向轨迹分析对太平洋上的六个海洋区进行了分类，并使用不同的离子浓度来评估人为或非人为来源的优势。在40°S和68°N之间的太平洋上，δ15N(p-NO2−)值在−15.4‰到2.5‰之间变化。根据从NO和NO 2到HNO 3氧化过程中的同位素交换/分馏计算了每个样品的δ15N(NOx)值范围，在太平洋上产生了−14.1到6.9‰的范围。与其他地区相比，赤道太平洋的δ15N(NOx)值在−14.1NOx值到NOx7.3‰之间存在极低的值，这是传统的−分配方法所不能匹配的。因此，提出了赤道太平洋NH3和烷基硝酸盐的特定海洋氮排放量。结果表明，赤道太平洋海洋和低层大气之间的氮循环过程具有重要意义。在大多数太平洋地区，Δ17O(p-NO3−)值与光通量总体上有很好的相关性，这一结果与光解对OH自由基浓度的贡献相对于臭氧对NOx生成HNO3的贡献是一致的。相反，东北太平洋东部的Δ17O(p-NO_3−)值高于其他光通量相近的地区，这表明卤素对p-NO_3−的形成有贡献。
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 VesselHakuho 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 NOxapportionment. Emissions of specific oceanic nitrogen emissions of NH3and 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 O3in producing HNO3from 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.