有机物与硝离子的反应作为有机气溶胶代理中有机硝酸酯的来源,ACS Earth and Space Chemistry

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有机物与硝离子的反应作为有机气溶胶代理中有机硝酸酯的来源
ACS Earth and Space Chemistry ( IF 2.9 ) Pub Date : 2023-08-09 , DOI: 10.1021/acsearthspacechem.3c00111
Robert F. Hansen ₁ , Evan Z. Dalton ₂ , Rebecca B. Abney ₃ , Mark H. Engelhard ₄ , Gerardo Castillo Valdes ₂ , Sarah D. Burton ₄ , Rosalie K. Chu ₄ , Daniel P. Veghte ₄ , Swarup China ₄ , Yaroslav Losovyj ₂ , John B. Cliff ₄ , Jonathan D. Raff _{2,

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Affiliation

有机硝酸酯化合物 (RONO ₂ ) 是氮氧化物 (NO _x == NO + NO ₂ ) 的重要汇，影响低层大气中臭氧和有机气溶胶的形成。虽然由气相氧化化学和涉及将NO _{3反应吸收到有机气溶胶中的非均相反应}_{形成的RONO 2}_已得到充分记录，但有机气溶胶内原位大量水相生产尚未得到广泛探索。在这里，我们提供证据表明 RONO ₂物质是在硝态氮 (NO ₂⁺）与腐殖酸和黄腐酸，它们被用作气溶胶有机物的替代物。X 射线光电子能谱 (XPS) 和高分辨率质谱用于表征硝化反应过程中氮官能团和本体化学成分的变化。反应后的腐殖酸和黄腐酸中的有机氮丰度与固态¹³ C NMR 测量的官能团丰度之间的相关性表明，NO ₂⁺以有机质的脂质部分为目标。_{对模型脂质化合物的傅里叶变换红外光谱 (FTIR) 分析表明，NO 2}⁺与末端醇 (ROH) 和烯烃的反应是稳定 RONO ₂的来源化合物。此外，大多数硝酸盐气溶胶的低 pH 环境预计会通过天然有机物类脂部分内的酸催化酯水解来增强总末端 ROH 池。_{我们的研究结果表明，NO 2}⁺对有机物的多相氧化，以及气相化学产物的空气-颗粒分配，可能是颗粒相有机硝酸盐的重要来源。

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Reaction of Organic Matter with Nitronium Ion as a Source of Organic Nitrate Esters in Proxies for Organic Aerosols

Organic nitrate ester compounds (RONO₂) are an important sink for nitrogen oxides (NO_x ≡ NO + NO₂) that impact ozone and organic aerosol formation in the lower atmosphere. While RONO₂ formation from gas phase oxidation chemistry and heterogeneous reactions involving reactive uptake of NO₃ into organic aerosols is well documented, in situ bulk-aqueous-phase production of RONO₂ within organic aerosols has not been explored as extensively. Here, we provide evidence that RONO₂ species are produced during aqueous phase reactions of nitronium (NO₂⁺) with humic and fulvic acids, which are used as surrogates for aerosol organic matter. X-ray photoelectron spectroscopy (XPS) and high-resolution mass spectrometry were used to characterize nitrogen functional groups and changes in bulk chemical composition during nitration reactions. Correlations between the organic N abundance in reacted humic and fulvic acids and functional group abundance measured by solid-state ¹³C NMR indicate that NO₂⁺ targets the lipid fraction of the organic matter. Fourier transform infrared spectroscopy (FTIR) analysis of model lipid compounds shows that the reaction of NO₂⁺ with terminal alcohols (ROH) and alkenes is a source of stable RONO₂ compounds. Further, the low-pH environment of most nitrate aerosols is expected to enhance the total terminal ROH pool through acid-catalyzed ester hydrolysis within the lipid-like fraction of natural organic matter. Our findings demonstrate that multiphase oxidation of organic matter by NO₂⁺, along with air-particle partitioning of products from gas-phase chemistry, may be an important source of particle-phase organic nitrates.

更新日期：2023-08-09

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