Gas-Phase Oxidation Rates and Products of 1,2-Dihydroxy Isoprene
Gas-Phase Oxidation Rates and Products of 1,2-Dihydroxy Isoprene
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DOI：
10.1021/acs.est.1c04177
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发表时间：
2021-10-07
影响因子：
11.4
通讯作者：
Nguyen, Tran B.
中科院分区：
文献类型：
--
作者：
Bates, Kelvin H.;Cope, James D.;Nguyen, Tran B.
1，2-二羟基异戊二烯（1，2-DHI）是异戊二烯氧化的产物，来自多种化学途径，在大气中大量产生;然而，其化学归宿尚未得到全面研究。在这里，我们进行室实验，以研究其气相反应。我们发现1，2-DHI与OH自由基和臭氧的反应是快速的（k（OH）= 8.0（+/-1.3）× 10（-11）cm ~ 3 molecule（-1）s（-1）; k（O_3）= 7.2（+/-1.1）× 10（-18）cm ~ 3 molecule（-1）s（-1））。与OH的反应，占主导地位的1，2-DHI损失，主要导致碎片和自由基再循环;在高和低NO条件下的主要产物包括羟基丙酮，乙醇醛和2，3-二羟基-2-甲基-丙醛（DHMP）。自由基终止氢过氧化物形成的过氧自由基（RO 2）与HO 2和有机硝酸盐形成从RO 2 + NO的反应中没有观察到在气相中，可能是由于低挥发性;限制其分支比，而不是来自质量平衡。我们还测量了二次有机气溶胶质量产率从1，2-DHI（0-23%），并表明，在含水颗粒的存在下，氧化导致甲酸和乙酸的生产。最后，我们将结果纳入全球化学传输模型GEOS-Chem中，计算1，2-DHI的全球产量（25.3 Tg a（-1））和气相损失（20.2 Tg a（-1）），并表明其氧化对羟基丙酮，乙醇醛，羟甲基氢过氧化物，甲酸和DHMP的大气预算提供了不可忽视的贡献。
1,2-Dihydroxy isoprene (1,2-DHI), a product of isoprene oxidation from multiple chemical pathways, is produced in the atmosphere in large quantities; however, its chemical fate has not been comprehensively studied. Here, we perform chamber experiments to investigate its gas-phase reactions. We find that the reactions of 1,2-DHI with OH radicals and ozone are rapid (k(OH) = 8.0 (+/- 1.3) x 10(-11) cm(3) molecule(-1) s(-1); k(O3) = 7.2 (+/- 1.1) x 10(-18) cm3 molecule-1 s-1). Reaction with OH, which dominates 1,2-DHI loss, leads primarily to fragmentation and radical recycling; major products under both high- and low-NO conditions include hydroxyacetone, glycolaldehyde, and 2,3-dihydroxy-2-methyl-propanal (DHMP). Radical-terminating hydroperoxide formation from the peroxy radical (RO2) reaction with HO2 and organonitrate formation from RO2 + NO are not observed in the gas phase, possibly due to low volatility; constraints for their branching ratios are instead derived by mass balance. We also measure secondary organic aerosol mass yields from 1,2-DHI (0-23%) and show that oxidation in the presence of aqueous particles leads to formic and acetic acid production. Finally, we incorporate results into GEOS-Chem, a global chemical transport model, to compute the global production (25.3 Tg a(-1)) and gas-phase loss (20.2 Tg a(-1)) of 1,2-DHI and show that its oxidation provides non-negligible contributions to the atmospheric budgets of hydroxyacetone, glycolaldehyde, hydroxymethyl hydroperoxide, formic acid, and DHMP.