John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138;
John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138.
Proc Natl Acad Sci U S A. 2022 Feb 8;119(6). doi: 10.1073/pnas.2113265119.
Formaldehyde (HCHO), the simplest and most abundant carbonyl in the atmosphere, contributes to particulate matter (PM) formation via two in-cloud processing pathways. First, in a catalytic pathway, HCHO reacts with hydrogen peroxide (HO) to form hydroxymethyl hydroperoxide (HMHP), which rapidly oxidizes dissolved sulfur dioxide (SO) to sulfate, regenerating HCHO. Second, HCHO reacts with dissolved SO to form hydroxymethanesulfonate (HMS), which upon oxidation with the hydroxyl radical (OH) forms sulfate and also reforms HCHO. Chemical transport model simulations using rate coefficients from laboratory studies of the reaction rate of HMHP with SO show that the HMHP pathways reduce the SO lifetime by up to a factor of 2 and contribute up to ∼18% of global sulfate. This contribution rises to >50% in isoprene-dominated regions such as the Amazon. Combined with recent results on HMS, this work demonstrates that the one-carbon molecules HMHP and HCHO contribute significantly to global PM, with HCHO playing a crucial catalytic role.
甲醛（HCHO）是大气中最简单、最丰富的羰基化合物，通过两种云内处理途径促进颗粒物（PM）的形成。首先，在催化途径中，HCHO 与过氧化氢（HO）反应形成羟甲基过氧化物（HMHP），HMHP 迅速将溶解的二氧化硫（SO）氧化为硫酸盐，从而再生 HCHO。其次，HCHO 与溶解的 SO 反应形成羟甲基磺酸盐（HMS），然后与羟基自由基（OH）氧化形成硫酸盐，并重新形成 HCHO。使用实验室研究 HMHP 与 SO 反应速率系数进行的化学输送模型模拟表明，HMHP 途径将 SO 的寿命缩短了高达 2 倍，并对全球硫酸盐的形成贡献了高达约 18%。在亚马逊等以异戊二烯为主的地区，这一贡献上升到超过 50%。结合最近关于 HMS 的结果，这项工作表明，一碳分子 HMHP 和 HCHO 对全球 PM 有显著贡献，其中 HCHO 发挥了关键的催化作用。
