Iodide Accelerates the Processing of Biogenic Monoterpene Emissions on Marine Aerosols
Iodide Accelerates the Processing of Biogenic Monoterpene Emissions on Marine Aerosols
复制标题
DOI：
10.1021/acsomega.9b00024
复制
发表时间：
2019-04
期刊：
影响因子：
4.1
通讯作者：
Shinichi Enami;M. Hoffmann;A. Colussi
中科院分区：
文献类型：
--
作者：
Shinichi Enami;M. Hoffmann;A. Colussi
海洋光合生物向边界层排放有机气体，包括聚烯烃异戊二烯（C5 H8）和单萜（MTPs，C10 H16）。它们在大气中的处理过程产生了影响云的形成和生长的粒子，从而影响了地球的辐射平衡。在这里，我们报告了溶解的α-蒎烯的非均相臭氧分解O3（g）在水表面上显着加速I-，在海洋上层微层和海喷雾气溶胶（SSA）中富集的阴离子。在我们的实验中，α-蒎烯溶液的液体微射流，添加和不添加I-，与O3（g）的剂量为τ < 10 μs，并在线分析气动电离质谱。在不存在I-的情况下，在当前条件下，α-蒎烯不会与O3（g）发生可检测的反应。相反，在≥ 0.01 mM I-存在下，在m/z = 169处出现新信号（C9H13O3-），m/z = 183（C10 H15 O3-），m/z = 199（C10 H15 O 4-），m/z = 311（C10 H16 IO 3-）和m/z = 461（C20 H30 IO 4-），加上m/z = 175（IO 3-）和m/z = 381（I3-）。碰撞裂解使CO2从C9 H13 O3-、C10 H15 O3-和C10 H15 O 4-中分离，I-加上IO-从C10 H16 IO 3-中分离，正如三氧化物IOOO·C10 H16-结构所预期的那样。我们推断，α-蒎烯在水表面上的氧化过程是显着加速由I-通过形成IOOO-比O3更活泼的中间体。IOOO-与α-蒎烯（可能与其他不饱和物质）竞争异构化为IO 3-的反应机制解释了目前的结果，以及SSA中可溶性碘主要以含碘有机物质而不是化学上更稳定的碘酸盐存在的事实。通过这一过程，很大一部分生物MTPs和其他不饱和气体可以转化为水溶性物质，而不是排放到大气中。
Marine photosynthetic organisms emit organic gases, including the polyolefins isoprene (C5H8) and monoterpenes (MTPs, C10H16), into the boundary layer. Their atmospheric processing produces particles that influence cloud formation and growth and, as a result, the Earth’s radiation balance. Here, we report that the heterogeneous ozonolysis of dissolved α-pinene by O3(g) on aqueous surfaces is dramatically accelerated by I–, an anion enriched in the ocean upper microlayer and sea spray aerosols (SSAs). In our experiments, liquid microjets of α-pinene solutions, with and without added I–, are dosed with O3(g) for τ < 10 μs and analyzed online by pneumatic ionization mass spectrometry. In the absence of I–, α-pinene does not detectably react with O3(g) under present conditions. In the presence of ≥ 0.01 mM I–, in contrast, new signals appear at m/z = 169 (C9H13O3–), m/z = 183 (C10H15O3–), m/z = 199 (C10H15O4–), m/z = 311 (C10H16IO3–), and m/z = 461 (C20H30IO4–), plus m/z = 175 (IO3–), and m/z = 381 (I3–). Collisional fragmentation splits CO2 from C9H13O3–, C10H15O3– and C10H15O4–, and I– plus IO– from C10H16IO3– as expected from a trioxide IOOO•C10H16– structure. We infer that the oxidative processing of α-pinene on aqueous surfaces is significantly accelerated by I– via the formation of IOOO– intermediates that are more reactive than O3. A mechanism in which IOOO– reacts with α-pinene (and likely with other unsaturated species) in competition with its isomerization to IO3– accounts for present results and the fact that soluble iodine in SSA is mostly present as iodine-containing organic species rather than the thermodynamically more stable iodate. By this process, a significant fraction of biogenic MTPs and other unsaturated gases may be converted to water-soluble species rather than emitted to the atmosphere.