Environment Research Institute, Shandong University, Qingdao, Shandong, China; School of Environmental Science & Engineering, Qilu University of Technology (Shandong Academy of Sciences), Ji'nan, Shandong, China.
Environment Research Institute, Shandong University, Qingdao, Shandong, China.
Sci Total Environ. 2020 Sep 15;735:139355. doi: 10.1016/j.scitotenv.2020.139355. Epub 2020 May 12.
Nitrous acid (HONO) is an important reservoir of the hydroxyl radical (OH) and thus plays a central role in tropospheric chemistry. Exhaust from engines has long been known as a major primary source of HONO, yet most previous studies focused on vehicle emissions on land. In comparison, ship emissions of HONO have been rarely characterized, and their impacts on the tropospheric oxidation chemistry have not been quantified. In this study, we conducted cruise measurements of HONO and related species over the East China Sea. Contrasting air masses from pristine marine background air to highly polluted ship plumes were encountered. The emission ratio of ΔHONO/ΔNO (0.51 ± 0.18%) was derived from a large number of fresh ship plumes. Using the in-situ measured emission ratio, a global ship emission inventory of HONO was developed based on the international shipping emissions of NO in the Community Emission Data System inventory. The global shipping voyage emits approximately 63.9 ± 22.2 Gg yr of HONO to the atmosphere. GEOS-Chem modelling with the addition of ship-emitted HONO showed that HONO concentrations could increase up to 40-100% over the navigation areas, leading to about 5-15% increases of primary OH production in the early-morning time. This study elucidates the potentially considerable effects of ship HONO emissions on the marine atmospheric chemistry, and calls for further studies to better characterize the ship emissions of HONO and other reactive species, which should be taken into account by global and regional models.
亚硝酸（HONO）是羟基自由基（OH）的重要储存库，因此在对流层化学中起着核心作用。发动机废气长期以来一直被认为是 HONO 的主要原始来源，但之前的大多数研究都集中在陆地上的车辆排放上。相比之下，船舶排放的 HONO 很少被描述，其对对流层氧化化学的影响也没有被量化。在这项研究中，我们在东海进行了 HONO 及相关物种的巡航测量。我们遇到了从原始海洋背景空气到高度污染的船舶羽流的对比空气团。大量新鲜船舶羽流的 ΔHONO/ΔNO（0.51±0.18%）排放比得出。利用现场测量的排放比，根据国际航运排放的 NO 在社区排放数据系统清单中的排放量，开发了全球船舶 HONO 排放清单。全球船舶航行向大气排放约 63.9±22.2 Gg yr 的 HONO。添加船舶排放的 HONO 的 GEOS-Chem 模型表明，在航行区域 HONO 浓度可能增加 40-100%，导致清晨时段初级 OH 生成增加约 5-15%。这项研究阐明了船舶 HONO 排放对海洋大气化学的潜在重大影响，并呼吁进一步研究更好地描述船舶 HONO 和其他反应性物种的排放，这应该被全球和区域模型所考虑。
