Kim Eunhye, Kim Byeong-Uk, Kim Hyun Cheol, Kim Soontae
Department of Environmental & Safety Engineering, Ajou University, Suwon, South Korea.
Georgia Environmental Protection Division, Atlanta, GA, 30354, USA.
Environ Pollut. 2021 Mar 15;273:116428. doi: 10.1016/j.envpol.2021.116428. Epub 2021 Jan 5.
Ammonia (NH) is an important precursor for forming PM. In this study, we estimated the impact of upwind transboundary and local downwind NH emissions on PM and its inorganic components via photochemical grid model simulations. Nine sensitivity scenarios with ±50% perturbations of upwind (China) and/or downwind (South Korea) NH emissions were simulated for the year 2016 over Northeast Asia. The annual mean PM concentrations in the downwind area were predicted to change from -3.3 (-18%) to 2.4 μg/m(13%) when the NH emissions in the upwind and downwind areas were perturbed by -50% to +50%. The change in PM concentrations in the downwind area depending on the change in NH emissions in the upwind area was the highest in spring, followed by winter. This was mainly attributed to the change in nitrate (NO), a secondary inorganic aerosol (SIA) that is a predominant constituent of PM. Since NH is mainly emitted near the surface and vertical mixing is limited during the night, it was modeled that the aloft nitric acid (HNO)-to-NO conversion in the morning hours was increased when the NH accumulated near the surface during nighttime begins to mix up within the Planetary Boundary Layer (PBL) as it develops after sunrise. This implies that the control of upwind and/or downwind NH emissions is effective at reducing PM concentrations in the downwind area even under NH rich conditions in Northeast Asia.
氨（NH₃）是形成颗粒物（PM）的重要前体物。在本研究中，我们通过光化学网格模型模拟估算了上风向跨境和下风向本地氨排放对PM及其无机成分的影响。针对2016年东北亚地区，模拟了9种敏感性情景，对上风向（中国）和/或下风向（韩国）氨排放进行±50%的扰动。当上风向和下风向地区的氨排放扰动幅度为-50%至+50%时，下风向地区的年平均PM浓度预计将从-3.3μg/m³（-18%）变化至2.4μg/m³（13%）。下风向地区PM浓度的变化取决于上风向地区氨排放的变化，春季变化最大，其次是冬季。这主要归因于硝酸盐（NO₃⁻）的变化，硝酸盐是二次无机气溶胶（SIA），也是PM的主要成分。由于氨主要在地表附近排放，夜间垂直混合受限，因此模拟结果表明，当夜间在地表附近积累的氨随着日出后行星边界层（PBL）的发展开始向上混合时，早晨时段高空硝酸（HNO₃）向NO₃⁻的转化率会增加。这意味着即使在东北亚地区氨含量较高的情况下，控制上风向和/或下风向的氨排放对于降低下风向地区的PM浓度也是有效的。
