Impact of Ship Emissions on Air Quality in the Guangdong-Hong Kong-Macao Greater Bay Area (GBA): With a Particular Focus on the Role of Onshore Wind

Abstract

Background: ship emissions have an adverse effect on air quality in coastal regions, and this effect can be exacerbated by onshore winds. Objectives and methods: to investigate the impact of ship emissions on air pollutant concentrations during the onshore wind period in a low-latitude region in China, this study applied the WRF/Chem model to simulate the contribution of ship emissions to PM2.5 and O3 by “zero-out” in 2018, in the Guangdong-Hong Kong-Macao Greater Bay Area (GBA). Results/findings: results show that the onshore winds facilitated the transport of ship-emitted pollutants to inland areas, causing the contribution of ship emissions to PM2.5 exceeding 4 μg/m3 to areas north of Guangzhou in April and west of the GBA in October. The impact of onshore winds on the ship contribution to the O3 concentration shows a bidirectional trend both spatially and monthly. The onshore winds raised the ship contribution to O3 concentrations in April by 1.54 μg/m3, while exacerbated the decreasing contribution in other months. In VOC-sensitive cities such as Foshan, onshore winds exacerbated the negative contribution of ship emissions to O3 concentrations; while in NOx-sensitive cities such as Huizhou, they enhanced the contribution of ship-induced O3. Novelty/Improvement: this paper fills a gap in the study of pollutants transportation characteristics from ship emissions under the influence of onshore winds in the GBA. Our results demonstrate the importance of considering meteorological conditions and atmospheric chemical mechanisms regarding the coastal air pollution prevention caused by ship emissions.