Impacts of Ship Emissions on Air Quality in Southern China: Opportunistic Insights from the Abrupt Emission Changes in Early 2020

Abstract

In early 2020, two unique events perturbed ship emissions of pollutants around Southern China, proffering insights into the impacts of ship emissions on regional air quality: the decline of ship activities due to COVID-19 and the global enforcement of low-sulfur (<0.5%) fuel oil for ships. In January and February 2020, estimated ship emissions of NO x , SO 2 , and primary PM 2.5 over Southern China dropped by 19, 71, and 58%, respectively, relative to the same period in 2019. The decline of ship NO x emissions was mostly over the coastal waters and inland waterways of Southern China due to reduced ship activities. The decline of ship SO 2 and primary PM 2.5 emissions was most pronounced outside the Chinese Domestic Emission Control Area due to the switch to low-sulfur fuel oil there. Ship emission reductions in early 2020 drove 16 to 18% decreases in surface NO 2 levels but 3.8 to 4.9% increases in surface ozone over Southern China. We estimated that ship emissions contributed 40% of surface NO 2 concentrations over Guangdong in winter. Our results indicated that future abatements of ship emissions should be implemented synergistically with reductions of land-borne anthropogenic emissions of nonmethane volatile organic compounds to effectively alleviate regional ozone pollution.

Characteristics of Trace Metal Elements in Ambient Sub-Micron Particulate Matter in a Coastal Megacity of Northern China Influenced by Shipping Emissions from 2018 to 2022

“…Different trace elements in PM 1 can be used as tracers of pollution sources [91]. Previous studies have shown that As was a tracer element for coal combustion sources, Cr was a tracer element for industrial sources, and V was a tracer element for ship sources [9,37,53,70,91,92]. The relative contribution of each pollution source to SO 2 during the observation period was explored, and the multi-linear regression model was as follows:…”

“…To reduce the impact of air pollution emissions from ships on the air quality of coastal cities, a series of policies have been introduced at home and abroad [9][10][11][12][13][14][15][16]. On 1 January 2016, the Ministry of Transport of China (MOT) determined the Beijing-Tianjin-Hebei region (BTH), the Yangtze River Delta (YRD), and the Pearl River Delta (PRD) as domestic emission control areas (DECA 1.0).…”

“…It required ships berthed in the control areas to use 0.5% m/m of low-sulfur fuel [17]. On 1 January 2019, the domestic emission control area (DECA 2.0) expanded upon the DECA 1.0 policy, with the emission control area extending about 12 nautical miles along the entire coastline of the country and ships being required to use 0.5% (m/m) sulfur fuel for navigation and berthing [9,10]. On 1 January 2020, the International Maritime Organization (IMO) issued a regulation that the sulfur content of fuel oil used by ships in the global seas shall not exceed 0.5% m/m in the future (IMO 2020) [2] (Figures S1-S3).…”