Simulating the impacts of ship emissions on coastal air quality: Importance of a high-resolution emission inventory relative to cruise- and land-based observations

Jingbo Mao; Yan Zhang; Fangqun Yu; Jianmin Chen; Jianfeng Sun; Shanshan Wang; Zhong Zou; Jun Zhou; Qi Yu; Weichun Ma; Limin Chen

doi:10.1016/j.scitotenv.2020.138454

Simulating the impacts of ship emissions on coastal air quality: Importance of a high-resolution emission inventory relative to cruise- and land-based observations

Sci Total Environ. 2020 Aug 1:728:138454. doi: 10.1016/j.scitotenv.2020.138454. Epub 2020 Apr 20.

Authors

Jingbo Mao¹, Yan Zhang², Fangqun Yu³, Jianmin Chen⁴, Jianfeng Sun¹, Shanshan Wang⁴, Zhong Zou⁵, Jun Zhou⁶, Qi Yu¹, Weichun Ma¹, Limin Chen⁷

Affiliations

¹ Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University, Shanghai 200438, China.
² Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University, Shanghai 200438, China; Shanghai Institute of Eco-Chongming (SIEC), Shanghai 200062, China; Institute of Atmospheric Science, Fudan University, Shanghai 200438, China. Electronic address: yan_zhang@fudan.edu.cn.
³ Atmospheric Sciences Research Center, State University of New York, 251 Fuller Road, Albany, NY 12203, USA.
⁴ Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University, Shanghai 200438, China; Shanghai Institute of Eco-Chongming (SIEC), Shanghai 200062, China.
⁵ Pudong New Area Environmental Monitoring Station, Shanghai 200135, China.
⁶ Ningbo Environmental Monitoring Center, Ningbo 315012, China.
⁷ Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University, Shanghai 200438, China. Electronic address: lmchen@fudan.edu.cn.

PMID: 32570333
DOI: 10.1016/j.scitotenv.2020.138454

Abstract

This work studied the impacts of ship emissions at a high temporal resolution on the real-time concentrations of PM_2.5, NO₂, and SO₂ in urban harbors and coastal sea areas, taking the Yangtze River Delta (YRD) as an example. The WRF-Chem model with 3 nested grids and ship emissions derived from an automatic identification system (AIS) were combined to simulate the air quality. The AIS data showed significant temporal fluctuations in ship emissions, with hourly mean fluxes of approximately 1082.41 ± 444.41 and 593.55 ± 404.95 g/h/km² near ports and in the channel waters of the YRD, respectively. The monthly mean contributions of shipping emissions reached 80.72% (2.15 ppbv) and 81.79% (8.79 ppbv) to ambient SO₂ and NO₂ in Ningbo Port, and 10.61% (6.96 μg/m³) to PM_2.5 in Shanghai Port, respectively, regions with dense ship traffic. The relative differences in the PM_2.5, SO₂, and NO₂ concentrations modeled using monthly and hourly ship emissions accounted for -10-15%, -10-30%, and - 5-30%, respectively. Compared with cruise- and land-based measurements, the simulations using hourly emissions were in much better agreement with the observations than those using monthly emissions and appropriately captured some air pollutant concentration peaks. Simulations during shipping-related periods with hourly ship emissions improved the normalized mean bias (NMBs) from -43.03%, 301.49%, and 223.02% to -27.28%, 90.45%, and 167.52%, respectively, for PM_2.5, SO₂, and NO₂, highlighting the importance of using ship emissions with a fine temporal resolution. Our study showed that ignoring hourly fluctuations in ship emissions during air quality modeling leads to considerable uncertainties, especially in coastal urban areas and harbors with high ship activities. These results imply that data with a high temporal resolution, such as hourly ship emissions, are necessary to understand the realistic impacts of shipping traffic and to implement more precise control policies to improve coastal air quality.

Keywords: Coastal air quality; High-resolution emission inventory; Ship emissions.