Abstract. Ship emissions and coastal air pollution around China are expected to be
alleviated with the gradual implementation of ship domestic emission control area
(DECA) policies. However, a comprehensive post-assessment on the policy's
effectiveness is still lacking. This study developed a series of high-spatiotemporal ship emission inventories around China from 2016 to 2019 based
on an updated Ship Emission Inventory Model (SEIM v2.0) and analyzed the
interannual changes in emissions under the influence of both ship activity
increases and gradually promoted policies. In this model, NOx,
SO2, PM and HC emissions from ships in China's inland rivers and the
200 Nm (nautical miles) coastal zone were estimated every day with a spatial resolution
of 0.05∘×0.05∘ based on a combination of automatic
identification system (AIS) data and the Ship Technical Specifications
Database (STSD). The route restoration technology and classification of
ocean-going vessels (OGVs), coastal vessels (CVs) and river vessels (RVs) has
greatly improved our model in the spatial distribution of ship emissions. From
2016 to 2019, SO2 and PM emissions from ships decreased by
29.6 % and 26.4 %, respectively, while ship NOx
emissions increased by 13.0 %. Although the DECA 1.0 policy was implemented in 2017, it was not until 2019 when DECA 2.0 came into
effect that a significant emission reduction was achieved, e.g., a
year-on-year decrease of 33.3 %, regarding
SO2. Considering the potential emissions brought by the continuous
growth of maritime trade, however, an even larger SO2 emission
reduction effect of 39.8 % was achieved in these 4 years
compared with the scenario without switching to cleaner fuel. Containers and
bulk carriers are still the dominant contributors to ship emissions, and
newly built, large ships and ships using clean fuel oil account for an
increasingly large proportion of emission structures. A total of 4 years of consecutive
daily ship emissions were presented for major ports, which reflects the
influence of the step-by-step DECA policy on emissions in a timely manner and
may provide useful references for port observation experiments and local
policy making. In addition, the spatial distribution shows that a number of
ships detoured outside the scope of DECA 2.0 in 2019, perhaps to save costs on
more expensive low-sulfur oil, which would increase emissions in farther
maritime areas. The multiyear ship emission inventory provides high-quality
datasets for air-quality and dispersion modeling, as well as verifications
for in situ observation experiments, which may also guide further ship
emission control directions in China.
Assessment of co-benefits of black carbon emission reduction measures in Southeast Asia: Part 1 emission inventory and simulation for the base year 2007
