Ship emission inventory and its impact on the PM_2.5 air pollution in Qingdao Port, North China

In this study, a first high temporal-spatial ship emission inventory in Qingdao Port and its adjacent waters has been developed using a “bottom-up” method based on Automatic Identification System (AIS) data. The total estimated ship emissions for SO₂, NO_X, PM₁₀, PM_2.5, HC and CO in 2014 are 3.32 × 10⁴, 4.29 × 10⁴, 4.54 × 10³, 4.18 × 10³, 1.85 × 10³ and 3.66 × 10³ tonnes, respectively. Emissions of SO₂ and NO_X from ships account for 9% and 13% of the anthropogenic totals in Qingdao, respectively. The main contributors to the ship emissions are containers, followed by fishing ships, oil tankers and bulk carriers. The inter-monthly ship emissions varied significantly due to two reasons: stopping of the fishing ship activities during the fishing moratorium and the reduction of freight volume around the Chinese New Year Festival. Emissions from transport vessels concentrated basically along the shipping routes, while fishing ships contributed to massive irregular spatial emissions in the sea. The impact of ship emissions on the ambient air quality was further investigated using the Weather Research and Forecasting with Chemistry (WRF/Chem) model. The results reveal that the contribution of ship emissions to the PM_2.5 concentrations in Qingdao is the highest in summer (13.1%) and the lowest in winter (1.5%). The impact was more evident over densely populated urban areas, where the contributions from ship emissions could be over 20% in July due to their close range to the docks. These results indicated that the management and control of the ship emissions are highly demanded considering their remarkable influence on the air quality and potential negative effects on human health.