Compliance and port air quality features of ship fuel switching regulation: by a field observation SEISO-Bohai

Abstract. Since January 1st, 2017, ships berth at the core ports of three designated Domestic Emission Control Area (DECA) in China should use fuel with sulphur content less than or equal to 0.5 %. In order to evaluate the impacts of switching fuel, a measurement campaign (SEISO-Bohai) was conducted from 28 December 2016 to 15 January 2017 at JingTang Harbor, an area within the 7th busiest port in the world, including meteorological monitoring, pollutants monitoring, aerosol sampling and fuel sampling. During the campaign, 16 ship plumes were captured by the on-shore measurement sites, and 4 plumes indicates the usage of high SF fuel. The average reduction of average ΔNOx / ΔSO2 ratio from high sulphur plumes (3.26) before January 1st to low sulphur plumes (12.97) after January 1st shows a direct SO2 emission reduction of 75 %, consistent with the sulphur content reduction (79 %). Average concentrations of PM2.5, NOx, SO2, O3 and CO during campaign were 147.85 μg m−3, 146.93 ppb, 21.91 ppb, 29.68 ppb and 2.21 ppm, respectively, among which NOx reached a maximum hourly concentration of 692.6 ppb and SO2 165.5 ppb. Mean concentrations of carbonaceous and dominant ionic species in particles were 6.52 (EC), 23.10 (OC), 22.04 (SO42−), 25.95 (NO3−) and 13.55 (NH4+) μg m−3. Although the carbonaceous species in particles were not significantly affected by fuel switching, the gas and particle pollutants in ambient air exhibited clear and effective improvements from implementation of low sulphur fuel. Comparison with the prevailing atmospheric conditions and wind map of SO2 variation concluded the prompt SO2 reduction by 70 % in ambient air after fuel switching. Given the high humidity in site, this SO2 reduction will abate the amount of secondary aerosols and improve the acidity of particulate matter. Based on enrichment factors of elements in PM2.5, vanadium was identified as marker for residual fuel ship emissions, decreasing significantly by 97.1 % from 309.9 ng m−3 before fuel switching and 9.1 ng m−3 after, which indicated a crucial improvement due to the implementation of low sulphur fuel. Ship emissions were proven to be significantly influential both directly and indirectly on port environment and coastal areas around Bohai Bay, in where the population density reaches 650 per square kilometre. The results from this study provide positive impact on air quality of fuel switching and indication of new method on identification of ship fuel type.