Compliance and port air quality features with respect to ship fuel switching regulation: a field observation campaign, SEISO-Bohai

Abstract

Abstract. Since 1\xa0January\xa02017, ships berthed at the core ports of three designated “domestic emission control\nareas” (DECAs) in China should be using fuel with a sulfur content less than\nor equal to 0.5\u2009%. In order to evaluate the impacts of fuel switching, a\nmeasurement campaign (SEISO-Bohai) was conducted from 28\xa0December\xa02016 to\n15\xa0January\xa02017 at Jingtang Harbor, an area within the seventh busiest port\nin the world. This campaign included meteorological monitoring, pollutant\nmonitoring, aerosol sampling and fuel sampling. During the campaign, 16 ship\nplumes were captured by the on-shore measurement site, and 4 plumes indicated\nthe usage of high-S F (S F refers to the sulfur content of marine fuels).\nThe average reduction of the mean ΔNOx∕ΔSO2 ratio from high-sulfur\nplumes (3.26) before 1\xa0January to low-sulfur plumes (12.97) after 1\xa0January\nshows a direct SO2 emission reduction of 75\u2009%, consistent with\nthe sulfur content reduction (79\u2009%). The average concentrations of\nPM 2.5 (particulate matter with a diameter less than 2.5\u2009 µm ),\n NOx , SO2 , O3 and CO during\ncampaign were 147.85\u2009 µ g\u2009m −3 ,\n146.93, 21.91, 29.68\u2009ppb and 2.21\u2009ppm, respectively, among\nwhich NOx reached a maximum hourly concentration of 692.6\u2009ppb, and\n SO2 reached a maximum hourly concentration of 165.5\u2009ppb.\nThe mean concentrations of carbonaceous and dominant ionic\nspecies in particles were 6.52 (EC – elemental carbon), 23.10 (OC – organic carbon), 22.04 ( SO 4 2 - ), 25.95\n( NO 3 - ) and 13.55 ( NH 4 + )\u2009 µ g\u2009m −3 .\nAlthough the carbonaceous species in particles were not significantly\naffected by fuel switching, the gas and particle pollutants in the ambient air\nexhibited clear and effective improvements due to the implementation of low-sulfur\nfuel. Comparison with the prevailing atmospheric conditions and a wind map of\n SO2 variation concluded a prompt SO2 reduction of 70\u2009% in\nambient air after fuel switching. Given the high humidity at the study site, this\n SO2 reduction will abate the concentration of secondary aerosols and improve\nthe acidity of particulate matter. Based on the enrichment factors of elements in\nPM 2.5 , vanadium was identified as a marker of residual fuel ship\nemissions, decreasing significantly by 97.1\u2009% from 309.9\u2009ng\u2009m −3 before fuel switching to 9.1\u2009ng\u2009m −3 after regulation, which\nindicated a crucial improvement due to the implementation of low-sulfur\nfuels. Ship emissions were proven to be significantly influential both\ndirectly and indirectly on the port environment and the coastal areas around Bohai\nBay, where the population density reaches over 650 people per square kilometer. The\nresults from this study report the positive impact of fuel\nswitching on the air quality in the study region and indicate\na new method for identifying the ship fuel type used by vessels in the area.