CHARACTERISTICS AND SHIP TRAFFIC SOURCE IDENTIFICATION OF AIR POLLUTANTS IN SHANGHAI PORT, CHINA

摘要

To know the characteristics of air pollutants in Shanghai Port and contribution of the ship traffic emission to them, field measurements have been conducted in 2011. The trace gases SO2, NO2 and O3 were monitored and aerosol samples of TSP, PM2.5 and size-segregated particles were collected in one working area of Shanghai Port. Also elements including V, Ni, Al, Fe, Si, Ca, Na, Mg, Mn, Zn, Co, Cr in aerosol samples and heavy fuel oils samples were analyzed. The results revealed that average hourly SO2 and NO2 concentrations in Shanghai Port were respectively 0.029 and 0.064 mg m-3, concentrations of TSP and PM2.5 were 114.39 and 62.60μg m-3, comparable with the ones in Shanghai land area. Ni and V were found enriched and mainly accumulate in fine particles with averaged concentrations of 80.0 and 14.8ng m-3 in PM2.5 respectively. Also ratio of V/Ni in aerosol under summertime airflow was 3.4, very close to the ratio of averaged V and Ni content in international Heavy Fule Oil used in Shanghai Port. The backward trajectory analysis further revealed that SO2, NO2, and V under coastal airflows were mainly from ship traffic emission. The mean concentration of vanadium was 15.84ng m-3 under hybrid coastal airflows, much higher than that of 9.84ng m-3 under continental airflows. Furthermore, V was found to be obviously positively correlated with ship fluxes, and was selected as an indicator of ship traffic emission in Shanghai. The estimated primary PM2.5 contribution from ship traffic ranged from 0.63 to 3.58ug m-3, with an average of 1.96μg m-3. This PM2.5 fraction accounted for 4.23% of the total PM2.5 in an average level, and reached to a maximum of 12.80%. Further, there would be 62% of primary PM2.5 contributed by ships in Shanghai Port transported to a land site estimated by the parallel sampling measurement. Our results suggest that ship traffic has an important impact on ambient levels of fine particles as well as SO2 and NO2 and major part of ship traffic emission could be transported to the surrounding land area.