||This study collected total suspended particulates (TSP) and quantified their polycyclic aromatic hydrocarbons (PAHs) concentrations in Dongsha Island during 2013 to 2015 to investigate the effect of long range transport and seasonal variation of TSP and PAHs concentrations on the study area. |
The result demonstrated that the monthly average concentration of Dongsha TSP ranged 12.2~99.4 μg/m3, and the annual average concentration was 46.3±20.9、51.1±29.0、47.7±17.4 μg/m3, respectively, during 2013~2015. Overall , the annual average TSP concentrations are lower than the annual average of Taiwan EPA standard (130μg/m3). The annual average TSP-PAHs concentrations were (0.70±0.56、0.55±0.80、0.23±0.30 ng/m3, during 2013~2015) were much lower than most of the other areas in the world.
The transport pathways of air parcels originated from China, Indochina, Philippines and Taiwan were identified by backward trajectories analysis. The highest monthly average TSP-PAHs concentration all occurred in winter which is also the season with strong long range transport effect. Additionally, the mid molecular weight PAHs was found dominant in the compositional pattern of PAHs in spring and summer, showing the contribution of biomass burning. It is thus speculated that air pollutants were long range transported from the Philippines and Indochina Peninsula, one of the major source regions of biomass burning, to the study area.
In addition, chemical fingerprint analysis, principal component analysis and hierarchical cluster analysis were used to determine the possible sources of PAHs in each season. Traffic emission was identifued as the major source of gaseous PAHs in the study period; while the major sources of particulate PAHs was traffic emission in winter and mixture of biomass burning and fossil fuel burning in spring and summer.