Transport route-based cluster analysis of chemical fingerprints and source origins of marine fine particles (PM) in South China Sea.

The fingerprints and source origins of marine PM at two background islands in the South China Sea were clustered via trajectory analysis and positive matrix factorization. High PM concentrations at the Dongsha Islands occurred for the north routes, while Nansha Islands had similar PM concentrations amongst the transport routes. However, the chemical characteristics of PM varied with the transport routes. Secondary inorganic aerosols (NO, SO, and NH) were abundant in water-soluble ions which dominated PM. Crustal metals were the abundant metals in PM, while trace metals were primarily originated from man-made sources. Organic carbon was superior to elemental carbon, and high concentrations of levoglucosan and organic acids were observed for the north routes. Overall, marine PM at the Dongsha Islands was highly influenced by long-range transport of Asian continental outflows, while particulate air quality at the Nansha Islands was mainly governed by clean air parcels blown from the SCS.