Organophosphate esters in atmospheric particles and surface seawater in the western South China Sea.

Abstract

Seven organophosphate esters (OPEs) in atmospheric particles and surface seawater were observed during a cruise in the western South China Sea (SCS) in 2014. The median concentrations of ∑OPEs were 688\u202fpg/m3 and 5.55\u202fng/L for particle and seawater samples, respectively. Total OPEs were dominated by tris(1-chloro-2-propyl) phosphate (TCPP) and tris(2-chloroethyl) phosphate (TCEP). The spatial distribution of OPEs indicated that the OPEs in particle phase were mainly influenced by air masses originating from China, Indochina Peninsula and Malay Archipelago, showing the significant contribution of anthropogenic sources from these regions. Significant positive correlations between Tri-n-butylphosphate (TnBP) and organic carbon (P\u202f<\u202f0.05) in particle phase over the western SCS suggests that it might be a potential tracer of the source regions of Indochina Peninsula and Malay Archipelago. The spatial distribution of OPEs in seawater were contributed by freshwater inputs associating with variations of human activities as well as salinity. Seawater pollution levels of OPEs in the eastern coast of Vietnam were increased compared to those measured in the northern SCS. The loadings of ∑OPEs transported to the vast area of western SCS vias atmospheric deposition and air-sea water gas exchange were estimated to be 59 tons/year and 105 tons/year, respectively. This work highlights the importance of transport processes and air-seawater interface behavior for OPEs in the oceanic area.