Concentrations, Sources, and Dry Deposition Fluxes of Different Forms of Phosphorus in Qingdao Aerosols in Summer

Abstract

Total suspended particulate (TSP) samples were collected in Qingdao from June to July 2016. Different forms of phosphorus in these samples-including total phosphorus (TP), dissolved phosphorus (DP), dissolved inorganic phosphorus (DIP), and dissolved organic phosphorus (DOP) were analyzed to investigate their distribution characteristics and sources, as well as their dry deposition fluxes. Results showed that the mass concentration of TP in aerosols was (49.3±30.6) ng·m-3, and the concentration of DP was (15.5±10.4) ng·m-3, accounting for 30.9%±11.0% of TP. DIP dominated in dissolved state P, contributing about 60%. The sources of different forms of P were analyzed, showing that the P in Qingdao aerosols in summer was derived from both crustal and anthropogenic sources, with the latter including biomass burning and agricultural fertilization. TP was mainly derived from soil sources, which contributed 38%, while the contribution of agricultural activities and industrial sources was about 20%. DIP in DP was mainly derived from agricultural activities and combustion sources, with contributions of 51% and 24%, respectively. DOP was mainly derived from soil sources and agricultural activities, contributing 41% and 27% respectively. The dry deposition flux of TP in Qingdao was (51.7±31.7) μg·(m2·d)-1, of which 23.2%±8.2% was the water-soluble fraction. DOP in the total dry deposition flux of DP was non-negligible, accounting for 40%. The atmospheric deposition of soluble P would support phytoplankton carbon production of (0.5±0.3) mg·(m2·d)-1, contributing about 1% to new productivity in the Yellow Sea.