Volume 15, No. 1, February 2015, Pages 38-45 PDF(844 KB)
Indirect Evidence for the Presence of Secondary Phosphorus in Continental Fine Aerosol
Krisztina Krassován1, Zsófia Kertész2, Kornélia Imre3, András Gelencsér1,3
1 Institute of Environmental Sciences, University of Pannonia, PO Box 158, Veszprém, H-8201, Hungary
2 Institute for Nuclear Research Hungarian Academy of Sciences, Laboratory of Ion Beam Applications, PO Box 51, Debrecen, H-4001, Hungary
3 MTA-PE Air Chemistry Research Group, PO Box 158, Veszprém, H-8201, Hungary
- We determined mass size distribution of aerosol phosphorus.
- The contribution of biomass burning to fine-mode P was determined.
- Excess P is defined as a difference between total and biomass-related fine P.
- Excess P is suggested to form in atmospheric reactions of gaseous phosphine.
- Secondary phosphorus could be important in the long-range transport of P.
The role of the atmosphere in the biogeochemical cycle of phosphorus (P) is generally associated with the emission of soil dust, sea-salt particles, bioaerosols and industrial aerosols. Quite independently, a reduced gaseous phosphorus compound (phosphine, PH3) was measured over various sources such as marshes and sewage plants and also in the global troposphere. Given that phosphine is a reactive gas that rapidly yields low-volatility phosphoric acid in the atmosphere, secondary aerosol formation can be an important sink that has never been considered in the global phosphorus cycle. In our study we present mass size-distribution measurements of phosphorus in aerosol samples collected at two locations in Hungary. The bimodal size distribution of phosphorus indicated two distinct formation mechanisms in the fine (d < 1 µm) and coarse modes (d > 1 µm). As expected, the mass concentration of phosphorus was dominated by the coarse particles; the contribution of fine mode phosphorus to the total was in the range of 11–61% (median 19%). The contribution of biomass burning and to a lesser extent bioaerosols to the fine mode phosphorus was inferred from measured ambient potassium (K) concentrations and P/K ratios reported for biomass smoke. It was found that biomass burning accounted for only a small fraction of fine mode phosphorus, the rest of which likely formed as secondary aerosol component from gaseous phosphine. Secondary aerosol phosphorus can be even more important in providing this essential nutrient for remote ecosystems because it is associated with fine aerosol particles which have longer residence time and thus are more prone to long-range atmospheric transport than coarse primary particles.
Phosphine; Secondary phosphorus; Fine aerosol; PIXE.