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Transport, Deposition and Detection of Bacterial Plant Pathogens: New Observations and Future Considerations

Robert Seem
Department of Plant Pathology and Plant-Microbe Biology,
New York State Agricultural Experiment Station,
Cornell University,
Geneva, NY USA

Joseph M. Prospero et al, recently (2005, Ref.. 1) described the daily sampling and bio-analysis of aerosols carried on the trade winds from Africa to Barbados, West Indies that yielded significant concentrations of viable bacteria and fungi. Prospero et al used air parcel back trajectories to determine the origin of the particles collected, daily. In addition they used 2 sampling systems. One collected 24 hour samples on sterile microbiological filters (cellulose nitrate) and the other was a 47 mm diameter Whatman filter used to collect samples for sulfate and an array of other anions and cations. In addition samples were collected only when the winds were in the sector 335 degrees through North to 130 degrees. This research is interesting in that they revealed, Saharan dust from Africa not only contributed to increased particle mass loading in Barbados but also carried bacteria. This work by Prospero suggests that it may be possible to implement a similar study in North America to determine the sources and presence of viable fungi and or bacteria collected at conventional PM 10 and/ or PM 2.5 µm monitoring sites using EPA’s receptor modeling methods and filter material compatible with bio-analysis. Our presentation will discuss two aspects of determining the presence and sources of biologically active fungi etc., in PM 2.5 and 2.5-10 µm particle samples.

That type of sampling and analysis methodology will yield both biologically viable samples but also provide samples that will serve as input to EPA’s new receptor models. The application of the US EPA receptor models (Ref 2, Positive Matrix Factorization-3.0, UNMIX- 6.0) to determine source types contributing to the receptor site will be discussed. In addition the application of US EPA’s Community Multi-Scale Air Quality Model( a Eulerian dispersion model to estimate impact of local, regional and global sources on selected receptor sites will be discussed. Recommendations of an approach to collect viable samples to determine the presence of bacteria, fungi and other biologically active bodies will be presented.

1. J.M. Prosero et al. Interhemispheric transport of viable fungi and bacteria from Africa in the Caribbean with soil dust” Aerobiologia (2005) 21:1-19.
2. C.W. Lewis, G. Norris & R. Henry. “Source apportionment of Phoenix PM2.5 aerosol with the UNMIX Receptor Model. J. A&WMA. (2003) 53: 325-338.