(2020) Release of Trace Metals during Wildfires
Isley CF & Taylor MP
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13h: Room 4, Thursday 25th June 05:54 - 05:57
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Dear Cynthia Isley, thank you for your presentation. In your slide 9, could you please explain how you distinguish factors 1 and 2? Do they correspond respectively to different samples? I thank you in advance. Best Regards. Jerome Labille
Hello Jerome, The 2 factors were determined using the multivariate statistical technique Positive Matrix Factorization (PMF). All concentration results (all elements, all samples) were input to the model. The model then found statistical groupings of elements that occurred together repeatedly in the same concentration ratio (across all samples). That is what we see here in the two factors. It is then up to the user to look at those concentration ratios and work out what sources they are likely to represent. Both of these factors/sources are likely to be present in any given sample, but the sample would contain, for example, 20% of one source and 80% of the other. Factor 1 (anthropogenic contaminants) contributed a greater percentage in samples collected during the wildfire period, compared to before and after wildfires. The model was run to determine 2,3,4,5,6,and 7 factors. The 2-factor solution was the most statistically sound and hence is what I have presented here. To determine more factors, which would allow more specific source identification, we would need to analyse a larger suite of elements. Kind regards, Cynthia
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