| Abstract |
From samples in Ohio and Pennsylvania, a regional elemental tracer system found two midwestern signatures which later showed that aerosol is routinely transported from Midwest to Northeast in distinct pulses of 2-8 days. The system was confirmed semi-quantitatively during CAPTEX '83, where pulses of tracer gas from Ohio appearing in New England were always accompanied by strong maxima of midwestern aerosol. Regional signatures were found to be stable: during transport from Midwest to Northeast, all four quantifiable elemental ratios changed by less than 25%. Regional least-squares apportionments were found to be insensitive to a variety of factors such as weighting scheme, scales of signatures, random elemental perturbations, duration of samples, local sources of V, etc. Factor and cluster analysis were found to be only moderately useful for determining regional signatures. In eastern North America, As/Se, noncr. V/Se, and In/Se have greater tracer power than Sb/Se, Zn/Se, and noncr. Mn/Se. |
