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Senior Theses 2003
Ryan Charles Miller (2003). Differences in aerosol trace
metals between the mid-eastern United States, mid-Atlantic United
States and the northern Caribbean
Faculty advisor: Gregg Brooks
Five Interagency Monitoring of Protected Visual Environments (IMPROVE) monitoring stations in the southeastern United States and the U.S. Virgin Islands clearly show that the metals in aerosols are derived from at least two different sources. Data sets for the Virgin Islands, Chassahowitzka National Wildlife Refuge (Chassahowitzka) and the Everglades National Park (Everglades) in Florida, the Okefenokee Wildlife Refuge (Okefenokee) on the Georgia-Florida border and Sipsy Wilderness in Alabama (Sipsy) were obtained from the IMPROVE database. The relationship among sites is based on soil, fine mass and elemental concentrations. This thesis focuses on the differences among the southern sites, Virgin Islands and Everglades, and the northern sites, Chassahowitzka, Okefenokee and Sipsy.
Several statistical methods were implemented to demonstrate the relationship among the five sites. Ward's method of cluster analysis revealed a distinction in the measured elemental concentrations between the northern and southern sites. The correlation among the five sites is represented as a dendrogram, a branching diagram representing the hierarchy of categories based on the degree of similarity, for each year. The dendrograms revealed a relationship among the Virgin Islands and Everglades during the summer from 1995 to 1997. The Okefenokee and Chassahowitzka sites maintained a strong relationship from 1995 to 1999 in the summer and from 1997 to 1999 in the winter. The distant Sipsy site remained an erratic relative to the remaining four sites throughout the study period.
The relationship among the southern sites appears to be strong during those years devoid of EI Nino or La Nina events. A strong ENSO event, such as the one in 1998-1999, can alter the relationship through a shift in the jet stream. In the midst of normal conditions, the relationship is expected to resume. The weaker La Nina events are more likely to decrease the level of relationship between the southern sites rather than terminate it as seen during EI Nino events.