Source/receptor reconciliation of ambient organic fine particulate matter in Palm Beach County

Airborne particulate matter (PM) is of environmental concern not only in urban but also rural areas that are easily inhalable and have been considered responsible, together with gaseous pollutants, for possible health effects. The objectives of this research study is to generate an extensive data set for ambient PM collected at Belle Glade and Delray Beach that ultimately was used together with published source profiles to predict the contributions of major sources to the overall airborne particle burden in Belle Glade and Delray Beach. ^ The size segregated particle sampling was conducted for one entire year. The samples collected during the months of January and May were further subjected to chemical analysis for organic compounds by Gas Chromatography-Mass Spectrometry. Additional, PM10 sampling was conducted simultaneously with size segregated particle sampling during January and May to analyze for trace elements using Instrumental Neutron Activation Analysis technique. Elements and organic marker compounds were used in Chemical Mass Balance modeling to determine the major source contribution to the ambient fine particle matter burden. ^ Size segregated particle distribution results show bimodal in both sampling sites. Sugarcane pre-harvest burning in the rural site elevated PM10 concentration by about 30% during the sugarcane harvest season compared to sugarcane growing season. Sea salt particles and Saharan dust particles accounted for the external sources. ^ The results of trace element analysis show that Al, Ca, Cs, Eu, Lu, Nd, Sc, Sm, Th, and Yb are more abundant at the rural sampling site. The trace elements Ba, Br, Ce, Cl, Cr, Fe, Gd, Hf, Na, Sb, Ta, V, and W show high abundance at the urban site due to anthropogenic activities except for Na and Cl, which are from sea salt spray. On the other hand, size segregated trace organic compounds measurements show that organic compounds mainly from combustion process were accumulated in PM0.95. ^ In conclusion, major particle sources were determined by the CMB8.2 software as follows: road dust, sugarcane leaf burning, diesel-powered and gasoline powered vehicle exhaust, leaf surface abrasion particles, and a very small fraction of meat cooking. ^

Dark matter in dwarf irregular galaxies, DDO 210 and DDO 169

It has been proposed that dwarf irregular galaxies can be separated into two classes based on their formation mechanism; that they are the result of the collapse of a primordial gas cloud or that they are the product of condensation of gas in the tidal tails of interacting galaxies. Simulations of galaxy interactions indicate that one can differentiate between these two scenarios by the dark matter content, with a low dark matter content indicating a fossil tidal dwarf. The purpose of this dissertation was to explore the dark matter distribution of two dwarf irregular galaxies using optical and neutral atomic hydrogen data. For DDO 210, the method of mass-modelling was used to determine its dark matter. About 64% of the galaxy mass was calculated to be in the form of dark matter and hence it is unlikely to be a fossil tidal dwarf. The method of mass-modelling could not be used for DDO 169 as the galaxy shows evidence of being tidally disrupted and hence, has a disturbed velocity field. Instead, the suggestion that dark matter might be responsible for a pressure anomaly in DDO 169 was tested to determine its dark matter content. According to this method, a pressure anomaly does exist but without a concrete value for the scale-height, it is unclear whether the anomaly is due to the presence of dark matter. Hence one cannot say how much dark matter might actually be present in DDO 169. A rotation curve would be required to do this. ^