Paper No. 9
Presentation Time: 10:30 AM
GEOSTATISTICAL ANALYSIS OF AMBIENT AIRBORNE CONTAMINANT VARIABILITY ACROSS AN INTERNATIONAL BORDER IN DETROIT AND WINDSOR
MOLARONI, Shannon M.1, LEMKE, Lawrence D.
1, MILLER, Lindsay
2, XU, Xiaohong
2, WHEELER, Amanda J.
3, GRGICAK-MANNION, Alice
4, KROUSE, Helene J.
5, KRAJENTA, Richard J.
6, REINERS Jr, John J.
7 and WEGLICKI, Linda
8, (1)Department of Geology, Wayne State University, 0224 Old Main, 4841 Cass, Detroit, MI 48202, (2)Department of Civil and Environmental Engineering, University of Windsor, 401 Sunset Ave, Windsor, ON N9B 3P4, Canada, (3)Health Canada, Air Health Science Division, 3rd Floor, 269 Laurier Avenue West, PL 4903c, Ottawa, ON K1A 0K9, Canada, (4)Great Lakes Institute for Environmental Research, University of Windsor, 2990 Riverside Drive West, Windsor, ON N9B 3P4, Canada, (5)College of Nursing, Wayne State University, 146 Cohn Building, 5557 Cass Avenue, Detroit, MI 48202, (6)Cancer Epidemiology, Prevention and Control, Henry Ford Health System, One Ford Place, JFCC-5C, Detroit, MI 48202, (7)Institute of Environmental Health Sciences, Wayne State University, 2727 Second Avenue, Room 4000, Detroit, MI 48201, (8)National Institute of Nursing Research, National Institutes of Health, 6701 Democracy Blvd., Suite 710, Bethesda, MD 20892, molaronism@wayne.edu
Spatial variability of airborne contaminants was assessed in an international airshed spanning
Detroit, Michigan, USA and
Windsor, Ontario, Canada. In this study, refined geostatistical methods were employed to characterize air pollutant distributions measured by the Geospatial Determinants of Health Outcomes Consortium (GeoDHOC), a multidisciplinary, international effort aimed at understanding the health effects of air pollution in urban environments. The GeoDHOC team deployed a combination of active and passive air sampling devices for a two-week period during September 2008. Passive diffusion monitors were used to measure nitrogen dioxide (NO
2), sulfur dioxide (SO
2) and 26 volatile organic compounds (VOCs) at 100 sampling sites. Active samplers collocated at 50 of the passive sites sampled particulate matter (PM) and 23 polycyclic aromatic hydrocarbons (PAHs). Active and passive samplers were distributed at an approximate spacing of 1 per 10 km
2 and 1 per 5 km
2, respectively.
Statistical and geostatistical analysis was conducted for PM and NO2, as well as 14 VOC and 7 PAH species measured above method detection limits at ≥80% of sampling locations. Mean concentrations for all analyzed contaminants except the 2.5-10 μm PM size fraction were lower in Windsor by a factor of two or less. Moderate positive correlation coefficients (statistically significant at p<0.05) were observed between NO2 and analyzed PAHs (r = 0.603), analyzed VOCs (r = 0.529), and PM1-2.5 (r = 0.555) for the study area. Cross-variogram analysis was performed to describe cross-continuity between these pollutants. Co-kriging was used to generate PM and PAH concentration maps taking advantage of NO2 as secondary data to improve resolution between the more widely distributed active samplers. Concentration maps produced through both ordinary kriging and co-kriging were compared. Map patterns for NO2 and total VOCs, with highs associated with major roadways and border crossings, suggest mobile emissions as the primary source of these compounds. Conversely, the spatial distributions of PM and PAH concentrations primarily reflect the distribution of individual point sources. Observed patterns in spatial variability among pollutants and between cities underscore the importance of local anthropogenic sources over regional background.
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