1. Methods IntroductionResults Research Goals and Hypothesis Discussion Conclusion References and Acknowledgments Special thanks to Dr. Mark Hafen, Jessica Norman Wilson, Dr. Zachary Atlas, and Dr. Jonathan Wynn for their mentorship throughout research design and implementation. ESRL Global Monitoring Division - Education and Outreach. (n.d.). Retrieved January 5, 2015, from http://www.esrl.noaa.gov/gmd/outreach/isotopes/mixing.html Flanagan, L. B., Ehleringer, J. R., & Pataki, D. E. (2005). Stable isotopes and biosphere-atmosphere interactions: Processes and biological controls. San Diego: Elsevier Academic. Pataki, D., Ehleringer, J., Flanagan, L., Yakir, D., Bowling, D., Still, C., &... Berry, J. (n.d). The application and interpretation of Keeling plots in terrestrial carbon cycle research. Global Biogeochemical Cycles, 17(1), THE RELATIONSHIP BETWEEN ATMOSPHERIC CO2 AND THE δ13C VALUES OF BROMUS TECTORUM. (n.d.). Retrieved February 5, 2015, from http://ecophys.utah.edu/download/Student_Theses/Thesis_Kammerdiener/Chapter 4.pdf Courtney McManus Department of Geosciences University of South Florida, Tampa, FL, USA CO 2 Concentrations and ∂C 13 values in Urban/ Rural Tampa From the results, it is clear that the data supports the hypothesis. The data shows a correlation between ∂C 13 and CO 2 ppm values. The data also illustrates urban areas with higher CO 2 ppm values than rural areas with associated negative ∂C 13 values. The R-squared value for each graphical representation provided were at or above 0.71, showing a mathematical correlation with the best-fit line for the data. The Keeling Plots represent a more accurate representation of the data and show that the urban areas have an overall lower ∂C 13 value, which is indicative of its location. This research project has potential continuation involving spatial analysis of CO 2 ppm and ∂C 13 values in the City of Tampa. This may have an effect on the overall health of the community involving potential changes in the transportation infrastructure, reducing the amount of fossil fuel emissions in the urban areas. There was a correlation between the ∂C 13 values and CO 2 ppm values. As CO 2 values increase in concentration, the ∂C 13 values decrease. The value of ∂C 13 recorded can help determine the source of the CO 2. Petroleum fossil fuel emissions take on a ∂C 13 value around -25.0 while natural gas emissions take on a ∂C 13 value around -40.0. The Keeling Plots for all locations, residential/ rural locations, and urban locations all displayed a correlation between the inverse CO 2 concentrations and ∂C 13 values. The best-fit line was extrapolated and the resulting y-axis intercept determined the ∂C 13 value for an infinite amount of CO 2 concentration. According to the intercept value from the best-fit line, the ∂C 13 expected for each Keeling Plot was about -20.0 although the plot representing the urban locations had a slightly more negative ∂C 13 value. The more negative ∂C 13 value in the urban areas may represent the presence of CO 2 from natural gas in the atmosphere. There was also a trend observed exclusively from CO 2 ppm values. This trend entailed higher concentrations over the urban downtown area and overall lower concentrations in the residential/ rural area. This could be attributed to the higher concentration of cars, power plants, and airports in the urban area resulting in more CO 2 emissions. The carbon isotopic composition and carbon dioxide ppm value for each sample was measured using the Gasbench-IRMS against known carbonate standards acidified with phosphoric acid. Glass vials were held out to the open atmosphere for 1 minute at a time, then capped and sealed for analysis. Samples were collected in borosilicate glass vials across an urban/ rural gradient at 16 locations in The City of Tampa. This research project aims to determine the CO 2 ppm and ∂C 13 values for the City of Tampa across an urban/ rural gradient. This project also aims to establish a correlation between ∂C 13 and CO 2 ppm values. It is hypothesized that urban areas in Tampa will have higher CO 2 ppm values than the rural areas in Tampa along with more negative ∂C 13 values. Average CO 2 ppm Average ∂C 13 Run 1564.7-13.8 Run 2335.3-13.4 Run 3437.6-14.5 Total Average445.9-13.9 Average Error750.09 One of the major ways humans have influenced the environment is through the increased emissions of greenhouse gases over the decades, specifically carbon dioxide. Carbon dioxide (CO 2 ) is typically measured in ppm (parts per million) with the upper safety limit for the atmosphere at 350 ppm. Measuring ∂C 13 (delta) values indicates the source of carbon, with more negative values as fossil fuels as the source. The ∂C 13 values are reported as a ratio R of 13 C/ 12 C with 13 C being the less abundant isotope of carbon, composing only 1.11% of Carbon on Earth. When air samples are taken from the atmosphere, it is representing a mixing of carbon dioxide from multiple sources. Some of these sources include fossil fuel and natural gas emissions, plant burning and decomposition, and oceanic release of CO 2. IdentifierLocation CM 1Riverfront Park CM 2I-75 & BBDowns CM 3Cross Creek Blvd & BBDowns CM 4Bearss Ave. & BBDowns CM 5USF Science Center CM 6Tampa Palms Elementary CM 7Hillsborough Aven. & Nebraska Ave. CM 8Hyde Park Village CM 9Ashley Dr. & Polk St. CM 1022nd St. & 8th Ave. CM 11Bay to Bay Blvd & Bayshore Blvd CM 12Davis Island CM 13Ballas Point Park CM 14The Florida Aquarium CM 15Busch Blvd. & N. Blvd. CM 1630th St. & Busch Blvd. Figure 1. Scatterplot of ∂C 13 (%) versus CO 2 ppm Figure 2. Averages of Data and Error of ∂C 13 (%) and CO 2 ppm Figure 3. Concentration map of CO 2 ppm Figure 4. Keeling Plot of All Locations Figure 5. Keeling Plot of Urban Locations (CM 7-14) Figure 6. Keeling Plot of Residential / Rural Locations (CM 1-6, 15-16) Figure 7. Labeled map of locations across the City of Tampa Figure 8. List of locations and identifiers Figure 9. References gases used for analysis Figure 10. Gasbench used for analysis Figure 11. Isotope Ratio Mass Spectrometer (IRMS)