Variations in carbon dioxide fluxes within a city landscape: Identifying a vehicular influence

Abstract

To date, studies examining carbon dioxide (CO2) fluxes in urban areas have been limited compared to those in rural environments. The objectives of our study were to examine the relationship between traffic volume and CO2 fluxes. We demonstrated that CO2 fluxes were strongly linked with surrounding land use, specifically impervious surfaces and traffic volume. A site near downtown Syracuse in New York State (USA) had relatively constant positive fluxes (source: +39 μmol CO2 m−2 s−1) throughout the year as a result of strong vehicular traffic influence from two nearby interstate highways. There was a strong positive relationship between traffic and CO2 fluxes (r2 = 0.93, p < 0.0001) with marked differences between the weekend days versus the workweek days. In contrast, a residential site in Syracuse was dominated by vegetative influences during the leaf-on period due to CO2 uptake by photosynthesis, reaching a maximum negative mean diurnal flux of −11 μmol CO2 m−2 s−1 around midday (sink). The spatial variations of CO2 fluxes identify the critical role played by local traffic volumes in affecting the CO2 dynamics of urban environments. Understanding the dynamic fluxes of CO2 in urban environments has important implications for local, regional and global evaluations of CO2 budgets and inventories, and carbon cycle and climate modeling.