The spatial distribution of fossil fuel CO2 traced by Δ(14)C in the leaves of gingko (Ginkgo biloba L.) in Beijing City, China.

Atmospheric fossil fuel CO2 (CO2ff ) information is an important reference for local government to formulate energy-saving and emission reduction in China. The CO2ff spatial distribution in Beijing City was traced by Δ(14)C in the leaves of gingko (Ginkgo biloba L.) from late March to September in 2009. The Δ(14)C values were in the range of -35.2 ± 2.8∼15.5 ± 3.2 ‰ (average 3.4 ± 11.8 ‰), with high values found at suburban sites (average 12.8 ± 3.1 ‰) and low values at road sites (average -8.4 ± 18.1 ‰). The CO2ff concentrations varied from 11.6 ± 3.7 to 32.5 ± 9.0 ppm, with an average of 16.4 ± 4.9 ppm. The CO2ff distribution in Beijing City showed spatial heterogeneity. CO2ff hotspots were found at road sites resulted from the emission from vehicles, while low CO2ff concentrations were found at suburban sites because of the less usage of fossil fuels. Additionally, CO2ff concentrations in the northwest area were generally higher than those in the southeast area due to the disadvantageous topography.