The spatial distribution of fossil fuel CO₂ traced by Δ¹⁴C in the leaves of gingko (Ginkgo biloba L.) in Beijing City, China

Atmospheric fossil fuel CO₂ (CO_2ff) information is an important reference for local government to formulate energy-saving and emission reduction in China. The CO_2ff spatial distribution in Beijing City was traced by Δ¹⁴C in the leaves of gingko (Ginkgo biloba L.) from late March to September in 2009. The Δ¹⁴C 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 CO_2ff concentrations varied from 11.6 ± 3.7 to 32.5 ± 9.0 ppm, with an average of 16.4 ± 4.9 ppm. The CO_2ff distribution in Beijing City showed spatial heterogeneity. CO_2ff hotspots were found at road sites resulted from the emission from vehicles, while low CO_2ff concentrations were found at suburban sites because of the less usage of fossil fuels. Additionally, CO_2ff concentrations in the northwest area were generally higher than those in the southeast area due to the disadvantageous topography.