A study on greenhouse gas emissions from asphalt pavement cross-sections: a comparison between roadside and central areas.

This study employed a greenhouse gas flux monitoring system equipped with LI-COR 7810/7820 portable trace gas analyzers to measure daily fluxes of CO2, CH4, and N2O across asphalt pavement sections during three time periods (8:00-9:00 AM, 1:00-2:00 PM, 6:00-7:00 PM). Using high-frequency data obtained from the analyzers, precise fluxes were calculated via an exponential fitting model in SoilFluxPro software. A comprehensive assessment, integrating spatiotemporal statistical analysis and global warming potential (GWP), was conducted. The results revealed the following: (i) Spatial distribution: Asphalt road surfaces act as carbon sources along both sides, with an average GWP of 920.762 nmol·m⁻2·s⁻1 per day, while the central section serves as a weak carbon sink, with an average GWP of -73.685 nmol·m⁻2·s⁻1 per day. (ii) Temporal distribution: Greenhouse gas emissions from asphalt pavements are higher during the daytime and lower at night. (iii) Gas composition: CO2 is the dominant contributor to greenhouse gas fluxes from asphalt pavements, accounting for over 98% of total emissions. (iv) Primary drivers: The primary source of greenhouse gas emissions from asphalt pavements is the organic debris covering the soil and vegetation along roadside areas.