Exploring the spatial heterogeneity effects of the urban land use characteristics on taxi CO2 emissions

As an integral part of urban transportation systems, taxis fulfill the personalized travel needs of a large number of residents, and their CO₂ emission levels are a focus of attention for industry management departments. This paper calculates the CO₂ emissions of taxis using GPS data from the main area of Xi'an, explores the spatiotemporal distribution characteristics and hotspots of taxi CO₂ emissions, and investigates the mechanism of impact of urban spatial structure and Points of Interest (POI) on the spatial heterogeneity of taxi CO₂ emissions from the perspective of land use. The findings are as follows: (1) The average daily CO₂ emission per taxi in Xi'an is 32.64 kg, with an annual emission estimate of approximately 156,140.73 tons; (2) There are significant spatiotemporal differences in taxi CO₂ emissions, with distinct high-emission periods and areas. Peak emissions on weekdays are mostly concentrated on the city's main roads and expressways, while on non-working days, peaks are more commonly found near transportation hubs, university towns, and shopping malls; (3) The contribution of non-collinear POI indicators to CO₂ emissions, in descending order, is government office density, financial institution density, accommodation service density, shopping place density, educational institution density, medical density, scenic spot density, and public facility density. Among these, government office density has the highest positive impact on CO₂ emissions. This study provides decision support for carbon emission reduction in Xi'an's urban transportation and the development of green public transportation.