Mobile monitoring of atmospheric terpene dynamics across the subtropical megacities Greater Bay Area

Currently, the relative importance of anthropogenic versus biogenic terpenes in subtropical megacities of developing countries remains poorly understood, particularly in rapidly urbanizing regions like the China's Greater Bay Area (GBA), characterized by high population density, intensive industrial activity, and subtropical climate favoring both emission sources. Herein, we provide spatially resolved measurements of ambient terpenes (isoprene and six monoterpenes) in the GBA, employing a vehicle-mounted platform across diverse land-use zones (urban, suburban and rural) during autumn 2022. Results showed total terpene concentrations averaged 0.922 ± 0.280 ppbv, with isoprene and α-pinene dominating (>80 %). Diurnal variations revealed monoterpenes peaking in early morning in urban areas, likely linked to volatile chemical products (VCPs) and residential cooking, whereas isoprene exhibited midday maxima driven by biogenic emissions. Strong correlations with anthropogenic tracers indicated significant co-emissions. Positive Matrix Factorization (PMF) source apportionment quantified VCPs as the primary urban source for monoterpenes, while industrial activities dominated suburban regions. Biogenic emissions prevailed in rural zones but were overshadowed by anthropogenic influences in urbanized areas. These findings underscore the pivotal role of anthropogenic sources in shaping terpene dynamics in subtropical megacities, and emphasizes the need for region-specific terpene emission inventories and targeted control strategies for the GBA and analogous regions globally.