Impacts of terrestrial vegetation on surface ozone in China: from present to carbon neutrality

Abstract

Despite many efforts to control anthropogenic sources, high ambient ozone (O3) concentrations remain a serious air pollution problem in China. Terrestrial vegetation can remove surface O3 through dry deposition but also enhance surface O3 through biogenic volatile organic compound (BVOC) emissions. However, the net impacts of terrestrial vegetation on surface O3 remains unclear. Here, we perform simulations using a chemistry-vegetation coupled model to assess the impacts of terrestrial vegetation on surface daily maximum 8 h average (MDA8) O3 in China through biogeochemical processes, including BVOC emissions and stomatal uptake. The results show that vegetation biogeochemical processes increase summer mean surface MDA8 O3 by 1.3 ppb in the present day in China, with 3.7 ppb from BVOC emissions but -2.7 ppb from stomatal uptake. However, the enhanced summer mean surface MDA8 O3 from vegetation biogeochemical processes decreases from 5.4 to 2.7 ppb in the North China Plain (NCP), from 7.2 to 0.8 ppb in the Yangtze River Delta (YRD), from 8.7 to 1.8 ppb in the Sichuan Basin (SCB) and from 4.2 to 0.4 ppb in the Pearl River Delta (PRD) by the period of carbon neutrality. Our study highlights that carbon neutrality-driven emission reductions can greatly mitigate the enhanced surface O3 related to terrestrial vegetation, though there is still a positive impact of terrestrial vegetation on surface O3 in some hotspots, including the NCP and the SCB.