Observation of ozone deposition flux and its contribution to stomatal uptake over a winter wheat field in eastern China

Abstract

Ground-level ozone (O3) poses a significant threat to food security in China. Therefore, it is imperative to conduct a comprehensive scientific evaluation of the potential hazards posed by O3 to agricultural crops. This study continuously observed variation in meteorological factors, O3 concentration, O3 deposition rate and flux, and quantified the distribution characteristics of O3 deposition flux in stomatal and non-stomatal pathways. Results suggested that the O3 dry deposition rate and flux in winter wheat fields exhibited relatively stable variations at night but pronounced fluctuations during the day. Their mean values were 0.31 cm s−1 and -0.0044 μmol m−2·s−1, respectively, with peak values occurring at 08:30 and 14:00. The cumulative O3 total flux during the main growth season of winter wheat was 26.1 mmol m−2, with stomatal and non-stomatal fluxes accounting for 7.7 mmol m−2 and 18.4 mmol m−2, respectively. The proportions of total O3 flux in stomatal and non-stomatal channels were 29.5% and 70.5%, respectively, with daytime proportions being 39.7% and 60.3%, respectively. These findings provide crucial insights for future accurate assessments of crop yield loss due to O3 at the earth's surface.