[Seasonal Variation in Surface Ozone and Its Effect on the Winter Wheat and Rice in Nanjing, China]

In recent years, surface ozone concentration has been increasing. A high concentration of ozone can affect the growth of crops, and reduce crop yields. In this paper, based on hourly ozone concentration data in the Nanjing area obtained from 2014 to 2016, we analyzed the variation characteristic of ozone concentration and its effect on the production and economic loss of winter wheat and rice. The results shows that the mean concentrations of ozone in 2014, 2015, and 2016 were 62.9, 68.6 and 69.1 μg·m^-3, respectively; the ozone concentration and the number of days exceeding the standard gradually increased each year. The order (high to low) of seasonal average ozone concentrations was summer, spring, autumn, and winter. The diurnal variation of ozone concentration in the four seasons showed a single-peak curve, with the peak and valley ozone values appearing at 15:00-16:00 and 07:00-08:00, respectively. The accumulated ozone exposure over a threshold of 40 ppb (AOT40) values during the growing season of winter wheat in 2014, 2015, and 2016 were 10.5, 14.4, and 9.4 μL·L^-1·h, respectively. The ozone AOT40 values during the growing season of rice in 2014, 2015, and 2016 were 8.5, 20.0, and 25.6 μL·L^-1·h, respectively. At the current ozone level, the impact of surface ozone on winter wheat is higher than that on rice; the range of ozone effect on the yield loss rate of winter wheat was 21.4%-32.8%, and the annual economic loss amounted to 150.766-277.996 million Yuan RMB. The range of ozone effect on the yield loss rate of rice was 8.1%-24.3%, and the annual economic loss amounted to 197.472-680.757 million Yuan RMB.