Assessment of Ambient Air Pollution in Nagasaki City, Japan, Based on Ozone Impacts on Growth of Radish (Raphanus sativus L.) using the Open-Top Chamber Method

Abstract

We assessed the ambient air pollution based on the ozone (O₃) impacts on the growth of radish (Rahapnus sativus L. cv. Comet) using the open-top chamber method in Nagasaki city, which faces transboundary air pollution such as tropospheric O₃. There were two treatments in the present study: ozone-removal filtered air (FA) and non-filtered air (NF) treatments. A one-week exposure experiment was conducted nine times in Nagasaki University (Nagasaki, Japan) from March to October 2015. The below-ground dry mass of radish grown in the NF treatment was significantly lower than that in FA treatment in the experiments in mid-May, September and October. There was no significant relationship between the mean O₃ concentration and relative value of the root dry mass in the NF treatment to that in the FA treatment. On the other hand, the reduction rate in the below-ground dry mass per unit O₃ concentration became greater with the increasing mean air temperature and relative air humidity. These results indicate that, depending on the climatic conditions, the O₃ concentrations observed in Nagasaki in the spring and autumn were high enough to reduce the growth of O₃-sensitive plants, such as radish.