The Study Of Phytotoxicity Exposed To NO₂and Nitric Acid Fog

With the increasing number of global automobile, the emissions of NOX are increasing day by day, and the associated environmental problem has become more and more serious. Therefore, the impact of NOX on the plant cannot be ignored. In addition, if NOX met the water vapors in air, nitric acid will be formed, and it plays an important role in forming acid rain. Acid rain causes serious damage to the earth ecological environment and socio-economic development. Previous studies have determined the indices about plant exposed to NO2, which consisted of plant growth, chlorophyll content, nitrogen content, nitrogen metabolism and other indices. However, analysis of the anti-oxidization system is scarce when plant exposed to NO2. Some similar analysis of its tolerance mechanism of plants exposed to the main atmospheric pollutants SO2and O3has been widely carried out, and the study of model plant exposed to NO2has not yet been found.Model plants have more superior characteristics than ordinary plants. Most genes of Arabidopsis can be found in other plants, and it is favorable to carrying out relative research at the molecular level. The findings of Arabidopsis can be applied to other plants. At present, the study of Arabidopsis has been widely used in plant genetics, developmental biology, molecular biology and other related disciplines. According to the change of morphological indicators, growth and antioxidant system in Arabidopsis, it will reveal the damage mechanisms of NO2, which will provide theoretical basis for the further research at molecular level.Based on these ideas, by establishing the dynamic fumigation model, this topic has mainly focused on the stress mechanism of Arabidopsis exposed to different concentrations of NO2, especially the mechanism of oxidative stress, which consisted of chlorophyll content, oxygen free radical production rate, hydrogen peroxide content, superoxide dismutase acitivity, peroxidase acitivity, catalase acitivity, ascorbic acid content, glutathione content, malonaldehyde content, protein carbonyl content and so on. In addition, the mechanism about growth and antioxidant system were also be discussed when Arabidopsis and barley were exposed to nitric acid mist in different duration time. The results showed that:Arabidopsis thaliana had different reaction when exposed to different concentrations of NO2, the antioxidant system plays an important role to resist the damage of NO2; plants are more sensitive than animals under the stress of NO2; different plants have different responsibility to the nitric acid mist, and showed different stress responses; the endangering mechanism of NO2and its secondary pollutant nitric acid mist is different. This study provides a basis for other pursuers to research the damage of combined pollutants in photochemical smog and acidic rain to plants. In addition, by studying the injury mechanism and resilience mechanism for the model plant Arabidopsis thaliana exposed to NO2, it will provide a theoretical foundation for phytoremediation of air pollution. Last but not the least, by comparing the effect to different plant exposed to nitric acid mist, it will provide a direct theory basis for choosing air pollution tolerant plants. This paper preliminarily discusses the reaction mechanism of plant exposed to NO2or nitric acid mist, but their related action mechanism needs further studying.