Changes Of Negative Oxygen Ion Concentration And The Influence Of Meteorological Factors In Aershan Area

In recent years,with the increasing frequency of air pollution incidents and increasing awareness of environmental protection,as a natural resource that is beneficial to the human and an important indicator for evaluating air quality,more and more attention has been paid to the research on negative oxygen ions.This study collected negative oxygen ion data from two stations(Wuliquan and Wusu Langzi Lake)in the Aershan region from July 2018 to August 2019.The temporal and spatial variation of negative ion concentration and the influence of meteorological factors on its concentration is analyzed.The meteorological elements with significant influence on negative oxygen ion concentration were screened by using the feature importances of random forests.Finally,combined with the negative oxygen ion grade evaluation criteria,the spatial and temporal distribution of negative oxygen ions in Aershan area was graded.The research results are as follows:(1)Seasonal changes of negative oxygen ion concentration from high to low,Wuliquan is winter,spring,autumn and summer,and Wusu Langzi Lake is winter,autumn,summer and spring.(2)The concentration of negative oxygen ions at the two monitoring stations varies greatly at night during the spring,summer and autumn,and the winter night daily change trend is similar;the daytime daily change trend is opposite in all seasons;The difference of daily average maximum occurrence time is more obvious in spring,summer and autumn,and it is closer in winter;The difference of daily average minimum occurrence time is more obvious in summer,autumn,and winter,and are relatively close in spring.(3)According to the feature importances,the negative oxygen ion concentration in Wuliquan is significantly affected by air temperature,and the negative oxygen ion concentration in Wusu Langzi Lake is significantly affected by water vapor conditions and temperature.In winter,the negative oxygen ion concentration is also significantly affected by wind speed.(4)According to the evaluation standard of negative oxygen ion concentration level,the two monitoring stations are mainly grade II days in summer and grade I days in winter;In spring,the Wuliquan monitoring station is mainly grade I days and Wusu Langzi Lake is mainly grade II;In autumn,the Wuliquan monitoring station is mainly grade III days and Wusu Langzi Lake is mainly grade I.