Study On Distribution Law Of Negative Air Ions In Urban Green Belt

With the rapid development of industry and towns,the growing urban heat island effect,haze and other environmental conditions caused serious problems.Residents are increasingly paying attention to spiritual pleasure and physical health.The green belt is one of the important components in the urban green space system,and air anion levels have become one of the important indicators to evaluate the degree of air cleanliness in the city.But there is little research on the negative ion concentration of air in the green belt.In this paper,we choose the green space near the meteorological station of the East Campus of Beihua University and the 10 m,20m,30 m,40m,50 m stripes of Jilin City as the experimental plots.At the same time,we observe and record the air positive and negative ions and air temperature,relative humidity,wind speed,atmospheric pressure,traffic volume,coverage,canopy closure and other data.There were the analysis of the level of air negative ions,the law of spatial and temporal changes,the distribution regularity and its influencing factors in the green belt of Jilin City,which can provide reference for urban ecological improvement and people's life,leisure and health care.The correlation test was also carried out.Get the following conclusions:(1)The diurnal variation of green belt in Jilin City showed that:Negative air ion concentrations reached the maximum at 24:00 observation time and reached the minimum value at 20:00.The monthly variation of green space near the meteorological observation station at the East Campus of Beihua University shows that:As a whole,the air negative ion concentration is lower than the air positive ion concentration in the green space.The maximum values appear respectively in August and September,just in the fall.And the lowest is in November.(2)In this study,the width of the trees grass structure and 50 m width in the green grassland of Jilin Province were the best.For structure of trees shrubs and herbs and The structure of trees and herbaceous in the green belt of Jilin City,the level of negative air ions in the structure of the grasses were extremely significant in width at30 m.Respectively,every 5m,10 m as the observation point in the green belt of JilinCity,the negative air ion concentration increases as the distance from the road increases,and it decreases as the distance from the road decreases.In order to study the green space of the same width and the different positions,this paper selected 30 m wide green space in Jilin Province as an example.As a whole,the concentration of negative ions increases with the distance from the road to different degrees.(3)The diurnal variation of the green belt in Jilin City showed that:Its correlation is not significant between negative air ion level and air temperature,relative humidity,wind speed,atmospheric pressure,traffic flow in a total of five influencing factors.The results show that the annual change of green space near the meteorological observation station at the East Campus of Beihua University shows that:The negative air ion concentration is positively correlated with temperature and relative humidity,respectively.The annual variation of negative air ion concentration was negatively correlated with atmospheric pressure.There was no correlation between air negative ion concentration and wind speed in annual variation.The monthly variation of air negative ion in green belt is only positively correlated with air temperature.(4)In this paper,the arbor trees in the greenbelt of Jilin City were the best,According to the investigation and analysis of the coverage rate,the canopy density and the number of plants per unit area in Jilin Province,there was a significant positive correlation between the concentration of negative ions and the coverage of trees.There was a significant positive correlation between the concentration of negative ions and the canopy density.But there was no correlation with the coverage of shrubs and herbs and the number of plants per unit area,and air negative ion concentration reaches the maximum at 500 m~2.