Study On Physical And Chemical Characteristics Of Atmospheric PM_2.5 In Hengyang City

With the rapid advancement of industrialization and urbanization,the complex atmospheric environmental problems with PM_2.5pollution in China had become increasingly prominent.To further understood the characteristics of atmospheric PM_2.5pollution in Hengyang City,atmospheric PM_2.5pollution characteristics were analyzed comprehensively in Hengyang City by collecting atmospheric pollution monitoring data in six national air pollution monitoring points of Hengyang from 2015 to 2017,and atmospheric PM_2.5membrane samples from two industrial and cultural areas in winter and spring were collected on the scene,and analyzed the micro-morphology of atmospheric PM_2.5and the pollution characteristics of heavy metals and carbon components in PM_2.5.The main results indicated that:?1?The atmospheric PM_2.5pollution in Hengyang City was relatively serious.In the past three years,the pollution level has shown the trend of rising first and then decreasing.the PM_2.5pollution was the most serious in 2016,and the atmospheric PM_2.5/PM₁₀value had been greater than 50%,it was indicated that the atmospheric particulate matter in Hengyang City was mainly based on fine particles with a particle size of?2.5?m.The seasonal distribution of PM_2.5in the past three years was basically the same as that of the monthly distribution,the PM_2.5pollution in Hengyang City always followed the order of winter>autumn>spring>summer,and the rate of PM_2.5exceeded the annual limit values of National Ambient Air Quality Standards.was highest in January,February and December each year.?2?The micromorphology analysis of atmospheric PM_2.5in Hengyang City revealed that:The PM_2.5particles in winter and spring in Songmu Industrial Park belongs to aluminosilicate or silicon oxide;PM_2.5particles in Hengyang Valin Steel Tube Company belongs to smoke/soot and mineral particles in winter,the PM_2.5particles in Spring belongs to iron oxide particles;The PM_2.5particles in Hunan Industry and Commerce Career Academy in winter and spring were aluminosilicate/silicon oxide;The PM_2.5particles in University of South China Hongxiang campus in winter was a soot aggregate,and the PM_2.5particles in spring was irregularly shaped carbon Particles.?3?The temporal and spatial distribution characteristics of heavy metals?Pb,Cd,Cu,Zn,Ni,Fe?in PM_2.5in Hengyang City in winter and spring were obvious.Except Hunan Industry and Commerce Career Academy,the pollution trends of heavy metals in PM_2.5in winter and spring were basically the same in the other three sampling points,it was indicated that the heavy metal pollution in PM_2.5in Hengyang was relatively stable,but the potential ecological pollution of heavy metals in PM_2.5in industrial areas was significantly higher than cultural areas,and the heavy metal Cd in the atmospheric PM_2.5has extremely strong ecological risks,the potential ecological risk grades of Pb and Cu were relatively low than Cd,and the risk grades of Zn and Ni were the lowest.?4?The carbon components?OC and EC?concentration of PM_2.5in Hengyang City in winter and spring all followed the order of Songmu Industrial Park>Hengyang Valin Steel Tube Company>University of South China Hongxiang campus>Hunan Industry and Commerce Career Academy,it was mainly related to the type and intensity of pollution emission sources.OC and EC concentration percentage of PM_2.5in the two industrial areas showed the characteristics of winter>spring,but in the two cultural areas showed the characteristics of spring>winter.Finally,the results of this study have certain reference effects on the prevention and control of atmospheric PM_2.5.5 pollution in relevant departments of Hengyang City.