The Pollution Characteristics And Health Risk Assessment Of Heavy Metals From Atmospheric PM_2.5and PM₁₀ In Heating Season Of Xi'an City

Xi'an is located in the Guanzhong Plain in the northwestern part of the country.Due to the influence of climate and terrain,the problem of urban air pollution is becoming more and more serious.Based on the historical environmental monitoring data,this paper conducts an analysis of the characteristics of air pollution in Xi'an,and uses the fuzzy comprehensive evaluation method to evaluate the atmospheric environmental quality of Xi'an from 2001 to 2010.At the same time,in order to study the pollution status of inhalable particulate matter and the characteristics of heavy metal elements in Xi'an,the pollution status of PM₁₀ and PM_2.5 in Xi'an was monitored and investigated from December 2016 to May 2017,and PM₁₀ was compared.And the pollution status of PM_2.5,the difference of indoor and outdoor atmospheric particulate matter pollution was analyzed,and the contents of heavy metal elements Cd,Zn and Cu in PM₁₀ and PM_2.5 were determined by atomic absorption spectrometry?AAS?.The pollution characteristics of heavy metal elements in atmospheric respirable particulates in Xi'an.The EPA health risk assessment model was used to evaluate the health risks of heavy metal elements in respirable particulates,in order to provide reference for the control and decision-making of air pollution control in Xi an.The following conclusions were obtained:?1?The characteristics of atmospheric pollutant concentration changes in Xi'an from 2001 to 2010 and 2013 to 2017 were analyzed.2001-2010:Contaminant concentration is TSP>S02>NO2,the inter-annual variation of SO2 and NO2 showed a trend of low first and then high,and TSP showed a trend of high first and then low,and the time points of change were all in 2003.2013-2017:PM₁₀,PM_2.5,SO2,CO showed a downward trend year by year,NO2 and O3 decreased first and then increased.The monthly mean value of each indicator showed obvious seasonal variation characteristics,except for O3,other indicators were the lowest in summer.The highest in winter,the indicators are highly correlated.The fuzzy comprehensive evaluation method was used to evaluate the atmospheric environmental quality of Xi'an from 2001 to 2010,and the air quality pollution situation in Xi'an was analyzed?2?The pollution characteristics of three heavy metal elements such as Cd,Zn and Cu in atmospheric PM_2.5 and PM₁₀ in Xi'an were analyzed.Heavy metal concentration is Zn>Cu,Cd,the concentration of heating season is higher than that of non-heating season,the concentration of heavy metal elements in PM₁₀ is greater than PM_2.5,the concentration of heavy metal elements in outdoor particles is greater than indoor,the concentration of three heavy metal elements and PM_2.5 concentrations showed a significant positive correlation?3?Health risk assessment of three heavy metal elements in atmospheric PM₁₀ and PM_2.5 in Xi'an using health risk assessment model.The non-carcinogenic risk value of heavy metals in PM₁₀ and PM_2.5 is Cd>Cu>Zn,and the Cd concentration in the heating season has certain respiratory cancer risk,which needs attention.