The environmental effects of fine particulate matter(PM2.5)are largely controlled by its chemical composition and abundance.This paper investigates the geochemical characteristics and health risks of polycyclic aromatic hydrocarbons(PAHs)in PM2.5 under different atmospheric environmental quality conditions during different seasons in resource-dependent cities with coal as the main source of energy,namely Hohhot,Baotou,and Bayannur.The results showed that during the heating season,the main species of PAHs in three cities were Phe(10.00-14.74 ngm-3),Fla(8.00-15.33 ng·m-3),and Pyr(9.22-16.33 ng m-3);during the non-heating season,Hohhot and Bayannur cities were dominated by BkF(2.02-2.44 ngm-3)and DBA(4.54-4.78 ng·m-3),while Baotou was dominated by Pyr(0.88 ng·m-3),BbF(0.97 ng·m-3),DBA(1.94 ng·m-3),and BPE(0.85 ng m-3).The contents of PAHs in three cities exhibit similar seasonal variations with PAHs concentrations during heating season significantly higher than non-heating season.The diurnal variations of PAHs in PM2.5 during the heating season exhibited as nighttime significantly higher than daylight.The concentrations of PAHs in PM2.5 followed the rule of"pollution days＞sandstorm days＞clean days".The dominant species of PAHs during the heating season were 4-ring PAHs,while the dominant species during the non-heating season are 5-ring PAHs.PAHs in PM2.5 during the heating season in the study area are mainly from coal combustion and motor vehicle exhaust emissions,while emissions from motor vehicle exhausts and industrial sources dominate during the non-heating season.The sources of PAHs in PM2.5 in the three cities exhibit significant seasonal and urban functional and development induced differences.The carcinogenic and non-carcinogenic risks of inhalation of PM2.5-bound PAHs during the heating and non-heating seasons in the study area are at an acceptable level.This study has important informational values in studying the environmental geochemical behavior effects of PAHs in PM2.5 in typical coal-fired energy-supply-dominated urban atmospheres,and may also provide a certain scientific basis for the prevention and control of regional air pollution.
万方数据