The Pollution Characteristics And Health Risk Assessments Of Heavy Metals In PM_2.5 Of Industrial And Urban Areas Of A Typical City In Yangtze River Delta

The air pollution of fine particulate matters(PM2.5)is a globally environmental issue,especially in China.Heavy metals in PM2.5 had received great attention,due to their great harms to the environment and human health.In this paper,the monthly sample was collected in urban and industrial areas of Nanjing.The temporal and spatial variations,sources,simulated lung fluid bioaccessibility and human health risks of heavy metals associated with PM2.5 were analyzed and compared.Results indicated that:(1)The pollution of PM2.5 in Nanjing was significant,showing a typical spatio-temporal distribution pattern:winter and spring>summer and autumn;industrial area>urban area.The PM2.5 concentrations were aeffected by precipitation and air temperature.(2)The airborne heavy metals also showed a typical temporal and spatial variations,and atmospheric As pollution in Nanjing was significant.The heavy metals in industrial area was higher than those in urban area.Most heavy metals in urban area show the seasonal distribution of winter-spring>summer-antumn.For industrial area,Ni,Cu and Cr were higher in summer and autumn,while other metals were higher in winter and spring.(3)The high enrichment factors(EFs)of Cd,Pb and As indicated their anthropogenic sources.The main sources of heavy metals in PM2.5 included coal burning,metallurgic dust,vehicle exhaust and soil dust,etc.The Co and Mn were from natural sources.The main metal sources in urban area included coal burning and vehicle exhaust,and Pb and Cd were mainly from vehicle exhaust,As was from coal burning.While in industrial area,heavy metals were from metallurgic dust and coal burning,and metallurgic dust was the main source of Pb,Cd,Ni and Cr,coal burning was the main source of As.(4)The human bioaccessibility of heavy metals in PM2.5 was in the order of As>Cr>Co>Cd>Ni>Mn>Pb>Cu.Most of them were higher in urban area.Their health risk assessment results didn't show non-carcinogenic health risks,but As and Cr showed the carcinogenic risk,especially the Cr in industrial area.The pollution from coal combustion and metallurgic dust demands the public concern.Generally,the pollution of PM2.5 and associated heavy metals in Nanjing was serious,both of which showed temporal and spatial patterns.Heavy metals in PM2.5 from different sources posed diverse health risks.The As from coal combustion and Cr in industrial area from metallurgic dust were dangerous.Therefore,reasonable human health risk assessments of airborne metals should consider the spatio-temporal variations in pollutant concentration and bioaccessibility owing to the sources.