Source apportionment and health risk assessment of metals in PM2.5 during autumn-winter of 2019 in Xi'an City
Background,aim,and scope In recent years,PM2.5 has become one of the most severe air pollutants worldwide and an essential factor in forming"smog"during the autumn-winter period.Xi'an,an important city in terms of economy and culture in China,suffers from heavy air pollution events in autumn and winter,seriously affecting local people's health.Therefore,conducting a metal source and health risk assessment of PM2.5 in Xi'an during autumn and winter is essential to control air pollution and reduce human health threats.Materials and methods PM2.5 filter samples were collected from October 2019 to January 2020 in Xi'an City,and the concentrations of eight metal elements(Al,Cr,Mn,Ni,Cu,Zn,As,and Pb)were analyzed.Combined with enrichment factor and correlation analysis,the source analysis of metal elements was conducted through the positive matrix factorization model(PMF).Finally,the EPA health risk model and PMF analysis results were used to evaluate the non-carcinogenic and carcinogenic risks of metallic elements in adults and children.Results During the sampling period,the average mass concentration of PM2.5 in Xi'an was 99.44 μg·m-3,and the enrichment factors of Zn(172.2)and Pb(194.9)among the eight metal elements were high.The correlation between Zn-Mn(0.85),Mn-Cu(0.67)and Cu-Zn(0.66)was significant.The sources of the eight metal elements were dust,traffic,coal-burning,and industrial sources,with their contributions being 42.6％,29.6％,24.6％,and 3.2％.The respiratory inhalation pathway is the main pathway of non-carcinogenic risk and carcinogenic risk in adults,and the main path of carcinogenic risk in children is hand-mouth ingestion.The primary sources of non-carcinogenic risk for adults and children from metals in PM2.5 in Xi'an in the autumn and winter of 2019 were traffic and coal-burning sources,while the primary sources of carcinogenic risk were dust and coal-burning sources and industrial sources.Discussion During the sampling period,the average mass concentration of PM2.5 in Xi'an was 1.3 times higher than the national standard(35 μg·m-3)and 6.6 times higher than the WHO standard(15 μg·m-3).The cumulative average concentration of 8 metal elements in PM2.5 is 990.58 ng·m-3,with the concentration of Cr was 22.4 times higher than the WHO standard(0.25 ng·m-3).From moderate quality to hazardous quality,the concentrations of metal elements all manifested an escalating trend,with Pb exhibiting the most significant increase.Zn and Pb were seriously affected by anthropogenic pollution.Zn-Mn-Cu and As-Pb had a strong correlation,indicating that these elements may have a common source.The primary sources of metals in PM2.5 in Xi'an City are attributed to dust,traffic,and coal-burning.Cr had a cancer risk in adults,and As had a non-cancer risk in children.Coal burning was the primary source that contributed the most to the non-carcinogenic risk and carcinogenic risk in adults and children.Conclusions The primary sources of eight metals in PM2.5 in Xi'an were dust,traffic,coal-burning,and industrial sources.There were non-carcinogenic risks and carcinogenic risks for adults and children,and coal-burning sources contribute more to the health risks of adults and children.Recommendations and perspectives To reduce heavy metal pollution in Xi'an and the threat to people's health,attention should be paid to the impact of coal burning,traffic,and dust sources.Coal burning should be strictly controlled to reduce pollutant emissions.
NETL
NSTL
万方数据
