Pollution Characteristic and Health Risk Assessment of Metal Elements in PM2.5 from a Certain District of Taizhou City in 2020-2022
The concentration of PM2.5 was generally fine while haze happened frequently in the urban area of Taizhou.The metal elements carried by PM2.5 in air enter human body through the respiratory route in a long time,which can affect human health seriously.Investigating the content variation and source of metal elements in fine particulate matter less than 2.5 µm from a certain district of Taizhou city helps to assess the healthy risk of local residents.PM2.5 samples were collected monthly from 2020 to 2022.Metal elements were detected by inductively coupled plasma mass spectrometry after ultrasonic extraction.The pollution degree was evaluated by geo-accumulation index,the possible source of metal elements was analyzed by positive definite matrix source apportionment,the health risk assessment of contaminant was performed to assess the exposure degree.From 2020 to 2022,the concentration of PM2.5 reduced slightly,which was lower in August,September and October,higher in January,November and December,and the corresponding annual average concentrations of PM2.5 were(48.4±33.6),(41.6±24.3)and(40.8±20.9)μg·m-3,respectively.According to the national secondary standard,annual average concentrations of PM2.5 exceeded standard rate by 11.9％(10/84),11.9％(10/84),10.7％(9/84),respectively.Among the 12 kinds of metal elements,the content ranked from high to low was Zn,Al,Mn,Pb,Cu,As,Cr,Se,Ni,Sb,Cd,and Tl,while the content of Mn and Ni did not exceed the standard of World Health Organization.According to GB 3095-2012 Ambient Air Quality Standard,the content of Pb and Cd did not exceed the limit value,while that of As and Cr exceeded standard rate by 17.2％and 86.3％,respectively.The geo-accumulation index indicated that all metal elements suffered from anthropogenic influence except Al,the pollution degree was higher in Se and Cd,while lower in Cr,Mn,and Ni.Health risk assessment revealed that the HQ value of Al,Cr,Ni,As,Se,Cd,and Sb were less than 1,and the CR value of Cr and As were in the range of 1×10-6～1×10-4.The source apportionment indicates that pollution source comes from combination release of coal combustion,traffic emission,nature,industry such as metallurgy and chemical.The average concentration of PM2.5 decreased slightly in 3 years,and the average concentration of the rest elements changed with different rules except for As,Pb,and Mn changing little.The non-carcinogenic risk level of Al,Cr,Ni,As,Se,Cd,and Sb was acceptable,while life time exposure of Cr and As could generate potential carcinogenic risk.Except for the reduction of nature source from dust,coal fuel source,industrial source,and traffic source,the pollution sources of As and Cr should be disposed in order to reduce exposure risk of residents pointedly.
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