Chemical Composition And Health Risk Assessment Of Atmospheric Particulate Matter And Road Dust In Baoding

Atmospheric particulate matter,as the most common air pollutants,has large specific surface area and wide distribution.It can absorb toxic and harmful heavy metals and organic pollutants in the air.Road dust is an important source of atmospheric particulate matter,it also has enrichment effect on environmental pollutants.Through the study of chemical composition of different environmental media,it is practical significance to combine the treatment of ecological environmental pollution with population health management.It is also helpful to carry out the prevention and control of ecological environmental pollution in a more targeted way.The quality of environmental decision-making,and accurate risk prevention will be improved.In this study,Baoding was selected as the research area to collect PM_2.5 and main road dust samples during the heating period and non-heating period from 2018 to 2019.The concentrations of 16 kinds of polycyclic aromatic hydrocarbons（PAHs）and 7kinds of heavy metals were determined by gas chromatography-mass spectrometry（GC-MS）and inductively coupled plasma emission spectrometry（ICP-AES）,and their pollution characteristics were analyzed.On this basis,characteristic ratio,principal component analysis（PCA）and PMF model were used to analyze the sources of PAHs and heavy metals.At last,health risk assessment model and potential ecological risk assessment model were used to assess the health risk and potential ecological risk of exposure to PAHs and heavy metals in different populations,and some meaningful results were obtained.（1）PM_2.5 pollution in Baoding is serious,and there are significant differences in PAHs and heavy metal pollution in different periods.The pollution in heating period is significantly higher than that in non-heating period.The PM_2.5 mass concentration in Baoding was 148.0±73.3μg/m~3 and 61.9±29.3μg/m~3 in heating and non-heating periods,respectively.The mass concentration of PAHs in PM_2.5 was 180.71±70.76 ng/m~3 and 81.75±16.34 ng/m~3 respectively,and Ba P exceeded the standard more seriously.The concentration of heavy metals in PM_2.5 in Baoding is between 0.002μg/m~3 and 0.193μg/m~3.（2）The pollution characteristics of PAHs and heavy metals in road dust in Baoding are different in different periods.The mass concentration of PAHs in road dust in Baoding was 4139.2±551.5μg/kg and 1933.0±477.4μg/kg.The concentration of heavy metals in road dust ranged from0.9 mg/kg to 239.3 mg/kg.（3）The PAHs in PM_2.5 and road dust in heating season have the same main emission sources,but in non-heating season don’t.The sources of heavy metal elements varied significantly in different periods.The results of source analysis show that the main emission sources of PAHs in PM_2.5 and road dust in Baoding city during heating season are natural gas combustion sources,and other sources also include transportation sources,petroleum sources,and fossil fuel combustion sources.In non-heating period,PCA-based method shows that the main emission source of PAHs in PM_2.5 is natural gas combustion source,and in road dust is traffic source.PMF-based method shows that the main emission source of PAHs in PM_2.5 is traffic source,and in road dust is natural gas combustion source.（4）The health risk of PAHs in PM_2.5 in Baoding is at an acceptable level,and PAHs in road dust has a certain carcinogenic risk to some people.The health risk of heavyThe carcinogenic risk of PAHs in road dust during heating season is more than10^-4in Baoding,which is above the acceptable level for all the people,and the health risk for children is>adult female>adult male.In non-heating season,the carcinogenic risk for children aged 6-14 is above the acceptable level,and the risk mainly comes from hand-mouth exposure.（7）The comprehensive ecological risk of heavy metals in road dust at different periods in Baoding is different,and there is a comprehensive ecological risk.The comprehensive ecological risk of heavy metals in road dust in Baoding was at a high risk level（RI=338）in heating season,and a slight risk level（RI=145）in non-heating season.To sum up,PM_2.5,PAHs,Cd and As pollution in Baoding are serious and exceed the standard.PAHs and heavy metal pollution in PM_2.5 and road dust were higher in heating period than in non-heating period.The main sources of PAHs are natural gas combustion source and transportation source,while the main sources of heavy metals are coal burning source,transportation source and industrial source,and there are seasonal differences.The carcinogenic and non-carcinogenic risks of PAHs and heavy metals in PM_2.5 in Baoding were both at an acceptable level.PAHs in road dust can cause unacceptable carcinogenic risk to people,while heavy metal pollution does not pose health risk to people.There is a comprehensive ecological risk of heavy metals in road dust in Baoding.