| Aldehydes and ketones compounds are highly reactive chemical components in volatile organic compounds?VOCs?.Their photolysis will produce ozone and oxidizing free radicals,which causes environmental pollution and endangers human health.Taiyuan's industrial structure and energy structure,combined with its special topographic condition,frequently cause various environmental pollution problems.As a key precursor of photochemical smog,aldehydes and ketones have not been reported in Taiyuan City.In this study,the DNPH-HPLC-UV analysis method was used to explore the pollution levels and variation characteristics of 13 aldehydes and ketone compounds in Taiyuan City from 2018to 2019.Qualitative analysis of potential sources of aldehydes and ketones compounds in different seasons was carried out using ratio diagnosis method and correlation analysis method.The photochemical reactivity of different compounds was explored by three methods:ozone formation potential?OFP?,propylene equivalent concentration?Prop-Equiv?and hydroxyl radical loss rate(LOH).Finally,the exposure levels of formaldehyde and acetaldehyde and the cancer risk in different seasons were evaluated.The results were as following:1.During the entire sampling period,the total concentration of aldehydes and ketones in Taiyuan City varied between 6.00?g/m3 and 62.70?g/m3,with an average concentration of 17.85?g/m3.Formaldehyde,acetaldehyde,and acetone are the most abundant compounds in Taiyuan City,which together account for79.91%of the total concentration of aldehyde and ketone compounds,followed by methyl ethyl ketone and hexanal,which account for 5.72%and 3.10%of the total concentration of aldehyde and ketone compounds,respectively.2.The diurnal variation trend of the compounds in different seasons are similar,all peaking between 10:00?13:00,but the reasons for the changes are different,and the pollutant levels during the day are higher than at night.The seasonal changes of aldehydes and ketones are summer?20.38?g/m3?>autumn?19.61?g/m3?>spring?17.14?g/m3?>winter?13.85?g/m3?.3.Ratio analysis and correlation analysis show that the main sources of pollutants in summer are atmospheric photochemical reactions and motor vehicle exhaust emissions.Industrial coal combustion and motor vehicle exhaust are the main sources of pollutants in spring,autumn and winter,and are more significant in winter.4.The contributions of aldehydes and ketones to OFP,Prop-Equiv and LOHare highest in summer and lowest in winter.Among them,formaldehyde and acetaldehyde are the main contributors,and their contributions to total OFP,total Prop-Equiv,and LOH exceed 80%,50%,and 77%,respectively.Acetone has a small contribution value due to its low reactivity.5.The calculated lifetime cancer risk of formaldehyde and acetaldehyde exceeds the generally accepted risk value of 1×10-6 in Europe,and has a significant high carcinogenic effect.The HQ value of formaldehyde and acetaldehyde is<1,which indicates that their long-term exposure risk is low,but its potential harm to human body is latent and still needs attention.In this study,the pollution levels and source characteristics of aldehydes and ketones in Taiyuan City were obtained.The compositional characteristics and photochemical reactivity of aldehydes and ketones were explored.The results can provide data support for the Taiyuan government to make corresponding policy to reduce aldehydes and ketones pollution. |
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