Study On The Pollution Characteristics And Sources Of Oxygen-containing Volatile Organic Compounds In Ambient Air In Fujian Province

Oxygenated volatile organic compounds(OVOCs)are important components of volatile organic compounds(VOCs).They play an important role in atmospheric photochemical reactions.Their chemical properties are lively and their sources are extremely complex.At the same time,OVOCs,as an important atmospheric pollutant,seriously endanger human health and ecological environment.Therefore,the study of ambient air OVOCs is of great significance to understand its pollution characteristics,atmospheric chemistry and its source.In May and October 2018,this study carried out observation experiments on ambient air OVOCs in eight cities and one district in Fujian Province,China(a total of 11 representative observation stations were selected),and aimed at the problems encountered during the experiment.The sampling method was optimized,and 16 kinds of ambient air OVOCs were selected as the target species for analysis.And using various data processing methods such as the backward airflow trajectory model and OBM model,combined with the routine 6 pollutant data of the national control point,the pollution characteristics of the spatial and temporal changes of the ambient air OVOCs in Fujian Province,composition analysis,impact on ozone and other Source analysis for discussion and analysis.The main research results and conclusions obtained are as follows:(1)This study optimizes the sampling method of ambient air OVOCs.First,it optimizes the ambient air OVOCs sampler so that it can continuously and automatically sample,greatly reducing the frequency of sample change,which is more time-saving and labor-saving than traditional samplers In addition,through multiple simulation experiments,comprehensive consideration of the scientific and cost of the experiment,the best sampling time was adjusted to 2h,and the sampling flow rate was 0.8L/min to ensure the accuracy of the analysis results.(2)The average concentration of ambient air OVOCs in the eight cities and one district of Fujian Province during the observation period was 5.59-21.24 ppbv.The results showed that the overall concentration of ambient air OVOCs in Fujian Province was slightly lower than that in Beijing,Guangzhou and other more polluted areas,and the coastal The ambient air OVOCs concentration at urban sites is generally greater than that at inland urban sites.Intensified observations of the capital city of Fuzhou in May and October 2018 found that the concentration of OVOCs in Fuzhou 's ambient air was higher in May than in October.The OBM model was used to simulate the May observations in Fuzhou.The model results show that Fuzhou's photochemical reactions and primary emissions from mobile sources both make important contributions to its formaldehyde concentration.Alkynes in anthropogenic VOCs are its key precursors,while NOx has an inhibitory effect on the production of formaldehyde.(3)During the observation period in Fujian Province,the main components of ambient air OVOCs in eight cities and one district were formaldehyde,acetaldehyde and acetone,and the highest daily changes in the average concentration of ambient air OVOCs occurred mostly during the period of strong solar radiation at noon or afternoon.It shows the contribution of atmospheric photochemical reactions to the concentration of ambient air OVOCs.During the observation period,the concentration of ambient air OVOCs in Fujian cities has a strong correlation with ozone concentration.As the concentration of ambient air OVOCs gradually increases,it may continue to participate in atmospheric photochemical reactions as ozone precursors,resulting in atmospheric ozone concentration Rise.(4)Ambient air OVOCs have a shorter atmospheric life and are more difficult to transmit regionally by airflow,but their precursors may affect the concentration of ambient air OVOCs in the transport city through regional transmission.The analysis of the sources of ambient air OVOCs in cities of Fujian Province based on the analysis results shows that the ambient air OVOCs in eight cities and one district of Fujian Province are mainly affected by anthropogenic emissions and the secondary generation of VOCs photochemical reactions from regional transmission,natural sources and anthropogenic sources.