Analysis of Volatile Organic Compounds in Aerosol Filters from Beijing using Proton-Transfer-Reaction Mass-Spectrometry

Abstract

Aerosols are colloids of fine solid particles or liquid droplets, in air or another gas. Aerosols in the atmosphere have several important effects on the environment and on the human health. Organic compounds are found in ambient aerosols. They include compounds from both biogenic and anthropogenic sources. Aerosols are important in the climate system and organics constitute a significant fraction of aerosols (∼50%) of which some are hazardous to the human health. Aerosols filters have been collected from a rural area close to Beijing to see what pollutants are present. The samples cover a time period of two weeks in the fall of 2013. Proton-Transfer-Reaction Mass-Spectrometry coupled with thermal desorption is used to measure the concentrations of the compounds on the filters, from which the original concentrations in the air can be calculated. The measurements are done at different settings to get a complete overview of the chemical composition of the organic aerosols. The concentrations in the air vary between 0.5 micrograms per cubic meter up to 6.5 micrograms per cubic meter. Some compounds show statistical differences between day and night and between weekdays and weekends. Almost all the compounds showed lower concentrations during the weekend. Biogenic emissions are not expected to change during the weekend, meaning that the change is to be found in anthropogenic resources.