Research On Characteristics Of Carbonyls In Beijing Urban Residences: Levels, Source Strengths And Factors

Carbonyls(aldehydes and ket ones) are a group of im portant gaseous pollutants which is known for ubiquity and perniciousness. It is very important to know the levels, source strengths and influential factors for prevention and control of in door air quality. However, there were no research w hich could show an overall carbonyls level for one city of China, and little was known about indoor source strengths and the main factors of carbonyls in China. Based on the condition aforementioned, related studies were carried out and the main contents and academic contributions are as follows:1. The concentrations of Carbonyl in 40 urban residences in Beijing were measured in this study. The carbonyls in indoor air were collected by a DNPH-pre-treated cartridge, extracted by acetonitrile and analyzed by HP LC. A questionnaire was adm inistrated to the residents in order to collect the information of building characteristics and families’ conditions and habits. T he results showed the concentrations of carbonyls in summ er were much higher than winter. The to tal concentrations of carbonyls were 136.0±77.5μg/m3 in summer, 55.3±50.7μg/m3 in winter. Formaldehyde was the most abundant species, following by acetaldeh yde, acetone and hexaldehyde. The concentrations of propionaldehyde, butyraldehyde, isovaleraldehyde, valeraldehyde were in the m iddle levels and detection rates were about 50%. The detection rates of crotonaldehyde, benzaldehyde, tolylaldehyde, 2,5-dimethyl benzene formaldehyde were lower than 20%. Indoor carbonyl concentra tions were much higher than outdoor concentrations. The I/O ratio of total concen trations was 1.6 in summ er, 3.2 in winter. The concentrations in this research were much higher than those in other researches of other countries. Especially for form aldehyde and hexaldehyde, the average concentrations in Beijing were about 5 times as high as the averag e concentrations in other countries.2. The air exchange rates were calculate d with tracer gas method which were conducted by measuring CO2 concentrations. Indoor source strengths of carbonyl species were estimated with One-compartment mass balance model. The indoor source strengths of formaldehyde, acetaldehyde, acetone, propionaldehyde, crotonaldehyde, benzaldehyde and hexaldehyde were estimated to be 11.6 mg/h, 4.41 mg/h, 1.17 mg/h, 0 mg/h, 0 mg/h, 0 mg/h and 4.85 m g/h, respectively. According to correlati on analysis, all carbonyls except 2,5-dimethyl benzene formaldehyde had significant correlation with each other.3. Analysis of variance(ANOVA) and general linear m odel were em ployed to examine the impacts of possible factors on the carbonyl concentrations. We found that sofa material, smoking, temperature and residence location had significant im pacts on formaldehyde concentration, smoking, temperature and kitchen structure on acetaldehyde, quantity of plants and kitchen structure on acetone, quantity of plants and temperature on hexaldehyde, respectively. Besides, formaldehyde, acetaldehyde, acetone and hexaldehyde were all influenced by temperature significantly.