Preliminary Research Of Carbonyl Emission And Removal By Plant

Carbonyl is an important component of trace volatile organic compounds in theatmosphere. With high activity, this kind of compounds not only participates in theatmospheric photochemical reaction by providing a mass of free radicals, but also canbe an important intermediate generated from the process of photochemical reaction,and directly involving in the formation of atmospheric secondary organic aerosols,then seriously affecting the city’s air quality. In addition, some carbonyl compoundshave high toxicity and irritation to human body and pose a potential hazard to humanhealth. The sources of atmospheric carbonyl compounds include artificial activity,natural source and atmospheric photochemical reaction, and plant emission plays animportant role in natural source. Besides emission, plants also have the ability toremove carbonyl compounds.The analytical method of carbonyl compounds applied in this dissertation wasPentafluorophenyl hydrazine/gas chromatography/mass spectrum (PFPH/GC/MS).At first, this method was applied in this study for the detection and analysis ofcarbonyl compounds in the atmosphere of Nanchang. According to the analysis resultsof formaldehyde/acetaldehyde (C1/C2) and acetaldehyde/propionaldehyde (C2/C3)ratios, we infered that the contribution of artificial source for the atmosphericcarbonyl compounds in Nanchang was less than other cities like Beijing, Guangzhou.In plant emission research, four common outdoor garden plant species includingPrunus lannesiana, waxberry tree, Osmanthus tree and Podocarpus macrophyllus wereselected to conduct experiments. Experiment results showed that at least six kinds ofcarbonyl compounds were detected in all samples from selected plant species while11kinds of aldehyde and ketone compounds (C1-C10aldehydes and acetone) wereunder test, and C1-C4carbonyl compounds were in existence in all samples. From theanalysis of experimental results, we might conclude that plant emission had animportant contribution to the carbonyl compounds in the atmosphere.In plant removal research, four common indoor plant species includingPeperomia tetraphylla, Schefflera octophylla, Dracaena sanderiana and Chamaedoreaelegans were selected as material for conducting experiments. As the main work inthis part, two kinds of plant including Schaffer octophylla and Chamaedorea eleganswere selected to perform a further research in absorbing low molecular aldehydes,which were conducted under different external conditions including different low concentration (20-160ppbv), different light intensity (0-6000lx) and different carbondioxide concentration (350-1400ppmv). Experiment results showed a certain ability toremove C1-C5aldehydes for these selected plants, and the absorption on the lowermolecular weight aldehydes (formaldehyde, acetaldehyde) seemed higher than otherhigher aldehydes (propanal, butylaldehyde and valeraldehyde). Moreover, the abilityto remove C1-C5aldehydes of two selected plant species has improved with theincrease of concentration of pollution components in a range of20to160ppbv, and asame trend was found when the light intensity changed from0to6000lx. On thecontrary, when the inlet carbon dioxide concentrations elevated from350to1400ppmv, the removal capacity of Schefflera octophylla and Chamaedorea elegansdecreased32%and43.1%, respectively.The sixth chapter of this dissertation showed the research work derived fromauthor’s participation in the research of atmospheric carbonaceous aerosols with thecooperation with China Research Academy of Environmental Science. Recentlybrown carbon (BrC） which have been suggested as an carbonaceous aerosolscomponent between ordinary organic carbon (OC, non-light-absorbing) and blackcarbon (BC, strongly light-absorbing) is becaming one of the most hot research topicsin atmospheric carbonaceous aerosols. China is believed to have huge BrC emissionsfrom residential coal combustion and agricultural biomass open burning, but nospecific data are available. In this paper a7-wavelength aethalometer was used tomonitor the light-absorbing features of primary aerosols from summertime openburning of wheat straw and from wintertime combustion of residential coal. Based onthe distinctions in spectral dependence between BrC and BC, the relative contributionof BrC and BC (RBrC/BCratio) was calculated. Bridged by the RBrC/BCobtained，preliminary estimates of China’s BrC emissions from residential coal and agriculturalbiomass open burning in2000were acquired with the help of joural-reported BCemissions. The yearly sum of BrC emissions from residential coal and agriculturalbiomass open burning was (270.6±101.6) Gg (BC equivalent) in China, with(175.4±27.8)Gg for field agricultural biomass and (95.2±73.7)Gg for residential coal.The findings lay the foundation for a more comprehensive measurement of BrCemissions in the future as well as the studies of brown carbon in atmosphericchemistry and radiation forcing.