BVOCs Emittion And Their Spatio-temporal Variation In A Pinus Bungeana Zucc. Stand

The amount of Biogenic Volatile Organic Compounds (BVOCs) occupies a considerableproportion of the Volatile Organic Compounds (VOCs) in the air, which has certain influenceon climate and human physical and mental health. It's important to thoroughly andsystematically research the components and spatio-temporal variation rules of BVOCs, whichis essencial for us to get a deep knowledge of BVOCs' synthesize mechanism, biological andecological characteristics of plants. Meanwhile, the results could provide theory forconfiguring reasonable woods, forming healthy forest that is good for sustainable developmentand human health. Based on this, we focused on Pinus bungeana Zucc. forest, one of the mostwidespread conifers in North China, investigating the components of BVOCs as well as thedaily, seasonal and vertical variation of Pinus bungeana Zucc. stand. Results showed asfollows:●The Pinus bungeana Zucc. stand could emit 99 kinds of compounds, containing Alkylhydrocarbon, Alkene, Alkine, Aldehyde, Acid, Ester and Ketone. 89.9 percent is compoundswhose atom number is less than 20.●The species of TBVOCs is the most in spring, containing Alkyl hydrocarbon, Alkene,Alcohol, Aldehyde, Acid and Ester. Less is summer, containing Alkyl hydrocarbon, Alkine,Alcohol and Este. Autumn is the least, only exists Alkyl hydrocarbon and Alkene. Hexane,α-pinene and Azulene are the common compounds in three seasons. In the vertical direction,top crown and middle stock are the main contributors to BVOCs species, while the space under1.5 meters is the poor donor. The top crown mainly contains Alkyl hydrocarbon and Alcohol.The middle crown mainly includes Alkyl hydrocarbon and Alkene.The main compounds atmiddle stock are Alkyl hydrocarbon, hydroxybenzene, Colchicine and Ethene. Alkylhydrocarbon and Alkene dominate at 1.5m. The predominant compounds on the ground areAlkyl hydrocarbon and terpene compounds.●BVOCs concentration varies with seasons. As to the concentration of TBVOCs, that insummer is the largest, then is spring, and autumn is the smallest. The concentration of Alkylhydrocarbon is kind of different from that of TBVOCs. Summer is bigger than in autumn, andbigger than spring. As to the Alkene, autumn is the most, then spring, and then summer.●The diurnal variation curve of TBVOCs is "two peaks, two vales",or "three peaks,three vales". Totally, 3:00, 9:00 and 21:00 are the common peak time, 6:00 and 15:00 are easyto be the least. In a detail, the variation curves of TBVOCs at top crown and middle stock are"two peaks, two vales", whose common peak is 21:00. That at middle crown, 1.5m and ground are "three peaks, three vales", whose common peaks are 3:00 and 9:00, while common valesare 0:00 and 6:00. The concentration of TBVOCs is the largest at 18:00 and least at 15:00 inspring. While 15:00 the largest and 6:00 the least in summer. In autumn, 9:00 the largest, 6:00the least. 9:00am is the same peak among three seasons.●The diurnal variation curves of Alkyl hydrocarbon is "one peak","two peaks, twovales",or "three peaks, three vales". 3:00, 9:00 and 15:00 are the usual peak time, 6:00, 18:00and 0:00 are the usual vale time. In a detail, the variation curves of Alkyl hydrocarbon on theground, at 1.5m and top crown are "three peaks, three Vales", whose common peaks are 3:00and 21:00, common vales are 6:00, 18:00 and 0:00. That at middle crown is "two peaks, twovales", whose common peaks are 3:00 and 15:00, while common vales are 6:00 and 18:00.There is no distinct variation at middle stock. The concentration of Alkyl hydrocarbon is thelargest at 18:00 and least at 15:00 in spring, while concentration at 0:00, 9:00 and 18:00 arethree top greatest in summer, 6:00, 12:00 and 21:00 three smallest. In autumn, 3:00 and 9:00are the largest.●Daily curves of Alkene is the same as Alkyl hydrocarbon, but peaks often appear at3:00,9:00,12:00, and wales usually appears at 6:00 and 0:00.In a In a detail, the space undermiddle stock and above top crown are rich in Alkene at 3:00 and 12:00. The whole space underthe crown is lack of Alkene at 6:00. In particular, the concentration of Alkene is less at 6:00 atthe space under and above 1.5m. The concentration of Alkene is the largest at 9:00 and least at0:00 in spring, 6:00 and 21:00 are the smallest. While concentration in summer is most at 9:00one day. In a day of autumn, 21:00 is the largest.●Diurnal variation curve ofα-pinene in May is "two peaks, two vales", two peaksappear at 0:00 and 12:00, two vales appear at 6:00 and 18:00. It didn't occur in July, butappeared at 0:00 in September.●BVOCs concentration varies with height above the ground. Totally, the concentrationof TBVOCs at middle stock and middle crown are the largest among the five heights. Then isthe concentration on ground. And that of 1.5m is the smallest. That amount at top crown variesdifferently with time. Alkyl hydrocarbon mainly distributes at the upper crown layer and on theground. Alkene mainly locates at crown and middle stock layers. The ground surface isabundant in terpene.