| The Biogenic Volatile Organic Compounds (BVOCs) has certain influence on atmospheric environment, air quality and and human physical and mental health. Platycladus orientalis and Pinus tabulaeformis are the main tree speices in Beijing. The variation of BVOCs is the mainly content in our experiment, meanwhile, measuring the eco-physiological index , try to present the release mechanism of two species, it's good for product developmentment, it can also supply scientific basis for plant selection of the ecological planning and ecotourism development. Based on this, this paper studies the composition,seasonal variation,diurnal variation and the correlation between VOCs concentration and impact factors of Platycladus orientalis and Pinus tabulaeformis, by collecting volatiles gas sample with headspace sampling method, analyzing gas sample by TCT-GC/MS, the result suggests that:1,Compsition of BVOCs:①There are ten types of VOCs which are Alkane, Alkene, Alkyne, Alcohol, Aldehyde, Acid, Ester, Ketone, Aromatic hydrocarbon and Ether released by Platycladus orientalis, this result is same to the type of Pinus tabulaeformis VOCs. Platycladus orientalis has totally 224 kinds and Pinus tabulaeformis has totally 178 kinds.②The seasonal variation of sepecies released by Platycladus orientalis is Spring>Summer>Autumn>Winter,but the Pinus tabulaeformis is Spring>Summer=Autumn>Winter.③We can see terpene is the mainly VOCs of Platycladus orientalis and Pinus tabulaeformis from occurrence frequency and relative concentration.2,The variation of TVOCs concentration:①Seasonal variation: both the Platycladus orientalis and Pinus tabulaeformis are Summer>Spring>Autumn>Winter.②Diurnal variation:Platycladus orientalis concentraion presents"two peaks two vales"in Spring and in Winter , presents"three peaks three vales"in Summer and in Autumn;Pinus tabulaeformis concentration presents"two peaks two vales"in Spring and in Summer , presents"three peaks three vales"in Autumn and in Winter. The commen gound of the two species TVOCs concentration are: it always presents a peak in 9:00～13:00 and in 20:00～3:00; it always presents a vales in 5:00～9:00 and in 17:00～21:00.③Mcroclimate and Physiological Change has the most influence on TVOCs of two species in Spring;because the temperature and humidiy are high in Summer, the correlation between transpiration rate and TVOCs of both two species is significant, net photosynthetic rate has significant influence on TVOCs of Pinus tabulaeformis because of the higher illumination; in autumn, the temperature has significant influence on TVOCs of Platycladus orientalis; in winter, temprature and light have little influence on both of the species TVOCs concentration, if the photosynthate is enough, the stomata wil open, the TVOCs concentration would rise.3,The variation of different kinds of VOCs:①the relative concentration of Alkene is highest in the TVOCs concentration, the second is Alkane, Aromatic hydrocarbon concentration is second only to Alkene and Alkane concentration in Spring,Summer and Autumn, Ether concentration of Pinus tabulaeformis is high all the year around.②The seasonal variation of Alkane relative concentration and Alkene relative concentration of both two trees are the same. Alkene relative concentration:Winter>Autumn>Summer>Spring;Alkane relative concentration:Spring>Summer>Autumn>Winter.③There are some points of similarity of Alkene concentration diurnal variation between Platycladus orientalis and Pinus tabulaeformis. In Spring, the higest Alkene concentration is in 13:00～17:00, the lowest Alkene concentration is in early moring; in Summer, the higest concentration is in 15:00～19:00, the second is in 21:00～7:00; the lowest is in 9:00～13:00; in Autumn, there some difference between two species, but the trend of the Alkene concentration is : the highest concentration is in 7:00～11:00,the second concentration is in night time, the lowest is in 9:00～13:00; in Winter, the commen gound is the lowest concentration is in 2:00～5:00.④Alkane concentration diurnal variation of two species are different in different season. In Spring, the higest Alkane concentration of Platycladus orientalis is in 1:00～3:00, the lowest Alkane concentration is in 9:00～13:00, while, the higest Alkane concentration of Pinus tabulaeformis. is in 17:00, the lowest Alkane concentration of Pinus tabulaeformis is in 13:00～15:00; in Summer, the higest Alkane concentration of Platycladus orientalis is in 21:00～1:00, Alkane concentration in daytime is lower, while, the higest Alkane concentration of Pinus tabulaeformis. is in 1:00～3:00, the concentration in 15:00～23:00 is lower, the lowest Alkane of Pinus tabulaeformis concentration is in 5:00～7:00; in Autumn, the higher concentration of both two trees is in 5:00～17:00, but the lower concentration of both two trees is in 21:00～1:00; in Winter, both of the two trees present a peak in 8:00.⑤The result of correlation between Alkene concentration and influence factors of both of two trees is coincidentally. In Spring, light, net photosynthetic rate and stomatal conductance have significant influence on Alkene concentration; in Summer, light, stomatal conductance have significant influence on Alkene concentration; but in Autumn and Winter, Alkene concentration are not appreciably influenced by the factors.⑥Alkane concentration influenced by the factors is weaker than Alkene concentration, different kinds of VOCs influenced by the factors in different season are different.4,We can get the results from consulting many papers about the VOCs'health function :①The VOCs good for health mainly are terpinenes, the VOCs bad for health mainly are alkyl chloride and Benzene Series.②The total Concentration seasonal variations of VOCs with obvious health effects of Platycladus orientalis is Spring>Summer>Autumn>Winter, but the Pinus tabulaeformis is Autumn>Spring>Summer>Winter.③Both of two trees VOCs concentration which good for health are higher than the VOCs concentration which bad for health. VOCs good for health arise in every time period in different season, but the peak of the concentration is different in different season, VOCs bad for health always arise in nighttime.5,Some suggestion and development directions about BVOCs research were put forward in this paper:①Increase the research object,enlarge the research scale;②Strengthen the release mechanism research of BVOCs;③Strengthen the health effects of BVOCs on human body and mind;④Strengthen the comprehensive research of BVOCs in different configuration mode.
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