Characteristics and chemical reactivity of biogenic volatile organic compounds from dominant forest species in the Jing-Jin-Ji area,China

Background:Biogenic volatile organic compounds(BVOCs)play an essential role in tropospheric atmospheric chemical reactions.There are few studies conducted on BVOCs emission of dominant forest species in the Jing-Jin-Ji area of China.Based on the field survey,forest resources data and the measured standard emission factors,the Guenther model developed in 1993(G93)was applied in this paper to estimate the emission of BVOCs from several dominant forest species(Platycladus orientalis,Quercus variabilis,Betula platyphylla,Populus tomentosa,Pinus tabuliformis,Robinia pseudoacacia,Ulmus pumila,Salix babylonica and Larix gmelinii)in the Jing-Jin-Ji area in 2017.Then the spatiotemporal emission characteristics and atmospheric chemical reactivity of these species were extensively evaluated.Results:The results showed that the total annual BVOCs emission was estimated to be 70.8 Gg C·year^(−1),consisting 40.5%(28.7 Gg C·year^(−1))of isoprene,36.0%(25.5 Gg C·year^(−1))of monoterpenes and 23.4%(16.6 Gg C·year^(−1))of other VOCs.The emissions from Platycladus orientalis,Quercus variabilis,Populus tomentosa and Pinus tabulaeformis contributed 56.1%,41.2%,36.0% and 31.1%,respectively.The total BVOCs emission from the Jing-Jin-Ji area accounted for 61.9% and 1.8%in summer and winter,respectively.Up to 28.8% of emission was detected from Chengde followed by Beijing with 24.9%,that mainly distributed in the Taihang Mountains and the Yanshan Mountains.Additionally,the Robinia pseudoacacia,Populus tomentosa,Quercus variabilis,and Pinus tabulaeformis contributed mainly to BVOCs reaction activity.Conclusions:The BVOCs emission peaked in summer(June,July,and August)and bottomed out in winter(December,January,and February).Chengde contributed the most,followed by Beijing.Platycladus orientalis,Quercus variabilis,Populus tomentosa,Pinus tabulaeformis and Robinia pseudoacacia represent the primary contributors to BVOCs emission and atmospheric reactivity,hence the planting of these species should be reduced.

Emission patterns of biogenic volatile organic compounds from dominant forest species in Beijing, China

Biogenic volatile organic compounds(BVOC s) have significant effects on atmospheric chemistry,ozone formation and secondary organic aerosol formation.Considering few investigations about BOVCs emissions in north China where is facing serious air pollution in recent years,emissions of various BVOCs from 24 dominant forest species in Beijing were measured from June to September in 2018,using a dynamic headspace sampling method.More than one hundred BVOCs in the collected samples were identified by using an automatic thermal desorption-gas chromatography/mass spectrometry,and their emission rates based on leaf biomass were calculated.Isoprene and monoterpenes were verified to be the dominant BVOCs emitted from the tree species,accounting for more than 50% of the total BVOCs.Generally,broad-leaved species displayed high isoprene emission rates,especially the Platanus occidentalis(21.36μg/(g·hr)),Robinia pseudoacacia(11.55μg/(g·hr)),and Lonicera maackii(9.17μg/(g·hr)),while coniferous species emitted high rates of monoterpenes,such as Platycladus orientalis(27.18μg/(g·hr)),Pinus griffithii(23.11μg/(g·hr)),and Pinus armandii(7.42μg/(g·hr)).High emission rates of monoterpenes from the broad-leaved species of Buxus megistophylla(13.07μg/(g·hr)) and Ligustrum uicaryi(5.74μg/(g·hr)),and high isoprene emission rate from the coniferous tree of Taxus cuspidata(5.86μg/(g·hr)) were also observed.The emission rates of sesquiterpenes from each tree were usually 10-100 times smaller than those of isoprene and monoterpenes.Additionally,relatively high emission rates of oxygenated volatile organic compounds and other alkenes than isoprene and monoterpenes were also found for several tree species.