The Effects Of Drought Stress On The Emission Of Biogenic Volatile Organic Compounds From Black Poplar(Populus Nigra)

As the frequency and intensity of drought increase,the impact of drought stress on Biogenic Volatile Organic Compounds(BVOCs)has received more and more attention.In order to figure out the impact of drought on BVOCs emission,including the impact of drought level,rehydration,and with other environmental factors on the emission rate of BVOCs.Emission characteristics of BVOCs from plants and its impact on regional air quality in Shandong province were studied by analyzing the volume data of ninth forest resources survey in Chian and investigating the BVOCs emission factors from relevant literatures.The result showed:(1)This article reviews the research progress made in the impact of drought stress on BVOCs emission.The effect of drought stress on BVOCs emission,summarized the mechanism of drought stress on BVOCs emission.The existing studies can be divided into three categories,based on duration of dress and loss of soil water,the drought levels as mild,moderate and severe.Previous studies find that BVOCs emissions increase during mild drought,but decreased during moderate and severe droughts.In the drought stress periods,the emission rates of BVOCs are expected to increase at the beginning of drought,and then decrease.Studies on the mechanism of drought stress on BVOCs have found that the net photosynthetic rate and stomatal conductance are more sensitive to water loss than BVOC emissions.(2)We studied black poplar emissions BVOCs in the drought stress.At the same we measured the net photosynthetic rate,stomatal conductance and other physiological parameters.The results showed that the effect of drought stress on black poplar isoprene emission was to stimulate isoprene emission in mild drought,and then inhibit isoprene emission.Both short-term and long-term droughts reached their peak emissions on the third day,an increase of 77.86%and 44.25%respectively from the first day.Poplar is the main isoprene-emitting species.The short-term drought and long-term drought-unstressed rates are 14.0 nmol/(m~2s)and 18.23 nmol/(m~2s),respectively.There is no significant difference in monoterpene emissions.The monoterpene emission species are limonene,myrcene,α-terpinene andγ-terpinene.(3)Based on the calculation of 16 types of plants,the total emissions of BVOCs in Shandong Province were 198 G g C,and the emissions of isoprene were 177 Gg C,accounting for 89.1%in 2016.The emissions of monoterpenes and OVOCs were 16.4 Gg C and 5.1 Gg C,accounting for 8.3%and 2.6%,respectively.BVOCs had the highest emissions flux in July,contributing 29.1%.The proportions of isoprene,monoterpenes and OVOCs were 90.8%,7.03%and 2.1%,respectively.The seasonal variation of BVOCs is obvious.Poplar is a major contributor to BVOCs and isoprene emission,are84.2 Gg C.Grassland emission are 11.4 Gg C,which is the most.The contribution of BVOCs to the formation potential of ozone is 1939 Gg C and isoprene is the main contributor,accounting for 96.6%.The contribution to the formation potential of secondary organic aerosol formation is 8.46 Gg C,with isoprene and monoterpenes accounting for 41.7%and 58.3%,respectively.