我国夏季不同类型植被BVOCs排放观测与模拟研究

Observation and Simulation of BVOCs Emission from Different Vegetation Types in Summer in China

植物排放的挥发性有机物(天然源VOCs,BVOCs)对大气二次污染的形成有重要作用,为了解我国不同植被类型BVOCs排放特征,应用动态封闭式采样法和热脱附-气相色谱质谱联用(TD-GC-MS)技术对不同植被类型植物的单萜烯排放进行定量观测,应用MEGAN 2.1排放模式建立2018年夏季我国高时空分辨率BVOCs排放清单.结果表明:针叶树具有较高的单萜烯排放速率,其中以排放异松油烯、顺式-β-罗勒烯、柠檬烯、香桧烯为主;阔叶树种排放的单萜烯以α-蒎烯为主;农作物、草地、灌木中排放速率最高的化合物分别为异松油烯、反式-β-罗勒烯和柠檬烯.2018年夏季我国BVOCs排放总量为33.6×10^(12) g,异戊二烯、单萜烯、倍半萜烯和其他VOCs分别占64.13%、9.63%、2.11%和24.31%,其中阔叶树排放贡献率最高,为56.01%,灌木排放贡献率为14.16%.我国夏季BVOCs排放主要分布在东北、华东和华中地区,6种植被类型的排放受植被分布的影响呈现出不同的空间分布特征.研究显示:各类型植被单萜烯排放速率大小呈针叶树>阔叶树>草地>农作物>灌木的特征,各植物排放的单萜烯组成不同;各植被类型的BVOCs排放量大小呈阔叶树>灌木>草地>农作物>针叶树>针叶阔叶混交林的特征,且化合物组成不同,其空间分布特征与各植被类型分布相关.

Volatile organic compounds emitted by plants(biogenic VOCs,BVOCs)play an important role in the formation of atmospheric secondary pollution.To understand the BVOCs emission characteristics from different vegetation types in China,quantitative observations of monoterpene emissions from the plants of different vegetation types were conducted using the dynamic enclosure method and thermal desorption-gas chromatography-mass spectrometry(TD-GC-MS)technique.The MEGAN 2.1 emission model was applied to establish a high-resolution BVOCs emission inventory in summer 2018.The results showed that needle leaf trees had higher monoterpene emission rates than other plants,and terpinolene,cis-β-ocimene,limonene,and sabinene contributed the most.α-Pinene was the major contributor to monoterpene emission from broadleaf tree species.Monoterpene emission rates of crop,grass and shrub plants were dominated by terpinolene,trans-β-ocimene and limonene,respectively.The total emission of BVOCs in China in summer 2018 was 33.63×10^(12) g,with isoprene,monoterpene,sesquiterpene,and other VOCs accounting for 64.13%,9.63%,2.11%and 24.31%,respectively.Broadleaf trees had the highest contribution to the total BVOCs emissions(56.01%),followed by shrubs(14.16%).Summer BVOCs emissions were mainly distributed in northeastern,eastern,and Central China.The emission distribution of six vegetation types differed due to their different vegetation distribution.This study indicates that the monoterpene emission rates of plants by different vegetation types rank as needle leaf tree>broadleaf tree>grass>crop>shrub,which differ in composition of monoterpenes.The BVOCs emissions of each vegetation type rank as broadleaf tree>shrub>grass>crop>needle leaf tree>coniferous and broad leaf mixed forest,which have distinguished BVOCs composition.Their spatial distributions are related to vegetation cover.