摘要
2012年7月至2013年1月,采用松弛涡度积累(Relaxed Eddy Accumulation)技术在我国浙江省亚热带竹林测量了挥发性有机物(BVOC)冠层尺度的排放通量,同步测量了气象参数、太阳辐射(总辐射、直接辐射、光合有效辐射PAR)。利用PAR能量平衡原理,建立了冠层尺度异戊二烯和单萜烯排放的经验模式,经验模式对于日变化、季节变化有较好的模拟。采用不同方法对经验模式进行检验,一般而言,BVOC的模拟值高于测量值。经验模式与MEGANv2.1全球生物排放模式对BVOC排放有比较一致的模拟结果,标准状况下(温度t=30℃、PAR=1 500μmol·m^(-2)·s^(-1)排放因子较接近(异戊二烯分别为4.00和3.60 mg·m^(-2)·h^(-1),单萜烯分别为0.12和0.16 mg·m^(-2)·h^(-1))。经验模式的计算结果表明:竹林BVOC排放主要集中于夏季(7-9月)且以异戊二烯为主(占BVOC排放的87.3%~95.8%)。利用经验模式计算了BVOC排放对各个因子(PAR、水汽、S/Q-散射因子,散射辐射/总辐射)变化的敏感性:当各个因子增加率大于40%时,异戊二烯对PAR的变化最敏感,其次是水汽因子,再次是S/Q;单萜烯对S/Q的变化最敏感,其次是水汽因子,再次是PAR;单萜烯比异戊二烯对S/Q的变化更敏感;异戊二烯和单萜烯对各因子变化的响应是非线性的。冠层尺度上BVOC的排放量与卫星测量的HCHO柱浓度(molec·cm^(-1))之间有良好的线性关系:异戊二烯排放量(mg·m^(-2)·h^(-1))=3.93×10^(-16)HCHO-2.81,单萜烯排放量(mg·m^(-2)·h^(-1))=1.24×10^(-17)HCHO-0.05。对比我国不同生态系统实测的排放通量、排放因子,异戊二烯排放以亚热带竹林最高,其次为温带森林,草地最低;单萜烯排放以温带森林最高,亚热带竹林次之,草地最低。
Biogenic volatile organic compound(BVOC) emission fluxes were measured using the relaxed eddy accumulation(REA)technique on an above-canopy tower in a subtropical bamboo forest in Zhejiang province,China from July,2012 to January,2013.Meteorological parameters,solar global and direct radiation,and photosynthetically active radiation(PAR) were also measured during the same time period.Empirical models for calculating canopy-scale isoprene and monoterpene emission fluxes were developed based on PAR energy balance.The models were able to explain much of the observed diurnal and seasonal variations.Different methods were used to validate the BVOC empirical models which,on average,simulated fluxes that were higher than observed values.BVOC empirical models were in good agreement with MEGANv2.1 model simulations of isoprene and monoterpene emissions.The emission factors at standard conditions(t=30℃,PAR=1 500μmol·m^(-2)·s^(_1)) estimated using empirical model and MEGANv2.1 model were 4.00 and 3.60 mg·m^(-2)·h^(-1) for isoprene,respectively,and 0.12 and 0.16 mg·m^(-2)·h^(-1) for monoterpenes,respectively.BVOC emissions estimated by the empirical model show that BVOC emissions are highest in summer(July to September),and isoprene is the dominant species,contributing 87.3%to 95.8%of BVOC emissions in summer.A sensitivity study of the response of BVOC emissions to changes in their controlling factors(i.e.,PAR,water vapor and S/Q-scattering factor,ratio of solar scattering radiation to solar global radiation) showed that when each factor was increased by > 40%,isoprene emission was more sensitive to PAR than to water vapor or S/Q.Monoterpene emissions were most sensitive to S/Q and were more sensitive to this scattering factor than isoprene.Isoprene and monoterpene emissions exhibited nonlinear responses to changes in their controlling factors.Good linear relationships were found between isoprene and monoterpene emissions on the canopy scale and with satellite retrieved HCHO vertical column densities(molec·cm^(-1)):isoprene emission(mg·m^(-2)·h^(-1))=3.93×l0^(-16) HCHO-2.81,monoterpene emissions(mg·m^(-2)·h^(-1))=1.24×l0^(-17) HCHO-0.05.Comparing measured BVOC emissions and BVOC emission factors at different ecosystems in China,isoprene emission is highest in subtropical bamboo forest,followed by temperate forest,and lowest in grassland.Monoterpene emissions are highest in temperate forest,followed by subtropical bamboo forest,and lowest in grassland.
出处
《生态环境学报》
CSCD
北大核心
2015年第12期1923-1937,共15页
Ecology and Environmental Sciences
基金
国家自然科学基金项目(40175031,41275137)
中华人民共和国科技部-欧洲空间局合作“龙计划”3期项目(ID10663)
欧盟第七科技框架计划(FP7)Marco Polo项目(Grant NO.606953)
关键词
挥发性有机物
排放通量
光合有效辐射
经验模式
排放因子
biogenic volatile organic compounds
emissions flux
photosynthetically active radiation
empirical model
emission factor
