短期干旱胁迫对马尾松排放挥发性有机物的影响

為探究干旱環境對BVOCs排放的影響,應用動態封閉式采樣系統和熱脫附-氣相色譜-飛行質譜儀,對短期干旱脅迫作用下馬尾松的BVOCs排放進行了實驗室測量,定量分析BVOCs排放速率和排放組成的變化.結果表明,干旱脅迫時異戊二烯的排放受到抑制,排放速率降低約50%;單萜烯和倍半萜烯的排放水平增強,排放速率分別為137.85和0.98μg/(m~2·h),是未受脅迫時的2.9和2.0倍.除反式-α-香檸檬烯外,干旱脅迫促進各單萜烯和倍半萜烯化合物的排放,是未受脅迫時的1.3～42.4倍,其中3-蒈烯排放的響應最敏感,α-葑烯、α-水芹烯和石竹烯的響應最弱.干旱脅迫時單萜烯和倍半萜烯的排放組成有所變化,但主導的化合物種類不變,單萜烯以α-蒎烯、香檜烯和β-蒎烯為主,占比分別為48%、17%和17%;倍半萜烯以石竹烯和長葉烯為主,占比分別為57%和34%. To explore the impact of drought on BVOC emissions, dynamic enclosure system and TD-GC-TOFMS were used to conduct laboratory measurements of BVOC emission from Pinus massoniana under short-term drought stress. The changes in emission rates and composition were analyzed quantitatively. The results showed that emission of isoprene was inhibited under drought stress, with a drop of around 50% in emission rate. Monoterpene and sesquiterpene emission rates were enhanced to 137.85 μg/(m2•h) and 0.98 μg/(m2•h) which were 2.9 and 2.0 times as high as those without stress, respectively. Except trans-α-bergamotene, emissions of all the detected monoterpene and sesquiterpene compounds were promoted under drought stress. Those emission rates were 1.3~42.4 times as high as those without stress. Among them, 3-carene emission had the most sensitive response to drought stress, while α-fenchene, α-phellandrene, and trans-caryophyllene had the lowest sensitivity. Under drought stress, the emission compositions of monoterpene and sesquiterpene were changed, but the dominant compounds remained the same. The main components of monoterpene were α-pinene, sabinene, and β-pinene, accounting for 48%, 17%, and 17% in the total monoterpene emissions, respectively. Trans-caryophyllene and longifolene dominated sesquiterpene emissions with contributions of 57% and 34%, respectively. © 2020, Editorial Board of China Environmental Science. All right reserved

典型树种挥发性有机物(VOCs)排放成分谱及排放特征

为研究典型树种的挥发性有机物(VOCs)排放特征,并获得基础排放速率,应用动态封闭式采样系统对毛果杨、北美枫香和马尾松的排放进行了实验室测量.利用热脱附-气相色谱-飞行质谱仪对排放样品进行定性和定量分析,包括异戊二烯、单萜烯、倍半萜烯、烷烃和烯烃,计算获得各树种VOCs排放速率及其排放谱特征.研究表明:毛果杨、北美枫香和马尾松的总VOCs排放速率分别为19.51、17.19和0.67mug/(g·h).毛果杨的异戊二烯排放最高(18.51mug/(g·h)),占其总排放的94.86%;马尾松排放的异戊二烯仅占4.03%,单萜烯贡献最高,为49.09%;北美枫香的单萜烯排放速率最高,为0.84mug/(g·h);3个树种排放的倍半萜烯占各自VOCs总排放的比重均较小(<1.5%);各树种的烷烃排放强度高于倍半萜烯,部分化合物甚至高于异戊二烯和单萜烯的排放强度.反式-beta-罗勒烯是毛果杨排放最多的单萜烯化合物,占其单萜烯总排放的99.84%;北美枫香排放的单萜烯主要以香桧烯和beta-蒎烯为主;马尾松以 alpha-蒎烯、香桧烯和beta-蒎烯为主.石竹烯、葎草烯、delta-杜松烯和beta-愈创木烯是主要的倍半萜烯物种.烷烃排放主要为C4和C5的化合物,特别是异丁烷和正丁烷;各树种排放的烯烃中,1-丁烯排放占比最高. In order to study the characteristics of biogenic volatile organic compounds (BVOCs) emission from typical trees and obtain their basic emission rates for each BVOC compound, a dynamic enclosed system was used to conduct laboratory measurements on poplar, sweetgum, and pine trees. BVOC compounds including isoprene, monoterpenes, sesquiterpenes, alkanes, and alkenes were analyzed by TD-GC-TOFMS. The normalized species-specific BVOC emission rates of three tree species were calculated and their emission profiles were investigated. The total BVOC emission rates of Populus trichocarpa, Liquidambar styraciflua, and Pinus massoniana were 19.51, 7.19, and 0.67mug/(g·h) (2086.91, 562.35, and 104.03mug/(m~2·h)), respectively. Populus trichocarpa had the highest isoprene emission rate of 18.51mug/(g·h), contributing 94.86% to the total BVOC emissions. Pinus massoniana had a lower isoprene contribution (4.03%), but the highest monoterpenes contribution (49.09%. Liquidambar styraciflua had the highest monoterpenes emission rate of 0.84mug/(g·h). Sesquiterpenes contributed less than 1.5% to the total BVOC emissions for the three plants. The emission rates of alkanes for each tree species were generally higher than those of sesquiterpenes, and some were even higher than those of isoprene and monoterpenes. Trans-beta-ocimene was the predominated monoterpene for Populus trichocarpa, accounting for 99.84% of its total monoterpene emissions. The monoterpenes emitted by Liquidambar styraciflua.was mainly composed by Sabinene and beta-pinene. alpha-Pinene, sabinene, and beta-pinene were observed as the dominated monoterpenes for Pinus massoniana. Trans-caryophyllene, humulene, delta-cadinene, and beta-guaiene were prominent sesquiterpenes. Alkanes emitted from the three plants were mainly C4 and C5 compounds, of which particularly were isobutane and butane. 1-Butene was the most abundant alkene for all plants

干旱胁迫对植物源挥发性有机物排放影响的研究进展

随着干旱频率和强度的增加，干旱胁迫对植物源挥发性有机物（BVOCs）的影响受到更多关注。文章综述了干旱胁迫对BVOCs排放影响方面取得的研究进展，探究了干旱胁迫对BVOCs排放的影响。根据近期国内外相关文献，将干旱程度进行划分，研究干旱、复水后对BVOCs排放速率、排放量的影响，探讨复合其他环境因子对BVOCs排放的影响，并探究干旱胁迫对BVOCs排放影响的机理。轻度干旱刺激BVOCs增加排放35%～190%，中度干旱抑制排放8%～97%，重度干旱抑制排放40%～100%。随着干旱程度的加深，BVOCs的排放先增加后减少。对复水的研究总结发现，轻度、中度干旱条件下，异戊二烯和单萜烯的排放速率恢复；重度干旱条件下，异戊二烯快速恢复，单萜烯未恢复。干旱导致BVOCs排放量的估算误差为-70%～40%。净光合速率和气孔导度对水分亏损的敏感度高于BVOCs。BVOCs的释放是植物应对干旱胁迫的保护机制。综述结果可以更好地评估BVOCs排放对当前及未来干旱胁迫情景下的响应，为大气复合污染防控提供支撑。As the frequency and intensity of drought increase the impact of drought stress on biogenic volatile organic com⁃pounds (BVOCs) has received more and more attentions. The research progress in the impact of drought stress on BVOCs emission was mainly reviewed. By characterizing the drought levels, the impact of drought parameters on BVOCs emission rates were reviewed, including the drought severity, rehydration, and other environmental factors. The mechanism of drought stress on BVOCs emission were also summarized and discussed. The existing studies can be divided into three categories, based on duration of dress and loss of soil water, including mild, moderate and severe levels. Previous studies found that BVOCs emission rates increased by 35%~190% during mild drought, but decreased by 8%~97% during moderate drought and by 40%~100% during severe droughts. Meanwhile, the emission rates of BVOCs were expected to increase at the beginning of drought and then decrease, because the release of BVOCs at certain degree can protect plants from drought stress. Previous studies on rehydration found that, under mild and moderate drought, the emission rates of isoprene and monoterpene were recovered after mild and moderate stress. Under severe drought conditions, the isoprene emission was recovered quickly, but monoterpene emission was not recovered. Studies on the mechanism of drought stress found the net photosynthetic rate and stomatal conductance were more sensitive to water loss than BVOC emissions. The uncertainties from drought stress on BVOCs emissions inventory varied by -70%~40%. The results of this review can better assess the response of BVOCs emissions from drought, and supports the prevention and control of complex air pollution in China

济南市城区大气挥发性有机物污染特征及来源

为研究济南市城区环境空气挥发性有机物(VOCs)污染特征及来源,2020-2021年于济南市城区开展了逐月离线观测,并于2020年6月开展加密观测,分析了VOCs年度、季节、日体积分数变化特征、化学组成及臭氧生成潜势,并利用特征比值法和正定矩阵因子分解模型解析了VOCs来源.结果表明,2021年济南市VOCs年均体积分数为(35.70±16.58)×10-9,较2020年改善14.48%,烷烃和OVOCs为VOCs中占比最高的两类组分.2020年VOCs体积分数均值呈冬高夏低季节特征,而2021年呈夏高春低季节特征,受济南市VOCs专项整治行动及北京冬奥会空气质量保障措施影响,2021年冬季VOCs体积分数均值较2020年改善最为明显,改善幅度为31.08%,2020年春季芳香烃贡献显著,可能与疫情管控后企业陆续复工复产有关.2020、2021年排名前十的组分主要为烷烃类与OVOCs,如丙烷、乙烷、正丁烷、甲醛、丙酮、乙醛等物种.2021年济南市城区OFP年均值为239.39μg/m3,较2020年下降22.46%,烷烃、炔烃、芳香烃、卤代烃OFP改善幅度分别为29.28%、3.09%、67.93%、83.49%,烯烃OFP明显上升,上升幅度为37.49%,OVOCs维持在较高水平.2020、2021年OFP排名前十的物种主要包括甲醛、乙醛、乙烯、1-丁烯、丙烯、对/间二甲苯等.臭氧重污染期间TVOCs体积分数日变化特征呈现明显的早晚高峰特征,中午时段为一天中的低值,夜间维持在较高水平.PMF解析结果表明:VOCs主要来源于工业源、燃烧源、油气挥发源、机动车尾气排放源、溶剂使用源、植物源及二次生成源,机动车尾气排放源、燃烧源及工业源为济南市VOCs的重点管控源. To study the characteristics and sources of ambient volatile organic compounds (VOCs) in urban Jinan, monthly offline observations from 2020 to 2021 and intensive observations in June 2020 were conducted. The inter-annual, seasonal, and daily concentration changes, chemical composition, and ozone formation potential (OFP) of VOCs were analyzed. Sources of VOCs were analyzed using the tracer ratio method and positive matrix factorization (PMF) model. The results indicated that the annual average mixing ratio of VOCs in urban Jinan in 2021 was (35.70 ± 16.58) ×10-9, an improvement of 14.48% compared to 2020, with alkanes and oxygenated VOCs (OVOCs) were the two major components of VOCs. The seasonal characteristics of the average mixing ratio of VOCs in 2020 showed a high in winter and a low in summer, while in 2021, it showed an increase in summer and a low in spring. Influenced by the special rectification action of VOCs in Jinan and the air quality assurance measures for the Beijing Winter Olympics, the average mixing ratio of VOCs in winter 2021 improved significantly compared to 2020, with an improvement rate of 31.08%. Aromatic hydrocarbons contributed significantly in the spring of 2020, which might be related to enterprises' gradual resumption of work under epidemic control. The top ten components in 2020 and 2021 are mainly alkanes and OVOCs, such as propane, ethane, n-butane, formaldehyde, acetone, and acetaldehyde. The annual value of OFP was 239.39µg/m3 in 2021, a decrease of 22.46% compared to 2020. The improvement rates of OFP for alkanes, alkynes, aromatics, and halogenated hydrocarbons were 29.28%, 3.09%, 67.93%, and 83.49%, respectively. The OFP for olefins increased significantly, with an increase rate of 37.49%. OVOCs remained at a relatively high level. The top ten species in OFP rankings in 2020 and 2021 mainly include formaldehyde, acetaldehyde, ethylene, 1-butene, propylene, and para/meta xylene. During heavy ozone pollution episodes, the daily variation characteristics of TVOCs volume fraction showed obvious morning and evening peak characteristics, with the noon period being the low value of the day and maintaining a high level at night. The PMF analysis showed that VOCs mainly came from industrial sources, combustion sources, oil and gas volatilization, motor vehicle exhaust emissions, solvent use sources, plant emissions, and secondary generation sources. Motor vehicle exhaust emissions, combustion sources, and industrial sources were critical sources of VOCs for O3 pollution control in Jinan. © 2024 Chinese Society for Environmental Sciences. All rights reserved

基于可解释性机器学习的滨海城市臭氧驱动因素

选取青岛16个环境空气监测点位（含8个国控点、7个省控点和1个背景点）大气污染物及相邻近气象点位数据，耦合极端梯度提升（XGBoost）模型，使用可解释性SHAP模块，探讨气象要素和大气污染物排放对臭氧(O3)的影响。结果表明，2019～2023年，气象因素对O3生成贡献率达67.7%，大气污染物排放对O3生成贡献率为32.3%。地表太阳辐射在10:00～17:00对O3生成贡献最大。相对湿度低于70%时有利于O3生成，特别是在12:00～16:00，相对湿度对O3生成有正向贡献，相对湿度高于70%对O3生成负贡献概率为94%。边界层高度低于500m时，对O3浓度有正向影响，超过该高度其影响将减弱，且早晨和午后时段，边界层高度对O3生成有正向作用。东风（E）到西南风（SW）对O3浓度有正向影响。NO2在06:00～11:00呈负响应，在12:00～15:00呈正响应。PM2.5在07:00～14:00对O3浓度有正向作用，在15:00～18:00则有抑制影响。O3浓度的主导因素在不同站点和季节间存在显著差异，其中崂山区西部、仰口、市南区西部、西海岸新区东部和西海岸新区西部点位地表面太阳辐射对O3影响明显低于其它各点位，崂山区西部、市南区西部、西海岸新区东部点位NO2的影响最大，西海岸新区东部、崂山区西部和仰口点位PM2.5对O3生成的影响显著高于青岛市其它点位。春季崂山区西部和市南区西部NO2的影响更为显著；夏季仰口、西海岸新区东部和西部、崂山区西部和市北区北部点位地表面太阳辐射影响更为显著，其余点位影响O3的关键因子为相对湿度；秋季温度和地表面太阳辐射是影响O3的主要因素；冬季NO2贡献高于其他季节，主要受高强度人为源排放的影响；O3超标日分析结果表明，地表面太阳辐射和NO2为主要驱动因素；各站点PM2.5和PM10对O3超标日总SHAP值在6.1～12.4μg·m-3。 Sixteen sites in the coastal city of Qingdao，including eight national control sites，seven provincial control sites，and one background site，were selected. By coupling the extreme gradient boosting（XGBoost）model with the interpretability SHapley Additive exPlanations（SHAP）module，the impact of meteorological elements and atmospheric pollutant emissions on ozone（O3）pollution was investigated. The results indicated that from 2019 to 2023，meteorological factors contributed 67.7% to O3 formation，whereas emissions from atmospheric pollutants accounted for 32.3%. Surface solar radiation significantly affected O3 formation from 10：00 to 17：00. A positive correlation existed between temperature and O3 concentration，peaking at 14：00. A relative humidity below 70% was conducive to O3 formation and a relative humidity above 70% had a 94% probability of negatively contributing to O3 production. Particularly between 12：00 and 16：00，relative humidity significantly and positively contributed to O3 formation. When the boundary layer height was below 500 meters，it positively affected O3 concentration，whereas above this height，its impact weakened. In the morning and late afternoon，boundary layer height promoted the formation of O3 concentration. Easterly（E）to southwesterly（SW）winds had a positive effect on O3 concentrations in Qingdao. NO2 showed a negative response in the morning（06：00-11：00）and a positive response in the afternoon（12：00-15：00）. PM2.5 had a nonlinear positive correlation with O3，positively affecting O3 concentration from 07：00 to 14：00 PM and suppressing it from 15：00 to 18：00. Significant differences existed in the dominant factors of O3 concentration across different areas and seasons. In the western Laoshan District，Yangkou，the western site of the Shinan District，and eastern and western parts of the West Coast New Area，surface solar radiation had a noticeably lower impact on O3 than in other locations. The effect of NO2 was most significant in the eastern parts of the West Coast New Area，western Laoshan District，and Yangkou. PM2.5 affected O3 formation more in these sites than in others of Qingdao. In spring，the impact of NO2 was more significant in the western Laoshan and Shinan Districts. In summer，surface solar radiation was more influential in Yangkou，the eastern and western parts of the West Coast New Area，the western Laoshan District，and the Shibei District，whereas，relative humidity was the key factor in other locations. In autumn，temperature and surface solar radiation were the main factors affecting O3. In winter，the contribution of NO2 was higher than that in different seasons，with anthropogenic emissions playing a more important role in O3 formation. The analysis of days exceeding O3 standards showed that surface solar radiation and NO2 were the main drivers of exceeding O3 concentrations. For all sites，the total SHAP values of PM2.5 and PM10 on days exceeding O3 standards ranged between 6.1 µg·m−3 and 12.4 µg·m−3 © 2025 Science Press. All rights reserved