我国大气中挥发性有机物的分布特征

李博伟，黄 宇，何世恒，薛永刚，刘随心，程 燕，王丽琴，曹军骥

我国大气中挥发性有机物的分布特征

李博伟1,2，黄 宇2，何世恒2，薛永刚2，刘随心2，程 燕1，王丽琴2，曹军骥2

1.西安交通大学 人居环境与建筑工程学院 地球环境科学系，西安 710049
2.中国科学院地球环境研究所 中国科学院气溶胶化学与物理重点实验室，西安 710061

大气中挥发性有机物（VOCs）是臭氧和二次有机气溶胶形成的关键前体物之一，研究表明烷烃、烯烃、芳香烃是我国大气VOCs的重要组分。在不同区域，城市地区烷烃含量最高，而偏远地区芳香烃为含量最丰富的VOCs。VOCs浓度日间变化多呈双峰分布趋势，峰值多出现在早晨与傍晚的上下班高峰期。目前对我国臭氧污染事件的研究均表明芳香烃和烯烃是对臭氧生成贡献最大的化合物。VOCs源解析中广泛运用的模型包括CMB、PMF和PCA/APCS，各模型均存在优点和局限性。比较各地VOCs源解析结果，发现交通排放源和工业排放源为我国VOCs的主要人为来源。VOCs的跨区域传输决定与周边地区的合作将是未来空气治理中的发展方向。

挥发性有机物（VOCs）；源解析；分布特征

挥发性有机物（volatile organic compounds，VOCs）是一类重要的空气污染物，主要包括烃类、醛酮类、酯类、醇类等。机动车尾气、溶剂使用、化石燃料的燃烧、工业生产过程为其主要人为来源（Mo et al，2014；王丽琴等，2016）。VOCs不仅对人体健康有明显的毒副作用，且是地表臭氧形成的重要前体物之一（Ait-Helal et al，2014）。此外，VOCs经过光化学反应可生成二次有机气溶胶（secondary organic aerosol，SOA）（曹军骥和李建军，2016）。Volkamer et al（2006）根据墨西哥市的研究结果推算出人为源VOCs每年可产生3 — 25 Tg SOA，占全球SOA总量的1/3。

高浓度的臭氧污染事件与人为源VOCs的大量排放密切相关。据统计，1990 — 2010年，随着欧美国家空气污染控制政策的有效实行，欧洲和美国VOCs浓度水平分别以每年3.3%、3.3%的速率下降，臭氧浓度水平分别以每年0.54%、0.66%的速率下降。受经济快速发展、汽车保有量急剧增加的影响，东亚国家VOCs和臭氧浓度水平近年来分别以每年2.3%和1.49%的速率上升（Xing et al，2015），在我国北京乡村地区夏季地表臭氧小时平均浓度最高可达286 ppbv（文中ppbv代表nL · L−1）（Xue et al，2014a）。高浓度的臭氧暴露可诱发人体呼吸系统、皮肤等机体的病变，从而引起住院率和死亡率增加，同时可导致农作物减产，研究表明美国小麦和大豆在高浓度臭氧环境中产量分别降低4.9%和6.7%（Wei et al，2014；Lapina et al，2016）。

光化学反应是近地表臭氧重要来源，臭氧的产率与VOCs和氮氧化物（nitrogen oxides，NOx）具有非线性关系（Perring et al，2013；Tie and Dai，2016）。当NOx浓度较低时，臭氧的产率随NOx浓度增加，称为NOx控制区；随着NOx浓度的增加，近地表臭氧的产率随NOx浓度增加的趋势减弱，臭氧产率随VOCs浓度升高而迅速升高，称为VOCs控制区（Sillman，1999）。我国多数城市臭氧的生成过程处于VOCs控制区，因此研究我国VOCs的排放特征和采取有效的控制措施对降低臭氧的生成量至关重要（Geng et al，2008；Shao et al，2009； Chen et al，2013；Tie et al，2013）。

在臭氧形成转换机制研究中，VOCs与NOx间比值等参数多是参考洛杉矶研究所确定的比值（Seinfeld，1989）。而中西方国家能源结构、植被覆盖率等因素的差异使臭氧形成机制的研究受到参考数据的限制。如我国汽油中烯烃含量远高于西方国家，机动车尾气产生的乙烯和丙烯对近地表臭氧具有重要贡献（Mo et al，2014）；而美国机动车尾气中烯烃含量显著低于中国，生物源异戊二烯为含量最高的不饱和烯烃（Baker et al，2008）。此外，我国大气组成（颗粒物，NOx，VOCs等）也与西方国家存在较大差异，因此国外标准不一定适用于我国污染情况，建立适用于我国的检测方法，结合WRF-Chem、CMAQ等数值模式对臭氧生成状况进行实际模拟是今后研究中亟待解决的问题。

研究我国大气VOCs的分布特征对采取有效的空气污染控制措施至关重要。本文综述了目前我国大气VOCs的时空分布特征，概述了高浓度臭氧事件与VOCs的关系，介绍了常用的VOCs源解析方法，包括正定矩阵因子分解法（positive matrix factorization，PMF）、化学质量平衡模型法（chemical mass balance，CMB），及主成分分析/绝对主成分得分法（principal component analysis/absolute principal component scores，PCA/ APCS），并展望了我国VOCs研究的发展趋势。

1 我国VOCs时空分布

VOCs的组成和分布随时间和空间而变化，了解我国不同区域VOCs的排放特征和分布状况，识别主要排放源和主要活性化合物，有利于确定应优先控制的污染物种类，提高污染物控制效率。

1.1 区域分布

我国幅员辽阔，南北方产业结构、气候条件和经济发展水平的差异导致排放到环境大气中的VOCs呈现出不同的理化特征。污染源强度是不同区域VOCs浓度与组成差异的重要原因。在城市地区，人为源是大气中VOCs的最主要来源，常见的VOCs人为源可分为六类：工业、居民煤燃烧，机动车尾气，燃料挥发，试剂挥发，石油化工，生物质燃烧等（Liu et al，2008b；Yuan et al，2010；Zhang et al，2013a；Zheng et al，2013； Wang et al，2014b；Wei et al，2014）。其中燃料挥发是大气中烷烃类VOCs的主要来源，异戊烷是其标志VOCs。而不饱和烃类和苯主要产生于燃料的不完全燃烧过程，常来源于汽车尾气排放。醇、醚、酯和苯系物等物质主要来自溶剂挥发，而工业过程易产生卤代烃（Wei et al，2012）。通过比较我国几个大城市地区的VOCs浓度水平（表1），发现广州和上海地区甲苯含量较高，可能与珠江三角洲地区存在较多的印刷、建筑装饰装修、电子和机械设备制造业大量的溶剂使用有关（Li and Wang，2012；Zou et al，2015）；而上海地区高浓度水平的甲苯（4.7 ppbv）主要与炼钢和燃煤电厂有关（Cai et al，2010）。不同于南方城市，北京地区机动车排放为VOCs的最大排放源，乙烷（6.38 ppbv）、丙烷（10.8 ppbv）较其他化合物含量高（Li et al，2015a）；与北京、上海、广州等地相比，兰州地区苯与甲苯比值最高，可能与存在不同于其他城市的一次排放源有关（Jia et al，2016）。

表1 我国主要城市VOCs平均浓度水平（ppbv）Tab.1 The average concentrations of VOCs in different cities in China （ppbv）

（待续 To be continued）

（续表1 Continued Tab.1）

城市地区能源消耗总量较高，燃料挥发、不完全燃烧及工业活动会排放大量的VOCs，与人类活动息息相关。如京津冀地区VOCs中浓度较高的是含碳数为4以下的烷烃，其次为烯烃和苯系物。Wang et al（2014b）估算了北京市VOCs的排放量，发现北京市TVOCs（total volatile organic compounds，TVOCs）排放量为（419 ± 201）Gg · a−1，其中非甲烷烃（non-methane hydrocarbons，NMHC）的排放量约为其他城市的两倍（表1）；而珠三角地区丙烷与苯系物的浓度较高，TVOCs的浓度（约20 — 40 ppbv）亦高于京津冀地区（约24 ppbv），与广州、深圳等地区制造业较多且珠三角地区出租车多使用液化石油气（liquefi ed petroleum gas，LPG）有关（Li et al，2015）。不同城市之间的VOCs排放特征差异显著。例如自1997年香港环保署推行清洁能源 —— 液化石油气的使用以来，截止到2010年底约有99%的出租车和51%的私家车以LPG为燃料，使香港地区大气中含量较高的VOCs由此前的甲苯转变为丙烷和丁烷（Ling and Guo，2014；Lyu et al，2016）；丙烯和乙炔在广州大气环境中含量较高（Li and Wang，2012）；北京地区机动车多以汽油为燃料，乙烯、乙炔和含碳数2 — 5的烷烃含量相对较高（Li et al，2015b）。

偏远地区大气中VOCs的组成与浓度主要受自然源排放及大气远距离传输的影响。研究显示，位于我国西南部的贡嘎山与山东中部泰山大气中主要产生自生物排放源的烯烃1-丁烯、异戊二烯等的排放比例（7% — 8%、4% — 7%）显著高于北京、上海、香港等城市（0.3% — 1%、0.2% — 2%），且由于芳烃较强的远距离传输能力，贡嘎山大气中芳烃类化合物排放比例相对较高，如贡嘎山和泰山大气中苯的比例分别为13.4%和12.8%，高于北京、上海、香港等城市地区（3% — 7%）（图1）（Mao et al，2009；Zhang et al，2014a）。Wei et al（2012）通过计算得出我国贵州、广西、四川等地大气中不饱和烃和苯比例高于东部发达城市（北京、天津、上海、浙江等），这与固定燃烧源和道路机动车排放源在各省市间的分布差异有关。

图1 不同地区1-丁烯、异戊二烯及苯的排放比例（单位：%）Fig.1 Emission ratios (Unit: %) of 1-butene, isoprene and benzene in different regions

1.2 垂直分布

VOCs的垂直分布受大气边界层结构、大气稳定性、风速风向和排放源等因素的影响，且不同高度处VOCs和NOx间存在不同的反应机制。飞机、热气球和高层建筑物是测定VOCs垂直浓度变化的主要辅助工具。VOCs浓度的垂直分布变化在雾霾天气或存在逆温层时更加明显，浓度峰值往往出现在近地面处。了解VOCs的垂直分布有助于对污染物垂直输送及化学传输模式的正确评估。

早在1996年，Kofl mann et al（1996）研究表明，随高度上升，高反应活性VOCs浓度比低反应活性VOCs浓度降低速度更快。Xue et al（2011）对我国东北地区NMHC的垂直分布进行了研究，发现化学寿命较长的物种，如乙烷和乙炔（寿命为数周至数月）在大气边界层及自由对流层中的混合比分别为地面处混合比的30% — 50%和12% — 34%，而对于化学寿命以时或天计的物种，如丁烷、戊烷和烯烃等，此值则分别为12% — 40%和3% — 23%。VOCs在垂直梯度上的变化亦可导致臭氧形成机制发生变化。Chen et al（2013）在2007 — 2010年对北京市航测实验的分析发现，在北京市上空约1 km处，臭氧生成从VOCs控制区转变为NOx控制区。不同大气污染条件下，VOCs的垂直分布存在较大差异。Mao et al（2008）在北京气象塔上布置VOCs的垂直梯度采样，发现晴天VOCs的垂直分布复杂，大多数VOCs的浓度与高度成反比，而雾霾天气下VOCs浓度在距地面8 — 140 m呈下降趋势，之后又开始上升直至280 m处，其中，乙酸乙酯及甲基异丁基酮仅存在于140 m以上，通过PCA及聚类分析证明不同高度处VOCs具有不同的来源。Lin et al（2011）研究发现，高雄市午夜23:00 — 1:00，13 m处的VOCs浓度水平高于地面，而早晨7:00 — 9:00，距地面32 m处浓度值高于13 m处，认为是受上风向工业污染源的影响或13 — 32 m有逆温层存在。

1.3 VOCs的时间变化

随着污染源强度和污染物归趋强度的变化，大气中VOCs的浓度与组成呈现显著的季节和昼夜差异。

1.3.1 季节变化趋势

驱动大气中VOCs浓度季节间变化的主要因素有以下几种：（1）光化学反应去除效应（主要是与OH自由基作用）。VOCs与OH自由基反应在温暖季节较快；（2）大气层混合稀释效应。温暖季节混合层较高，有利于污染物稀释扩散；（3）排放源的季节变化。

Guo et al（2004a）研究发现香港大气中VOCs的浓度与组成存在显著季节差异，其中城区大气中VOCs浓度的季节变化受一次排放源的控制，二氯甲烷、二甲苯和三甲苯在夏季时浓度略高于冬季，而氯甲烷、苯和四氯乙烯大气浓度峰值出现于冬季；北京地区由于夏季光化学反应较强，烷烃和烯烃浓度通常在11月份较高，在7月份浓度最低，而夏季芳香烃（甲苯、乙苯、二甲苯等）浓度与冬季相当且高于春季，可能与挥发作用的季节性变化有关（Liu et al，2005）；与城区不同，郊区大气VOCs浓度受大气边界层扩散速率的影响，从而郊区大气中多数VOCs化合物冬季的浓度高于夏季。Li and Wang（2012）研究中也发现类似的结果，由于广州属典型的亚热带气候，且受亚洲季风影响显著，大气VOCs浓度最高值往往出现在秋季，低值出现在春季。

在背景区，由于人为源影响减弱，大气中VOCs主要来源于大气远距离传输以及生物源排放（Tang et al，2007；Zhang et al，2014a），此外，人类的旅游活动也可能影响背景区大气VOCs的浓度与组成。由于春季旅游活动、较弱的光降解反应及大气混合效应，贡嘎山大气VOCs的浓度水平在春季（12.9 ppbv）高于秋季（6.44 ppbv）（Zhang et al，2014a）。对青藏高原高海拔地区的研究显示，夏季时大气中颗粒物主要由生物源VOCs氧化生成的气溶胶组成，而冬季则主要由远距离传输多环芳烃组成，间接说明偏远地区生物源VOCs排放主要集中于夏季（Shen et al，2015）。

1.3.2 昼夜变化趋势

VOCs浓度的昼夜变化主要受排放源、气象条件和光化学活性等因素的影响。在城市地区，VOCs浓度的日间变化多呈双峰变化（北京、上海、广州、南京等地）（Wang et al，2012），峰值多出现于早晨（8:00 — 10:00）及傍晚（18:00 — 20:00），最低值出现在14:00左右。早晨的VOCs浓度峰值多源于上班高峰期时较大的车流量，大量污染物难以在短时间内扩散而累积，之后随着太阳辐射增强，地面温度逐渐升高，诱导上层包含污染物的冷空气下移与近地面空气混合，从而使VOCs在早间出现浓度峰值（Xiong et al，2013）。与之相似，傍晚的浓度峰值可归结为以下两个原因：傍晚的下班高峰期及近地面空气随着阳光照射强度减弱而快速降温形成的逆温层阻止了污染物的扩散。午后较低的VOCs浓度则源于较强的太阳辐射和大气扩散能力。研究表明在中午日光照射最强且城区边界层高度达3000 m以上，有利于光化学反应的进行和污染物的扩散，从而使VOCs浓度在这一时间段内出现最低值（Guinot et al，2006）。大气生物源VOCs（biogenic volatile organic compounds，BVOCs）的浓度主要受植被影响，BVOCs的排放与植物生长密切相关。与人为污染源产生的VOCs不同，主要受天然排放源影响的异戊二烯的日间变化呈单峰变化，其峰值多出现在上午或者午后（Tang et al，2007；Wang et al，2013）。

2 大气VOCs的转化及其产物

2.1 含氧挥发性有机物（oxygenated volatile organic compounds，OVOCs）

OVOCs不仅可由人为源直接排放，也可由VOCs经大气自由基的氧化作用产生，图2以活性较强的异戊二烯为例展示了其在O3的强氧化作用下产生OVOCs的过程。OVOCs是VOCs氧化产生臭氧和SOA的重要中间产物，醛酮类为其主要组分。不同地区醛酮化合物含量差异显著，研究表明，北京市醛酮类化合物水平约为香港的3 — 5倍，为墨西哥城的35%（Liu et al，2015）。

图2 异戊二烯臭氧化的中间产物及反应产物Fig.2 Possible intermediates and reaction products generated in the ozonolysis of isoprene

目前用于定量醛酮化合物来源的常用方法有多元线性回归法及基于光化学反应强度的参数化方法（de Gouw et al，2005），后者考虑了醛酮化合物传输过程中的化学损失和二次生成。各计算过程中存在的诸多假设使研究者所得结果不一。Li et al（2010）用多元线性回归法得出北京市大气中的甲醛约76%来自人为源直接排放；而Yuan et al（2012）用参数化方法所得结果仅为22%，与Liu et al（2009）对北京市夏季的研究结果相似。诸多研究表明甲醛、乙醛和丙酮是我国各城市中检出的含量最丰富的OVOCs（Ho et al，2002；Mu et al，2007；Lü et al，2010；Dai et al，2012；Yuan et al，2012）。图3为各地检测出的甲醛、乙醛和丙酮的浓度水平，其中香港地区含量较低，而北京市丙酮含量显著高于其他城市。Louie et al（2013）研究发现，珠江三角洲地区大气中甲醛、乙醛和丙酮的浓度分别为（2530 ± 370）pptv（pptv=10−3ppbv）、（1110 ± 140）pptv、（2470 ± 370）pptv，约占OVOCs总量的80%。OVOCs的分布易受温度、光照强弱、相对湿度（relative humidity，RH）植被覆盖率等因素的影响。严重污染事件时，上海市醛酮化合物浓度水平与北京相当，略高于广州（图3）。Ho et al（2015）分析了我国九个城市中OVOCs的浓度水平，发现醛酮化合物含量最高的两个城市为武汉和成都，可能是由于武汉和成都光化学反应较强且存在大量的工业排放源；浓度最低值则出现在受海风影响较大的厦门和人为排放源较少的青海湖。

甲醛/乙醛（C1/C2）和乙醛/丙醛（C2/C3）的摩尔比常被用于判定甲醛的来源，城市地区C1/C2的值一般在1 — 2，乡村地区此值可达10（Shepson et al，1991；Possanzini et al，1996）（图3）。Ho et al（2015）分析了我国九个城市C1/C2值，其值为0.15 — 15.7，较高的比值说明受自然源影响严重。相比于其他醛酮类化合物，丙醛仅受人为源影响，因此C2/C3的值常表现为乡村高、城区低。

图3 我国各地甲醛、乙醛、丙酮含量（单位：μg · m−3）及C1/C2、C2/C3（据Ho et al（2014，2015）、 Cheng et al（2014）、Wang et al（2010b）修改））Fig.3 Concentration level (Unit: μg · m−3) of formaldehyde, acetaldehyde and acetone plus the molar ratio of C1/C2 and C2/C3 in different (Modifi ed from Ho et al (2014, 2015), Cheng et al (2014), Wang et al (2010b))

2.2 VOCs与地表臭氧污染

臭氧是大气的重要组成部分，平流层臭氧通过阻挡紫外线直接进入地表保护人类居住环境，而近地表臭氧由于具有较强的氧化能力，可危害人体健康。北半球观测到近地面臭氧浓度呈逐渐上升趋势，其中中纬度地表臭氧浓度在20 —45 ppbv，与一个世纪之前相比约增加了两倍，背景区臭氧浓度目前仍在上升（Vingarzan，2004）。在我国，华东地区的臭氧浓度在1990 — 2010年以每年1.49%的速率增长，北京市臭氧浓度以每年2%的速率增加（Xing et al，2015）。

地表臭氧主要来源于大气光化学反应和高层大气臭氧入侵（Vingarzan，2004），在臭氧形成的光化学反应中，VOCs与NOx是形成地表臭氧的前体物，目前研究中多认为地表臭氧浓度的升高趋势主要源于人类向环境大量排放的VOCs及NOx。Wu et al（2016）指出我国TVOCs年排放量在2008 — 2012年以每年7.38%的速率上升，而同时期内Ma et al（2016）发现我国东北部一乡村地区臭氧浓度水平亦呈上升趋势（图4）。由于各地区天气状况、盛行风向和污染源等因素不同，臭氧形成机制及其前体物来源存在差异。其中，Xue et al（2014a）研究发现广州、上海和兰州等地臭氧前体物主要来自本地源的贡献，而北京、香港近地面高浓度臭氧的生成则与周边地区VOCs污染物传输有关。Li et al（2015b）研究了京津冀地区近地面臭氧形成机理及VOCs在此过程中的作用，发现北京市35% — 60%的臭氧前体物来自天津、河北地区；2005 — 2011年，北京市夏季TVOCs浓度以每年6%的速率下降，而臭氧浓度则以每年5.3%的速率增长。此外，2002 — 2013年，香港地区活性芳香烃排放量逐渐下降，而臭氧浓度仍呈上升趋势，说明VOCs的区域传输可影响周边地区大气中的臭氧浓度（Xue et al，2014b；Zhang et al，2014b）。因此，若要有效治理VOCs和臭氧的污染，应加强同周边地区的合作。

图4 2008 — 2012年中国东北一乡村地区O3和全国TVOCs排放量变化趋势Fig.4 Temporal trend of O3in a rural area of northeastern China and TVOCs in China between 2008 — 2012

不同VOCs化合物因其活性不一，在臭氧生成中的贡献也不同。分析与甄别各地的活性VOCs及其来源对控制臭氧污染具有重要意义。通常采用最大增量反应活性法（maximum incremental reactivity，MIR）及等效丙烯浓度法评价不同反应活性的VOCs物种在臭氧生成中的贡献（Chameides et al，1992；Carter，1994）。研究表明，珠江三角洲地区臭氧形成中的关键活性物种为芳香烃（Shao et al，2009；Cheng et al，2010；Zhang et al，2012）。An et al（2014）用MIR法估算了南京地区VOCs的光化学反应活性，研究表明，烯烃对臭氧生成潜势（ozone formation potential，OFP）的贡献最大，说明该地影响臭氧生成的关键活性物质为烯烃。Wei et al（2014）在北京市炼油厂区的研究中发现烯烃亦是对OFP贡献最大的物种，占44.3%，其次为烷烃（29.6%）和芳香烃（26.1%）。其他城市的关键活性物种见表2。

基于光化学模式对我国臭氧的生成机制的研究表明，大城市中臭氧生成多处于VOCs控制区，而偏远地区多处于NOx控制区。Pan et al（2015）用区域大气化学机制模式（regional atmospheric chemistry mechanism，RACM），对长江三角洲乡村地区秋收期（露天秸秆燃烧频发）臭氧的生成进行了研究，结果表明臭氧生成在早晨受控于VOCs，下午由于光化学反应对NOx的快速去除而受NOx控制。NOx/VOCs排放比的变化对区域范围内臭氧生成具有重要影响，Tie et al（2013）用WRF-Chem模式对上海市臭氧形成的研究表明，当NOx/VOCs值约为0.4时，上海地区处于VOCs控制区，当NOx/VOCs值为0.1左右时则处于NOx控制区。

3 我国VOCs源解析

我国 VOCs 排放源种类多、排放成分复杂。了解各地主要VOCs排放源及各排放源所占比例，对我国大气复合污染研究的开展及污染控制策略的制定具有重要意义。

3.1 常用源解析方法

VOCs源解析受体模型包括多种多元统计方法，因其不受排放源的排放条件、地形和气象数据等因素的限制，而常被用于识别空气污染物的来源及其贡献。常见污染源有特征示踪物（表3），如乙烯和乙炔为燃烧源示踪物；汽油挥发源常以异戊烷、正丁烷和异丁烯作示踪化合物；工业排放源中卤代烃含量较高；甲苯、乙苯和二甲苯等芳香烃则常来自于溶剂使用源。目前我国常用的受体模型有CMB、PCA/APCS和PMF模型等，其中PMF模型和CMB模型是美国环保署（United States Environmental Protection Agency，USEPA）推荐的源解析技术（http://www3.epa.gov/ttn/scram/ receptorindex.htm）。CMB、PCA/ APCS和PMF各有其优缺点（详见表4），如CMB虽然原理清楚、容易操作，但需要预先了解详细的VOCs源成分谱；而PMF虽不需预先知道污染源成分谱，却难以解析活性较强的VOCs来源。生物源排放的VOCs多为活性较强的物质，受体模型对该来源进行解析时往往只选取异戊二烯作为示踪物质，从而所得生物源占比往往较低（Fujita et al，1995）。因此本文只重点讨论我国大气中VOCs的主要人为来源。

表2 我国城市地区对臭氧生成贡献最大的10种VOCsTab.2 The top 10 VOCs contribute to ozone formation in urban areas

表3 常见排放源的相应示踪物Tab.3 Tracers of common emission sources

表4 主要源解析方法比较Tab.4 Comparisons between different source apportionment methods

3.2 我国VOCs的主要人为源

国外对大气中VOCs的源解析研究起步较早，20世纪70年代USEPA就发行了应用软件CMB1.0，经不断完善，目前已发展至CMB8.0版本（Fujita et al，1995；Scheff et al，1996；Na and Pyo Kim，2007；Zielinska et al，2014）。我国VOCs源解析的工作于20世纪80年代末才逐渐开展，由于我国相应的源谱信息匮乏，所以CMB模型应用不如PMF应用广泛。Wang et al（2010a）运用CMB解析了北京地区55种VOCs的来源，CMB模型运行参数R2、χ2变化范围分别为0.83 — 0.90和2.74 — 4.08，结果表明该地区VOCs主要来源为机动车尾气和汽油挥发。

PMF能够同时确定污染源个数及其所占百分比，但需要的样品量较大，Huang et al（2015）用PMF解析出LPG为香港路边大气环境中VOCs的最大来源；相比于其他源解析方法，PCA对活性较强的化合物具有较好的解析结果，但该源解析模型只能识别5 — 8个排放源且要求用于分析的样品数量不低于50个，解析结果不及PMF细致，如在PMF解析结果中汽车尾气和汽油挥发为两个源，而PCA中不能将两个源分开；An et al（2014）运用PCA/APCS模型解析南京工业区环境中VOCs来源，结果表明工业生产和机动车排放为该地区VOCs的主要来源。

众多研究表明，我国城市地区VOCs的主要来源为交通排放源和工业排放源（图5）。研究表明，北京市加强空气质量管理期间，环境中VOCs水平降低主要由对机动车与工业源排放的控制所引起，两者在VOCs减排中的贡献分别为50%和27%，源解析结果亦表明北京市VOCs主要来源于机动车（46%）和工业源排放（24%）。与北京、南京、香港等城市相比，上海市溶剂使用源贡献较高（19.4%），或与上海市存在较多的印刷制造业有关。香港地区机动车多以LPG为燃料且家庭烹饪中LPG的运用也日益增多，使LPG对香港大气中VOCs的贡献（41.3%）显著高于我国其他地区（Lau et al，2010）。汽油车排放、工业排放和LPG与助燃剂排放为珠江三角洲地区VOCs最主要来源，三者贡献率分别为23%、16%、13%，其中交通排放源的贡献率与上海地区（25%）相近而显著低于北京地区（46%），可能与北京市较大的机动车保有量相关（Cai et al，2010；Yuan et al，2013；Li et al，2015a）。而且归类方法（交通排放源是否包括汽油车尾气和汽油蒸发等）、源解析方法和采样时间段的差异也可能是部分原因。天津城区所植绿化树种多为释放VOCs较多的阔叶树种，使该地区植被排放源贡献（14%）显著，甚至高于其在植被覆盖率较高的贡嘎山VOCs来源（5%）中所占比例。随着产业结构及相关政策的转变，Wei et al（2012）研究表明，我国溶剂使用源和工业过程源正在逐渐代替道路交通源，成为VOCs的最大排放源。

图5 我国各地区排放源所占百分比Fig.5 Contribution percentages for major emission sources in different areas

4 结论与展望

目前，国内学者对大气中VOCs的研究主要集中在其浓度组成的时空变化特征、来源，及对臭氧生成的贡献等方面，多数研究表明，烷烃、烯烃、芳香烃为我国各大城市中VOCs的主要组分，其中城市地区烷烃含量最高，而泰山、贡嘎山等背景地区，芳香烃为含量最丰富的VOCs。VOCs浓度日间变化多呈双峰分布趋势，峰值常在早晨及傍晚的上下班高峰期出现。各地区臭氧污染事件不仅与本地排放源有关，外地污染气团的跨界传输也不容忽视。

随着国家对环境保护的重视，VOCs被纳入主要污染物总量控制范围，目前北京、上海、江苏、安徽、湖南5个地区已出台VOCs排污费征收办法，明确指出对石油炼制、油品储运及销售、汽车船舶制造等企业征收VOCs排污费。在现有法规和政策逐步出台及强化的现状下，根据以往研究中所得结论与经验，建立各地排放清单、完善源解析手段及监测方法、确定各地臭氧形成中的关键活性化合物是我国今后VOCs研究的主要内容。

曹军骥, 李建军. 2016. 二次有机气溶胶的形成及其毒理效应[J]. 地球环境学报, 7(5): 431 – 441. [Cao J J, Li J J. 2016. Formation and toxicological effect of secondary organic aerosols [J]. Journal of Earth Environment, 7(5): 431 – 441.]

王丽琴, 李博伟, 黄 宇, 等. 2016. 环境中挥发性有机物监测及分析方法[J]. 地球环境学报, 7(2): 130 – 139. [Wang L Q, Li B W, Huang Y, et al. 2016. The monitoring and analysis methods of volatile organic compounds in the ambient air [J]. Journal of Earth Environment, 7(2): 130 – 139.]

Ait-Helal W, Borbon A, Sauvage S, et al. 2014. Volatile and intermediate volatility organic compounds in suburban Paris: variability, origin and importance for SOA formation [J]. Atmospheric Chemistry and Physics, 14(19): 10439 – 10464. An J, Zhu B, Wang H, et al. 2014. Characteristics and source apportionment of VOCs measured in an industrial area of Nanjing, Yangtze River Delta, China [J]. Atmospheric Environment, 97: 206 – 214.

Baker A K, Beyersdorf A J, Doezema L A, et al. 2008. Measurements of nonmethane hydrocarbons in 28 United States cities [J]. Atmospheric Environment, 42(1): 170 – 182.

Bertman S, Robert J, Parrish D D, et al. 1995. Evolution of alkyl nitrates with air massage [J]. Journal of Geophysical Research, 100(D11): 22805 – 22813.

Blake D R, Rowland F S. 1995. Urban leakage of liquefied petroleum gas and its impact on Mexico City air quality [J]. Science, 269: 953 – 956.

Cai C, Geng F, Tie X, et al. 2010. Characteristics and source apportionment of VOCs measured in Shanghai, China [J]. Atmospheric Environment, 44(38): 5005 – 5014.

Carter W P L. 1994. Development of ozone reactivity scales for volatile organic compounds [J]. Air & Waste Management Association, 44: 881 – 899.

Chameides W L, Fehsenfel F, Rodger M O, et al. 1992. Ozone precursor relationships in the ambient atmosphere [J]. Journal of Geophysical Research, 97(D5): 6037 – 6055.

Chen P, Quan J, Zhang Q, et al. 2013. Measurements of vertical and horizontal distributions of ozone over Beijing from 2007 to 2010 [J]. Atmospheric Environment, 74: 37 – 44.

Cheng H R, Guo H, Saunders S M, et al. 2010. Assessing photochemical ozone formation in the Pearl River Delta with a photochemical trajectory model [J]. Atmospheric Environment, 44(34): 4199 – 4208.

Cheng Y, Lee S C, Huang Y, et al. 2014. Diurnal and seasonal trends of carbonyl compounds in roadside, urban, and suburban environment of Hong Kong [J]. Atmospheric Environment, 89: 43 – 51.

Dai W T, Ho S S H, Ho K F, et al. 2012. Seasonal and diurnal variations of mono- and di-carbonyls in Xi’an, China [J]. Atmospheric Research, 113: 102 – 112.

de Gouw J A, Middlebrook A M, Warneke C, et al. 2005. Budget of organic carbon in a polluted atmosphere: results from the New England air quality study in 2002 [J]. Journal of Geophysical Research, 110(D16). DOI: 10.1029/2004JD005623.

Duan J, Tan J, Yang L, et al. 2008. Concentration, sources and ozone formation potential of volatile organic compounds (VOCs) during ozone episode in Beijing [J]. Atmospheric Research, 88(1): 25 – 35.

Fujita E M, Watson J G, Chow J C, et al. 1995. Receptor model and emissions inventory source apportionments of nonmethane organic gases in California’s San JoaquinValley and San Francisco Bay Area [J]. Atmospheric Environment, 29: 3019 – 3035.

Geng F, Tie X, Xu J, et al. 2008. Characterizations of ozone, NOx, and VOCs measured in Shanghai, China [J]. Atmospheric Environment, 42(29): 6873 – 6883.

Gertler A W, Fujita E M, Pierson W R. 1996. Apportionment of NMHC tailpipe vs non-tailpipe emissions in the Fort McHenry and Tuscarora Mountain Tunnels [J]. Atmospheric Environment, 30(12): 2297-2305.

Guenther A, Hsewit C N, Erickso D, et al. 1995. A global model of natural volatile organic compound emissions [J]. Journal of Geophysical Research, 100(5): 8873 – 8892.

Guinot B, Roger J C, Cachier H, et al. 2006. Impact of vertical atmospheric structure on Beijing aerosol distribution [J]. Atmospheric Environment, 40(27): 5167 – 5180.

Guo H, Lee S C, Louie P K, et al. 2004a. Characterization of hydrocarbons, halocarbons and carbonyls in the atmosphere of Hong Kong [J]. Chemosphere, 57(10): 1363 – 1372.

Guo H, So K L, Simpson I J, et al. 2007. C1— C8volatile organic compounds in the atmosphere of Hong Kong: Overview of atmospheric processing and source apportionment [J]. Atmospheric Environment, 41(7): 1456 – 1472.

Guo H, Wang T, Louie P K. 2004b. Source apportionment of ambient non-methane hydrocarbons in Hong Kong: application of a principal component analysis/absolute principal component scores (PCA/APCS) receptor model [J]. Environmental Pollution, 129(3): 489 – 498.

Han M, Lu X, Zhao C, et al. 2015. Characterization and source apportionment of volatile organic compounds in urban and suburban Tianjin, China [J]. Advances in Atmospheric Sciences, 32(3): 439 – 444.

Ho K F, Ho S S H, Dai W T, et al. 2014. Seasonal variations of monocarbonyl and dicarbonyl in urban and sub-urban sites of Xi’an, China [J]. Environmental Monitoring and Assessment, 186(5): 2835 – 2849.

Ho K F, Ho S S H, Huang R J, et al. 2015. Spatiotemporal distribution of carbonyl compounds in China [J]. Environmental Pollution, 197: 316 – 324.

Ho K F, Lee S C, Louie P K K, et al. 2002. Seasonal variation of carbonyl compound concentrations in urban area of Hong Kong [J]. Atmospheric Environment, 36: 1259 – 1265.

Hopke P K. 2003. Recent developments in receptor modeling [J]. Journal of Chemometrics, 17: 255 – 265. Huang Y, Ling Z H, Lee S C, et al. 2015. Characterization of volatile organic compounds at a roadside environment in Hong Kong: An investigation of influences after air pollution control strategies [J]. Atmospheric Environment, 122: 809 – 818.

Jia C H, Mao X X, Huang T, et al. 2016. Non-methane hydrocarbons (NMHCs) and their contribution to ozone formation potential in a petrochemical industrialized city, Northwest China [J]. Atmospheric Research, 169: 225 – 236.

Kofl mann M, Vogel H, Vogel B, et al. 1996. The composition and vertical distribution of volatile organic compounds in Southwestern Germany, Eastern France and Northern Switzerland during the TRACT Campaign in September 1992 [J]. Physics and Chemistry of the Earth, 21(5/6): 429 – 433.

Lai C H, Peng Y P. 2012. Volatile hydrocarbon emissions from vehicles and vertical ventilations in the Hsuehshan traffi c tunnel, Taiwan [J]. Environmental Monitoring and Assessment, 184(7): 4015 – 4028.

Lam S H M, Saunders S M, Guo H, et al. 2013. Modelling VOC source impacts on high ozone episode days observed at a mountain summit in Hong Kong under the infl uence of mountain-valley breezes [J]. Atmospheric Environment, 81: 166 – 176.

Lapina K, Henze D K, Milford J B, et al. 2016. Impacts of foreign, domestic, and state-level emissions on ozone-induced vegetation loss in the United States [J]. Environmental Science &Technology, 50(2): 806 – 813.

Lau A K, Yuan Z B, Yu J Z, et al. 2010. Source apportionment of ambient volatile organic compounds in Hong Kong [J]. Science of the Total Environment, 408(19): 4138 – 4149.

Li J, Xie S D, Zeng L M, et al. 2015a. Characterization of ambient volatile organic compounds and their sources in Beijing, before, during, and after Asia-Pacific Economic Cooperation China 2014 [J]. Atmospheric Chemistry and Physics, 15(14): 7945 – 7959.

Li L F, Wang X M. 2012. Seasonal and diurnal variations of atmospheric non-methane hydrocarbons in Guangzhou, China [J]. International Journal of Environmental Research and Public Health, 9(5): 1859 – 1873.

Li L Y, Xie S D, Zeng L M, et al. 2015b. Characteristics of volatile organic compounds and their role in ground-level ozone formation in the Beijing-Tianjin-Hebei region,China [J]. Atmospheric Environment, 113: 247 – 254.

Li Y, Shao M, Lu S H, et al. 2010. Variations and sources of ambient formaldehyde for the 2008 Beijing Olympic Games [J]. Atmospheric Environment, 44(21/22): 2632 – 2639.

Lin C C, Lin C, Hsieh L T, et al. 2011. Vertical and diurnal characterization of volatile organic compounds in ambient air in urban areas [J]. Journal of the Air & Waste Management Association, 61(7): 714 – 720.

Ling Z H, Guo H. 2014. Contribution of VOC sources to photochemical ozone formation and its control policy implication in Hong Kong [J]. Environmental Science & Policy, 38: 180 – 191.

Liu Y, Shao M, Fu L, et al. 2008a. Source profiles of volatile organic compounds (VOCs) measured in China: Part Ⅰ [J]. Atmospheric Environment, 42(25): 6247 – 6260.

Liu Y, Shao M, Kuster W C, et al. 2009. Source Identifi cation of Reactive Hydrocarbons and Oxygenated VOCs in the Summer time in Beijing [J]. Environmental Science &Technology, 43(1): 75 – 81.

Liu Y, Shao M, Lu S, et al. 2008b. Volatile organic compound (VOC) measurements in the Pearl River Delta (PRD) region, China [J]. Atmospheric Chemistry and Physics, 8: 1531 – 1545.

Liu Y, Shao M, Zhang J, et al. 2005. Distributions and source apportionment of ambient volatile organic compounds in Beijing city, China [J]. Journal of Environmental Science and Health Part A, Toxic, 40(10): 1843 – 1860.

Liu Y, Yuan B, Li X, et al. 2015. Impact of pollution controls in Beijing on atmospheric oxygenated volatile organic compounds (OVOCs) during the 2008 Olympic Games: observation and modeling implications [J]. Atmospheric Chemistry and Physics, 15(6): 3045 – 3062.

Louie P K K, Ho J W K, Tsang R C W, et al. 2013. VOCs and OVOCs distribution and control policy implications in Pearl River Delta region, China [J]. Atmospheric Environment, 76: 125 – 135.

Lü H X, Cai Q Y, Wen S, et al. 2010. Seasonal and diurnal variations of carbonyl compounds in the urban atmosphere of Guangzhou, China [J]. Science of the Total Environment, 408(17): 3523 – 3529.

Lyu X P, Guo H, Simpson I J, et al. 2016. Effectiveness of replacing catalytic converters in LPG-fueled vehicles in Hong Kong [J]. Atmospheric Chemistry and Physics, 16(10): 6609 – 6626.

Ma Z Q, Xu J, Quan W J, et al. 2016. Signifi cant increase of surface ozone at a rural site, north of eastern China [J]. Atmospheric Chemistry and Physics, 16(6): 3969 – 3977.

Mao T, Wang Y S, Jiang J, et al. 2008. The vertical distributions of VOCs in the atmosphere of Beijing in autumn [J]. Science of the Total Environment, 390(1): 97 – 108.

Mao T, Wang Y S, Xu H H, et al. 2009. A study of the atmospheric VOCs of Mount Tai in June 2006 [J]. Atmospheric Environment, 43(15): 2503 – 2508.

Mo Z W, Shao M, Lu S H. 2014. Review on volatile organic compounds (VOCs) source profi les measured in China [J]. Acta Scientiae Circumstantiae, 34(9): 2179 – 2189.

Mu Y, Pang X, Quan J, et al. 2007. Atmospheric carbonyl compounds in Chinese background area: A remote mountain of the Qinghai-Tibetan Plateau [J]. Journal of Geophysical Research, 112(D22). DOI: 10.1029/2006JD008211.

Na K, Pyo Kim Y. 2007. Chemical mass balance receptor model applied to ambient C2—C9VOC concentration in Seoul, Korea: Effect of chemical reaction losses [J]. Atmospheric Environment, 41(32): 6715 – 6728.

Ou J, Guo H, Zheng J, et al. 2015. Concentrations and sources of non-methane hydrocarbons (NMHCs) from 2005 to 2013 in Hong Kong: A multi-year real-time data analysis [J]. Atmospheric Environment, 103: 196 – 206.

Pan X, Kanaya Y, Tanimoto H, et al. 2015. Examining the major contributors of ozone pollution in a rural area of the Yangtze River Delta region during harvest season [J]. Atmospheric Chemistry and Physics, 15(11): 6101 – 6111. Perring A E, Pusede S, Cohen R C. 2013. An observational perspective on the atmospheric impacts of alkyl and multifunctional nitrates on ozone and secondary organic aerosol [J]. Chemical Reviews, 113: 5848 – 5870.

Possanzini M, Dipalo V, Petricca M, et al. 1996. Measurements of lower carbonyls in Rome ambient air [J]. Atmospheric Environment, 30(22): 3757 – 3764.

Scheff P A, Wadden R A, Kenski D M, et al. 1996. Receptor model evaluation of the Southeast Michigan Ozone Study ambient NMOC measurements [J]. Journal of the Air & Waste Management Association, 46(11): 1048 – 1057.

Seila R L, Main H H, Arriaga J L, et al. 2001. Atmospheric volatile organic compound measurements during the 1996 Paso del Norte Ozone Study [J]. Science of the Total Environment, 276: 153 – 169.

Seinfeld J H. 1989. Urban air pollution: state of the science [J]. Science, 243: 745 – 752.

Shao M, Zhang Y H, Zeng L M, et al. 2009. Ground-level ozone in the Pearl River Delta and the roles of VOC and NOxin its production [J]. Journal of Environmental Management, 90: 512 – 518.

Shen R, Ding X, He Q, Cong Z, et al. 2015. Seasonal variation of secondary organic aerosol in Nam Co, Central Tibetan Plateau [J]. Atmospheric Chemistry and Physics Discussions, 15: 7141 – 7169.

Shepson P B, Hastie D R, Schiff H I, et al. 1991. Atmospheric concentrations and temporal variations of C1—C3carbonyl compounds at two rural sites in central Ontatio [J]. Atmospheric Environment, 25(9): 2001 – 2015.

Sillman S. 1999. The relation between ozone, NOxand hydrocarbons in urban and polluted rural environments [J]. Atmospheric Environment, 33: 1821 – 1845.

Simpson I J, Blake N J, Blake D R, et al. 2003. Photochemical production and evolution of selected C2— C5alkyl nitrates in tropospheric air influenced by Asian outflow [J]. Journal of Geophysical Research: Atmospheres (1984—2012), 108(D20). DOI: 10.1029/2002JD002830.

Song Y, Dai W, Shao M, et al. 2008. Comparison of receptor models for source apportionment of volatile organic compounds in Beijing, China [J]. Environmental Pollution, 156(1): 174 – 183.

Song Y, Shao M, Liu Y, et al. 2007. Source apportionment of ambient volatile organic compounds in Beijing [J]. Environmental Science &Technology, 41: 4348 – 4353.

Tan J H, Guo S J, Ma Y L, et al. 2012. Non-methane hydrocarbons and their ozone formation potentials in Foshan, China [J]. Aerosol and Air Quality Research, 12: 387 – 398.

Tang J H, Chan L Y, Chan C Y, et al. 2007. Characteristics and diurnal variations of NMHCs at urban, suburban, and rural sites in the Pearl River Delta and a remote site in South China [J]. Atmospheric Environment, 41: 8620 – 8632.

Tie X X, Dai W T. 2016. Ozone (O3) pollution in eastern China: It’s formation and a potential air quality problem in the region [J]. Journal of Earth Environment, 7(1): 37 – 43.

Tie X X, Geng F, Guenther A, et al. 2013. Megacity impacts on regional ozone formation: observations and WRF-Chem modeling for the MIRAGE-Shanghai fi eld campaign [J]. Atmospheric Chemistry and Physics, 13(11): 5655 – 5669. Tsai J H, Lin K H, Chen C Y, et al. 2008. Volatile organic compound constituents from an integrated iron and steel facility [J]. Journal of Hazardous Materials, 157(2/3): 569 – 578.

Vingarzan R. 2004. A review of surface ozone background levels and trends [J]. Atmospheric Environment, 38: 3431 – 3442.

Volkamer R, Jimenez J L, San Martini F, et al. 2006. Secondary organic aerosol formation from anthropogenic air pollution: Rapid and higher than expected [J]. Geophysical Research Letters, 33(17). DOI: 10.1029/2006GL026899.

Wang B, Shao M, Lu S H, et al. 2010a. Variation of ambient non-methane hydrocarbons in Beijing city in summer 2008 [J]. Atmospheric Chemistry and Physics, 10(13): 5911 – 5923.

Wang H K, Huang C H, Chen K S, et al. 2010b. Measurement and source characteristics of carbonyl compounds in the atmosphere in Kaohsiung city, Taiwan [J]. Journal of hazardous materials, 179(1/2/3): 1115 – 1121.

Wang H L, Chen C H, Wang Q, et al. 2013. Chemical loss of volatile organic compounds and its impact on the source analysis through a two-year continuous measurement [J]. Atmospheric Environment, 80: 488 – 498.

Wang H, Qiao Y, Chen C, et al. 2014a. Source profiles and chemical reactivity of volatile organic compounds from Solvent Use in Shanghai, China [J]. Aerosol and Air Quality Research, 14(1): 301 – 310.

Wang M, Shao M, Chen W, et al. 2014b. A temporally and spatially resolved validation of emission inventories by measurements of ambient volatile organic compounds in Beijing, China [J]. Atmospheric Chemistry and Physics, 14(12): 5871 – 5891.

Wang Y S, Ren X Y, Ji D S, et al. 2012. Characterization of volatile organic compounds in the urban area of Beijing from 2000 to 2007 [J]. Journal of Environmental Sciences, 24(1): 95 – 101.

Wang Y, Qi F, Lun X X, et al. 2010c. Temporal and spatial distribution rule of volatile organic compounds in ambient air around urban traffi c roads in Beijing [J]. Research of Environmental Sciences, 23(5): 596 – 600.

Watson J G, Chow J C, Fujita E M. 2001. Review of volatile organic compound source apportionment by chemical mass balance [J]. Atmospheric Environment, 35: 1567 – 1584.

Wei W, Cheng S Y, Li G H, et al. 2014. Characteristics of ozone and ozone precursors (VOCs and NOx) around a petroleum refinery in Beijing, China [J]. Journal of EnvironmentalSciences, 26(2): 332 – 342.

Wei W, Wang S X, Hao J M, et al. 2012. Trends of chemical speciation profiles of anthropogenic volatile organic compounds emissions in China, 2005—2020 [J]. Frontiers of Environmental Science & Engineering, 8(1): 27 – 41.

Wu R R, Bo Y, Li J, et al. 2016. Method to establish the emission inventory of anthropogenic volatile organic compounds in China and its application in the period 2008—2012 [J]. Atmospheric Environment, 127: 244 – 254.

Xia L, Cai C J, Zhu B, et al. 2014. Source apportionment of VOCs in a suburb of Nanjing, China, in autumn and winter [J]. Journal of Atmospheric Chemistry, 71(3): 175 – 193.

Xing J, Mathur R, Pleim J, et al. 2015. Observations and modeling of air quality trends over 1990—2010 across the Northern Hemisphere: China, the United States and Europe [J]. Atmospheric Chemistry and Physics, 15(5): 2723 – 2747.

Xiong Z H, Qian F, Feng X, et al. 2013. Review of distribution characteristics and sources of volatile organic compound in atmosphere [J]. Advanced Materials Research, 726/727/728/729/730/731: 944 – 949.

Xue L K, Wang T, Gao J, et al. 2014a. Ground-level ozone in four Chinese cities: precursors, regional transport and heterogeneous processes [J]. Atmospheric Chemistry and Physics, 14(23): 13175 – 13188.

Xue L K, Wang T, Louie P K, et al. 2014b. Increasing external effects negate local efforts to control ozone air pollution: a case study of Hong Kong and implications for other Chinese cities [J]. Environmental Science &Technology, 48(18): 10769 – 10775.

Xue L K, Wang T, Simpson I J, et al. 2011. Vertical distributions of non-methane hydrocarbons and halocarbons in the lower troposphere over northeast China [J]. Atmospheric Environment, 45(36): 6501 – 6509.

Yuan B, Chen W T, Shao M, et al. 2012. Measurements of ambient hydrocarbons and carbonyls in the Pearl River Delta (PRD), China [J]. Atmospheric Research, 116: 93 – 104.

Yuan B, Shao M, Lu S, et al. 2010. Source profi les of volatile organic compounds associated with solvent use in Beijing, China [J]. Atmospheric Environment, 44(15): 1919 – 1926. Yuan Z, Zhong L, Lau A K H, et al. 2013. Volatile organic compounds in the Pearl River Delta: Identification of source regions and recommendations for emission-oriented monitoring strategies [J]. Atmospheric Environment, 76: 162 – 172.

Zhang J K, Sun Y, Wu F K, et al. 2014a. The characteristics, seasonal variation and source apportionment of VOCs at Gongga Mountain, China [J]. Atmospheric Environment, 88: 297 – 305.

Zhang Q, Yuan B, Shao M, et al. 2014b. Variations of groundlevel O3and its precursors in Beijing in summertime between 2005 and 2011[J]. Atmospheric Chemistry and Physics, 14(12): 6089 – 6101.

Zhang Y L, Wang X M, Barletta B, et al. 2013a. Source attributions of hazardous aromatic hydrocarbons in urban, suburban and rural areas in the Pearl River Delta (PRD) region [J]. Journal of hazardous materials, 250: 403 – 411. Zhang Y L, Wang X M, Blake D R, et al. 2012. Aromatic hydrocarbons as ozone precursors before and after outbreak of the 2008 financial crisis in the Pearl River Delta region, south China [J]. Journal of Geophysical Research, 117(D15). DOI: 10.1029/2011JD017356.

Zhang Y L, Wang X M, Zhang Z, et al. 2013b. Species profi les and normalized reactivity of volatile organic compounds from gasoline evaporation in China [J]. Atmospheric Environment, 79: 110 – 118.

Zheng J, Yu Y, Mo Z, Zhang, Z, et al. 2013. Industrial sectorbased volatile organic compound (VOC) source profiles measured in manufacturing facilities in the Pearl River Delta, China [J]. Science of the Total Environment, 456: 127 – 136.

Zielinska B, Campbell D, Samburova V. 2014. Impact of emissions from natural gas production facilities on ambient air quality in the Barnett Shale area: A pilot study [J]. Journal of the Air & Waste Management Association, 64(12): 1369 – 1383.

Zou Y, Deng X J, Zhu D, et al. 2015. Characteristics of 1 year of observational data of VOCs, NOxand O3at a suburban site in Guangzhou, China [J]. Atmospheric Chemistry and Physics, 15(12): 6625 – 6636.

Characteristics of volatile organic compounds in China

LI Bowei1,2, HUANG Yu2, HO Steven Sai Hang2, XUE Yonggang2, LIU Suixin2, CHENG Yan1, WANG Liqin2, CAO Junji2
1. Department of Environmental Science and Technology, School of Human Settlements and Civil Engineering, Xi’an Jiaotong University, Xi’an 710049, China
2. Key Laboratory of Aerosol Chemistry and Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710061, China

Background, aim, and scope Volatile organic compounds (VOCs) are a series of atmospheric pollutants that are characterized as high volatility, and strong environmental impact. Some of VOCs are smelly, toxic and carcinogenic, which do harm to human health. In addition, Most of VOCs are key precursors of tropospheric ozone and secondary organic aerosol. In recent years, the concentrations of ground level ozone are increasing in many megacities of China, especially in Beijing, Pearl River Delta (PRD) and Yangtze River Delta (YRD) region. Consequently, identifying the distributions and profiles of VOCs is in urgent need for environmental management. In contrast to our country, USA and Europe have conducted more comprehensive studies on VOCs, and most information we use are referenced from these foreign countries, thus it’s necessary to establish our own test method and database. Materials and methods This paper reviews studies about VOCs in China, of which thedistribution, sources apportionment, and effects on ozone and secondary organic aerosol (SOA) formation were discussed in detail. Results In China, the concentrations of VOCs are mainly affected by anthropogenic sources, such as combustion processes (utilizing fossil fuels, petroleum refi ning, and storage), distribution of petroleum products, solvent use and other industrial processes. Alkanes, alkenes and aromatics are the most abundant VOCs in China, and concentrations and composition of VOCs vary with sites. In China, ground-level ozone production was limited by the concentrations of VOCs in most eastern urban areas, and limited by NOxin western areas. Industry and traffi c emissions are the top two emission sources of VOCs in China. Discussion In general, concentrations of VOCs is higher in megacities, and it is found that VOCs level in Beijing, Shanghai, Guangzhou is higher than other cities, while composition of VOCs in remote sites is mainly infl uenced by long range atmospheric transport and biogenic emission. The concentration of atmospheric VOCs generally presented signifi cant temporal variations because of emission strength and photochemical reactions. Levels of VOCs in urban areas were mainly controlled by emission sources, while in suburban the diffusion rate of atmospheric boundary layer is the main factor, which results in the VOCs level higher in winter than that in summer in most cases. In the remote sites, VOCs mainly come from biogenic source and air pollutant transportation. For diurnal variations, it’s common to see bimodal distributions of atmospheric concentrations, concentration peaks are highly correlated with the traffi c fl ow, and concentrations mainly peak at 8:00 LST (local standard time, LST) and a second one from 16:00 to 19:00 LST. Under the effect of free radical, ozone, atmospheric VOCs could be oxidized to carbonyls, and carbonyls are one of the most important radical sources, especially for the wintertime in polluted urban environments. Formaldehyde, acetaldehyde and acetone were found to be the most abundant OVOCs in China, and the lowest concentration levels were found in Xiamen and Qinghai. It was reported that formaldehyde/acetaldehyde (C1/C2) ratio usually varied from 1 to 2 at urban areas and was about 10 at forest areas; therefore, the C1/C2 ratio could be used as a measure of a biogenic source of formaldehyde, while acetaldehyde/propionaldehyde (C2/C3) ratio was often used as effective indicators of anthropogenic carbonyls. In recent years, increasing ground-level ozone concentrations were observed in both the background and urban sites. As key ozone precursors, VOCs are the most important chemicals contributing to high ozone production rates in Pearl River Delta and Beijing-Tianjin-Hebei region, where ozone formation is sensitive to VOCs. It is found that ozone in the lower troposphere over Beijing had a strong positive trend (2% per year) during the period 1995 to 2005. As VOCs-sensitive chemistry has been found to be most likely to occur in urban sites of China, it is critical to distinguish the contribution of individual VOCs to ambient ozone formation for efficient emission control. The ozone formation potential (OFP) is a widely used method for evaluating the maximum ozone formation capacity, and aromatics and alkenes take the most part of OFP in China. Principal component analysis (PCA), chemical mass balance (CMB), and positive matrix factorization (PMF) are widely used source apportionment tools in the world, each of them have advantages and shortages. PMF results are not affected by uncertainties in emission profiles, making it the most popular method among these three tools. Conclusions Nowadays, most studies on VOCs are concentrated in megacities such as Beijing, Shanghai and Guangzhou in China, and most of researches were focused on factors like wise source apportionment, VOCs compositions, spatialtemporal variation etc. Recommendations and perspectives Although studies on OVOCs were rarely today, there will be more related studies coming up because of their important role in ozone formation. By targeting the high OFP-contributing species rather than the high emission-contributing species, reactivity-based control was more effi cient than the emission-based approach in alleviating ozone pollution.

volatile organic compounds (VOCs); sources apportionment; distribution characteristics

Date: 2016-12-29; Accepted Date: 2017-03-24

National Natural Science Foundation of China (41401567, 41573138)

HUANG Yu, E-mail: huangyu@ieecas.cn

2016-12-29；录用日期：2017-03-24

国家自然科学基金项目（41401567，41573138）

黄 宇，E-mail: huangyu@ieecas.cn

李博伟，黄 宇，何世恒, 等. 2017. 我国大气中挥发性有机物的分布特征[J]. 地球环境学报, 8(3): 225 – 242.

: Li B W, Huang Y, Ho S S H, et al. 2017. Characteristics of volatile organic compounds in China [J]. Journal of Earth Environment, 8(3): 225 – 242.