The winter effect on formation of PCDD_Fs in Guangzhou by vehicles_ A tunnel study
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蔡秀华, 吕文忠, 陈龙泉. 2021. 福清核电厂厂址区域龙卷风设计基准参数的估算[J]. 气候与环境研究, 26(3): 351−358. CAI Xiuhua, LÜWenzhong, CHEN Longquan. 2021. Estimation of Design Basis Tornado Parameters for the Zone around the Fuqing Nuclear Power Plant [J]. Climatic and Environmental Research (in Chinese), 26 (3): 351−358. doi:10.3878/j.issn.1006-9585.2020.20088福清核电厂厂址区域龙卷风设计基准参数的估算蔡秀华 1 吕文忠 2 陈龙泉31 中国气象科学研究院,北京 1000812 中国气象局气象干部培训学院,北京 1000813 中国辐射防护研究院,太原 030006摘 要 基于1959~2017年福清核电厂区龙卷风的调查资料,采用Rankine 涡模型估算该区域超过某一特定风速的概率分布,通过概率值导出设计基准龙卷风和基准设计风速,按照压降模型计算出龙卷风的压降,研究结果表明:福清核电评价区域龙卷风的总压降为4.29 kPa ;平移速度13.8 m/s ,最大旋转风速57.6 m/s ,最大压降速率为1.18 kPa/s ,基准设计风速为71.4 m/s ,属于F3级别的龙卷风;在125 kg 下落的穿甲弹类和2.5 cm 实心钢球两种不同情景下计算出的龙卷风产生的飞射物的最大水平碰撞速度均为24.99 m/s 、碰撞动量依次为3123.75 kg m s −1和1.615 kg m s −1。
这些计算结果,从龙卷风的角度,为政府相关部门在规划和建设福清核电厂时提供了可靠的理论依据。
关键词 龙卷风 核电厂 基准设计参数 碰撞动量文章编号 1006-9585(2021)03-0351-08 中图分类号 X321 文献标识码 A doi:10.3878/j.issn.1006-9585.2020.20088Estimation of Design Basis Tornado Parameters for the Zonearound the Fuqing Nuclear Power PlantCAI Xiuhua 1, LÜ Wenzhong 2, and CHEN Longquan31 Chinese Academy of Meteorological Sciences , Beijing 1000812 China Meteorological Administration Training Centre , Beijing 1000813 China Institute for Radiation Protection , Taiyuan 030006Abstract Based on the investigation data of tornadoes in the Fuqing Nuclear Power Plant area from 1959 to 2017, the probability distribution of exceeding a specific wind speed is calculated using the Rankine model. The design basis tornado wind speeds are derived from the probability values, and the pressure drop of tornadoes is calculated using the pressure drop model. Results show that the design basis wind speed of an F3 category tornado is 71.4 m/s, with a probability of 1 × 10−8. Moreover, the total pressure drop of an F3 category tornado is 4.29 kPa, the translation speed is 13.8 m/s, the maximum rotating wind speed is 57.6 m/s, and the maximum pressure drop rate is 1.18 kPa/s. Furthermore,the collision velocity and momentum of the projectile produced by the tornado in two different scenarios are calculated.These two scenarios involve an air penetrator with a weight of 125 kg and a solid steel ball with a radius of 2.5 cm. The maximum horizontal collision velocity of the projectile caused by the tornado is 24.99 m/s in both scenarios. The collision momentum is 3123.75 kg m s −1 in the air penetrator with a weight of 125 kg and 1.615 kg m s −1 in the solid steel ball with收稿日期 2020-07-20;网络预出版日期 2020-10-16作者简介 蔡秀华,女,1963年出生,高工,主要从事环境评价、极端气象和工程气象的研究。
温湿度进行了研究。
张志军[2]依据现已公认的博物馆环境标准,提出秦俑坑内的温度范围为5~25 ℃,相对湿度40%~70%。
张楠[3]借鉴其他类型博物馆温湿度研究成果提出顺天门遗址保护区适宜温度范围为(14±5)℃。
吴士杰 [4]利用聚类分析法,根据国内多个土遗址博物馆温湿度样本的最大频率范围,分别提出了封闭式以及开敞式遗址博物馆内的适宜温湿度范围。
从上述仅有的研究可知,其所得出的各种土遗址保存适宜温湿度主要是通过借鉴其他类型博物馆的研究成果或以遗址博物馆最高频率温湿度波动范围得出的经验值,没有从土遗址本体出发来研究适宜土遗址长久保存的温湿度标准。
针对上述研究不足,本文以黄冶唐三彩窑址为研究对象,从窑址本体材质性质出发,根据黄冶唐三彩窑址本体材质性质测试预测窑址最易发生的病害种类为温度剥蚀、裂隙、盐析酥碱、微生物损害,并对这四种病害发育与温湿度参数的定量关系进行研究,综合提出黄冶唐三彩窑址保存的适宜温湿度参数范围。
2黄冶唐三彩窑址病害预测分析2.1黄冶唐三彩窑遗址概况巩义黄冶窑遗址位于河南省巩义市的大黄冶村、小黄冶村,是我国发现最早的一处唐三彩窑址[5],现处于回填保护状态,并计划建立遗址博物馆进行展示保护。
根据发掘报告[5],黄冶窑址中主体遗迹如水井、灰坑、作坊、窑炉、陈腐池、淘洗池等材质均为土壤。
2.2黄冶唐三彩窑址土壤性质测试为预测黄冶唐三彩窑址可能发生的病害种类,通过现场取样实验对遗址本体土壤性质进行分析。
黄冶唐三彩窑址土样的含水率及颗粒组成、矿物成分、可溶盐成分分别见表1、表2、表3。
摘要 本文以巩义黄冶唐三彩窑遗址为研究对象,通过对窑址土体的物性的测试分析,预测提出温度剥蚀、裂隙、盐析酥碱、微生物损害为最易发生的病害种类,并依据这四种病害与温湿度参数的定量关系综合提出黄冶唐三彩窑址文物保存温度建议为13.5~18.9℃,相对湿度为78%~80%。
研究结果可为黄土地区土遗址文物保存适宜环境研究提供参考。
废物焚烧过程中产生二噁英的控制方法张丽军;陈扬;陈岚【摘要】本文针对垃圾焚烧过程中面临的二噁英污染问题,主要介绍垃圾焚烧过程中二噁英特征、产生的途径,综述了近年来以催化氧化法、吸附法、生物法、等离子体技术为主的处理垃圾焚烧过程中产生二噁英的研究进展.根据这些技术的研究现状,指出未来等离子体技术应用在处理二噁英方面有着巨大的潜力.【期刊名称】《化学工程师》【年(卷),期】2016(000)012【总页数】4页(P50-53)【关键词】垃圾焚烧;二噁英;方法;降解【作者】张丽军;陈扬;陈岚【作者单位】华北电力大学环境科学与工程学院,河北保定071003;中国科学院北京综合研究中心,北京100083;中国科学院北京综合研究中心,北京100083;华北电力大学环境科学与工程学院,河北保定071003【正文语种】中文【中图分类】X701(1.华北电力大学环境科学与工程学院,河北保定071003;2.中国科学院北京综合研究中心,北京100083)二噁英(PCDD/Fs)作为持续性有机污染物(persistentorganic pollution,POPS)具有环境持久性、生物蓄积性、长距离迁移能力和生物危害性,被列为《POPS公约》的首批控制名单[1]。
它包括75种多氯二苯并二噁英(polychlorinated dibenzo-p-dioxin, PCDDs)和135种多氯二苯并呋喃(polychlorinated dibenzofuran,PCDFs),通常伴随着废弃物焚烧等热处置过程而产生[2,3]。
美国环境保护协会在1994年6月发表报告,指出二噁英是一种严重威胁公众健康的物质,它会极大损害人体免疫、生殖、内分泌等系统,具有致癌、致畸、致突变作用。
此外,二噁英属于持续性有机污染物的一种,一旦形成便能在生态系统中残留数年,甚至更久。
我国在2014年7月1日实施了新的《生活垃圾焚烧污染控制标准》(GB18485-2014)将二噁英的排放限值从原来的1ngTEQ/Nm3下调至0.1ngTEQ/Nm3,和欧盟的排放标准相持平[4]。
低温影响植物的生长发育与地理纬度分布,低温灾害是造成作物减产的主要逆境之一。
随着全球气候变化加剧,低温冷冻等极端气候将会更为频繁发生。
因此,研究植物如何响应低温胁迫对于保障经济作物生产与粮食安全等重大问题有着重要的理论与实践价值,植物低温响应分子机制研究一直是植物研究领域中的热点话题。
本文将根据相关研究现状,围绕已知信号途径从植物对外界信号的感知、细胞内的信号传递、信号通路中的信号转导以及植物激素等与低温信号的交叉反应进行论述。
1植物的低温响应1.1植物对低温的生理响应根据低温程度的不同,低温胁迫可以划分为冷害(0~20℃)和冻害(<0℃)[1~2]。
在热带和亚热带气候区,冷害是主要的低温胁迫,影响着水稻、玉米等作物的生产;在温带气候区,冻害是主要的DOI:10.16605/ki.1007-7847.2020.08.0239植物低温响应的分子机制研究进展收稿日期:2020-08-20;修回日期:2020-10-03;网络首发日期:2021-07-23基金项目:国家自然科学基金资助项目(3117117);湖南省自然科学基金项目(2018JJ3036)作者简介:吴丹(1997—),女,湖南浏阳人,硕士研究生;*通信作者:赵小英(1973—),女,湖南慈利人,博士,湖南大学教授,主要从事植物功能基因组学研究,Tel:*************,E-mail:*****************.cn 。
吴丹1,2,毛东海2,赵小英1*(1.湖南大学生物学院植物功能基因组学与发育调控湖南省重点实验室,中国湖南长沙410082;2.中国科学院亚热带农业生态研究所亚热带农业生态过程重点实验室,中国湖南长沙410125)摘要:低温是限制植物生长发育与植被分布的重要环境因子,植物在长期的环境适应过程中获得了冷驯化机制。
关于低温响应机制的解析,目前研究最为清楚的信号通路是模式植物拟南芥CBF /DREB 1(C-repeat binding transcription factor /dehydrate responsive element binding factor )依赖型低温响应信号通路。
植物抗低温机理的分子生物学研究进展摘要:笔者从不同的方面综述了植物低温抗性的分子生物学研究进展,对低温抗性的机理做了阐释,并且给出以后的研究方向和重点。
关键词:低温抗性细胞膜透性不饱和脂肪酸丙二醛保护酶系统脱落酸钙调素低温诱导蛋白温度在植物营养生长、生殖生长的过程中都具有重要的作用。
对于温度的调控是改善植物生长环境,调节植物生长状态的一项重要措施。
在自然环境下,植物对于低温的抗性,体现了植物在温度方面的适应性,体现植物物种、品种的生态位的广度。
也影响着植物产品的质量和产量。
植物的低温胁迫根据温度的不同范围分为两种类型:冷害,是指零上低温对于植物生理机制的影响所造成的伤害;冻害,是指零下低温对于植物生理机制的影响所造成的伤害。
目前,对于植物影响较大的是冷害。
【1~4】冷害的影响程度不仅取决于温度低的程度,也取决于植物受低温影响的时间的长度。
温度越低,时间越长则冷害对于植物的影响越大。
由于温度这一自然因素存在于植物体的整个生命周期中,因此,对于温度的调控,抗低温机制的研究就显得至关重要。
以往的研究中,有对于低温敏感植物和低温驯化植物的对比研究,说明了对植物的低温驯化可以在一定程度上提高植物的抗低温能力。
也有从水分的平衡,蛋白质,碳水化合物,氨基酸,核酸水平上的研究;还有从细胞壁的特性,细胞膜的结构的研究以及生长调节物质的影响。
前面的这些的研究,都说明了植物对于低温的反应和这些条件对于植物抗低温机制的一些影响。
然而所有这些因素都不是某一种因素的单独作用,而是多种因素共同作用,相互影响的结果,不同因素之间存在着互作、制约等的作用。
上面的这些研究也只是停留在膜保护系统、冷调节蛋白的生理调节的水平。
随着生物分子工程、基因工程方面的研究水平的不断提高,给植物抗低温的研究有提出了一个新的方向。
特别是低温信号转导的研究,分子标记的应用,将进一步揭示低温适应性的调控机理。
1、通过影响植物细胞膜透性影响植物低温抗性20世纪70年代,Lyons等提出细胞膜是低温冷害的首要部位,在低温条件下,植物细胞膜由液晶态转变为凝胶态,膜收缩,导致细胞膜透性改变,膜酶和膜功能系统代谢改变,功能紊乱。
苯为前驱物形成二噁英的反应机理高正阳;韩文涛;丁艺;孙尧;李明晖【摘要】苯作为垃圾中普遍存在的成分是形成多氯二苯并对二噁英/呋喃(PCDD/Fs)的重要前驱物之一.应用密度泛函理论(DFT)在B3LYP/6-311+G(d,p)水平上研究了苯生成PCDD/Fs的两阶段气相反应机理,获得相关基元反应的势垒与反应热.采用隧道效应校正的变分过渡态理论(VTST)对300~1300K的各基元反应进行速率常数计算.结果表明:苯的氯化过程在合成PCDD/Fs各基元反应中势垒最高,是整个过程的控速步骤;氯酚更有可能被HO·进攻氯苯发生亲核反应后经分子内脱氢形成;邻位Cl能提高芳香烃H的抽取势垒,降低分子反应活性;苯氧自由基经碳碳或碳氧耦合二聚化过程形成不同PCDD/Fs存在竞争机制.相关计算结果可以用于在总二噁英产量基础上评估由苯产生的PCDD/Fs贡献率.%Benzene was one of the important precursors for the formation of polychlorinated dibenzo-p-dioxins (PCDD/Fs) which widespreadly present in waste. The two stage gas-phase formation mechanisms of PCDD/Fs by benzene were studied by density functional theory (DFT) at the B3LYP/6-311+G (d, p) level, the corresponding potential barriers and reaction heats were calculated. The variational transition state theory (VTST) was used to calculate the rate constants of the elementary reactions in the 300~1300K temperature range. The chlorination process of benzene was the determining step of the whole synthesis process of PCDD/Fs with the highest barrier; Chlorophenol was more likely formed via the intramolecular dehydrogenation of chlorobenzene which attacked by HO· radicals; Ortho Cl can raise the extraction barrier of aromatic hydrocarbon H and reducethe molecular reactivity; competition mechanism existed in the formation of PCDD/Fs which was formed by phenoxy radicals via coupling of carbon-carbon or carbon-oxygen. The calculation results could be applied to evaluate the contribution of PCDD/Fs formed by benzene on the basis of total dioxin production.【期刊名称】《中国环境科学》【年(卷),期】2018(038)001【总页数】8页(P59-66)【关键词】密度泛函;苯;二噁英;反应机理;速率常数【作者】高正阳;韩文涛;丁艺;孙尧;李明晖【作者单位】华北电力大学能源动力与机械工程学院,河北保定 071003;华北电力大学能源动力与机械工程学院,河北保定 071003;华北电力大学能源动力与机械工程学院,河北保定 071003;华北电力大学能源动力与机械工程学院,河北保定071003;华北电力大学能源动力与机械工程学院,河北保定 071003【正文语种】中文【中图分类】X13氯代二噁英(PCDD/Fs)一直深受人们关注,垃圾焚烧是生成二噁英类物质的主要途径,在垃圾燃烧以及热解过程中PCDD/Fs形成主要经由两种方式[1]:一种为denovo合成反应,该反应发生的条件为存在无定型碳或者石墨退化层,必须有氧源以及氯源,需要 CuCl2或者过渡金属物质的催化,反应主要发生在 200~400℃[2],这是一种高温下的非均相反应.另一种为氯化前驱物均相气态合成,其化学反应温度范围主要处于 400~800℃之间,后者的反应生成速率远远大于前者[3-4].形成二噁英的前驱物种类多样,包括脂肪族化合物、苯、带官能团的单环芳香族化合物、氯代的芳香族化合物以及蒽醌的衍生物等[5].在前驱物合成PCDD/Fs机理研究中,氯酚为最直接的典型前驱物,因此相关研究主要以氯酚为主,其次为对氯苯的研究,对于其他前驱物机理反应报道较少.这其中Ghorishi等[6]与 Stieglitz等[7]分别研究了氯代芳香烃类物质1,2-二氯苯、2,4-二氯酚以及 1,2,4,5-四氯苯生成二噁英的化学反应特性,发现氯酚的催化反应活性远高于氯苯,前者二噁英生成量远大于后者;相同条件下,氯苯类前驱物生成PCDDs的反应速率比PCDFs高约 2个数量级,且大部分的二噁英均以气态形式存在. Ryan等[8]与Schoonenboom等[1,9]探索以甲苯与苯为代表的非氯代芳香烃在飞灰、CuCl2/Al2O3催化条件下的反应产物,均检测到了氯代二噁英以及氯代呋喃的存在.由于二噁英产生过程的复杂性,实验方法很难检测到反应过程中的中间产物及过渡态等物质,而量子化学克服了实验上的缺陷,从本质上揭示化学反应机理,因此很多学者采用量化计算的研究手段对不同类型二噁英前驱物的反应机理进行探究[10-12].但是目前为止还鲜见以苯为前驱物形成PCDD/Fs的相关理论研究报道,为此本文应用量子化学方法研究了苯为前驱物二噁英气相反应机理,研究其氯化、氧化反应,生成2,3-二氯苯酚及 3,4-二氯苯酚过程,进一步以二氯苯酚为前驱物交叉反应生成PCDD/Fs的气相反应机理,并对反应涉及的基元过程做出相关动力学分析.1 研究方法基于前人实验结果推测PCDD/Fs很有可能经由两步反应机制,第1步是苯在催化作用下发生亲电芳香取代过程,第2步是氯化碳基的氧化分解,并进一步环化生成最终产物.采用密度泛函理论[13-14]在 B3LYP[15]/6-311+G(d,p)水平下计算获得反应路径中涉及到的反应物、过渡态、中间体、产物等各个驻点的空间结构参数.对涉及到的所有驻点结构进行了频率分析,确保反应物、中间体、产物不出现虚频,保证结构的稳定性;过渡态有且仅有一个虚频,保证过渡态结构的唯一性.过渡态是在初猜结构的基础上采用 TS算法定位并优化得到,对每个过渡态在同一方法基组水平下做内禀反应坐标(IRC)计算,验证该过渡态结构与该基元反应的反应物与产物相关联. 在 B3LYP[15]/6-311+G(d,p)水平下对各驻点结构进行了自由能以及热化学焓的计算,并考虑了零点能的校正,进一步计算得到各基元反应的反应势垒及反应热.变分过渡态理论 VTST在温度越高、势垒越低的情况下优势明显[16],本文计算采用变分过渡态理论对于关键基元反应进行化学反应速率常数的计算,并考虑隧道效应,对计算结果进行了校正,在此基础上拟合得到阿伦尼乌兹(Arrhenius)方程.计算方法与基组的稳定性、可靠性已经得到 Dar等[17]在三氯硫酚生成硫代二噁英的研究中验证.所有计算均应用Gaussian09软件包[18]在型号为 ServMaxPSC-201GAMAX 服务器完成.2 结果与讨论2.1 苯的氯化、氧化及生成苯氧自由基2.1.1 苯的氯化、氧化途径在当前工业苯酚的制备过程中,采用O2、H2O2等氧化剂可以将苯直接氧化成苯酚[19-20].主要的机理为:H2O2在催化剂作用下形成的HO·会进攻苯环,通过形成中间体羟基环己二烯自由基进而形成苯酚[21].O2的催化反应路径主要有2条,路径1为O2在催化剂作用下发生氧化还原反应生成 H2O2,进一步以H2O2为氧化剂催化制取苯酚;路径2为O2直接在催化剂条件下与苯反应而不经过形成中间反应物H2O2形成苯酚[21].基于苯酚的制取,推测在复杂的垃圾焚烧过程中,苯到氯酚的反应途径亦有可能有相似的反应路径,如图1所示,各基元反应中涉及到的过渡态结构见支持信息图 1.以Cl2为氯源提供Cl·取代基取代苯分子上 H,发生两次取代反应依次越过两个较高的势垒形成 1,2-二氯苯(o-DCB),可以发现芳香烃的二氯取代比一氯取代反应势垒高度更大,而放出的反应热降低.o-DCB可能被高温条件下氧化性强的单线态O2直接氧化形成中间体IM1,再经H2还原形成中间体IM2,IM2经分子内H质子的迁移重排、脱水形成产物.同时o-DCB也可能被高能HO·进攻形成IM3或IM4,之后经H⋅、Cl⋅或HO·抽提中间体羟基位H形成2,3-二氯苯酚或 3,4-二氯苯酚,该基元反应为强放热反应.前一种反应路径基元反应普遍势垒高度远高于后一种路径,因此在竞争反应形成最终产物上存在明显劣势.2.1.2 二氯苯酚形成苯氧自由基氯代苯酚分子结构相对稳定,之前的研究结果表明PCDD/Fs可以经过自由基-自由基、自由基-分子、氯酚分子之间反应形成[22].其中苯氧自由基之间的反应是占主导地位,氯代苯氧自由基由于自身不易分解,毒性强,被归类于持久性有机污染物,同时它与其他物质反应活性尤其是氧气反应活性比较低,因此可以进一步作为生成PCDD/Fs的前驱物[23].生成苯氧自由基(XPRs)是均相反应生成PCDD/Fs的重要步骤之一[22].在高温热解条件下,二氯苯酚最有可能通过热分解反应发生以下反应[24-25]:图1 由苯形成2,3-二氯酚及3,4-二氯酚的反应机理Fig.1 Formation of 2,3-dichlorophenol and 3,4-dichlorophenol through the benzene E*:势垒,kcal/mol;△H:反应热,kcal/molXu等[26]在1070~1150K下对于苯酚的动力学模型做了单分子热解模拟,由于苯酚中羟基O-H键作用力弱于芳香环C-H键,因此苯酚分子中H-X最有可能是H-O 键分解,化学反应速率常数为k = 2 .67× 1 016 e(-44700K/T)s-1.Ritter(phenol)等[27]在 1070~1028K温度范围下拟合氯苯脱除Cl原子化学反应速率常数为 k (chlorobenzene)=3.0× 1015 e(-48100K/T)s-1.Cl脱离芳香环的化学反应速率低于苯酚形成苯氧自由基 H-O键断裂的化学反应速率1个数量级以上,因此氯代苯酚的热分解反应最有可能发生的是苯氧基的 O-H键断裂形成苯氧自由基的过程.在高温以及垃圾焚烧复杂的环境下,苯氧自由基可能经过单分子、双分子或其他形式的基元反应形成,其中单分子反应指酚羟基 O-H键断裂,双分子反应包括复杂环境中高能 H⋅、HO·以及 Cl⋅的进攻等[28].在温度高于900K时,苯氧自由基的形成更倾向于单分子解离;而在温度低于900K时,其他高能原子及自由基团的进攻更容易脱除苯氧基上的H[29].表1 2,3-DCP及3,4-DCP形成2,3-DCPR及3,4-DCPR的势垒与反应热Table 1 The potential barriers E* and reaction heats △H for the formation of the 2,3-DCPR and 3,4-DCPR from 2,3-DCP and 3,4-DCP through various processess注:-为无势垒反应.基元反应势垒(kcal/mol) 反应热(kcal/mol)2,3-DCP→2,3DCPR·+H· - 82.08 2,3-DCP+H·→2,3DCPR·+H2 8.23 -22.47 2,3-DCP+Cl·→2,3DCPR·+HCl - -18.04 2,3-DCP+HO·→2,3DCPR·+H2O 1.37 -32.77 3,4-DCP→3,4DCPR·+H· - 82.66 3,4-DCP+H·→3,4DCPR·+H2 8.94 -21.89 3,4-DCP+Cl·→3,4DCPR·+HCl - -17.47 3,4-DCP+HO·→3,4DCPR·+H2O 1.32 -32.19研究发现C-H键的直接断裂是一个强吸热反应;使用HO·提取二氯酚酚羟基上H的势垒要远小于H·提取,但放出的反应热较高;尤其说明的是使用Cl·抽提获得的经零点能校正的过渡态总能量,要低于2,3-DCP及3,4-DCP与Cl反应的总能量,因此该反应为无势垒反应.这一计算结果与 Zhang等[10]在 MPWB1K/6-311+G(3df,2p)对Cl提取2,4,6-TCP及2,4-DCP羟基上的H生成2,4,6-TCPR及2,4-DCPR的结论一致.相关反应势垒及反应热见表1.2.2 由2,3DCPR及3,4DCPR形成PCDD/Fs的过程分析2.2.1 由2,3-DCPR与3,4-DCPR形成1,2,8,9-TCDD及1,2,7,8-TCDD的机理基于2,3-DCPR与3,4-DCPR形成1,2,8,9-TCDD及1,2,7,8-TCDD过程主要的基元反应包括:二氯代苯氧自由基之间发生的碳氧耦合二聚化反应、H提取反应、环闭合反应、以及最后分子内H消除反应.其形成机理见图 2,相关过渡态结构见支持信息图3.图2 以2,3-DCPR与3,4-DCPR为前驱物形成1,2,8,9-TCDD及1,2,7,8-TCDD的机理Fig.2 1,2,8,9-TCDD and 1,2,7,8-TCDD formation routes from the 2,3-dichlorophenol and 3,4-dichlorophenol precursor E*:势垒,kcal/mol;△H:反应热,kcal/mol图3 以2,3-DCPR与3,4-DCPR为前驱物形成2,3,6,7-TCDF 及1,2,6,7-TCDF的气相机理Fig.3 2,3,6,7-TCDF and 1,2,6,7-TCDF formation routes from the2,3-dichlorophenol and 3,4-dichlorophenol precursor E*:势垒,kcal/mol;△H:反应热,kcal/mol在1,2,8,9-TCDD形成过程的基元反应中,2,3-DCPR与3,4-DCPR的碳氧二聚化耦合反应为无势垒放热反应,反应热为13.73kcal/mol.利用高能H·去提取中间体IM5上H,脱除H2的过程,比HO·自由基去提取H脱除H2O需跨越的势垒高度大,但基元反应放热量少.从中间体IM6经过环闭合反应需要跨越较大的势垒同时吸收一定反应热生成中间体IM7.与上一基元反应相比,从中间体IM7到最终产物1,2,8,9-TCDD需要跨越更高的势垒,达30.51kcal/mol,同时吸收更多的反应热,为本反应形成过程的决速步.1,2,7,8-TCDD与1,2,8,9-TCDD形成过程的基元反应基本相同,只是在最初的碳氧耦合反应时不同碳原子之间发生二聚化反应,形成同分异构中间体IM8,该步基元反应放热量高于1,2,8,9-TCDD基元反应放热.对IM8与IM5的空间结构进行几何结构优化发现,两分子结构芳香环碳氧耦合处 IM8分子C-H键键级为 0.283,IM5分子 C-H键键级为0.209,因此IM8分子C-H键共价键力要强于后者,C-H键更稳定,因此在H提取过程中需要放出更多的热量;同时我们也发现,提取IM8分子中H跨越的势垒高度要高于IM5分子,最可能的原因是邻位卤素原子Cl提高了H提取的活化能,增大了H·提取的难度.从中间体 IM10至最终产物1,2,7,8-TCDD也是本反应过程的决速步骤,该基元反应需要跨越的势垒以及需要消耗的反应热略小于 1,2,8,9-TCDD 的形成过程,因此在形成1,2,7,8-TCDD时有一定的优势,理论上 1,2,7,8-TCDD的产率要略高于1,2,8,9-TCDD.同时由于两基元反应的势垒与反应热差值较小,因此二者在形成过程中可能存在竞争机制.2.2.2 由 2,3-DCPR与 3,4-DCPR形成 1,2,6,7-TCDF及2,3,6,7-TCDF的机理Werber等[30]研究显示,基于氯代苯氧自由基邻位C-C原子的耦合形成中间体二氯代二氧代联苯是多氯联苯并呋喃形成的关键基元反应.由 2,3-DCPR与3,4-DCPR形成1,2,6,7-TCDF及2,3,6,7- TCDF的过程主要包含的基元反应包括:不同苯氧自由基邻位碳原子耦合二聚化反应,H的抽提,单原子或双原子H的迁移重排,环闭合反应,OH消去反应.如图 3所示,1,2,6,7-TCDF的形成过程中,IM11的进一步可能的基元反应包括H的抽提或者双 H 迁移重排,因此有两条反应路径.利用H·以及HO·抽提IM11上的H需要跨越的势垒均远小于双 H 的迁移重排,因此IM11→IM12比IM11→IM13更加容易发生.从IM13→IM14发生羟基中H的抽提,势垒高度要大于IM11→IM12,但反应热约为后者的一半,说明 IM13中羟基中H 提取难度大于IM11中C-H,且H-O键能小于C-H.从IM14→IM15在反应路径中势垒最高达27.50kcal/mol,同时吸收 13.87kcal/mol反应热,为本过程的控速步骤.IM15→1,2,6,7-TCDF为最终OH消去反应,同样需要吸收反应热.2,3,6,7-TCDF的形成过程与 1,2,6,7-TCDF相同(图 3,图 4).由 2,3-DCPR 与 3,4-DCPR 经C-C耦合二聚化生成的IM16与IM11互为同分异构体,前者的反应热略高于后者.基元反应IM16→IM17、IM16→IM18、IM18→IM19 跨越的势垒以及反应热与同过程1,2,6,7-TCDF无明显数值差异.IM17→IM19基元反应势垒比IM12→IM14大5.18kcal/mol,可能的原因是IM12苯氧基同侧邻位Cl提高了生成羟基的势垒,但反应热无明显变化.环闭合反应IM19→IM20也是本反应的决速步骤,势垒高度为27.19kcal/mol,吸收反应热 13.52kcal/mol.最后中间体经过 OH脱除形成2,3,6,7-TCDF.2.3 速率常数计算表2 300~1300K温度范围内苯形成苯氧自由基涉及基元反应的Arrhenius方程Table 2 Arrhenius formulas in the formation of phenoxy radical from the benzene over the temperature range of 300~1300K注:单双分子基元反应单位分别为为 s-1, cm3/(mol·s).基元反应阿伦尼乌兹方程C6H6+Cl2→C6H5Cl+HCl k(T)=(2.01×10-06)e(-34356.93/T)C6H5Cl+Cl2→C6H4Cl2+HCl k(T)=(6.10×10-12)e(-34294.15/T)C6H4Cl2+O2→IM1 k(T)=(8.26×10-14)e(-20273.73/T)IM1+H2→IM2 k(T)=(1.99×10-12)e(-26468.60/T)IM2→2,3-DCP+H2O k(T)=(5.41×1013)e(-44301.88/T)IM2→3,4-DCP+H2Ok(T)=(2.74×1014)e(-36260.34/T)C6H4Cl2+HO·→IM3 k(T)=(2.08×10-12)e(-4945.05/T)IM3+H·→2,3-DCP+H2 k(T)=(1.24×10-12)e(-11956.51/T)C6H4Cl2+HO·→IM4 k(T)=(2.02×10-12)e(-4790.94/T)IM4+H·→3,4-DCP+H2 k(T)=(1.70×10-12)e(-12270.89/T)2,3-DCP+H·→2,3-DCPR+H2 k(T)=(2.70×10-11)e(-4098.74/T)2,3-DCP+HO·→2,3-DCPR+H2O k(T)=(1.49×10-12)e(-1310.82/T)3,4-DCP+H·→3,4-DCPR+H2 k(T)=(5.24×10-11)e(-4473.76/T)3,4-DCP+HO·→3,4-DCPR+H2O k(T)=(1.33×10-12)e(-1252.06/T)环境监督与风险决策分析通过建立数学模型研究污染物释放到环境中的潜在结果,PCDD/Fs形成过程中各基元反应阿伦尼乌斯公式中的指前因子、活化能、速率常数是数学模型建立过程中重要的参数[29].为此,基于变分过渡态理论VTST拟合了300~1300K温度范围内的TST速率常数的速率-温度关系式,该温度范围已经涵盖了垃圾焚烧过程中可能涉及到的形成温度.得到各相关过渡态基元反应的阿伦尼乌斯公式,到目前为止,相关文献缺乏直接的相关实验值与理论值.为验证本文拟合公式的准确性,与Gao 等[31]及 Zhang 等[10]在 MPWB1K/ 6-311+G(3df,2p)水平下计算得到的类似基元反应的数据进行对比,并分析在 CVT/SCT拟合的化学反应速率常数,发现相似基元反应的数量级处于同等水平.例如,本文计算得到 2,3-DCP+ H·→2,3-DCPR+H2指前因子为2.70×10-11s-1, Zhang等[10]获得 2,4-DCP+H→2,4-DCPR+H2的指前因子为5.01×10-11s-1.形成 1,2, 8,9-TCDD 环闭合反应IM7→1,2,8,9-TCDD+H·指前因子为4.05×1013s-1,Zhang等拟合获得2个2,3-DCPR分子形成1,3,6,8-TCDD、1,3,7,9-TCDD各基元反应,相同闭环反应的指前因子分别为3.17×1013s, 2.96×1013s-1,因此本文计算数据可靠.由苯两阶段生成PCDD/Fs涉及的基元反应并拟合获得的阿伦尼乌斯公式如表2,表3所示. 表3 300~1300K温度范围内2,3-DCPR和3,4-DCPR为前驱物形成PCDD/Fs涉及基元反应的Arrhenius方程Table 3 Arrhenius formulas in the formation of PCDD/Fs from the 2,3-DCPR and 3,4-DCPR precursor over the temperature range of 300~1300K基元反应阿伦尼乌兹方程IM5+H·→IM6+H2k(T)=(5.18×10-09)e(-5058.68/T)IM1+HO·→IM6+H2O k(T)=(1.25×10-12)e(-4089.24/T)IM6→IM7 k(T)=(8.33×1011)e(-12165.86/T)IM7→1,2,8,9-TCDD+H· k(T)=(4.05×1013)e(-15866.91/T)IM8+H·→IM9+H2k(T)=(1.22×10-10)e(-3305.23/T)IM8+HO·→IM9+H2O k(T)=(2.53×10-12)e(-2688.27/T)IM9→IM10 k(T)=(3.88×1011)e(-12336.58/T)IM10→1,2,7,8-TCDD+H· k(T)=(5.12×1013)e(-15778.00/T)IM11+H·→IM12+H2k(T)=(4.62×10-11)e(-3980.51/T)IM11+HO·→IM12+H2O k(T)=(1.09×10-12)e(-2596.36/T)IM11→IM13 k(T)=(1.88×1012)e(-9136.73/T)IM13+H→IM14+H2 k(T)=(1.08×10-11)e(-5709.59/T)IM12→IM14k(T)=(4.51×1012)e(-7714.56/T)IM14→IM15 k(T)=(3.13×1012)e(-14010.49/T)IM15→1,2,6,7-TCDF k(T)=(4.91×1013)e(-7847.38/T)IM16+H·→IM17+H2 k(T)=(6.97×10-11)e(-3796.36/T)IM16+HO·→IM17+H2O k(T)=(1.63×10-12)e(-2729.08/T)续表3注:单双分子基元反应单位分别为为 s-1, cm3/(mol·s).基元反应阿伦尼乌兹方程IM16→IM18 k(T)=(8.29×1011)e(-9594.25/T)IM18+H·→IM19+H2k(T)=(2.36×10-11)e(-5435.61/T)IM17→IM19 k(T)=(1.43×1012)e(-10273.46/T)IM19→IM20 k(T)=(1.76×1012)e(-13753.87/T)IM20→2,3,6,7-TCDF k(T)=(5.16×1013)e(-7911.31/T)3 结论3.1 基于密度泛函理论研究了以苯为前驱物分两阶段形成PCDD/Fs的均相反应机理.在第一阶段苯的氯化、氧化各基元反应中,氯化取代反应势垒较高,羟基自由基进攻二氯苯进而形成二氯酚过程势垒明显低于氧气直接氧化氯苯经加氢分子内脱水反应.3.2 苯氧自由基的之间的碳氧耦合二聚化反应比碳碳耦合二聚化释放的反应热多.邻位Cl能够提高芳香烃环H的抽取势垒,也会增加邻位羟基反应势垒,降低了分子反应活性.3.3 环闭合基元反应在第二阶段的反应中需要越过的势垒最大,是形成 1,2,7,8-TCDD、1,2,8,9-TCDD、1,2,6,7-TCDF、2,3,6,7-TCDF的决速步.3.4 苯为反应活性较低的二噁英前驱物,以苯为前驱物生成PCDD/Fs化学反应速率的快慢主要取决于苯的氯化基元反应.参考文献:[1]Schoonenboom M H, Tromp P C, Olie K. 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绿洲农业科学与工程Oasis Agriculture Science and Engineering第9卷第2期2023年12月Vol.9No.2Dec.2023利用BSA-Seq 技术初步鉴定棉花芽黄候选基因王娟,王新,周小凤,马晓梅,田琴,李保成,余渝,董承光*(新疆农垦科学院/农业农村部西北内陆区棉花生物学与遗传育种重点实验室,新疆石河子832000)摘要:芽黄性状可作为棉花育种的标记性状,在棉花杂交选育中可减轻棉花杂交制种和鉴定过程,还可以作为叶绿素等生理代谢研究的理想材料。
研究棉花芽黄突变体具有重要的理论和实践意义。
本研究以芽黄突变体115-23与绿叶正常材料JSH1527为亲本,构建F 2分离群体,鉴定后代芽黄性状,选择30个芽黄单株和30个正常绿叶单株构建混合池,对4个样本(2个亲本池和2个混合池)开展全基因组重测序,采用SNP-index 进行关联分析,确定芽黄基因的候选区域,筛选芽黄候选基因。
结果表明,在2个亲本之间共获得840,612个多态性SNP ,利用Δ(SNP-index )方法,在95%的置信区间内将候选区域定位到染色体D02区间,包含93个候选基因,其中4个基因功能注释与叶绿体合成等相关,可能是调控棉花叶色的候选基因。
研究结果可为棉花芽黄分子机制及芽黄相关基因的克隆奠定理论基础。
关键词:棉花;芽黄;BSA-Seq ;候选基因Preliminary Identification of Candidate Genes withVirscent Gene inCotton Based on BSA-SeqWANG Juan ,WANG Xin ,ZHOU Xiao-feng ,MA Xiao-mei ,TIAN Qin ,LI Bao-cheng ,YU Yu ,DONGCheng-guang *(Xinjiang Academy of Agricultural and Reclamation Science/Northwest Inland Region Key Laboratory of CottonBiology and Genetic Breeding ,Ministry of Agriculture and Rural Affairs ,Shihezi 832000,Xinjiang )Abstract :Virescent trait could be used as a natural marker for breeding to reduce time and process of hybrid breeding ,moreoverthey were ideal model systems to study chlorophyll and chloroplast biosynthesis and biodegradation process.the virescent mutant in cot⁃ton is of great theoretical and practical implications.In this study ,an F 2segregation population was constructed derived from 115-23(virscent mutant )and JSH1527(Normal green trait ),based on the identification of virescent trait ,30virescent and 30green plants were selected to construct a mixed pool ,four samples (2parent pools and 2mixed pools )were sequenced ,SNP-index were used for association analysis to determine the candidate regions of virescentgenes.As a result ,840,612SNPs were obtained between the two parents ,one candidate physical regions showing confidence indices higher than 95%were obtained on chromosome D02,which con⁃tained 93annotated genes ,four of these genes were functional annotations related to chloroplast synthesis and may be candidate genes for the regulation of cotton leaf color.This study laid a foundation for further analyzing the genetic mechanism and clones of genes ofcotton virescent formation.Keywords :Cotton;Virescent;BSA-Seq;Candidate genes棉花芽黄性状是棉花叶片颜色突变的一种典型性状,一般表现为苗期从第一片真叶开始叶片颜色黄化,到蕾期以后叶片叶绿素含量逐渐增加,又逐渐由黄化变为绿色,表现为正常植株叶片颜色[1]。
第37卷第12期2017年12月环㊀境㊀科㊀学㊀学㊀报㊀ActaScientiaeCircumstantiaeVol.37,No.12Dec.,2017基金项目:环保公益性行业科研专项(No.201109001);中央级公益性科研院所基本科研业务费专项(No.PM⁃zx703⁃201607⁃225)SupportedbytheSpecialFundforEnvironmentalProtectionScientificResearchinthePublicInterest(No.201109001)andtheBasicResearchFundforCentralPublicResearchInstitutes(No.PM⁃zx703⁃201607⁃225)作者简介:付建平(1983 ),男,E⁃mail:fujianping@scies.org;∗通讯作者(责任作者),E⁃mail:renmingzhong@scies.orgBiography:FUJianping(1983 ),male,E⁃mail:fujianping@scies.org;∗Correspondingauthor,E⁃mail:renmingzhong@scies.orgDOI:10.13671/j.hjkxxb.2017.0325付建平,青宪,冯桂贤,等.2017.基于污泥掺烧的某生活垃圾焚烧厂烟道气㊁飞灰及炉渣中的二英特征[J].环境科学学报,37(12):4677⁃4684FuJP,QingX,FengGX,etal.2017.Characteristicsofpolychlorinateddibenzo⁃p⁃dioxinsanddibenzofurans(PCDD/Fs)influegas,flyashandbottomslagfromamunicipalsolidwasteincineration(MSWI)plantbasedonco⁃firingofsewagesludge[J].ActaScientiaeCircumstantiae,37(12):4677⁃4684基于污泥掺烧的某生活垃圾焚烧厂烟道气㊁飞灰及炉渣中的二英特征付建平,青宪,冯桂贤,尹文华,杨艳艳,黄锦琼,韩静磊,张素坤,谢丹平,任明忠∗环境保护部华南环境科学研究所,广州510655收稿日期:2017⁃05⁃10㊀㊀㊀修回日期:2017⁃08⁃03㊀㊀㊀录用日期:2017⁃08⁃15摘要:以我国南方某生活垃圾焚烧厂掺烧10%市政污泥的生活垃圾为研究对象,对前/后口废气㊁飞灰㊁炉渣及用于掺烧的污泥中17种二英的含量进行了测定,并分析了其指纹分布特征.结合焚烧工况及处理设施,从生成机理角度探讨了二英的排放特征㊁毒性当量浓度主成分特征及主要单体的排放因子线性关系.结果表明:掺烧10%的市政污泥后,废气中二英的去除率为99.4%,低于国家排放标准;固体废物中二英含量为飞灰>炉渣>污泥.这说明采用高温焚烧和 活性炭喷射+布袋除尘 装置不会影响掺烧10%污泥的达标排放.指纹分布特征表明,前口废气以1,2,3,4,6,7,8⁃HpCDF和OCDD为主,后口废气以OCDD和OCDF为主;飞灰㊁炉渣及污泥中的主要单体为OCDD㊁1,2,3,4,6,7,8⁃HpCDD㊁OCDF㊁1,2,3,4,6,7,8⁃HpCDF.主成分分析显示,前口废气和飞灰中的二英毒性分布特征相似;炉渣和污泥的毒性分布特征相似;后口废气有自身的特征.这说明在相同工况条件下,经同一设施处理的废物中二英排放特征相似.排放因子分析表明,2,3,4,7,8⁃PeCDF和1,2,3,6,7,8⁃HxCDF㊁1,2,3,6,7,8⁃HxCDD和1,2,3,7,8,9⁃HxCDD与总毒性排放因子具有较强的线性关系,且呋喃类(PCDFs)强于二英类(PCDDs).关键词:二英;生活垃圾焚烧;主成分分析;排放因子文章编号:0253⁃2468(2017)12⁃4677⁃08㊀㊀㊀中图分类号:X705㊀㊀㊀文献标识码:ACharacteristicsofpolychlorinateddibenzo⁃p⁃dioxinsanddibenzofurans(PCDD/Fs)influegas,flyashandbottomslagfromamunicipalsolidwasteincineration(MSWI)plantbasedonco⁃firingofsewagesludgeFUJianping,QINGXian,FENGGuixian,YINWenhua,YANGYanyan,HUANGJinqiong,HANJinglei,ZHANGSukun,XIEDanping,RENMingzhong∗SouthChinaInsitituteofEnvironmentalSciences,MinistryofEnvironmentalProtection,Guangzhou510655Received10May2017;㊀㊀㊀receivedinrevisedform3August2017;㊀㊀㊀accepted15August2017Abstract:DeterminationandfingerprintanalysisofPCDD/Fsofthefront/backfluegas,flyash,bottomslagandsewagesludgesampledfromaMSWIplantwithco⁃combustionofsewagesludgeat10%inSouthernChinawereperformed.Basedonincinerationoperatingconditionsandtreatmentfacilities,weexploredtheemissioncharacteristics,principalcomponent(PC)characteristicsofinternationaltoxicityequivalent(I⁃TEQ)andlinearrelationshipofemissionfactorofmaincongenersfromaperspectiveofformationmechanismsofPCDD/Fs.TheresultsrevealedthattheremovalrateofPCDD/Fsinfluegaswas99.4%,whichwaslowerthanthenationalemissionstandard.TheconcentrationsofPCDD/Fsinsolidwasteswereintheorderasfollows:flyash>bottomslag>sewagesludge.Theseindicatedthattheapplicationofhightemperaturecombustionandactivatedcarboninjection+bagfilterhadnoeffectonthestandardizedemissionofco⁃firingsewagesludgeat10%.Thefingerprintanalysisshowedthatthemaincongenersinthefrontfluegaswere1,2,3,4,6,7,8⁃HpCDF,OCDD,andthoseinthebackfluegaswereOCDDandOCDF.Themajorcongenersinflyash,bottomslagandsludgewereOCDD,1,2,3,4,6,7,8⁃HpCDD,OCDFand1,2,3,4,6,7,8⁃HpCDF.Resultsofprincipalcomponentanalysis(PCA)revealedthatthesimilarityofI⁃环境科学学报环㊀㊀境㊀㊀科㊀㊀学㊀㊀学㊀㊀报37卷TEQdistributioncharacteristicsofPCDD/Fsinthefrontfluegasandflyash;theI⁃TEQdistributioncharacteristicsofPCDD/Fsinashandsludgewerealsosimilar,whileasthesewerespecificinthebackfluegas.ThisindicatedthattheemissioncharacteristicsofPCDD/Fsweresimilaraftertreatedwiththesamefacilityandthesameoperatingcondition.Analysisofemissionfactorshowedthat2,3,4,7,8⁃PeCDF,1,2,3,6,7,8⁃HxCDF,1,2,3,6,7,8⁃HxCDDand1,2,3,7,8,9⁃HxCDDsignificantlycorrelatedwithtotaltoxicemissionfactor.AndPCDFsshowedmoresignificantlinearcorrelationswiththetotaltoxicemissionfactorincomparisonwithPCDDs.Keywords:PCDD/Fs;MSWI;principalcomponentanalysis,emissionfactor1㊀引言(Introduction)随着经济的快速发展和生活水平的提高,城市垃圾问题日益突出.为实现资源的综合利用,垃圾焚烧已成为当前城市生活垃圾处理与处置的主要技术手段.但该技术会不可避免地产生二次污染,尤其是二英的污染引起了全社会的广泛关注.垃圾焚烧过程中生成的二英主要有3种途径,即原料中固有二英释放㊁低温异相催化反应㊁高温均相催化反应(Stieglitzetal.,1987;Hagenmaieretal.,1987;Tuppurainenetal.,1998),生成的二英主要通过废气㊁炉渣及飞灰等途径释放到环境中.据调查,这几种产生方式对二英的贡献为:飞灰>烟气>炉渣,其中,飞灰的贡献率占整个产生源的58% 88%(UNEPChemicals,2005).目前,针对垃圾焚烧行业二英的排放特征已有相关的研究报道(刘劲松等,2010;张海军等,2008;杨志军等,2004).而市政污泥作为城市污水处理过程产生的另一类固体类废物,因含有病原菌㊁重金属及有机物等毒害物质,若不经处理直接排入环境,既会造成环境污染,也会影响人类健康.据报道,截止2010年底,全国城镇污水处理厂脱水污泥产生量近2200万t, 十二五 期间还将进一步增长(张韵,2010).当前,污泥处置已有相关的成熟技术,如卫生填埋㊁堆肥㊁焚烧及土地利用等.因焚烧具有减量化㊁资源化及无害化优势,因此,被认为是比较可靠的污泥处理方式(曹秀芹等,2013;Chenetal.,2012),但污泥焚烧也会造成二英的排放(Dengetal.,2009).基于此,本文选取南方某生活垃圾焚烧厂,针对该厂在生活垃圾焚烧的基础上,掺烧一定比例的市政污泥,对各类型废物(膛燃烧后排放废气㊁炉渣㊁飞灰及经处理后排放废气)中排放的二英进行研究,并测定市政污泥中二英的含量,以探讨生活垃圾掺烧市政污泥后二英的排放情况及行为特征,以期为我国生活垃圾掺烧一定量市政污泥的环境管理提供借鉴.2㊀材料与方法(Materialsandmethods)2.1㊀样品采集本文以南方某生活垃圾焚烧厂为研究对象,该厂主要采用90%生活垃圾+10%的干化污泥(含水率20% 30%)掺烧技术;烟气净化系统采用半干式反应塔+活性炭喷射+布袋除尘器.废气采集:选取经炉膛燃烧后排放废气(前口),以及经活性炭喷射㊁高效布袋除尘器废气处理装置后的烟囱排放废气(后口),采样方法参照EN1948,采用等速采样,采样时长大于2h,采样体积大于2m3,前㊁后口各采集3个废气样品.飞灰㊁炉渣采集:在每个废气样品采集0.5㊁1和1.5h时采集经炉膛燃烧冷却后的炉渣和处理后的飞灰样品并混匀,各采集3个.污泥采集:从待掺烧的经压滤脱水后的污泥中随机取3份后混合成1个样品.焚烧厂焚烧设施及废气处理装置见图1.各类型废物废物产生量及工况参数情况见表1.从表1可以看出,炉渣产生量较飞灰多,前㊁后图1㊀焚烧装置及采样点位示意图Fig.1㊀Incinerationunitsandsamplingsites8764环境科学学报12期付建平等:基于污泥掺烧的某生活垃圾焚烧厂烟道气㊁飞灰及炉渣中的二英特征表1㊀固废及工况参数信息Table1㊀Informationofsolidwastesandworkparameters垃圾/(t㊃d-1)污泥/(t㊃d-1)炉渣/(t㊃d-1)飞灰/(t㊃d-1)烟气流量/(m3㊃h-1)前口氧量后口氧量炉膛温度/ħ前口温度/ħ后口温度/ħ45050388783209508.54%8.25%940226148采样口烟气氧含量基本一致,说明整个装置的密封性能良好.同时,各处理设施的温度满足垃圾焚烧二英控制的有关技术要求.由总体情况可知,整个焚烧设施及关键工况参数在研究开展期间处于正常的状态.2.2㊀样品前处理废气样品处理:滤筒和树脂用300mL甲苯索氏抽提24h后浓缩至2mL,冷凝水用二氯甲烷液液萃取3次浓缩后与甲苯抽提液合并.炉渣及污泥经冷冻干燥后研磨过200目筛,取筛下样品,与飞灰样品分别用300mL甲苯索氏抽提24h后浓缩至2mL.所有样品提取前加净化内标.浓缩后样品依次过多层硅胶柱(从上到下依次为:酸性硅胶㊁中性硅胶㊁碱性硅胶㊁中性硅胶㊁中性氧化铝㊁弗洛里硅土).上样前用80mL正己烷预淋洗层析柱,上样后依次用120mL正己烷㊁30mL正己烷ʒ二氯甲烷混合液(体积比为95ʒ5)洗脱以去除干扰物;然后用100mL二氯甲烷淋洗,洗脱液旋转蒸发至2mL,最后用高纯氮气吹扫浓缩至50μL后加入13C标记的进样内标,待仪器分析.2.3㊀仪器分析分析仪器为HP6890HRGC和AutoSpecPremierHRMS联用分析仪.色谱条件:选用DB⁃5MS(60mˑ0.25mmˑ0.25μm)色谱柱对17种二英单体进行分离.色谱柱升温程序:初温140ħ,保持2min,然后以8ħ㊃min-1升温至220ħ,再以1.4ħ㊃min-1升温至260ħ,最后以4ħ㊃min-1升温至310ħ,并保持4min.采用无分流方式进样,进样量为1μL.质谱条件:分辨率ȡ10000;离子源选用EI源,源温为300ħ.采用选择性离子(SIM)进行测定,电离能为35eV,离子化电流为600μA.2.4㊀质量保证与质量控制采用13C同位素内标稀释定量法对废气㊁炉渣㊁飞灰及污泥中二英进行定量,以实验空白扣除背景干扰.结果表明,实验空白的回收率介于63.4%118.0%,OCDD和OCDF是主要干扰物;样品回收率范围为60% 121.3%,说明此方法能满足研究要求.3㊀结果(Results)3.1㊀各类型排放废物中二英分布情况由表2可知,前口排放烟气中二英平均浓度表2㊀各类型废物中4 8氯代二英浓度及毒性当量浓度分布Table2㊀TheconcentrationsofPCDD/Fsinvarioustypesofwastes成分前口废气(n=3)后口废气(n=3)炉渣(n=3)飞灰(n=3)污泥(n=1)浓度/(ng㊃m-3)毒性当量浓度/(ng㊃m-3)浓度/(ng㊃m-3)毒性当量浓度/(ng㊃m-3)浓度/(ng㊃kg-1)毒性当量浓度/(ng㊃kg-1)浓度/(ng㊃kg-1)毒性当量浓度/(ng㊃kg-1)浓度/(ng㊃kg-1)毒性当量浓度/(ng㊃kg-1)TCDF1.010.10㊀㊀1.57ˑ10-31.57ˑ10-42.220.22174.0017.401.440.14PeCDFs3.280.871.12ˑ10-23.93ˑ10-36.251.83515.00130.004.721.41HxCDFs4.060.413.24ˑ10-23.24ˑ10-310.901.09596.0059.608.700.87HpCDFs2.932.93ˑ10-25.95ˑ10-25.95ˑ10-422.300.22455.004.5516.250.16OCDF0.878.74ˑ10-38.91ˑ10-28.91ˑ10-520.802.08ˑ10-2144.000.1416.700.02PCDFs12.101.410.197.99ˑ10-362.603.391884.00212.0047.812.60TCDD0.190.19N.D.N.D.N.D.N.D.33.3033.300.000.00PeCDDs0.400.20N.D.N.D.0.990.3358.0029.000.000.00HxCDDs0.686.76ˑ10-22.19ˑ10-22.06ˑ10-32.530.25143.0014.301.740.17HpCDDs0.858.52ˑ10-38.98ˑ10-28.98ˑ10-412.100.12263.002.637.950.08OCDD1.461.46ˑ10-30.111.12ˑ10-446.804.68ˑ10-2474.000.4738.500.04PCDDs3.570.470.223.08ˑ10-362.400.75971.0079.7048.190.29S PCDD/Fs15.701.870.420.01125.004.102855.00292.0096.002.90㊀㊀注:N.D.表示未检出;毒性当量浓度以I⁃TEQ计.9764环境科学学报环㊀㊀境㊀㊀科㊀㊀学㊀㊀学㊀㊀报37卷为15.7ng㊃m-3,平均毒性当量浓度为1.87ng㊃m-3(以I⁃TEQ计);后口烟气中二英平均浓度为0.42ng㊃m-3,平均毒性当量浓度为0.01ng㊃m-3(以I⁃TEQ计).根据我国颁布的生活垃圾焚烧行业二英的排放限值(0.1ng㊃m-3,以I⁃TEQ计)标准(GB18485 2014),该厂二英属达标排放.相对于前口排放废气,后口废气中二英毒性当量浓度去除率达到99.4%.这说明生活垃圾掺烧10%污泥对二英的达标排放并未造成影响.有学者对西班牙某垃圾焚烧厂的研究发现,原生垃圾中的二英含量对其排放没有影响(Abadetal.,2002).为探究产生该现象的原因,进一步对烟气处理工艺进行分析发现,本研究使用了活性炭喷射+布袋双重除尘装置,这可能是导致后口排放废气能达标排放的主要原因.研究指出,布袋除尘器和活性炭的联用可以有效去除飞灰中的二英,去除效率可达90%以上(周志广等,2007;张文斌等,2008).由表2可知,其他3类固体废物中二英含量介于国内外同类行业中低水平(Abadetal.,2006;Linetal.,2008).3类固体中二英含量依次为飞灰>炉渣>污泥,对应的平均值分别为2855㊁125㊁96.0ng㊃kg-1,毒性当量浓度(以I⁃TEQ计)分别为294㊁4.14㊁2.90ng㊃kg-1.这说明生活垃圾与污泥共焚烧排放的二英主要集中在飞灰中,少部分存在于炉渣中,而掺烧污泥对二英排放影响比较小.这可能是因为采用了活性炭喷射装置,提高了活性炭对二英的吸附效率,而布袋除尘装置对活性炭及其他颗粒具有过滤作用.现有研究指出,在垃圾焚烧过程使用活性炭喷射会增加飞灰中二英含量(Zhangetal.,2012).为初步判断生活垃圾掺烧污泥与不掺烧污泥两种工况时二英的排放特征,列举了部分国内外生活垃圾焚烧时烟气㊁飞灰及炉渣中二英的排放情况(表3).从表3可以看出,生活垃圾在焚烧过程经不同的烟气净化装置处理,所排放的二英毒性当量浓度并不相同,这可能是由于垃圾的成分及不同的燃烧条件造成的.但所列举的生活垃圾经焚烧设施处理后烟气㊁飞灰及底渣中呋喃类和二英类的质量浓度比值表现出基本一致的特征,即PCDD/PCDF<1,这与本研究的特征基本相似.这可能是因为生活垃圾在经过焚烧及相应的净化装置处理后,大部分二英都集中于PCDFs,少部分集中在PCDDs中.以上分析表明,生活垃圾掺烧污泥和不掺烧污泥的二英排放水平虽然不同,但PCDFs与PCDDs的比值具有相似的特征.表3 生活垃圾焚烧烟气、飞灰及炉渣中二英浓度水平Table3㊀ConcentrationofPCDD/Fsinfluegas,flyashandbottomslagofMSWIplant处理量/(t㊃d-1)二英毒性当量浓度烟气飞灰炉渣烟气净化装置数据来源2400.1923724.00活性炭+旋风除尘+布袋除尘张海军等,20083000.541500/静电除尘+湿式除尘Takaokaetal.,2003450/204021.8活性炭+布袋除尘Linetal.,20084000.0051200.03布袋除尘+湿法除尘Giuglianoetal.,20024500.030.46/活性炭+布袋除尘Wangetal.,200911400.07863963.4活性炭+布袋除尘Linetal.,20105000.012924.14活性炭+布袋除尘本研究㊀㊀注:烟气中二英毒性当量浓度(以I⁃TEQ计)单位为ng㊃m-3,飞灰㊁炉渣中二英毒性当量浓度(以I⁃TEQ计)单位为ng㊃kg-1.3.2㊀各类型废物中二英单体指纹分布特征各类型废物中17种二英单体指纹分布特征见图2.对于废气中二英指纹分布而言(图2a),前口废气二英主要集中于PCDFs,其中,1,2,3,4,6,7,8⁃HpCDF平均浓度为2.50ng㊃m-3,其余单体浓度介于0.099 1.710ng㊃m-3;PCDDs中以OCDD为主,平均浓度为1.46ng㊃m-3,其余单体浓度介于0.185 0.852ng㊃m-3.后口排放废气(图2b)二英与前口废气分布不一致,主要集中于PCDDs,以OCDD(平均浓度0.11ng㊃m-3)为主,其余单体浓度介于ND0.898ng㊃m-3;PCDFs除OCDF平均浓度为0.089ng㊃m-3外,其余单体浓度都低于0.05ng㊃m-3.所有废气除1,2,3,7,8,9⁃HxCDF外,PCDDs和PCDFs单体浓度都随着氯原子数增加而增大,这与现有的研究结果基本一致(Nietal.,2009;Abadetal.,2006).飞灰㊁炉渣与污泥中17种二英单体分布特征相似,PCDD/Fs含量随氯原子增加而增大(分别见图2c和图2d).飞灰样品中PCDDs以OCDD㊁1,2,0864环境科学学报12期付建平等:基于污泥掺烧的某生活垃圾焚烧厂烟道气㊁飞灰及炉渣中的二英特征3,4,6,7,8⁃HpCDD为主,平均含量分别为474和263ng㊃kg-1,其余单体平均含量介于31.0 64.5ng㊃kg-1;PCDFs以1,2,3,4,6,7,8⁃HpCDF(平均含量400ng㊃kg-1)为主,其余单体平均含量介于16.6 283ng㊃kg-1.飞灰中二英分布与Lin等(2008)的研究结果基本一致,而与其他研究结论不同(Panetal.,2013).这说明不同处理工艺对飞灰中二英的分布产生不同的影响.炉渣中PCDDs和PCDFs平均含量分别为62.4和62.6ng㊃kg-1(图2d),其中,PCDDs以OCDD(均值46.8ng㊃kg-1)和1,2,3,4,6,7,8⁃HpCDD(均值12.1ng㊃kg-1)为主,PCDFs以OCDF(均值20.8ng㊃kg-1)和1,2,3,4,6,7,8⁃HpCDF(均值19.5ng㊃kg-1)为主.这与现有研究对底渣中二英研究分布规律一致(Linetal.,2008).同样,污泥中二英分布规律与炉渣具有相似性,PCDDs主要单体是OCDD和1,2,3,4,6,7,8⁃HpCDD,含量分别为38.5和7.91ng㊃kg-1;PCDFs以OCDF和1,2,3,4,6,7,8⁃HpCDF为主,含量分别为16.7和14.3ng㊃kg-1.这与某研究对污水处理厂污泥中二英测定的结论一致(Delaetal.,2011).图2㊀各废物样品中17种二英单体指纹分布(a.前口废气,b.后口废气,c.飞灰,d.炉渣和污泥)Fig.2㊀Profilesof17congenersinvarioustypesofwastes1864环境科学学报环㊀㊀境㊀㊀科㊀㊀学㊀㊀学㊀㊀报37卷4㊀讨论(Discussion)4.1㊀各类型废物中二英排放特征有学者指出,垃圾焚烧过程中若PCDFs/PCDDs>1,二英主要以 从头合成 为主;若PCDFs/PCDDs<1,二英主要以 前驱物合成 为主(陈彤,2006).根据这一规律,并结合前面二英浓度分析可知,本研究各类型废物中前口废气㊁飞灰和炉渣中PCDFs/PCDDs>1,发生从头合成.从本研究的生产工艺(图1)及工况条件(表1)分析可知,这可能是因为生活垃圾与污泥在炉膛内经过高温焚烧(940ħ)后,各种污染物被完全分解,随后废物经余热锅炉后温度降至226ħ,此过程导致分解产物中的大分子碳与氯在催化剂的作用下生成二英,从而被飞灰吸附.而炉渣则是通过高温焚烧后,在降温后进行处理.有研究指出,PCDFs的最佳生成温度区间在400 500ħ,并且发生在垃圾焚烧炉尾部低温区域(Wikstromdetal.,2001;Stieglitzetal.,1987).而对于后口废气,PCDFs/PCDDs<1,发生的是前驱物反应.这可能是由于炉膛燃烧后的某些分解产物在降温过程中重新合成或燃烧后废物中本身含有的二英前驱物,并且这些前驱物在温度降低到一定程度时,在飞灰表面发生分子异构反应及缩合反应,从而导致PCDDs生成.同样有研究指出,由前驱物在飞灰表面生成PCDDs的最佳温度范围为250 400ħ,且主要在催化剂作用下通过偶联反应及异构反应等生成(Dicksonetal.,1987;Tuppurainenetal.,1998).4.2㊀各类型废物二英毒性当量浓度相关性为进一步探明二英毒性当量浓度在各类型排放废物中的分布特征,研究采用主成分法进行分析.从图3可知,该厂各类型废物17种二英毒性当量浓度可以由主成分1(91.9%)和主成分2(6.36%)解释98.26%的变化,并且可以分为3组不同的类型.一组为前口废气和飞灰样品的相似度比较大,这说明前口废气和飞灰中二英的毒性当量浓度分布特征相似;另一组为炉渣和污泥相似度较大,说明这两类样品中二英毒性当量浓度具有相似的分布特征;后口废气自成一簇,说明后口废气具有其自身的排放特征.同样结合本研究的生产工艺(图1)和工况信息(表1)进行分析,推断各类型废物中二英毒性当量浓度的主成分分布特征现象发生的原因可能是:图3㊀各类型废物17种二英毒性当量浓度主成分分析Fig.3㊀ThePCAofPCDD/Fsinvarioustypesofwastes由于垃圾和污泥共焚烧后产生的飞灰随废气流一同经过余热锅炉降温,使飞灰和前口废气在相同的生产工艺及工况条件下的改变一致,从而导致前口废气和飞灰的主成分特征相似;后口废气是前口废气经半干式反应塔脱酸及 活性炭喷射+布袋除尘 装置净化处理后的烟道气体,因此,导致其主成分特征与前口废气不同;而炉渣是由垃圾掺烧10%的污泥后所形成的大粒径固体类废物,其中可能包含有污泥焚烧后形成的残渣,从而也导致炉渣和污泥的主成分特征相似.4.3㊀各类型废物中二英排放因子行为分析为掌握垃圾焚烧厂二英排放情况,目前已有相关文献对排放因子进行深入研究报道(Linetal.,2010;Choietal.,2008).为进一步摸清本研究中各类型废物二英的产生及排放情况,结合表1,计算得到每燃烧1t生活垃圾的排放因子情况如表4所示.从表4可以看出,污泥中二英质量排放因子最大(514μg㊃t-1,以Waste计,下同),其次是飞灰(445μg㊃t-1)和前口排放废气(242μg㊃t-1),最小的为炉渣(96.7μg㊃t-1)和后口排放废气(6.42μg㊃t-1).而从毒性排放因子看,飞灰(45.5μg㊃t-1,以每tWaste的I⁃TEQ(μg)计,下同)和前口排放废气(28.9μg㊃t-1)最大,炉渣(3.22μg㊃t-1)和污泥(2.18μg㊃t-1)次之,后口排放废气(0.171μg㊃t-1)最小.总体上看,除污泥外,其他类型废物中的二英排放因子均以PCDFs为主.而后口排放废气中二英排放因子介于现有研究结果(Nietal.,2009)之间.4.4㊀主要毒性贡献体排放因子的线性分析结合各类型废物中17种单体二英的毒性当量浓度分析可知,2,3,4,7,8⁃PeCDF㊁1,2,3,6,7,8⁃2864环境科学学报12期付建平等:基于污泥掺烧的某生活垃圾焚烧厂烟道气㊁飞灰及炉渣中的二英特征表4㊀各类型废物中二英排放因子分布情况Table4㊀TheemissionfactorofPCDD/Fsinvarioustypesofwastesμg㊃t-1前口废气排放因子a后口废气排放因子a炉渣排放因子a飞灰排放因子a污泥排放因子b质量毒性质量毒性质量毒性质量毒性质量毒性187.021.702.990.124048.62.63029433.157.10.96655.17.163.430.047448.20.58215112.4457.01.210242.028.906.420.171096.73.22044545.5514.02.180㊀㊀注:质量排放因子以Waste计,毒性排放因子以每tWaste的I⁃TEQ(μg)计;a.n=3,b.n=1.HxCDF㊁1,2,3,6,7,8⁃HxCDD和1,2,3,7,8,9⁃HxCDD对总毒性排放因子贡献最大,平均毒性贡献率分别为18.3% 42.0%㊁5.11% 8.92%㊁1.29%11.6%和1.33% 4.82%.因此,对类型废物中4种主要单体的排放因子与总毒性排放因子进行线性分析.从图4a可以看出,2,3,4,7,8⁃PeCDF和1,2,3,6,7,8⁃HxCDF的线性可决系数分别为0.997和0.995;而从图4b可知,1,2,3,6,7,8⁃HxCDD和1,2,3,7,8,9⁃HxCDD的线性可决系数分别为0.893和0.976.由此分析可以判断,呋喃类(2,3,4,7,8⁃PeCDF和1,2,3,6,7,8⁃HxCDF)对总毒性排放因子的线性关系强于二英类(1,2,3,6,7,8⁃HxCDD和1,2,3,7,8,9⁃HxCDD).说明毒性贡献单体对总毒性排放因子贡献越大,其线性关系越强.图4㊀主要毒性单体与总毒性排放因子线性分析Fig.4㊀Thelinearcorrelationanalysisofemissionfactor5㊀结论(Conclusions)1)生活垃圾掺烧10%的市政污泥后,后口排放废气相对于前口废气,二英去除率达99.4%,低于国家排放标准.而固体类废物二英排放强度为飞灰>炉渣>污泥,这表明通过半干式反应塔与活性炭喷射+布袋除尘双重装置对废气进行处理,能够满足生活垃圾掺烧10%污泥后废气的达标排放要求.但采用活性炭喷射装置,会使飞灰中二英含量显著高于其他固体废物.与现有不掺烧污泥的生活垃圾焚烧研究结论相比,生活垃圾掺烧污泥与不掺烧污泥时二英具有相似性的排放特征.2)各类型废物中,前口废气以1,2,3,4,6,7,8⁃HpCDF和OCDD为主,后口废气以OCDD和OCDF为主.所有废气样品除123789⁃HxCDF外,其余单体浓度随氯原子增加而增大.飞灰㊁炉渣及污泥中主要单体集中在OCDD㊁1,2,3,4,6,7,8⁃HpCDF㊁OCDF和1,2,3,4,6,7,8⁃HpCDF,3类固体样品中PCDDs单体浓度随氯原子增加而增大.从垃圾焚烧二英生成机理推断,前口废气㊁飞灰及炉渣的PCDFs/PCDDs>1,发生 从头合成 反应;后口废气的PCDFs>PCDDs<1,发生 前驱物 合成反应.3)不同类型废物中二英毒性当量浓度主成分分析显示,前口废气和飞灰样品中二英的毒性当量浓度分布特征相似,炉渣和污泥毒性当量浓度分布特征相似,后口废气具有自身的排放特征,该现象可能与焚烧设施处理工艺有关.4)各类型废物的毒性当量排放因子的线性关3864环境科学学报环㊀㊀境㊀㊀科㊀㊀学㊀㊀学㊀㊀报37卷系研究结果显示,2,3,4,7,8⁃PeCDF㊁1,2,3,6,7,8⁃HxCDF㊁1,2,3,6,7,8⁃HxCDD和1,2,3,7,8,9⁃HxCDD对总毒性排放因子贡献最大,且呋喃类(PCDFs)对总毒性排放因子强于二英类(PCDDs).责任作者简介:任明忠(1973 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第8卷第5期2012年9月第三极环境专栏313 1981—2010年青藏高原地区气温变化与高程及纬度的关系王朋岭,唐国利,曹丽娟,刘秋锋,任玉玉320 2001—2010年青藏高原干湿格局及其影响因素分析王敏,周才平,吴良,徐兴良,欧阳华327 2006—2011年西藏纳木错湖冰状况及其影响因素分析曲斌,康世昌,陈锋,张拥军,张国帅334 西藏普莫雍错介形类反映的中晚全新世以来湖面波动与环境变化彭萍,朱立平,鞠建廷,Peter Frenzel,Claudia Wrozyna中国冰川资源专栏342 21世纪天山南坡台兰河流域径流变化情景预估孙美平,姚晓军,李忠勤,李晶350 天山托木尔峰南坡科其喀尔冰川流域径流模拟李晶,刘时银,韩海东,张勇,王建,魏俊锋357 托木尔型冰川融水对气候变化敏感性的模型分析韩海东,邵进荣,林凤,王建364 中国积雪时空变化分析刘俊峰,陈仁升,宋耀选温室气体排放372 国际气候谈判背景下的国家温室气体排放清单编制朱松丽,王文涛简讯378 BCC气候系统模式开展的CMIP5试验介绍辛晓歌,吴统文,张洁科学知识:全球变暖专题383 气候变化承诺王绍武,罗勇,赵宗慈,闻新宇,黄建斌385 暖大洋冷大陆王绍武,罗勇,赵宗慈,闻新宇,黄建斌387 全球变暖预估的不确定性王绍武,罗勇,赵宗慈,闻新宇,黄建斌信息与动态319 从现代和过去看未来全球变化研究的前景Vol. 8 No. 5 September 2012Special Section on the Third Pole319 Surface Air Temperature Variability and Its Relationship with Altitude & Latitude over the Tibetan Plateau in 1981-2010 Wang Pengling, Tang Guoli, Cao Lijuan, Liu Qiufeng, Ren Yuyu 326 Aridity Pattern of Tibetan Plateau and Its Influential Factors in 2001-2010Wang Min, Zhou Caiping, Wu Liang, Xu Xingliang, Ouyang Hua 333 Lake Ice and Its Effect Factors in the Nam Co Basin, Tibetan PlateauQu Bin, Kang Shichang, Chen Feng, Zhang Yongjun, Zhang Guoshuai 341 Lake Level Fluctuations and Environmental Changes Reflected by Ostracods of Pumayum Co on Tibetan Plateau Since Middle-Late HolocenePeng Ping, Zhu Liping, Ju Jianting, Peter Frenzel, Claudia WrozynaSpecial Section on China Glacial Resources349 Estimation of Tailan River Discharge in the Tianshan Mountains in the 21st CenturySun Meiping, Yao Xiaojun, Li Zhongqin, Li Jing 356 Evaluation of Runoff from Koxkar Glacier Basin, Tianshan Mountains, ChinaLi Jing, Liu Shiyin, Han Haidong, Zhang Yong, Wang Jian, Wei Junfeng 363 Modeling the Sensitivity of Meltwater Runoff of Tuomuer-Type Glacier to Climate ChangesHan Haidong, Shao Jinrong, Lin Feng, Wang Jian 371 Distribution and Variation of Snow Cover in ChinaLiu Junfeng, Chen Rensheng, Song Yaoxuan Greenhouse Gas Emissions377 National Greenhouse Gas Emission Inventory Development in the Context of International Climate Negotiation Zhu Songli, Wang WentaoNotes378 Introduction of CMIP5 Experiments Carried out by BCC Climate System ModelXin Xiaoge, Wu Tongwen, Zhang JieKnowledge: Special Topic on Global Warming383 Climate Change CommitmentsWang Shaowu, Luo Yong, Zhao Zongci, Wen Xinyu, Huang Jianbin 385 Warm Oceans and Cold ContinentsWang Shaowu, Luo Yong, Zhao Zongci, Wen Xinyu, Huang Jianbin 387 Uncertainties in Global Warming ProjectionWang Shaowu, Luo Yong, Zhao Zongci, Wen Xinyu, Huang Jianbin第三极包括青藏高原及毗邻地区,是全球中、低纬度冰川面积分布最广的地区。
持久性有机污染物在水体中的环境化学行为一、持久性有机污染物概述持久性有机污染物(Persistent Organic Pollutants,简称POPs)指人类合成的能持久存在环境中,能够通过生物食物链网累积,并对人类健康产生有害影响的化学物质。
持久性有机物具有环境持久性、生物蓄积性、半挥发性和高毒性的特点臼。
化学品协会国际理事会(ICCA)推荐:①持久性基准:水体中半衰期>180 d, 土壤和底泥中半衰期>360 d;②生物蓄积性基准:生物富集系数(BCF)>5000;③长距离越境迁移基准:大气中半衰期>2 d (蒸气压在0.01〜1 kPa);④偏远极地地区是否存在标准:水中质量浓度>10 ng/L0。
2001年5月23日,在瑞典首都签署的《关于持久性有机污染物的斯德哥尔摩公约》(简称《公约》),分别是艾氏剂、氯丹、狄氏剂、滴滴涕、异狄氏剂、七氯、灭蚁灵、毒杀芬、六氯苯、多氯联苯、二嗯英、多氯二苯并呋喃,标志着人类全面展开削减和淘汰POPs的国际合作⑶。
2009年5月举行的斯德哥尔摩公约缔约方大会第四届会议决定:全氟辛基磺酸及其盐类、全氟辛基磺酰氟、商用五溴联苯醚、商用八溴联苯醚、开蓬、林丹、五氯苯、六六六、六溴联苯/醚等9 类化学物质新增列入公约,标志着这些化合物也将在全球范围内被缔约方禁止生产和使用图。
POPs具有持久性、远距离传输性、生物蓄积性。
在环境中对于正常的生物降解、光解和化学分解作用有较强抵抗能力,因此它们一旦排到环境中,可以在大气、水体、土壤和底泥等环境中长久存在,它们易于进入生物体的脂肪组织, 并且积累的浓度会随着食物链的延长而升高,即生物放大作用⑶。
二、水体中的持久性有机污染物(一)水体中持久性有机污染物的来源水体中的持久性有机污染物的天然源较少,往往由人类活动产生,包括农药的使用和工业废水的排放。
1.农药的使用1938年滴滴涕类(DDTs)惊人的杀虫效果首次被发现,到20世纪60年代末有机氯农药(OCPs)成为世界上产量和使用量最大的农药。
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2024 年第 44 卷航 空 材 料 学 报2024,Vol. 44第 1 期第 152 – 162 页JOURNAL OF AERONAUTICAL MATERIALS No.1 pp.152 – 162引用格式:王瑞林,杨新岐,唐文珅,等. 搅拌摩擦沉积增材2219铝合金组织及性能[J]. 航空材料学报,2024,44(1):152-162.WANG Ruilin,YANG Xinqi,TANG Wenshen,et al. Microstructure and properties of 2219 aluminum alloy fabricated via additive friction stir deposition[J]. Journal of Aeronautical Materials,2024,44(1):152-162.搅拌摩擦沉积增材2219铝合金组织及性能王瑞林1*, 杨新岐1*, 唐文珅1, 罗 庭1, 赵耀邦2, 窦恩慧2(1.天津大学 材料科学与工程学院,天津 300354;2.上海航天精密机械研究所,上海 201600)摘要:在主轴转速250~350 r/min、横向移动速度50~150 mm/min工艺参数下进行2219-T87铝合金搅拌摩擦沉积增材(additive friction stir deposition,AFSD)实验,探究工艺参数与多层热循环对沉积层宏观成形、微观组织和力学性能的影响。
结果表明:在主轴转速250 r/min,移动速度100 mm/min工艺参数下可获得成形良好的单道16层增材试样。
增材区晶粒尺寸发生显著细化,在4~6 μm之间,细小等轴晶组织取代沉积棒料粗大的无规则晶粒组织。
增材试样发生剧烈的动态再结晶,整体再结晶晶粒在80%以上,试样底部(第1层)受到多次热循环影响,再结晶晶粒达到91.8%。
增材区域织构基本由Cube、Copper、P和RtB四种再结晶织构以及S、T和Brass织构构成。
低温胁迫对切花菊叶片光化学反应参数的影响赵鹏飞;聂林杰;王磊;栗燕;张开明;李永华【摘要】A study on the changes in photochemical reaction parameters of cut chrysanthemum leaf under different temperatures was conducted by taking cut chrysanthemum cultivar'White Pingpang'as the experimental material,and three processing temperatures of 15 ℃(CK) ,4 ℃ and - 4 ℃ were set with each sustaining for 12 h to measure the chlorophyll fluorescence parameters. The results showed that compared with 16 ℃,Fo decreased by 9. 7% and 51. 5%,while RC /Cso experienced a decline by 15. 4% and 86. 6%at 4 ℃ and - 4 ℃,respectively. The OJIP curve,MR/Mro curve and other photochemical reaction parameters were significantly changed as temperature decreased. It indicated that the LHCII resolved under low temperature stress,opening degree of PSII reaction center reduced, partial reaction center was deactiviated,and PSI reaction center activity reducd. Besides, - 4 ℃ treatment caused serious damage to PSI of cut chrysanthemum leaf,and the photosynthetic activity of the whole plant decreased.%以切花菊品种'白乒乓'为材料,设置16、4、-4 ℃共3个处理温度,处理时间为12 h,对光系统叶绿素荧光参数进行测定,研究不同温度下切花菊叶片光化学反应的变化.结果表明,与16 ℃相比,在4 ℃和-4 ℃条件下,叶片初始荧光(Fo) 分别降低了9. 7%和51. 5%,单位面积有活性反应中心数量(RC/Cso) 降低了15. 4%和86. 6%,快速荧光动力学(OJIP) 曲线、光系统I(Photosystem I,PSI) 活性(MR/Mro) 曲线和其他光化学反应参数均变化显著.切花菊叶片在低温胁迫下捕光色素降解,光系统II(Photosystem II,PSII) 反应中心开放程度降低,部分反应中心失活,PSI反应中心活性降低,-4 ℃处理对切花菊叶片PSI造成了严重的伤害,植株整体光合活性降低.【期刊名称】《河南农业大学学报》【年(卷),期】2019(053)002【总页数】7页(P193-199)【关键词】切花菊;低温胁迫;叶绿素快速荧光;光系统;OJIP曲线【作者】赵鹏飞;聂林杰;王磊;栗燕;张开明;李永华【作者单位】河南农业大学林学院,河南郑州 450002;河南农业大学林学院,河南郑州 450002;河南农业大学林学院,河南郑州 450002;河南农业大学林学院,河南郑州 450002;河南农业大学林学院,河南郑州 450002;河南农业大学林学院,河南郑州 450002【正文语种】中文【中图分类】S682.11菊花(Chrysanthemum morifolium Ramat)是世界四大切花之一。
The winter effect on formation of PCDD/Fs in Guangzhou by vehicles:A tunnel studyYunyun Deng a ,b ,Pingan Peng a ,*,Man Ren a ,Jianzhong Song a ,Weilin Huang caState Key Laboratory of Organic Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China bShanghai Academy of Public Measurement,Shanghai 201203,China cDepartment of Environmental Sciences,Rutgers,The State University of New Jersey,14College Farm Road,New Brunswick,NJ 08901,USAa r t i c l e i n f oArticle history:Received 26August 2010Received in revised form 10February 2011Accepted 10February 2011Keywords:PCDDs/Fs VehicleWinter effect Emission factora b s t r a c tPrior studies showed that the polychlorinated dibenzo-p -dioxin and dibenzofuran (PCDD/F)concentra-tions in the atmosphere are much higher in the winter than in the summer.This so called winter effect was explained via meteorology-dependent factors such as dispersion,mixing and photo chemical degradation or home heating related formation of PCDDs/Fs.In this study,we took vehicle emission as an example to investigate winter effect on PCDD/Fs formation by fossil fuel combustion.We hypothesized that vehicle emission of PCDDs/Fs may be elevated in the winter season due to the promoted supplies of Cl À(via particular matter)in winter.We collected particulate and gaseous samples from the Pearl River Tunnel and its adjacent open air during spring/summer and winter seasons.Chemical analyses of the tunnel samples showed that the PCDD/F concentrations in the tunnel ranged from 18.6to 20.4pg m À3(1.28e 1.39pg I-TEQ m À3)in the winter,which were 3e 5times higher than in the spring/summer.In the open atmosphere adjacent to the tunnel,the PCDD/F concentrations were much lower than in the tunnel;e.g.,approximately one fifth of the tunnel air concentrations during the winter.The emission factors (EFs)calculated based on the tunnel data were 3440(or 230I-TEQ)and 1580(or 27.8I-TEQ)pg km À1vehicle À1in winter and spring/summer season,respectively.The much higher PCDD/F concentrations in the tunnel air and much greater EF value during the winter are likely related to higher content of Cl Àassociated with small size particulates.This suggests that the winter effect observed in the open atmosphere is not only caused by meteorology-dependent factors and home heating,but also may partly results from much greater PCDD/F formation rates during the combustion processes of fossil fuels such as gasoline-and diesel-fuel in the winter.Ó2011Elsevier Ltd.All rights reserved.1.IntroductionPolychlorinated dibenzo-p -dioxins and dibenzofurans (PCDDs/Fs)are mainly generated as unintended by-products during combustion processes.It is estimated that 96%of PCDDs/Fs in the environment is emitted firstly to the atmosphere (Smit et al.,2004).Municipal solid waste incineration (MSWI)and fossil fuel burning have long been regarded as major emission sources of PCDDs/Fs (Yu et al.,2006).Recent research suggested that emission from MSWI has gradually lessened due to the advancement of better controlled combustion technologies (Yu et al.,2006).Instead,automobiles may become an important emitter of PCDDs/Fs.Ballschmiter et al.(1986)detected PCDDs/Fs in used motor oil and thus provided the first evidence that PCDDs/Fs might be emitted by the combustion processes in gasoline-and diesel-fueled engines.Fuster et al.(2001)reported that,in Tar-ragona Province of Spain,the PCDD/F emission from MSWI may contribute about 0.04%whereas the emission from diesel motors accounted for 18%of the total PCDD/F emissions.Several prior studies showed that the PCDD/F concentrations in the atmosphere are much higher in the winter than in the summer,which is often called winter effect.Hovmand et al.(2007)measured combined PCDD/F concentration from 12-m high tower in one Danish rural forest sites.The ratio between winter (October e March)and summer (April e September)mean values of atmospheric I-TEQ concentrations was 3.90,calculated for the period 2002e 2004.Coutinho et al.(2007)found the average ratio of the combined PCDD/F concentrations between winter (October e March)and summer (April e September)was 3.30at most.Sin et al.(2002)measured 27ambient air samples in Hong Kong.The combined PCDD/F concentrations ranged from 0.03to 0.43pg I-TEQ m À3in winter months (January and March),and 0.018to 0.025pg I-TEQ m À3in the summer months (July and August).When compared*Corresponding author.E-mail address:pinganp@ (P.Peng).Contents lists available at ScienceDirectAtmospheric Environmentjournal homep age:www.elsevi/locate/atmosenv1352-2310/$e see front matter Ó2011Elsevier Ltd.All rights reserved.doi:10.1016/j.atmosenv.2011.02.022Atmospheric Environment 45(2011)2541e 2548with the same sampling location,the ratio of the combined concentrations in the winter to summer ranged from1.10to20.4.The observed winter effect is often explained via seasonally-controlled dominant factors for the emission and degradation of PCDDs/Fs and/or seasonal change in air mass movement(Hippelein et al.,1996;Duarte et al.,1997;Lee et al.,1999;Lohmann et al., 1999).The former generally refers to higher emission of home heating in the winter and faster PCDD/F degradation rates in the summer.The latter is related to the seasonal variation of the atmospheric boundary layer generally referred to as the mixing layer(Coutinho et al.,2007).In a typical region of mid latitude,the heights of the convective mixing layer are very different between summer and winter.During summer as more heating of daytime than cooling during shortened nights,the convective mixing layer starts shallow in the morning,but rapidly grows to its full extent in early afternoon.On the contrary,during winter as more cooling at night than heating during the shortened daytime,the convective mixing layer remains relatively stable(Coutinho et al.,2007). Hence,local emissions to the atmosphere will be less welldispersed during winter.This process is particularly effective for emissions that occur near ground level because a reduced height of the well-mixed atmosphere favors an accumulation of pollutants and result in increasing ambient concentrations.In this study,we hypothesized that formation of PCDDs/Fs may be elevated in the winter season due to the promoted supplies of ClÀ(via particular matter),hence contributing partly to the often observed winter effect.We took vehicles as an example and initi-ated a systematic study to quantify the emission factor of PCDDs/Fs for vehicles in the Pearl River Delta area using a tunnel method.The major focus of the work was to quantify seasonal changes of PCDD/F concentrations in both open atmosphere and the tunnel air.The results presented here are consistent with our hypothesis,indi-cating that the formation of PCDD/Fs in the winter of Guangzhou by vehicles is higher,which provides an alternative explanation for winter effect.2.Materials and methods2.1.Sampling sitesGuangzhou,the capital of Guangdong province,is a subtropical city with an area of7430km2and a population over6.40million.It was estimated that1890thousand tons of gasoline and2720 thousand tons of diesel oil were consumed in2005and about1.77 million cars are running on the roads of Guangzhou according to the Statistical Bureau of Guangzhou(2006).Recent studies con-ducted by our research group(Yu et al.,2006;Ren et al.,2007) indicated that the atmospheric depositionfluxes of total2,3,7,8-substituted PCDD/F congeners ranged from2.10to41.0(mean20) pg WHO-TEQ mÀ2dayÀ1in Guangzhou,and that the particle-bound PCDDs/Fs in the atmosphere of Guangzhou ranged from0.105to 0.769pg I-TEQ mÀ3.It is expected that the sources of PCDDs/Fs are very diverse as rapid industrialization in this region may have brought in a spectrum of emitters of PCDDs/Fs.As fast growing of privately owned vehicles may have outpaced any other emitters, quantification of the contribution of vehicles to the total emissions is urgent for source control of PCDDs/Fs in this region.This study targeted the Pearl River tunnel located in the central city of Guangzhou which connects Fangchun District and Liwan District(Fig.1).It has a length of1240m and height of8.10m with two lanes per bore.Each day approximately120,000vehicles pass the tunnel at an average speed40.0km hÀ1(Guangzhou Transport Planning Research Institute,2006,Annual Report of Transportation Development in Guangzhou).Four sampling sites were selected in this study(Fig.1).Site A and Site B are located respectively in the midpoint and the southbound exit of the tunnel.They were selected for sampling the gaseous and particulate-bound PCDD/F pollutants in the atmosphere influenced directly by the traffic within the tunnel.Site C and Site D are located in Liwan district in the vicinity of the tunnel.They were selected for monitoring background air quality in the central city of Guangzhou.Site C is near the Tunnel Management Station,which is located200m away from the tunnel exit(Site B).The samples taken from this site should represent a mixture of the background atmosphere in central city and the atmosphere exit from the tunnel.Site D is located in Shamian Park(north side of the tunnel)situated on an island of the Pearl River.The samples taken from the park likely represented background atmosphere within the central city.The geographical locations of the four sampling sites are shown sche-matically in Fig.1.2.2.Air sampling in tunnel and ambient atmosphereTwo samples for each site were taken in the spring(April 11e12th),summer(July10e12th)and winter(December10e12th) of2006respectively.Both gaseous and particulate samples were simultaneously collected with a high-volume air sampler(Tian-hong Intelligent Instrument Co,Wuhan).The gaseous samples were collected with polyurethane foam(PUF,90mmÂ65mm i.d.). Whatman glassfiberfilters(GFF,20.3cmÂ25.4cm)were pre-treated at450 C for6h before being used for collecting the total suspended particulates(TSP).The airflow rate passing through the sampler was calibrated before and after the sampling.After sampling,thesefilters and polyurethane foams were removed from the sampler and wrapped with aluminum foil.Thefilters were weighed after equilibrated for24h at25 C and50%relative humidity.At both Site A and B,the speed of airflow within the tunnel was monitored with an anemometer.The vehicleflux was counted on a video tape kindly provided by the Pearl River tunnel administration station.The recorded data are summarized in Table1.We checked PCDD/F concentrations in the two samples collected for each site and season.The discrepancy was minor; therefore,only one set of concentration data was reported in this paper.To investigate the influence of particle-bound ClÀand Cu on the formation of PCDDs/Fs,six particle sizes of aerosols(<0.49m m, 0.49e0.95m m,0.95e1.5m m,1.5e3.0m m,3.0e7.2m m,and7.2e10m m) in Site D were further collected in the summer and winter of2009. Particulates were collected with an Andersen sampler(modelSA235)Fig.1.Locations of the sampling sites.Y.Deng et al./Atmospheric Environment45(2011)2541e2548 2542at an airflow of1.13m3minÀ1.Quartzfilters(Environmental Tisch TE-230QZ)were used as impaction substrates(slotted14.3Â13.7cm)for the collection of thefive size fractions and rectangular backup quartzfilters(20.3Â13.7cm)for thefinest size fraction.The quartzfiberfilters were pretreated at450 C for5h before use.2.3.Sample analysis2.3.1.Reference standards and chemicals for cleanupAll13C12-labeled PCDD/F standards were purchased from Cam-bridge Isotope Laboratories Inc.(Boston,USA).All solvents and reagents used in this study were all pesticide grades or higher purchased from Merck,Germany.These solvents included meth-anol,acetone,dichloromethane(DCM),toluene,and n-hexane. Silica gel(70e230mesh)and basic alumina used in cleanup procedure were purchased from Merck,Germany.2.3.2.Clean-up procedureThe US EPA Method1613was followed for the analysis of PCDDs/Fs.The detailed procedure can be found in Ren et al.(2007). In brief,thefilters or foams were spiked with a stock solution (10m l)of13C12-PCDD/F internal standards,which includedfifteen PCDD/F compounds.Thefilters and foams were Soxhlet extracted with toluene(250ml)for48h.The extracts were cleaned sequentially with acid silica gel bed,multi-layer silica gel column and basic alumina column following the procedures briefed below. Each sample extract wasfirst cleaned in aflask containing20g of 40%H2SO4/silica gel and100ml of hexane.After stirred for2h,the content of theflask wasfiltered through a funnelfilled with glass wool and10g of Na2SO4.Hexane(100ml)was used to rinse the flask and the slurry.The hexanefiltrates were further cleaned on a multi-layer silica gel column eluted successively with20ml of hexane(discarded)and100ml of3%dichloromethane/hexane (retained).The later solvent mixture was loaded on a10-g basic alumina column,which was eluted sequentially with20ml of hexane(discarded),80ml of2%dichloromethane/hexane(dis-carded)and100ml of dichloromethane e hexane mixture (v:v50:50)(retained).The last solvent mixture was concentrated to 1ml on a rotary evaporator,which was then transferred to a1.5-ml teardrop vial.Before analysis,injection standards(10m l)consisted of13C12-labled1,2,3,4-TCDD and13C12-labled1,2,3,7,8,9-HxCDD were added into the vial and thefinal volume was reduced to 20m l on an N2blower.Cu contents in the samples were determined using the following procedures.A part of quartzfilter charged in a platinum crucible was completely dissolved in a mixture of HNO3,HF and HClO4.After dryness,the residue was dissolved with8M HNO3(2ml)and finally diluted to100ml with pure water for subsequent Cu determination using ICP-MS.ClÀcontents in the samples were determined by rinsing quartz filter with Milli-Q ultra pure water and then analysis with ion chromatography.2.3.3.Instrumental analysisPCDDs/Fs were identified and quantified using high-resolution gas chromatography coupled with high-resolution mass spec-trometry(HRGC/HRMS)(Trace GC2000and Thermo Electron Fin-nigan MAT95XP;GC column:J&W Scientific,CA,60mÂ0.25mm i.d.Â0.25mmfilm thickness).Helium was used as the carrier gas at aflow rate of0.8ml minÀ1.The sample(1m l)was injected with a splitless injection mode.The temperature of GC was programmed to increase to90 C,stayed for1min,then increased to200 C at 76 C minÀ1and stayed at200 C for7min,then to275 C at 1.2 C minÀ1andfinally to300 C at 1.7 C minÀ1.The injector temperature was kept at250 C and the HRGC/HRMS interface temperature was held at250 C.The HRMS was operated in the EI positive(electric impact ionization)and LOCK MID mode with a mass resolution of10,000(313.9839,perfluorotributylamine).The electron impact ionization energy was55eV with a source temperature of250 C.Cu measurement was performed using an Elan6000ICP-MS spectrometer(Perkin e Elmer,USA).Instrumental conditions are listed as the following.Rf power,1050W;Plasma gasflow rate, 15l minÀ1;Intermediate gasflow rate,1.2l minÀ1;Nebulizer gas flow,0.83l minÀ1;Auto lens,On;Measurement mode,Peak hopping;Sweeps/reading,8;Reading/replicate,1;Dwell time, 100ms.The identification and quantification of chlorine ions were performed by a Dionex ICS900IC(Dionex,Sunnyvale,CA,USA), equipped with a RFIC IonPacAS19analytical column(250mmÂ4mm id),a RFIC IonPacAG19guard column(50mmÂ4mm id)and a conductivity detector.The mobile phase,containing20mM KOH was pumped at aflow rate of1.0ml minÀ1.The injection volume was200m l.Quantification of ClÀwas performed by external calibration.2.3.4.Quality assurance and quality control(QA/QC)Standard procedures were employed during sampling,extrac-tion and quantification of target contaminants for QA/QC purpose. Before sampling,all glassfiberfilters were heated at450 C for6h to remove possible background organic contaminants.The poly-urethane foams were Soxhlet extracted sequentially with methanol, DCM,toluene,and acetone for4Â24h,vacuum dried,and kept in pre-cleaned amber glass jars.The air samplers were calibrated in thefield before and after each sampling event.During extraction and chemical analysis in the lab,afield blank and a method blank were used for every batch of twelve samples.During extraction,all samples and blanks were spiked with15kinds of internal13C12-labeled PCDD/F standards to trace the recovery efficiency of theTable1Background information of the four sampling sites.Sampling date Sampling time(min)Sampling volume(m3)Temperature( C)Vehicle volume(vehicles duringthe sampling)TSP(mg mÀ3)Site A(Middle of tunnel)2006-4-1141384.252216,726 1.72 2006-7-11259102.953111,204 1.172006-12-1142396.871919,466 1.48Site B(Outlet of tunnel)2006-4-1127252.872011,016 1.89 2006-7-1125886.993211,164 2.592006-12-1141589.11918,837 1.93Site C2006-7-11720201.6330.295 2006-12-11664183.26200.49Site D2006-7-11630155.82310.225 2006-12-11600128.82190.228Y.Deng et al./Atmospheric Environment45(2011)2541e25482543method.According to the surrogate standards run in parallel to the samples,the recovery ef ficiency ranged from 63to 97%,which meets the limit of 32e 123%given in US EPA Method 1613.The detection limits of the method were ca.0.1pg for 2,3,7,8-TCDF,0.2pg for 2,3,7,8-TCDD,and 0.8pg for OCDD.3.Results and discussion3.1.PCDD/F concentrations in the Pearl River TunnelTable 1lists the background data of the gaseous and particulate samples taken inside and outside of the tunnel.Table 2summarizes the concentrations of individual 2,3,7,8-substituted PCDD/F congeners in both gaseous and particulate samples taken at Site A and B of the tunnel.As shown in Table 1,the average concentrations of the particulate materials in the tunnel were 1.81,1.88and 1.71mg m À3in spring,summer and winter,respectively.These total particulate concentrations remained fairly constant for the three sampling times,but they were 4e 6times higher than those from the atmosphere outside the tunnel,which were collected on the same day.Note that relative constant meteorological condition and single vehicle emission source may have resulted in similar concentrations of particulates in the tunnel air.One striking feature of the data listed in Table 2is that,for the two sampling sites within the tunnel,the particulate-bound PCDD/F concentrations were approximately 1e 10times higher in the winter than in the spring and summer,suggesting an strong winter effect on the overall concentration of the particulate-bound PCDDs/Fs.As shown in Table 2,the particulate-bound PCDD/F concentrations ranged widely from 2.25to 19.6pg m À3(or 0.114e 1.30pg I-TEQ m À3),and there is no appreciable difference between the spring and summer,which had the average concentrations of 3.05and 3.40pg m À3(or 0.217and 0.127pg I-TEQ m À3)respectively.The particulate-bound PCDD/F average concentrations in the winter were 18.4pg m À3(or 1.24pg I-TEQ m À3).Such a winter effect was much less for the gaseous PCDD/F concentrations,which ranged narrowly from 0.715to 1.54pg m À3(or 0.091e 0.22pg I-TEQ m À3)for all the three sampling times at the two tunnel sites.Table 1also showed no signi ficant difference of the total suspended particulate (TSP)concentrations between spring/summer and winter.Therefore,it is unlikely that the observed winter effect is related to the concentrations of particulate materials in the air.To our knowledge,no prior publications reported the winter effect from the tunnel studies.Wevers et al.(1992)reported that the combined (gas þparticulate)PCDD/F concentrations in a Belgium tunnel were approximately 0.0803pg I-TEQ m À3.Geueke et al.(1999)conducted PCDD/F sampling of diesel engine at a constant load rate with about 30%of its nominal power.The emission concentrations were from 0.21to 58.0pg I-TEQ m À3.Chang et al.(2004)reported the total PCDD/F concentrations of 0.0473(outlet)and 0.0571(midpoint)pg I-TEQ m À3for a tunnel of northeastern Taipei,Taiwan.All these published data are in general comparable to our data summarized in Table 2.Further inspection of the data in Table 2indicated that,for the same sampling trip,the PCDD/F concentrations measured at Site B (exit)(4.55e 20.4pg m À3or 0.218e 1.39pg I-TEQ m À3)were slightly higher than those at Site A (midpoint of the tunnel)(3.79e 18.6pg m À3or 0.207e 1.27pg I-TEQ m À3).The higher concentra-tions measured at the exit of the tunnel were likely due to the so called piston effect,referring to the forced air flow inside a tunnel caused by moving vehicles.The air pollutants were pushed out of the tunnel by the cars,leading the higher concentrations at the exit (Chang et al.,2004).Table 3presents the PCDD/F concentrations of open atmosphere (Site C and D)in the summer and winter;they were collected on the same days as the samples from the tunnel.The combined partic-ulate-bound and gaseous PCDD/F concentrations measured at Site C were 3.59pg m À3(0.186pg I-TEQ m À3)and 16.1pg m À3(1.17pg I-TEQ m À3)respectively in July and December.The combined concentrations measured at Site D were 3.08pg m À3(0.186pg I-TEQ m À3)and 9.23pg m À3(0.247pg I-TEQ m À3)respectively in July and December.These values were all lower than those within the tunnel.Note that the difference of the combined I-TEQ concentra-tions between inside and outside the tunnel was insigni ficant in summer,but signi ficant in winter.The combined I-TEQ concentra-tions within the tunnel (Site A and B)were 1.14times higher than the background I-TEQ concentrations (Site D)in the summer,but they were 7.16times as high as the background I-TEQ concentra-tions (Site D)in the winter.Meanwhile,the ratios of the combined concentrations between the samples of 11th December and 11th July were 1.33at Site D,but the ratios increased to 6inside theTable 2Concentrations (pg m À3)of 2,3,7,8-substituted congeners.CongenersTunnel Site A (Middle of tunnel)Tunnel Site B (Outlet of tunnel)2006-4-112006-7-112006-12-112006-4-112006-7-112006-12-11ParticulateGaseous Particulate Gaseous Particulate Gaseous Particulate Gaseous Particulate Gaseous Particulate Gaseous 2378-TCDF 8.40E-02 5.79E-01 1.92E-02 2.51E-01 1.45E þ00 1.87E-01 1.88E-01 4.67E-029.12E-027.09E-02 1.45E þ00 6.37E-0212378-PeCDF 1.40E-01 4.36E-01 5.97E-02 1.05E-01 2.06E þ00 5.87E-02 2.57E-01 3.82E-02 5.76E-027.39E-02 2.17E þ00 6.72E-0223478-PeCDF 1.77E-01 1.84E-01 1.09E-019.27E-028.53E-01 6.22E-02 3.06E-01 4.80E-02 1.40E-018.30E-029.50E-017.68E-02123478-HxCDF 6.39E-02 3.40E-02 1.01E-01 3.00E-02 1.58E þ008.59E-02 1.00E-01 4.98E-02 4.28E-02 2.12E-02 1.99E þ00 5.84E-02123678-HxCDF 4.53E-02 3.92E-027.77E-02 2.68E-027.97E-01 3.52E-02 1.02E-01 6.66E-02 2.60E-02 1.30E-029.57E-01 5.15E-02234678-HxCDF 1.11E-01 1.06E-02 1.17E-01 1.45E-02 6.56E-01 6.17E-02 2.44E-01 3.18E-02 1.11E-01 3.54E-027.58E-01 4.33E-02123789-HxCDF 5.10E-03 3.68E-03 4.25E-02 3.69E-03 4.19E-01 1.34E-02 1.12E-02 4.35E-03 6.78E-03 1.22E-02 4.90E-01 2.41E-021234678-HpCDF 3.00E-01 5.38E-02 3.83E-017.64E-02 2.33E þ00 1.66E-01 4.97E-018.42E-02 5.04E-01 4.64E-02 2.66E þ00 1.19E-011234789-HpCDF 6.45E-02 2.97E-03 4.82E-02 3.11E-03 5.27E-01 1.44E-02 4.88E-028.51E-03 2.77E-02 4.71E-03 6.09E-018.64E-03OCDF1.60E-01 1.28E-022.11E-013.05E-02 2.05E þ004.94E-02 2.54E-01 3.01E-02 2.95E-01 2.05E-02 2.34E þ00 3.77E-022378-TCDD 2.73E-03 2.52E-02 1.12E-03 2.17E-038.52E-037.19E-038.51E-03 3.22E-03 1.06E-02 1.22E-027.52E-03 1.17E-0212378-PeCDD 2.55E-02 2.31E-027.23E-03 1.09E-02 1.50E-01 2.02E-025.92E-02 1.06E-01 2.97E-02 4.83E-03 1.13E-01 1.48E-02123478-HxCDD 5.58E-03 3.32E-03 1.84E-020.00E þ00 5.97E-02 1.37E-029.46E-03 2.27E-030.00E þ000.00E þ00 1.12E-01 1.26E-02123678-HxCDD 9.50E-038.19E-03 2.45E-02 2.33E-03 1.17E-016.04E-02 1.17E-02 1.08E-02 2.47E-02 1.46E-02 1.57E-01 1.28E-02123789-HxCDD 8.66E-037.10E-04 2.48E-02 1.23E-039.11E-02 1.92E-02 2.67E-027.00E-03 1.15E-03 3.91E-03 1.46E-01 1.45E-021234678-HpCDD 1.91E-01 4.93E-02 3.05E-01 2.42E-028.49E-01 1.70E-01 3.40E-01 4.79E-02 3.66E-01 3.59E-029.50E-01 6.16E-02OCDD 8.57E-017.37E-02 1.40E þ00 1.17E-01 3.10E þ00 4.77E-01 1.37E þ00 1.30E-01 2.21E þ00 2.94E-01 3.76E þ008.60E-02TEQ(pg I-TEQ m À3) 1.51E-01 2.20E-01 1.14E-019.34E-02 1.17E þ00 1.03E-01 2.84E-01 1.06E-01 1.40E-017.81E-02 1.30E þ009.09E-02Total PCDDs/Fs2.25E þ001.54E þ002.95E þ007.92E-011.71E þ011.50E þ003.83E þ007.15E-013.94E þ007.47E-011.96E þ017.65E-01Y.Deng et al./Atmospheric Environment 45(2011)2541e 25482544tunnel (Site A and B).These ratios were consistent with other studies summarized in the Introduction Section.3.2.Homolog and congener pro filesFig.2illustrates the relative contributions of different homolog compounds to the combined gaseous and particulate phase PCDDs/Fs for the samples taken within the tunnel.It indicates that the greater is the degree of chlorination of the compounds,the higher is the combined PCDD concentration.However,the combined PCDF concentrations were not correlated well with the degree of their chlorination,which was different from the negative correlation revealed in a previous study by Lohmann and Jones (1998).Fig.2shows slightly different homolog distribution of the PCDDs/Fs between the winter and the spring e summer of the combined PCDD/F concentrations within the tunnel.In the spring e summer,the predominant homolog was OCDD,which constituted approximately 37.9%of the combined PCDD/F concen-trations.This is consistent with an EPA report of PCDDs/Fs for the total emissions from various combustion processes including unleaded gasoline combustion and diesel-fuel combustion (US EPA,2006).Other major homologs included PeCDF,HpCDF and HxCDF,which accounted respectively for 14.1,12.8and 9.61%of the combined PCDD/F concentrations.In the winter,however,HxCDF was the predominant compound which accounted for 20.5%of the total 2,3,7,8-substituted PCDD/F homologs.Other major homologs were OCDD,HpCDF and PeCDF,which accounted respectively for 19.1,16.5and 16.2%of the total 2,3,7,8-substituted PCDD/F concentrations.Congener pro files of the combined PCDD/F concentrations shown in Fig.3for the spring and summer samples indicated that OCDD was the largest contributor to the total PCDDs/Fs,accounting for 37.9%on average,whereas 1,2,3,4,6,7,8-HpCDF,2,3,7,8-TCDF,and 1,2,3,4,6,7,8-HpCDD were also found as the major congeners,accounting for 11.5,8.33and 8.06%of the total TCDDs/Fs,respec-tively.Meanwhile,the total PCDD contributions were slightly greater than the total PCDF concentrations.Our spring and summer data were consistent with the studies of Rappe et al.(1988),Wevers et al.(1992)and Gertler et al.(1998),both showing that OCDD,1,2,3,4,6,7,8-HpCDD,OCDF,and 1,2,3,4,6,7,8-HpCDF were the dominant congeners.During the winter,the congener pro files were slightly different.The dominant congeners were OCDD (19.1%),1,2,3,4,6,7,8-HpCDF (13.5%),OCDF (11.5%)and 1,2,3,7,8-PeCDF (11.2%),and theTable 3Concentrations (pg m À3)of 2,3,7,8-substituted congeners of open atmospheric samples in Shameen Park.Tunnel Management Station Site C Shameen Park Site D 2006-7-112006-12-112006-7-112006-12-11ParticulateGaseous Particulate Gaseous Particulate Gaseous Particulate Gaseous 2378-TCDF 1.90E-02 1.35E-01 1.32E þ00 1.04E-01 4.31E-02 1.24E-01 5.39E-02 6.29E-0212378-PeCDF 4.33E-02 1.04E-01 2.03E þ00 2.75E-02 3.52E-02 1.13E-018.64E-02 4.40E-0223478-PeCDF 6.25E-02 1.02E-018.08E-01 3.28E-02 5.76E-02 1.16E-01 1.18E-01 5.76E-02123478-HxCDF 1.18E-01 3.54E-02 1.71E þ00 1.77E-02 3.96E-02 1.37E-02 1.39E-01 2.78E-02123678-HxCDF 1.14E-01 4.35E-027.49E-01 2.27E-02 5.30E-02 1.35E-02 1.62E-01 4.97E-02234678-HxCDF 1.50E-01 1.97E-02 6.05E-01 1.57E-02 3.47E-02 1.78E-02 1.71E-01 4.47E-02123789-HxCDF 1.30E-02 2.33E-03 4.34E-01 4.72E-03 1.19E-027.57E-03 4.26E-02 1.40E-021234678-HpCDF 4.42E-01 2.94E-02 2.31E þ00 3.14E-02 4.61E-01 5.47E-02 6.62E-019.79E-021234789-HpCDF 4.75E-02 1.84E-03 5.49E-01 2.33E-03 2.07E-02 1.29E-028.27E-02 1.86E-02OCDF2.37E-01 6.20E-03 2.26E þ009.88E-03 2.14E-019.43E-03 4.52E-013.91E-022378-TCDD 1.29E-03 2.48E-039.17E-03 5.70E-03 6.29E-039.75E-03 1.81E-03 1.93E-0212378-PeCDD 1.07E-02 1.46E-02 1.39E-01 6.35E-03 1.62E-02 2.77E-02 2.89E-029.05E-03123478-HxCDD 1.09E-02 2.13E-037.34E-02 1.36E-03 2.60E-02 5.20E-03 2.41E-028.98E-03123678-HxCDD 2.40E-02 2.33E-03 1.09E-01 6.24E-039.11E-03 5.26E-034.90E-02 1.85E-02123789-HxCDD 1.24E-02 2.43E-039.94E-02 4.23E-03 1.75E-02 2.25E-03 4.05E-028.03E-031234678-HpCDD 2.66E-01 4.86E-037.12E-01 2.27E-02 3.41E-015.19E-02 5.95E-018.48E-02OCDD1.46E þ00 4.70E-02 1.87E þ00 1.44E-02 1.04E þ00 5.93E-02 5.75E þ00 1.64E-01TEQ(pg I-TEQ m 3)9.54E-029.05E-02 1.13E þ00 4.49E-027.79E-02 1.08E-01 1.67E-018.04E-02Total PCDD/DFs3.03E þ005.55E-011.58E þ013.29E-012.43E þ006.45E-018.46E þ007.69E-01Fig. 2.Relative abundance of 2,3,7,8-PCDD/F homologs of the different sites and seasons in tunnel.Y.Deng et al./Atmospheric Environment 45(2011)2541e 25482545。