环境化学与生态毒理学国家重点实验室知识库

      氯代和溴代多环芳烃（Cl/Br-PAHs）是多环芳烃（PAHs）的卤代衍生物。其结构与二恶英相似，具有与二恶英相似的毒性。Cl/Br-PAHs在环境中广泛存在。研究 Cl/Br-PAHs的环境污染特征和来源对认识Cl/Br-PAHs的环境风险具有重要意义。目前关于环境中 Cl/Br-PAHs相关研究还比较缺乏，原因之一是Cl/Br-PAHs的分析方法存在局限。大气是 Cl/Br-PAHs传输的重要媒介，目前  Cl/Br-PAHs在大气中的存在特征已有相关研究，但是在极端天气下，比如雾霾天下Cl/Br-PAHs的浓度水平、气固分配和不同粒径颗粒物上的分配等的相关研究还没有开展。另外，Cl/Br-PAHs容易在工业热过程中生成，但是关于相关污染源的研究还十分匮乏。针对目前 Cl/Br-PAHs研究存在的问题，本研究建立了  Cl/Br-PAHs的新分析方法，分析研究了雾霾天Cl/Br-PAHs的存在特征和气固分配，并量化表征了Cl/Br-PAHs的新排放源。具体结果如下：
1.本研究建立了同位素稀释高分辨气相色谱/高分辨质谱联用的新方法分析检测复杂环境样品中的 19种Cl-PAHs和19种Br-PAHs。本方法的检出限比之前普遍采用的气相色谱/低分辨质谱联用检测 Cl/Br-PAHs的分析方法低2–3个数量级。同时，本研究还建立了Cl/Br-PAHs同系物的半定量分析方法。将该方法应用于空气样品和垃圾焚烧厂烟气样品的 Cl/Br-PAHs分析检测中，方法的回收率和重现性良好，38种 Cl/Br-PAHs均能检出，其中19种Cl/Br-PAHs同类物被首次报道。
2.通过对北京空气样品中Cl/Br-PAHs的分析检测，本研究首次报道了供暖期和非供暖期大气中 Cl/Br-PAHs的浓度，并探讨了其气固分配和在不同粒径颗粒物上的分配规律。本研究发现供暖期空气中Cl/Br-PAHs的浓度是非供暖期Cl/Br-PAHs浓度的3–9倍，供暖期  Cl/Br-PAHs的浓度升高主要来自颗粒相Cl/Br-PAHs浓度的升高。以往的研究认为  Cl/Br-PAHs主要存在于气相中，而本研究发现供暖期颗粒相 Cl/Br-PAHs的占比更高。对不同粒径（<1μm、1–2.5 μm、2.5–10 μm和>10   μm）颗粒物上 Cl/Br-PAHs的分析发现，超过  80%的 Cl-PAHs和超过70%的 Br-PAHs存在粒径<2.5μm的颗粒物上。供暖期Cl/Br-PAHs倾向于存在粒径更小的颗粒物上。进一步分析影响 Cl/Br-PAHs气固分配和在不同粒径颗粒相上的分配因素，我们提出温度和 Cl/Br-PAHs的物理化学性质影响其分配的规律。温度越低，Cl/Br-PAHs同类物的蒸气压越低，Cl/Br-PAHs同类物越倾向于存在粒径小的颗粒物上。
3.本研究通过对再生铜冶炼和水泥窑协同处置固废过程各工艺阶段烟气和飞灰的分析研究，量化了再生铜冶炼和水泥窑协同处置固废过程 Cl/Br-PAHs的排放特征。再生铜冶炼过程烟气中，Cl-PAHs和Br-PAHs的浓度水平分别为5.8–271 ngm−3和 0.59–52.4ng m−3。本研究提出的再生铜冶炼过程 Cl/Br-PAHs同类物分布特征为再生铜冶炼 Cl/Br-PAHs指纹谱图的建立提供依据。进一步分析再
生铜冶炼过程 Cl/Br-PAHs的生成机制，我们发现氯化和溴化不是Cl/Br-PAHs的主要生成途径。水泥窑协同处置固废的烟气中，Cl-PAHs和  Br-PAHs的浓度水平分别为 15.6–94.1 ngm–3和1.04–4.28 ng m–3。对各个工艺阶段 Cl/Br-PAHs的分析发现，窑尾是水泥窑协同处置固废过程 Cl/Br-PAHs的主要生成区域。通过不同水泥窑协同处置固废过程对比研究，我们发现固废的构成将影响烟气中  Cl/Br-PAHs的分布特征。另外，基于再生铜冶炼过程和水泥窑协同处置固废过程Cl/Br-PAHs的排放因子，我们估算了行业的年排放总量，该数据将为建立Cl/Br-PAHs的排放清单提供理论依据。

      Chlorinated and brominated polycyclic  aromatic hydrocarbons (Cl/Br-PAHs) are halogenated derivatives  of polycyclic aromatic  hydrocarbons (PAHs). They  have the similar structures with dioxins, and have been identified to have toxicities. Cl/Br-PAHs are ubiquitous in the environment. Studies  on the characteristics of Cl/Br-PAHs in the
environment are still lacking, one of the reasons is that there are still limitations on the analytical methods. Atmosphere is the major matrice through which Cl/Br-PAHs could transport from one place to another. There are studies on characteristics of Cl/Br-PAHs in atmosphere, but the gas-particle partition and particle size distribution of Cl/Br-PAHs under haze days have not been  studied yet. In addition, Cl/Br-PAHs could easily form during thermal processes of  industries, but limited studies  have identified the sources of Cl/Br-PAHs. With the aim to  solve these problems, we established the new method for analysis  of Cl/Br-PAHs,  studied the  characteristics  and gas-particle  partitions of Cl/Br-PAHs in haze days,  and identified new sources  of Cl/Br-PAHs. Specific results of the studies are listed as belows:
1.   This   study   established    a   new   isotopic   dilution   high    resolution   gas chromatography coupled with  high resolution mass spectrometry method  for analysis of  19 Cl-PAHs  and 19  Br-PAHs  in complex  environmental  samples. The  detection limits Cl/Br-PAHs of the  method established in this study were  two to three orders of magnitude lower  than previous method  which used the  gas chromatography  coupled with  low resolution  mass  spectrometry  for  analysis of  Cl/Br-PAHs.  A quantitative method  for  the Cl/Br-PAH  homologues  was  also  established  in this  method.  This isotopic  dilution GC-HRMS  method  was  applied to  analyze  38  Cl/Br-PAHs in  air samples and stack  gas samples from waste incinerators,  recoveries and repeatabilities could  meet the  requirement  for  analysis of  Cl/Br-PAHs  in  complex environmental matrices. Among  the congeners, 19  Cl/Br-PAH congeners were  detected for the  first time.
2.   Air samples in heating  and non-heating period in  Beijing were collected and analyzed for  the Cl/Br-PAHs.  This is  the  first study  which reported  the levels,  gas-particle distributions  and particle  size  distributions of  Cl/Br-PAHs in  atmosphere in heating and non-heating period. Concentrations of atmospheric Cl/Br-PAHs in heating period were  3–9 times of those  in non-heating period,  and the increase  of the Cl/Br-PAH concentrations  in heating  period was  mainly brought  by  the particulate  phase. Previous  studies  reported  that   Cl/Br-PAHs  mainly  existed  in  the  gaseous  phase,however, in our study, we found the fractions of Cl/Br-PAHs in particulate phase were higher than gas phase in heating period. Particles  with sizes of <1 μm, 1–2.5 μm, 2.5–10 μm and >10 μm were collected and analyzed for Cl/Br-PAHs. More than 80% of Cl-PAHs and 70% of Br-PAHs were associated with particles with size lower than 2.5 μm.In addition, Cl/Br-PAHs tended to exist in finer particles in heating period than in non-heating period. Temperature  and physicochemical properties  of the Cl/Br-PAHs were important  influencing   factors   of  the   gas-particle  distributions   and  particle   size distributions of Cl/Br-PAHs. With the decrease of  the temperature and the decrease of vapor pressures, Cl/Br-PAHs tended to be associated with particles of lower diameters.
3.   In this  study, we analyzed  the Cl/Br-PAHs in  stack gas  and fly ash  samples from  different stages  of  secondary  cooper smelting  processes  and  cement kiln  co-processing solid  wastes processes, and  identified the  secondary cooper smelting  and cement kiln co-processing solid wastes as new emission sources of Cl/Br-PAHs. In the stack gases of secondary cooper smelting processes, the concentrations of Cl-PAHs and Br-PAHs  were 5.8–271  ng  m−3  and  0.59–52.4 ng  m−3,  respectively.  The  congener distributions of Cl/Br-PAHs in  stack gases from secondary cooper  smelting processes were also analyzed,  and could be used  for establishment of the  fingerprints of Cl/Br-PAHs.  In addition,  we  found the  chlorination  and bromination  were  not  the major formation pathways  for Cl/Br-PAHs  during secondary cooper  smelting processes.  In the stack  gases of  cement kiln  co-processing solid wastes,  the concentrations  of Cl-PAHs and  Br-PAHs were 15.6–94.1  ng m–3 and 1.04–4.28  ng m–3, respectively.  Kiln end is the major formation zone for Cl/Br-PAHs during cement kiln co-processing solid wastes. Based on the emission factors of Cl/Br-PAHs during secondary cooper smelting and cement kiln co-processing solid wastes, we evaluated the annual emission of Cl/Br-PAHs from  these industries. This  data was helpful  for establishment  of the emission inventory of Cl/Br-PAHs.