Recent survey and effects of cooking processes on levels of PCDDs,PCDFs and Co-PCBs in leafy vegetables in Japan

We report here the latest levels of polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/Fs) and coplanar polychlorinated biphenyls (Co-PCBs) in leafy vegetables in Japan as well as the effect of cooking processes on the reduction of these contaminants. Three kinds of leafy vegetables (“komatsuna”, lettuce and spinach) from seven districts in Japan in 1998 were analyzed for the 2,3,7,8-chlorine substituted PCDD/Fs and three non-ortho-PCBs (#77, 126 and 169). The mean total TEQ levels (using the WHO-TEFs) in the komatsuna, lettuce and spinach were 0.094, 0.025 and 0.196 pg/g fresh weight, respectively. The TEQ levels are dominated by 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, 2,3,4,7,8-PeCDF and 3,3^′,4,4^′,5-PeCB in many of the samples. For one of these isomers, the 2,3,4,7,8-PeCDF TEQ levels showed good correlation with the total TEQ levels in the samples (r=0.957). This suggests that 2,3,4,7,8-PeCDF may be an indicator for dioxin contamination in the analysis of the leafy vegetables. Also, the effects of two cooking processes (washing and washing followed by boiling) on the dioxin levels in two types of spinach samples were investigated. On average, in both samples, the total concentrations of the PCDDs, PCDFs and Co-PCB were reduced to about 38%, 73% and 88% of the initial concentrations by washing, and to 21%, 35% and 61% of the initial concentrations by washing followed by boiling. The total TEQ levels were reduced to about 30% of the initial TEQ levels by washing followed by boiling. Significant reductions in the TEQ levels were observed in the cooked samples. Thus, the cooking processes may reduce the risk of dioxin intake from the leafy vegetables.     

氯苯类生产过程POPs污染风险点分析及环境管理建议

我国氯苯类生产过程中的二噁英类、五氯苯、六氯苯等非故意产生类持久性有机污染物对环境具有潜在风险。对具有典型工艺特征的氯苯类生产过程中关键节点的二噁英类进行了检测和分析,在残渣、残液、废水和副产品(多氯苯混合物)中发现高浓度二噁英类,主要成分为多氯代二苯并呋喃,推测可能与原料中呋喃类杂质有关。为践行我国《关于持久性有机污染物的斯德哥尔摩公约》的履约责任和控制二噁英类排放造成的环境风险,结合国内外相关管理制度提出了法规制度、监督管理、工艺改进、产品质控和废物处置等方面的环境管理建议。     

Optimization of the ionization conditions for the trace analysis of PCDD/PCDF with ion trap MS/MS

Commercial ion trap mass spectrometer provides easy-to-operate MS/MS analysis for the determination of PCDD/PCDF. The limit of quantification is appropriately low (0.2 pg for 23478-P5CDF) because all the stages are performed in the trap and sample losses associated with the ion transportation are minimized. However, if excessive ions are injected into the trap, its electrical fields are distorted and an overall reduction in performance arises. Ionization condition is an important parameter as it affects the amount of the total ions produced. If the amount of interfering compounds are negligible, such as standard solution or cleaned-up sample, lower ionization condition (e.g. electron energy: 30 eV, emission current (EC): 150 μA) is preferable. On the contrary, in case excessive interfering ions are coexisting with PCDD/PCDF, such as crude extract or semi-cleaned-up sample, the ionization condition should be high (e.g. electron energy: 90 eV, EC: 350 μA) for the reproductive quantification.     

垃圾焚烧飞灰或炉渣中二噁的分布特征

分别采集了3种生活垃圾焚烧炉产生的飞灰或熔融炉渣样品,分析了其中的二口恶口英含量及其毒性当量,并讨论了17种2,3,7,8位氯取代的二口恶口英分布特征及其对总毒性当量的贡献.结果表明,机械炉排焚烧炉产生的飞灰中二口恶口英最多,总浓度为319ng/g,毒性当量为6.7ngI-TEQ/g;其次为流化床焚烧炉,产生的飞灰中二口恶口英总浓度为38.7ng/g,毒性当量为0.8ngI-TEQ/g;气化熔融焚烧炉产生的熔融炉渣中二口恶口英很少,总浓度为38.7pg/g,毒性当量仅为1.1pgI-TEQ/g;所有的2,3,7,8位氯取代的13C同位素标记内标化合物回收率在39%~156%之间.尽管不同的垃圾焚烧炉在二口恶口英的生成量上有明显的差别,但是产生的二口恶口英同类物的归一化浓度以及对毒性当量贡献的归一化结果分布特征十分相似,表明3种垃圾焚烧炉在垃圾焚烧过程产生二口恶口英可能具有相似的反应机理.     

Detailed analysis of PCBs and PCDD/Fs impurities in a dielectric oil sample （ASKAREL Nr 1740） from an imported transformer in China

Homolog and congener profiles of polychlori- nated biphenyls （PCBs）, polychlorinated dibenzo-p- dioxins （PCDDs） and polychlorinated dibenzofurans （PCDFs） in commercial PCBs formulations are useful information for the source appointment of PCBs contam- ination as well as the risk assessment caused by potential exposure. Dielectric oil （ASKAREL Nr 1740） in an imported transformer found in China was sampled and analyzed by isotope dilution technology using high resolution gas chromatography-high resolution mass spectrometry （HRGC/HRMS）. The detailed homolog and congener profiles of PCBs obtained were compared with those of known Aroclor formulations. High similarity in the homolog profile between the oil sample and Aroclor 1260was found, with the hexachlorinated and hepta- chlorinated biphenyls accounting for more than 80.2% of the total PCBs concentration. Severn indicator PCBs contribute about 30%, while 12 PCB congeners （i.e., # 153, #143, #168, #180, #149, #165, #138, #170, #190, #187, #174, #181） account for more than 50% of the total PCB concentrations. Total concentration ofPCDDs, PCDFs and dioxin-like PCBs （DL-PCBs） was found to be 740 ng TEQ/g, of which 620 ng TEQ/g came from DL-PCBs. The contribution of PCDDs to the total TEQ was neglectable. The concentration of PCDFs homologs follows the order of OCDF 〉 HxCDFs 〉 HpCDFs 〉 PeCDFs 〉 TeCDFs, which is in consistence with the previous study on Aroclor 1260. Three DL-PCBs congeners （i.e., #118, #156, #157） accounted for 77% of the total concentration of DL-PCBs, also they contribute 72% in the TEQ caused by DL-PCBs.     

广州某工业区大气中PCDD/Fs含量水平及其季节性变化特征

通过对广州某工业区大气中2,3,7,8-PCDD/Fs的季节性监测,并对大气中PCDD/Fs的浓度与季节性变化进行了分析.结果表明,该工业区大气中PCDD/Fs的浓度范围为2.33~75.4 pg·m-3,平均值为23.2 pg·m-3,毒性当量浓度I-TEQ范围为0.229~10.7 pg·m-3,平均值为2.00 pg·m-3,高于日本环境空气质量标准推荐年均值0.6 pg·m-3.该工业区PCDD/Fs浓度季节性变化明显,最高的季节为春季(37.8 pg·m-3),浓度最低的季节为夏季(13.5 pg·m-3),其次为秋季(22.3 pg·m-3)和冬季(19.1 pg·m-3);毒性当量浓度变化高低顺序为:春季(5.58 pg·m-3)>夏季(1.06 pg·m-3)>秋季(0.839 pg·m-3)>冬季(0.525 pg·m-3).降雨、季风的季节性变化可能是引起大气中PCDD/Fs浓度季节性变化的原因.     

典型再生铜冶炼厂周边土壤中PCDD/Fs、PCBs和PCNs的污染特征及健康风险评估

本研究同时测定了1家典型再生铜冶炼厂周边土壤中PCDD/Fs、PCBs和PCNs的含量,进而分析和评估了该冶炼厂对周边环境的影响和研究区域工人的健康风险.冶炼厂周边土壤中PCDD/Fs、PCBs和PCNs的含量范围分别为17.2~370、1.20~14.2和70.9~950 pg·g^-1.在冶炼厂附近（<300 m）的采样点检出了高含量的PCDD/Fs和PCNs,其含量随距离的增加呈指数型下降.源解析结果表明,再生铜冶炼厂对其周边300 m内土壤中PCDD/Fs和PCNs的含量和单体分布特征影响显著.此外,除再生铜冶炼厂外,周边土壤中PCDD/Fs的污染可能还受到历史使用五氯酚或五氯酚钠的影响.健康风险评估结果表明,工人暴露周边土壤中PCDD/Fs、PCBs和PCNs的非致癌和致癌风险均处于可接受水平范围内,经口摄入是最主要的暴露途径.虽然健康风险评估只考虑工人工作时间内对室外环境中这些污染物的暴露,两份土壤样品的致癌风险值已达到0.47×10^-6和0.15×10^-6（阈值10^-6）,值得关注.PCDD/Fs对总致癌风险（PCDD/Fs+PCBs+PCNs）的贡献率最高（96%）,是该区域需首要关注和控制的二英类化合物.