Hydrothermal treatment of MSWI fly ash for simultaneous dioxins decomposition and heavy metal stabilization

Researches on the hydrothermal treatment of municipal solid waste incineration (MSWI) fly ash were conducted to eliminate dioxins and stabilize heavy metals. In order to enhance decomposing polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzo-furans (PCDFs) during hydrothermal process, a strong reductant carbohydrazide (CHZ) is introduced. A hydrothermal reactor was set up by mixing raw MSWI fly ash or the pre-treated fly ash with water and then heated to a pre-set temperature; CHZ was spiked into solution according to specially defined dosage. Experimental results showed that under the temperatures of 518 K and 533 K, the decomposition rates of PCDDs/PCDFs were over 80% and 90%, respectively, by total concentration. However, their toxic equivalent (TEQ) decreased only slightly or even increased due to the rising in concentration of congeners 2, 3, 7, 8-TCDD/TCDF, which might be resulted from the highly chlorinated congeners losing their chlorine atoms and being degraded during the hydrothermal process. Better results of TEQ reduction were also obtained under the higher tested temperature of 533 K and reactor with addition of 0.1%wt CHZ was corresponded to the best results. Good stabilization of heavy metals was also obtained in the same hydrothermal process especially when ferrous sulphate was added as auxiliary agent.     

太湖流域水源地多氯联苯分布特征与污染水平

为系统了解太湖流域主要水源地多氯联苯(PCBs)的污染现状,于2012年3月和6月分别采集水相、悬浮颗粒物和沉积物样品,并利用气相色谱-质谱联用仪(GC-MS)对PCBs的浓度进行了分析。结果表明,3月水相、悬浮颗粒物和沉积物中均未检测出PCBs类物质。6月水相中PCBs质量浓度在ND~1.04 ng·L~(-1)之间,平均值为0.57 ng·L~(-1),悬浮颗粒物和沉积物中PCBs质量浓度分别在0.96~2.72 ng·g-1和0.47~1.29 ng·g-1之间。Aroclor 1016和Aroclor 1260在3种介质中均有检出,且Aroclor1016浓度均为最高。与国内外研究相比较,太湖流域主要水源地PCBs污染水平较低。水相中PCBs浓度水平低于我国地表水环境质量标准;悬浮颗粒物和沉积物中PCBs浓度水平均低于加拿大保护水生环境沉积物化学品风险评价标准的LEL值,说明各样点PCBs对底栖动物无毒性影响。     

青岛近海沉积物PCBs的水平与垂直分布及贝类污染

利用13C同位素内标法及气相色谱-质谱方法对青岛胶州湾内外8个表层沉积物,1个沉积物柱状岩心和2个贝类样品中包括14种共平面PCBs在内的50种PCBs同系物含量进行了测定,在所有样品中均检测出了PCBs化合物.讨论了PCBs的分布特征.表层样品以胶州湾东岸的含量最高,从北岸、西岸、胶州湾口及胶州湾外PCBs含量逐渐降低.表层沉积物中总PCBs含量在0.65～32.9ng/g dw. PCBs总含量落在国内外海洋近岸表层沉积物含量范围的中值区.表明污染来源有城市污水排放及大气来源2种,而不属于工业污染类型.多氯联苯主要以低氯取代PCBs为主,大部分高氯取代PCBs的含量低于检出限.柱状样中共平面PCBs的含量及毒性当量浓度总的垂直变化趋势是从1951年到现在逐渐减少.贝类样品的总PCBs含量为4.9～8.4ng/g dw,属低污染水平.     

珠江广州段水体、沉积物及底栖生物中的多氯联苯

对珠江广州江段水体、沉积物及底栖生物体内多氯联苯有机污染物进行了初步的调查研究.结果表明,广州江段7个样点水体中多氯联苯类有机污染物平均含量为2.3ng/L,各点含量无显著差异;沉积物中多氯联苯类有机污染物平均含量为31.52g/kg,各点有显著差异,其中以广州江段南航道y03样点最高,达65.31g/kg;底栖生物体内多氯联苯含量平均为181.77g/kg,其中也以y03样点最高,达317.37g/kg.多氯联苯在水体、沉积物及生物体3者之间存在明显的富集和放大作用.     

洞庭湖及入湖河流中209种多氯联苯同类物分布特征与风险评估

为全面了解洞庭湖水域多氯联苯(PCBs)的污染情况,采用同位素稀释-高分辨质谱法对洞庭湖及入湖河流共21处表层水进行了 209种PCB同类物测定分析结果表明,共检出50种PCB同类物,ρ(∑ PCBs)在0.077～10 ng·L-1之间,平均值为2.7ng·L-1,中值为1.9 ng·L-1,污染浓度为:入湖河流＞湖...     

典型污染地区底泥和土壤中残留多氯联苯（PCBs）的情况调查

为了解PCBs在生态系统中的分布,利用毛细管气相色谱对受PCBs污染地区的土壤、底泥进行实际环境样品的调查。在底泥和土壤样品中测定近50个同属物的含量,并对其分市规律进行了探讨。指出在实际环境样品中PCBs的同属物分布和工业产品有明显不同。通过不同深度底泥样品测定,证明PCBs在底泥中的渗透作用较弱。     

超声波-蒸汽蒸馏萃取技术富集沉积物样品中的氯代农药和多氯联苯

为方便快速分离沉积物中含氯农药和多氯联苯,将眼声波技术和蒸汽蒸馏萃取技术相结合,萃取沉积物中的微量含氯农药和多氯联苯,所得萃取物不需进一步的净化和浓缩,可直接用于色谱分析。实验表明,在进行蒸汽蒸馏萃取之前,使用辅助的超声波技术台将大部分待测物的回收率提高２０％－３０％,较好地解决了由于沉积物吸附作用而导致的蒸汽蒸馏回收率偏低的缺陷。     

鱼中氯化二苯并二噁(PCDD)和氯化二苯并呋喃(PCDF)的分析

本工作建立了鱼中从四氯到八氯的二苯并二(口恶)(口英)和二苯并呋喃的分析方法。鱼样品经消化后以己烷提取,提取液经两套层析柱净化后,用反相HPLC进一步净化并分为两个级份。采用GC/SIM-MS测定各PCDD和PCDF。     

长江口东滩湿地柱状沉积物中多氯联苯的分布和变化趋势

采用同位素稀释质谱法,用高分辨率气相色谱-高分辨率质谱仪(HRGC-HRMS)对长江口崇明东滩湿地柱状沉积物30个层段中7种指示性多氯联苯(PCB28,PCB52,PCB101,PCB118,PCB153,PCB138和PCB180)的含量进行了测定. 结合近几十年长江下游气候变化情况,对PCBs垂直分布历史记录特征以及异构体的物理化学性质参数进行了探讨. 结果表明,w(PCBs)为0.138～0.400 ng/g(以干质量计,下同),平均值为0.228 ng/g,属于轻度污染. 东滩沉积物中PCBs呈现明显的周期性分布,在20世纪50年代初期开始快速增长,高峰期出现在70年代,之后呈减少趋势,反映了世界主要生产国家禁止生产PCBs的情况.      

Levels and congener distributions of PCDDs,PCDFs and dioxin-like PCBs in environmental and human samples: a review

The term “dioxins” is often used in a confusing way. In toxicological considerations—and also in the present report—the term is used to designate the PCDDs, the PCDFs and the coplanar (“dioxin-like”) PCBs, since these classes of compounds show the same type of toxicity. Because of the large number of congeners, relevant individual congeners are assigned with a toxic equivalency factor (TEF) that relate their toxicity to that of tetrachlorodibenzo-p-dioxin (TCDD) (2,3,7,8-TCDD) and are to be evaluated as dioxins. Each concentration of an individual congener in a mixture is multiplied with its TEF, and the resulting TCDD equivalents are added up and expressed as WHO-endorsed toxic equivalents (WHO-TEQ). Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are mainly the by-products of industrial processes (such as metallurgical processing, bleaching of paper pulp, and the manufacturing of some herbicides and pesticides) but they can also result from natural processes like volcanic eruptions and forest fires. Waste incineration, particularly if combustion is incomplete, is among the largest contributors to the release of PCDDs and PCDFs into the environment. Due to their persistence, PCDDs, PCDFs and PCBs are part of the so-called persistent organic pollutants group of compounds that also include some chlorinated pesticides. Since they have a high lipophilicity and resist transformation, they bio-accumulate in animal and human adipose tissues. Consumption of food is considered as the major source of non-occupational human exposure to PCDD/Fs with foodstuffs from animal origin accounting for more than 90% of the human body burden. With meat, dairy, and fish products being the main contributors. The aim of the present review was to summarize experimental data regarding dioxin emissions from contaminated and uncontaminated biological and environmental samples, from the available literature. The information will be presented chronologically with respect to distribution in human milk, serum; food, water, air, soils and sediments.