Polychlorinated dibenzo-p-dioxins and dibenzofurans in different tissues of the cormorants (Phalacrocorax carbo) from Dongting Lake, China

Tissue distribution provides important information regarding the pharmacokinetic behavior of pollutants and is invaluable when analyzing the risk posed to avian species by the exposure to such kind of pollutants. In this study, concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were determined in muscle, liver, spleen, kidney, stomach, gall bladder, skin, heart, pancreas, intestine and lung tissue extracts of cormorants collected from Dongting Lake, China. Tissue distribution results showed preferential accumulation of PCDD/Fs in both liver and skin. The total concentration of PCDD/Fs ranged from 421 to 5696 pg/g lipid weight. Octachlorinated dibenzo-p-dioxin (OCDD) was the predominant congener in all tissues and contributed between 31% and 82% to all 17 PCDD/Fs in different tissues. The liver/muscle ratios progressively increased with the degree of chlorination of PCDDs, except for OCDD. The relative toxic potential of PCDDs and PCDFs in tissues were calculated using the World Health Organization (WHO) Toxic Equivalency Factors (TEFs) for birds. The concentrations of WHO-toxic equivalent in different tissues ranged between 14.8 and 2021 pg/g lipid weight. These results indicated PCDD/Fs may have been bio-accumulated in cormorant via food-web. Furthermore, when compared with studies reported in the literatures, the PCDD/Fs levels in the cormorant collected from Dongting Lake were still relatively high.     

苜蓿根瘤菌对多氯联苯降解转化特性研究

采用溶液摇瓶实验研究了苜蓿根瘤菌(Rhizobium meliloti)对三氯代联苯(2,4,4′-trichlorobiphenyl)单体以及18种多氯联苯(polychlorinated biphenyls,PCBs)混合物的降解转化能力.结果表明,接入苜蓿根瘤菌转化7d后,随着溶液中底物2,4,4′-TCB浓度的增加,该菌株对其的降解能力也逐渐提高,在1.0、5.0、10.0、25.0、50.0 mg.L-1浓度条件下该菌对2,4,4′-TCB的降解率分别为34.0%、48.3%、69.7%、96.0%、98.5%,并且通过气相质谱分析,发现溶液中出现了一些新的代谢产物.同时,苜蓿根瘤菌对不同浓度下18种PCBs同系物混合物的降解能力,随着底物浓度的升高呈现出从低到高,然后降低,并趋于平衡的趋势,其最高降解率可达54.7%,并存在高氯代PCBs向低氯代PCBs的转化过程.     

废旧电容器封存点土壤中的PCBs污染特征和健康风险评价

以某废旧电容器封存点为例,研究了废旧电容器封存点土壤中PCBs的污染特征以及类二英类PCBs的毒性风险,并应用健康风险模型评估了居住用地和工业用地方式下封存点土壤PCBs污染对人体的致癌和非致癌风险.结果表明:封存点0~30 cm、30~100 cm及200~250 cm土壤中ΣPCBs平均浓度分别达到6.23、19.3和1 540 mg·kg-1,并以3~4氯代PCBs为主.毒性当量结果表明,封存点ΣWHO-TEQ最高达到457μg·kg-1,具有较高的毒性风险,其中PCB126是封存点土壤中总TEQ的主要贡献者.健康风险评价结果表明,在居民用地方式下,多种暴露途径导致的儿童及成人的累积非致癌风险(0.927~1 760)几乎都超过可接受非致癌风险水平,其中儿童为最敏感受体.工业用地方式下,除表土以外,工人的累积非致癌风险均超过了可接受水平.居住和工业用地方式下土壤中PCBs的总致癌风险均超过了可接受风险水平(10-6~10-5).不同土地利用方式下对于所有人群,经口暴露的致癌和非致癌风险都最大.     

长江口滨岸水体悬浮颗粒物中PCBs分布特征

对长江口滨岸带14个采样点水体悬浮物中的多氯联苯(PCBs)进行GC-ECD测试,结果表明PCBs含量水平为2.5～51.5ng/g,平均值为13.2ng/g,普遍高于相应表层沉积物中的含量,但没有表现出明显的与排污有关的地域性分布规律;PCBs的含量与悬浮物的粒径和有机质含量不显著相关,而可能与有机质来源和矿物组成有关;在大多数采样站位,低氯代联苯(2～5CB)占PCBs总量的70%以上,其中2CB在悬浮物中占有绝对优势地位.这一组成特征可能与我国主要生产和使用低氯代联苯有关,但与过去表层沉积物中以3CB为主的特征不同,表明可能有新的PCBs的输入.与国内外相关研究结果对比,本区PCBs的污染属中等水平.     

中国部分沿海海域水体中溶解态有机氯农药和多氯联苯的残留分布特征

分析调查了中国部分海域海水中溶解态有机氯农药(OCPs,25种)和多氯联苯(PCBs,6种)的残留分布特征。结果表明,所有采样点都不同程度地受到了OCPs和PCBs的污染,其中福建省福州平潭和莆田湄洲岛的OCPs污染较为严重,浓度分别达到1752.59和796.19 ng/L;而辽宁省的大连老虎滩OCPs污染较轻,浓度为53.63 ng/L。各采样点海域海水中HCHs污染程度一般高于DDTs,HCHs主要以早期残留为主;根据DDT/DDTs的比值推测,在福州平潭、莆田湄洲岛和珠海淇澳岛水体显示有新的DDT输入。在各海域水体中溶解态PCBs的浓度为33.55~474.92 ng/L,均超过了美国环保局规定的海水浓度限值。因此目前我国沿海海域水体中持久性有机污染物有机氯农药和多氯联苯污染仍不能忽视。     

PCDD/Fs-induced oxidative damage and antioxidant system responses in tobacco cell suspension cultures

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) are ubiquitous contaminants and can be considerably accumulated by natural plants. In order to elucidate the biochemical and physiological responses of plant to PCDD/Fs, tobacco Bright Yellow-2 (BY-2) cells were selected as model plant and treated with time- and concentration-dependent PCDD/Fs. The toxic effect and oxidative stress caused by PCDD/Fs were evident, which could be indicted by the reduction in fresh mass, the increase in malondialdehyde (MDA) content, and the damage of tobacco cell ultrastructure. PCDD/Fs tolerance was correlated with changes in antioxidant system and hormones of tobacco cells. Superoxide dismutase (SOD) and peroxidase (POD) exhibited peak enzyme activities at the PCDD/Fs concentration of 1000 ng WHO₉₈-TEQ g⁻¹ fresh weight. Glutathione reductase (GR) enzyme activity increased monotonically at high level PCDD/Fs, but the activity of catalase (CAT) was only slightly affected at all treatment. Meanwhile, the exposure to PCDD/Fs resulted in the changes of hormones content. With the increase of exposure concentration of PCDD/Fs, the levels of indole-3-acetic acid (IAA) and abscisic acid (ABA) increased, whereas the concentration of jasmonates (JAs) decreased. The above results suggest that tobacco cells had the ability to cope with the oxidative stress induced by low concentration of PCDD/Fs through increasing the activities of antioxidant enzymes and alternating plant hormones levels. However, oxidative stress and toxicity would burst out when plant cells were exposed to the high levels of PCDD/Fs.     

污染地块土壤多氯联苯风险筛选值研究

污染地块土壤多氯联苯（PCBs）污染主要来自含PCBs电力设备封存点的泄漏及非故意产生源,建立土壤PCBs筛选标准是开展PCBs污染地块调查、评估和修复的基础.本研究通过文献分析统计了典型PCBs单体的占比,并基于人体健康风险评估模型推导了污染地块土壤PCBs风险筛选值.结果表明,不同商用PCBs混合物中共平面PCBs总量（∑Co-PCBs）占比为0.01%~16.10%,难以代表PCBs的总体风险水平.研究建立了PCBs总量、指示性PCBs总量（∑Id-PCBs）及∑Co-PCBs等3个指标共同作为土壤PCBs筛选值体系,敏感用地和非敏感用地情景下,PCBs总量、∑Id-PCBs、∑Co-PCBs分别为2.10、0.24、0.03 mg·kg^-1和6.20、0.71、0.09 mg·kg^-1.通过6个含PCBs电容器地下封存点485个污染土壤样品的分析,进一步证明了仅控制∑Co-PCBs将低估PCBs污染风险,采用本研究提出的3个指标进行筛选能够更有效地识别和评估PCBs污染地块的风险.     

滨海城市大气中多氯联苯的污染特征

选取滨海城市厦门的城区、郊区、工业区和背景区为研究对象,于2008年10月至2009年9月对厦门市大气进行了为期四个季节的采样工作,用GC-MS对气相和颗粒相中的28种多氯联苯(PCBs)同系物进行测定。研究结果表明,厦门市PCBs具有明显的时空分布特征,PCBs的含量在66.94～689.59 pg/m3之间,平均值...     

环境样品中多氯联苯的分析技术

作为一种持久性有机污染物,多氯联苯在地球上的分布十分广泛。然而由于多氯联苯在环境样品中残留浓度低、干扰物质多且组成复杂,必须对环境样品进行预处理。目前较为常用的含多氯联苯样品的前处理技术有：溶剂萃取技术、固相萃取技术、固相微萃取技术、超临界萃取技术、微波萃取技术和加速溶剂萃取技术等,分析经过技术处理以后的样品常用的方法有化学分析方法和生物分析方法,化学方法包括气相色谱法,气相色谱质谱分析法等;生物方法有生物传感器测定法、表面胞质团共振检测、以Ah受体为基础的生物分析法和酶联免疫检测法。中国在这方面的研究投入不够,应加大人力、财力和物力的支持,提高环境样品中多氯联苯的检测水平。     

城市不同功能区径流中PCBs的污染特征及毒性评价

选取温州不同城市功能区小区路面、停车场、汇流口、小区屋面以及交通干道作为研究对象,采集径流样品测定了14种多氯联苯(PCBs)的浓度,并对其进行多元统计分析,探讨了其可能的污染来源.结果表明,不同城市功能区径流中PCBs含量和检出率有所差别但变化不大,其中小区屋面要高于交通干道、汇流口、停车场和小区路面(均值分别为337.9, 306.3, 240.1, 193.2, 172.7ng/L);径流中以五氯代PCBs为主,占到总量31.4%~56.2%;径流中PCBs跟SS浓度相关性较差;由多元统计分析结果可以看出,高低氯代PCBs污染来源不同;TEQs在汇流口、小区路面、停车场径流中浓度相对较大,分别达到4.4, 4.1, 4.0ng/L,这跟其径流中CB126含量较高有关.