Characteristics of sorption losses of polychlorinated biphenyl congeners onto glass surfaces

Sorption losses to glass surfaces of five polychlorinated biphenyl (PCB) congeners in aqueous solutions were investigated. Adsorption/desorption experiments were conducted under conditions that simulated actual sample handling procedures for environmental samples. It was found that the adsorption loss is related to the degree of chlorination. PCB congener 180 lost the most onto glass surfaces, followed by congeners 138, 101/28, and 52, in decreasing order. More PCB adsorption occurred onto glass under conditions of agitation and higher temperature (22°C) during the five-day experimental period. The salinity effect (“salting out effect”) was also observed in this work. The efficiency of desorption (rinsing three times with solvent) was found to be ineffective in extracting adsorbed PCBs. It was necessary to use mechanical shaking for extraction. Storage of samples up to five days resulted in sorption losses as much as 30%, 17%, 30%, 40%, and 55% of PCB 28, 52, 101, 138, and 180, respectively. Sorption losses need to be considered when conducting water sampling or toxicological studies to avoid underestimation of the actual PCB concentrations and their toxic effects.     

Digestibility, retention and incorporation of low-level dietary PCB contents in laying hens

Polychlorinated biphenyls (PCBs) are persistent and hazardous environmental contaminants, which tend to bioaccumulate in the food chain. In the present report the long-term effect of low-level dietary PCB concentrations was studied on performance, egg quality, apparent PCB digestibility, apparent PCB retention and PCB accumulation in laying hens that were fed experimental diets for 41 weeks. The tested dietary concentrations of supplemented PCBs, based on the sum of seven reference congeners, were 0, 1.5 and 6 ng/g. PCB ingestion did not significantly affect performance or egg quality parameters. The PCB concentration in egg yolk reached a nearly constant level after approximately 40 and 70 days of consumption of the diets containing 1.5 and 6 ng PCBs/g, respectively. Apparent faecal PCB digestibility and apparent retention were not influenced by dietary levels of added fat varying between 1.5% and 4.5%, but were significantly higher in hens fed diets containing added PCBs. Moreover, apparent PCB digestibility and retention increased significantly with age. Among the seven individual PCB congeners, no systematically significant differences with regard to apparent faecal digestibility were observed throughout the experiment. Accumulation of PCBs in the fat fraction of egg yolk, abdominal adipose tissue and thigh and breast muscle greatly depended upon PCB intake, but never exceeded the maximally allowed concentration of 200 ng/g. As PCBs 52 and 101 were hardly found in egg yolks and hen tissues, it was concluded that both congeners were greatly metabolised. Comparison of relative contents of individual PCB congeners revealed that PCBs 118, 138 and 153 were preferentially incorporated in yolk and body tissues.     

城市污水中PCBs的分析及其QA/QC研究

报道了一种城市污水中痕量PCBs的分析方法,并进行了QA/QC研究,采用二氯甲烷萃取剂对城市污水进行液-液萃取,联合运用浓硫酸和硅胶层析柱将PCBs与杂质分离,以毛细管GC-ECD和内标法对PCBs定量.空白加标回收试验得出,PCBs的回收率为58%～125%,标准偏差为0.00173～0.00778μg/L,相对标准偏差为1.58%～12.43%.以实际城市污水作为加标基质,得出加入污水中的19种PCBs的分析方法回收率为57.6%～129.2%,方法的检测限为0.010～0.056μg/L,满足了US EPA对PCBs回收率要求.经过3次平行测定,测得实际城市污水中PCBs含有9种PCBs,PCBs总量的平均值为0.0235μg/L,相对标准偏差为9.63%,该分析方法所需的仪器简便、容易操作.     

加速溶剂萃取-气相色谱质谱法同时测定土壤及沉积物中34种有机氯农药及18种多氯联苯类化合物

建立了加速溶剂萃取-气相色谱质谱法同时测定34种有机氯农药(OCPs)和18种多氯联苯类化合物(PCBs)的方法。当取样量为10. 0 g时,52种有机化合物的检出限为0. 03～0. 29μg/kg,以空白样品为基体进行加标回收试验,平均回收率为44. 7%～123. 0%,相对标准偏差(RSD,n=7)为1. 8%～21. 5%。该方法灵敏度高,实现了低浓度有机化合物的定量分析,分析结果准确可靠,满足土壤和沉积物中34种有机氯农药和18种多氯联苯类化合物分析的要求。     

南四湖表层沉积物中多氯联苯的空间分布特征

采用气相色谱-电子俘获检测(GC-ECD)方法对从南四湖湖区采集表层沉积物中的12种多氯联苯(PCBs)同系物进行了分析测定。PCBs的含量范围为7.84~42.8ng/g,主要以低氯代物为主。湖内各监测点位的PCBs浓度要高于入湖河口各监测点位;湖内各监测点位中,上级湖各点位的浓度要高于下级湖的点位。污染物来源分析表明,PCBs主要来自造纸漂白过程和焚烧炉排放。与类似水体相比,南四湖表层沉积物中PCBs含量属中低含量水平。整体而言,南四湖表层沉积物中PCBs的含量属于低生态风险水平。     

Bioaccumulation Factors (BAFs) and Biota to Sediment Accumulation Factors (BSAFs) for PCBs in pike and eels

“Freely-dissolved” aqueous concentrations of 9 trichlorothrough heptachlorobiphenyls are reported, alongside those in sediments and fish from the R. Severn. For most congeners, BSAFs and lipid-normalised BAFs for pike exceed those for eels. Whilst R. Severn BSAFs are comparable with those for L. Ontario trout and New Bedford Harbour flounder, R. Severn BAFs are 1–2 orders of magnitude lower. This discrepancy may be due to inter-species variability, as well as inter-laboratory differences between operational definitions of “freely-dissolved” aqueous PCB, underlining that the same operational definition must be employed if R. Severn BAFs are extrapolated elsewhere. For eels, correlation of Log K^ow with Log BAF is better (R² = 0.66) than with BSAF (R² = 0.13), whilst similar correlation coefficients (R² = 0.81 and 0.82) were observed for pike. When Log K^ow is plotted against BSAF and Log BAF for both species combined, better correlation is observed for Log BAF (R² = 0.65), than BSAF (R² = 0.36). For both species combined, the observed relationship between Log BAF and Log K^ow for trichloro-through heptachlorobiphenyls is: Log BAF = 0.96 * Log K^ow −0.24.     

Assessing the human health effects of PCBs

Toxic effects can be induced in experimental animals by high doses of pure PCBs, and in man by PCDF-contaminated PCB. In order to assess the effects of ordinary, uncontaminated PCB on man, a group of capacitor workers who had direct occupational exposure to Aroclors 1254, 1242, and 1016 during the period 1946 to 1977 has been under medical surveillance since 1976. This group presented some indications of non-AhR-mediated microsomal enzyme induction during the period of direct exposure, but no chloracne or increased cancer mortality. Multiple regression studies revealed no significant associations between lipid PCB levels and clinical indicators of hepatotoxicity, hypertension, or pulmonary impairment.     

焚烧炉及周围环境样品中多氯联苯的监测分析

对焚烧炉禁烧处理多氯联苯的效果及其周围环境样品中的多氯联苯进行了监测分析，建立了不同基体中ＰＣＢｓ高效毛细管色谱／质谱，气相色谱／电子捕获鉴定器检测的常规方法，燕根据对炉渣、尾气及环境样品的分析结果，认为多氯联苯的焚烧处理达到设计要求。     

土壤中多氯联苯监测分析方法

文章综述了国内外现有的土壤中多氯联苯的标准监测方法及其它文献报道方法，评述了各方法的优、缺点，介绍了本文所研制的适用性强、能满足监测需求的方法。