甲基叔丁基醚(MTBE)在不同粘性土壤中的吸附特性

土壤对有机物的吸附是污染土壤及地下水原位修复技术中的重要参数.通过静态间歇吸附实验研究了甲基叔丁基醚(MTBE)在不同粘性土壤中的吸附特性.结果表明,MTBE在粘性土壤中的吸附行为均可用线性方程很好描述,粘粒是土壤对MTBE吸附的主要影响因素,吸附常数与土壤粘粒含量呈y=4.382×10-3x-0.817 ×10-3直线关系.对不同温度下的吸附数据分析发现,粘性土壤对MTBE的平衡吸附量随温度的升高而降低,由吸附热力学推导可得等量吸附焓变△H与平衡吸附量无关,且△H＜0,表明该吸附为故热过程.     

水体中悬浮颗粒物对十溴二苯醚的吸附/解吸特性研究

采用室内试验法,以沉积颗粒物和浮游植物颗粒(铜绿微囊藻和普通小球藻)作为水体中悬浮颗粒物(SPM),研究了SPM对十溴二苯醚(BDE-209)的吸附/解吸特性.结果表明,沉积颗粒物和浮游植物颗粒对BDE-209的吸附分别在1.5h和0.5h内达到最大,在3h内可以充分达到平衡;沉积颗粒物和浮游植物颗粒对BDE-209的吸附能力存在差异,这与颗粒物中有机质的浓度和类型有关;在实验浓度范围内,BDE-209在SPM上的吸附可用Freundlich等温吸附方程较好地拟合;解吸过程表现出一定的迟滞性,且沉积颗粒物比浮游植物颗粒物具有更明显的迟滞性;pH中性、温度20～30℃的水体有利于SPM对BDE-209的吸附.     

Polybrominated diphenyl ethers in food and associated human daily intake assessment considering bioaccessibility measured by simulated gastrointestinal digestion

The concentrations of PBDEs in 299 vegetable and animal-based food samples of 31 species, collected in Shanghai, China, and the bioaccessibility of PBDEs in part of the samples were determined. The PBDE concentrations ranged from 0 to 1245.4 pg g⁻¹ with animal-based food containing more PBDEs than vegetables. The bioaccessibility of PBDEs, determined by a method simulating human gastrointestinal digestion process, were from 2.6% to 39.9% in vegetables, and from 5.2% to 105.3% in animal-based food. For animal-based food, good correlations were observed between the bioaccessibility of PBDEs and the fat content, thus the fat content in animal-based food was able to be used to estimate the bioaccessibility of PBDEs. The total daily intake of PBDEs via ingestion of vegetables and animal-based food for an average Shanghai resident was estimated as 13 235.7 and 13 668.0 pg d⁻¹, respectively, but the amounts available for human absorption were reduced to 2674.4 and 4316.6 pg d⁻¹ after the PBDE bioaccessibility was considered. Finally, the contributions of different food groups to the total daily intake of PBDEs were evaluated. The results revealed that, when not considering the bioaccessibility of PBDEs, vegetables were the leading contributor (49.2%), followed by fish (34.0%). However, the sequence was reversed after the PBDE bioaccessibility was taken into account. The results indicated that human exposure to PBDEs via food ingestion might have been significantly overestimated and the exposure assessment could be misleading if the bioaccessibility of PBDEs was not considered.     

Polybrominated diphenyl ethers (PBDEs) and alternative brominated flame retardants in air and seawater of the European Arctic

The spatial distribution of polybrominated diphenyl ethers (PBDEs) and several alternative non-PBDE, non-regulated brominated flame retardants (BFRs) in air and seawater and the air-seawater exchange was investigated in East Greenland Sea using high-volume air and water samples. Total PBDE concentrations (Ó₁₀PBDEs) ranged from 0.09 to 1.8 pg m⁻³ in the atmosphere and from 0.03 to 0.64 pg L⁻¹ in seawater. Two alternative BFRs, Hexabromobenzene (HBB) and 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE), showed similar concentrations and spatial trends as PBDEs. The air-seawater gas exchange was dominated by deposition with fluxes up to −492 and −1044 pg m⁻² day⁻¹ for BDE-47 and DPTE, respectively. This study shows the first occurrence of HBB, DPTE and other alternative flame retardants (e.g., pentabromotoluene (PBT)) in the Arctic atmosphere and seawater indicating that they have a similar long-range atmospheric transport potential (LRAT) as the banned PBDEs.     

Human maternal and umbilical cord blood concentrations of polybrominated diphenyl ethers

Polybrominated diphenyl ethers (PBDEs), widely used as flame retardants in commercial products, have become ubiquitous environmental contaminants. Although adult human exposure to PBDEs is well documented, developmental exposure is less well characterized. The objectives of this study were to measure maternal and fetal exposure to nine PBDE congeners and to investigate potential associations with birth weight. PBDE congeners were quantified in maternal serum at 24-28 weeks of pregnancy, delivery, and umbilical cord serum (UCS) by gas chromatography-mass spectrometry (GC/MS/MS). Complete blood sample sets were obtained from 97 pregnant women (mean age 33.1 ± 0.5 years). PBDE-28, -47 and -99 were quantified in all samples tested and PBDE-47 was the most abundant congener measured in both maternal (mid-pregnancy and delivery samples geometric mean = 26.9 and 26.9, respectively) and UCS (GM = 56.0 ng g⁻¹ lipid). The UCS concentration for all congeners with the exception of PBDE-153 was higher vs. maternal delivery samples (p < 0.001). Only the UCS concentration of PBDE-17 and -99 were significantly associated (β = −49.860, p = 0.032, and β = −3.645, p = 0.05) with birth weight. However, after adjustment for potential confounders only the association between PBDE-99 and birth weight remained significant (β = −3.951 and p = 0.016). We conclude that: the fetus is exposed to PBDEs from at least the second trimester of pregnancy onward; PBDE congeners are higher in UCS compared to maternal serum samples collected at delivery; and that developmental PBDE exposure is potentially associated with lower birth weight.     

光源和溶剂对十溴联苯醚光降解的影响

研究了不同光源和溶剂对十溴联苯醚(DecaBDE)光降解特性的影响,并对其降解产物进行了探讨.结果表明,在所试光源和溶剂条件下,DecaBDE均有一定程度的光降解,且都近似符合一级降解动力学.同一光源下,不同溶剂对DecaBDE降解表现出不同的影响.在太阳光照射下,DecaBDE降解速率为甲苯>甲醇>正己烷>正己烷/丙酮>甲醇/水>乙醇/水;在模拟光源照射下,DecaBDE降解速率为甲苯>甲醇>甲醇/水>乙醇/水>正己烷>正己烷/丙酮;在紫外光照射下,DecaBDE降解速率为甲苯>甲醇>正己烷/丙酮>正己烷>甲醇/水>乙醇/水.同一溶剂中,DecaBDE降解速率均为紫外光>太阳光>模拟光源.尽管光源和溶剂对DecaBDE降解速率产生了一定影响,但降解途径基本一致,均为DecaBDE经光解脱溴产生低溴联苯醚.     

Photocatalytic debromination of preloaded decabromodiphenyl ether on the TiO(2) surface in aqueous system

There have been serious concerns about polybromodiphenyl ethers (PBDEs) in the environment because of their global distribution and bioaccumulation. Owing to strong hydrophobicity of PBDEs, the regular photocatalytic system, in which the substrate is solvated in the bulk solution, is not applicable to the removal of the PBDEs in water. In this work, the photocatalytic reduction degradation of decabromodiphenyl ether (BDE209), the most-used PBDEs, was investigated in aqueous system, by pre-adsorbing it on the surface of photocatalyst. It was found that the preloaded BDE209 underwent efficient reductive debromination in aqueous system under irradiation with wavelength larger than 360 nm in the presence of electron donors such as methanol. Our experiments further show that such a preloaded system exhibits different characteristics from that in the organic solution. The meta-debrominated intermediate is predominant in the present system, while the ortho-debrominated one is the main nona-BDE products in the organic solution. In addition, different from other photocatalytic system, the pH has little effect on the photocatalytic reaction. We propose that these differences are originated from the formation of overlayer of hydrophobic BDE209 to limit the motion of BDE209 and the access of water and H⁺/OH⁻ to the TiO₂ surface.     

Tri-decabrominated diphenyl ethers and hexabromocyclododecane in indoor air and dust from Stockholm microenvironments 2: indoor sources and human exposure

Data on polybrominated diphenyl ether (PBDE) and hexabromocyclododecane (HBCD) concentrations from Stockholm, Sweden, indoor microenvironments were combined with information from detailed questionnaires regarding the sampling location characteristics, including furnishing and equipment present. These were used to elucidate relationships between possible flame-retarded sources and the contaminant concentrations found in air and dust. Median concentration ranges of ΣPenta-, ΣOcta-, ΣDecaBDE and HBCD from all microenvironments were 19-570, 1.7-280, 29-3200 and < 1.6-2 pg/m³ in air and 22-240, 6.1-80, 330-1400 and 45-340 ng/g in dust, respectively. Significant correlations were found between concentrations of some PBDEs and HBCD in air and/or dust and the presence of electronic/electrical devices, foam furniture, PUF mattresses and synthetic bed pillows in, as well as floor area and construction year of the microenvironment. Car interiors were a source to indoor air in dealership halls. Using median and maximum concentrations of ΣPenta-, ΣOcta-, ΣDecaBDE and HBCD in air and dust, adult and toddler (12-24 months) intakes from inhalation and dust ingestion were estimated. Toddlers had higher estimated intakes of ΣPenta-, ΣDecaBDE and HBCD (7.8, 43, 7.6 ng/d, respectively) from dust ingestion than adults (5.8, 38, 6.0 ng/d, respectively). Air inhalation in offices was also an important exposure pathway for ΣPenta-, ΣOcta- and ΣDecaBDE in adults. For ΣPentaBDE and HBCD, air inhalation and dust ingestion play minor roles when compared to previously published Swedish dietary intakes (median exposures). However, in worst case scenarios using maximum concentrations, dust ingestion may represent 77 and 95% of toddler intake for ΣPentaBDE and HBCD, respectively.     

活性炭纤维吸附模拟废气中的乙醇和乙醚

采用动态吸附法研究了5种活性炭纤维（ACF）对乙醇、乙醚及模拟混合废气中的乙醇和乙醚的吸附性能。实验结果表明：当ACF-1,ACF-2,ACF-3,ACF-4分别吸附乙醇和乙醚时,在室温、乙醇质量浓度12.0 mg/L、乙醚质量浓度13.0 mg/L的条件下,4种ACF对乙醇的穿透吸附量和饱和吸附量分别为60~70 mg/g和339~409 mg/g,对乙醚的穿透吸附量和饱和吸附量分别为50~65 mg/g和301~344 mg/g;在室温、模拟混合废气中乙醇和乙醚的质量浓度均为11.6 mg/L、吸附时间120 min的条件下,具有较大的比表面积和微孔体积的ACF-5对乙醇的吸附量为205 mg/g,对乙醚的吸附量为223 mg/g;在脱附真空度-0.95 Pa、脱附时间20 min的条件下,经17 次使用的ACF-5对模拟混合废气中乙醇和乙醚的穿透吸附量均为87 mg/g,穿透时间均为12 min。     

地下水浅埋区某加油站特征污染物空间分布简

加油站渗漏污染地下水已经是一个世界性的问题。由于浅埋区加油站储罐与地下水密切接触,更加剧储罐的腐蚀。为揭示加油站渗漏的典型污染物石油烃（TPH）、苯系物（BTEX）、萘和甲基叔丁基醚（MTBE）在该水文地质条件下的迁移变化,在浅埋区某加油站开展了平、枯、丰水期的地下水监测工作。在水平分布上,TPH、BTEX、萘基本相似,均在加油岛附近形成高浓度区,而MTBE则更易随地下水流动而迁移,呈现出不同的污染晕。在垂直分布上,地下水的水位变动是污染物浓度分布的主要影响因素。