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The octanol–air partition coefficients (KOA) for PBB15, PBB26, PBB31, PBB49, PBB103 and PBB153 were determined as a function of temperature using a gas chromatographic retention time technique with 1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane (p,p′-DDT) as a reference substance. The internal energies of phase change from octanol to air (ΔOAU) were calculated for the six compounds and were in the range from 74 to 116 kJ mol−1. Simple regression equations of log KOA versus relative retention times (RRTs) on gas chromatography (GC), and log KOA versus molecular connectivity indexes (MCI) were obtained, for which the correlation coefficients (r2) were greater than 0.985 at 283.15 K and 298.15 K. Thus the KOA values of the remaining PBBs can be predicted by using their RRTs and MCI according to these relationships. 相似文献
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为了更有效地开展空域安全风险管理工作,本文总结了目前国内外空域安全风险评估的研究成果,重点概述了空域安全风险因果模型、空域安全风险人因可靠性分析、空域安全风险雷达模拟机验证法和碰撞风险模型四类空域安全风险评估方法,并对这四类方法进行了对比分析,剖析了各模型的应用领域、解决的问题、优缺点、限制条件以及发展方向,以为空域安全风险评估研究与风险管理的深入开展和具体实施提供理论依据. 相似文献
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Sorption of nonpolar (phenanthrene and butylate) and polar (atrazine and diuron) organic chemicals to oil-contaminated soil was examined to investigate oil effects on sorption of organic chemicals and to derive oil–water distribution coefficients (Koil). The resulting oil-contaminated soil–water distribution coefficients (Kd) for phenanthrene demonstrated sorption-enhancing effects at both lower and higher oil concentrations (Coil) but sorption-reducing (competitive) effects at intermediate Coil (approximately 1 g kg−1). Rationalization of the different dominant effects was attempted in terms of the relative aliphatic carbon content which determines the accessibility of the aromatic cores to phenanthrene. Little or no competitive effect occurred for butylate because its sorption was dominated by partitioning. For atrazine and diuron, the changes in Kd at Coil above approximately 1 g kg−1 were negligible, indicating that the presently investigated oil has little or no effect on the two tested compounds even though the polarity of the oil is much less than soil organic matter (SOM). Therefore, specific interactions with the active groups (aromatic and polar domains) are dominantly responsible for the sorption of polar sorbates, and thus their sorption is controlled by available sorption sites. This study showed that the oil has the potential to be a dominant sorptive phase for nonpolar pollutants when compared to SOM, but hardly so for polar compounds. The results may aid in a better understanding of the role of the aliphatic and aromatic domains in sorption of nonpolar and polar organic pollutants. 相似文献
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为了解"引江济太"过程中塑化剂类污染物对贡湖的输入特征,于2013年8月对14个采样点的7种邻苯二甲酸酯类化合物(PAEs)的浓度进行采样分析,并通过美国环保署(USEPA)推荐的方法,对其环境风险进行评价.结果表明:各采样点邻苯二甲酸二丁酯(DBP)和邻苯二甲酸二环己酯(DCHP)均有检出,除采样点10、11和12外,邻苯二甲酸二乙酯(DEP)也有检出,其余4种均未检出,长江引水经望虞河进入贡湖后,DEP、DBP和DCHP浓度均有不同程度的降低,且其最高浓度均出现在望虞河长江引水处(采样点1),说明在引水过程中长江水对望虞河有明显的PAEs输入,而贡湖锡东水厂DEP浓度高于贡湖其他采样点,南泉水厂DBP和DCHP浓度高于贡湖其他采样点,金墅湾水厂PAEs浓度总体处于较低水平.环境健康风险评价结果显示:DEP的最大非致癌风险值为3.91×10-8a~(-1),未超过国际组织规定范围,而DBP的最大非致癌风险值为1.17×10-5a~(-1),超过英国皇家协会RS规定的1×10-6a~(-1),但均对人体无明显非致癌危害. 相似文献
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Norfloxacin (NOR), an ionizable antibiotic frequently used in the aquaculture industry, has aroused public concern due to its persistence, bacterial resistance, and environmental ubiquity. Therefore, we investigated the photolysis of different species of NOR and the impact of a ubiquitous component of natural water — dissolved organic matter (DOM), which has a special photochemical activity and normally acts as a sensitizer or inhibiter in the photolysis of diverse organics; furthermore, scavenging experiments combined with electron paramagnetic resonance (EPR) were performed to evaluate the transformation of NOR in water. The results demonstated that NOR underwent direct photolysis and self-sensitized photolysis via hydroxyl radical (·OH) and singlet oxygen (1O2) based on the scavenging experiments. In addition, DOM was found to influence the photolysis of different NOR species, and its impact was related to the concentration of DOM and type of NOR species. Photolysis of cationic NOR was photosensitized by DOM at low concentration, while zwitterionic and anionic NOR were photoinhibited by DOM, where quenching of UOH predominated according to EPR experiments, accompanied by possible participation of excited triplet-state NOR and 1O2. Photo-intermediate identification of different NOR species in solutions with/without DOM indicated that NOR underwent different photodegradation pathways including dechlorination, cleavage of the piperazine side chain and photooxidation, and DOM had little impact on the distribution but influenced the concentration evolution of photolysis intermediates. The results implied that for accurate ecological risk assessment of emerging ionizable pollutants, the impact of DOM on the environmental photochemical behavior of all dissociated species should not be ignored. 相似文献
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External organic carbon sources are needed to provide electron donors for the denitrification of wastewater with a low COD/NO3--N(C/N) ratio, increasing the treatment cost. The economic strategy is to enhance the bioactivity and/or biodiversity of denitrifiers to efficiently utilize organic substances in wastewater. In this study, novel zero-valent iron(ZVI) composite carriers were prepared and implemented in a suspended carrier biofilm reactor to enhance the bioactivity an... 相似文献