Environmental risk assessment of selected organic chemicals based on TOC test and QSAR estimation models

Environmental risks of organic chemicals have been greatly determined by their persistence,bioaccumulation, and toxicity(PBT) and physicochemical properties. Major regulations in different countries and regions identify chemicals according to their bioconcentration factor(BCF) and octanol–water partition coefficient(Kow), which frequently displays a substantial correlation with the sediment sorption coefficient(Koc). Half-life or degradability is crucial for the persistence evaluation of chemicals. Quantitative structure activity relationship(QSAR) estimation models are indispensable for predicting environmental fate and health effects in the absence of field-or laboratory-based data. In this study, 39 chemicals of high concern were chosen for half-life testing based on total organic carbon(TOC) degradation,and two widely accepted and highly used QSAR estimation models(i.e., EPI Suite and PBT Profiler) were adopted for environmental risk evaluation. The experimental results and estimated data, as well as the two model-based results were compared, based on the water solubility, Kow, Koc, BCF and half-life. Environmental risk assessment of the selected compounds was achieved by combining experimental data and estimation models. It was concluded that both EPI Suite and PBT Profiler were fairly accurate in measuring the physicochemical properties and degradation half-lives for water, soil, and sediment.However, the half-lives between the experimental and the estimated results were still not absolutely consistent. This suggests deficiencies of the prediction models in some ways, and the necessity to combine the experimental data and predicted results for the evaluation of environmental fate and risks of pollutants.     

钩吻毒素的研究进展

近些年来对钩吻毒素的研究愈加全面，主要表现在：中国钩吻已分离出17种单体，其中以钩吻素子含量最高，钩吻素已毒性最强．毒理作用主要抑制呼吸中枢，作用于迷走神经，还能直接作用于心肌和血管平滑肌，在临床上的应用也愈加广泛．主要用于抗肿瘤、镇痛以及促生长等方面．     

系统毒理学及其应用

系统毒理学是近5年来发展起来的一门新兴学科,代表着后基因组时代毒理学发展的新方向.所谓系统毒理学是指通过了解机体暴露后在不同剂量、不同时点的基因表达谱、蛋白质谱和代谢物谱的改变以及传统毒理学的研究参数,借助生物信息学和计算毒理学技术对其进行整合,从而系统地研究外源性化学物和环境应激等与机体相互作用的一门学科.系统毒理学有望在阐明毒物对机体损伤分子机制、分子生物标志物和危险度评价等方面取得突破.在总结国内外相关研究的基础上,综述了系统毒理学的诞生背景、研究策略、研究技术及其主要应用.尽管还有不足之处,但可以肯定系统毒理学的发展和应用将会对人类的环境与健康研究产生极大的推动作用.     

细胞培养技术在藻毒素毒理研究中的应用

随着水体富营养化的加剧,藻毒素对人类的危害愈加明显,对其机理的研究也愈发显得重要。在目前广泛采用的小鼠活体实验不能很好满足研究需要的时候,细胞培养技术将实验带入了微观细胞世界,并在越来越多的应用中体现出优越性,使对藻毒素毒理研究研究取得了巨大的进展。本文对藻毒素研究的现状以及细胞培养较之常规方法的优势和其应用进行综述,同时展望该技术的良好发展前景。     

数值仿真在钱塘江引水入城工程水质预测中的应用

使用二维浅水波方程及传质模型,对工程前期排人钱塘江的废水中污染物的传播及分布进行预测,其预测结果可为工程排污口附近钱塘江水质保护对策制定提供依据。     

硫丹的环境行为及水生态毒理效应研究进展

有机氯农药硫丹作为一种典型的持久性有机污染物(POPs)曾广泛应用于农业生产,我国曾大量使用。硫丹作为一种重要的污染物通过地表径流、淋、溶、干/湿沉降等方式进入水体,在直接影响大型水生植物和浮游藻类的同时,给鱼类等水生动物也带来了一定的毒性效应。由于其半衰期较长、迁移能力强、富集性高,在水体环境中已普遍检测出硫丹的存在,因此,对硫丹的水生生态安全性评价显得十分重要。硫丹对水生生物具有高毒性,它可影响生物正常受体配体作用、损伤生物膜、影响活性氧代谢并具有潜在的内分泌干扰作用。本文介绍了硫丹的环境行为效应,并综述了硫丹对水生生物的毒性及几种致毒机制,展望了该领域今后的研究重点和方向。     

Self-sustained catalytic combustion of CO enhanced by micro fluidized bed: stability operation,fluidization state and CFD simulation

● Catalytic combustion in fluidized bed realizes efficient heat and mass transfer. ● Catalytic combustion in fluidized bed reduces the lean combustion limits. ● Catalytic combustion and flame combustion can be coupled. ● The diffusion/kinetics limited reaction model is suitable for catalytic combustion. A micro fluidized bed reactor was used to study the self-sustaining catalytic combustion of carbon monoxide (CO). The Cu_1−xCe_xO_y catalyst, as well as the pure CuO and CeO₂, are used to investigate the contributing mechanism of different active sites including dispersed CuO and Cu–Ce solid solutions. The ignition temperature (T_i) of CO over these catalysts at a flow rate of 2000 mL/min followed the order: 74 °C (Cu_0.5Ce_0.5O_y) < 75 °C (Cu_0.25Ce_0.75O_y) < 84 °C (Cu_0.75Ce_0.25O_y) < 105 °C (CuO) < 500 °C (CeO₂). Furthermore, the lean combustion limits (equivalence ratio ϕ) over these catalysts under the flow rates of 750–3000 mL/min (through fixed, bubbling, and fluidized bed) were also measured, which are Cu_0.5Ce_0.5O_y < Cu_0.25Ce_0.75O_y < Cu_0.75Ce_0.25O_y < CuO < CeO₂. The fluidized bed was simulated using the Eulerian two-fluid model (TFM) coupled with a diffusion/kinetic-limited reaction model to evaluate the influence of operation conditions on the self-sustained combustion of CO. The predicted maximum temperature agreed with the experimental measurements, demonstrating the validity of the kinetic model and simulation parameters. The results of catalytic combustion with increasing CO concentrations suggest that the catalytic combustion reaction could co-exist with the flamed combustion. When a high concentration of CO is used, a blue-purple flame caused by CO combustion appears in the upper part of the fluidized bed, indicating that the range of CO-containing exhaust gas purification could be expanded to a larger range using the fluidized-bed catalytic combustion technique.     

3-D dispersion model for simulation of accidental toxic gas releases in a metropolitan area

Computational fluid dynamic (CFD) simulations were performed to assess the potential chlorine leak scenario in the super-urban area of South Korea, where the human population density is very high and numerous buildings exist near operational water treatment facilities. Flame acceleration simulator (FLACS) was used to predict the consequence from accidental chlorine releases out of one of the water treatment facilities for the nearby area having a size of 5 km × 3 km approximately. The ability to precisely implement 3-D geometries is crucial for a successful 3-D simulation. Thus, a method was proposed to rapidly and accurately implement geometry by importing computer aided-design (CAD) files provided by a government agency, and processing them using Auto CAD and MicroStation software programs. An accidental release from an 18-ton tank was simulated with three different wind directions to determine the expected evacuation distances. Results from the study showed that the endpoint distances varied depending on the density and arrangement of the buildings. Moreover, we employed physical barriers with varying heights for mitigating the effects of toxic gas releases and simulated how effectively they decreased the concentration of released chlorine.     

Computational fluid dynamics simulations of hydrogen releases and vented deflagrations in large enclosures

This paper presents model predictions obtained with the CFD tool FLACS for hydrogen releases and vented deflagrations in containers and larger enclosures. The paper consists of two parts. The first part compares experimental results and model predictions for two test cases: experiments performed by Gexcon in 20-foot ISO containers (volume 33 m³) as part of the HySEA project and experiments conducted by SRI International and Sandia National Laboratories in a scaled warehouse geometry (volume 45.4 m³). The second part explores the use of the model system validated in the first part to accidental releases of hydrogen from forklift trucks inside a full-scale warehouse geometry (32 400 m³). The results demonstrate the importance of using realistic and reasonably accurate geometry models of the systems under consideration when performing CFD-based risk assessment studies. The discussion highlights the significant inherent uncertainty associated with quantitative risk assessments for vented hydrogen deflagrations in complex geometries. The suggestions for further work include a pragmatic approach for developing empirical correlations for pressure loads from vented hydrogen deflagrations in industrial warehouses with hydrogen-powered forklift trucks.     

Ground influence on high-pressure methane jets: Practical tools for risk assessment

High-pressure gaseous methane release is a relevant safety-related problem mainly in the Oil and Gas industry. As well documented, the reason for these safety concerns is connected with the severe consequences of the domino effect subsequent to the possible ignition. In risk assessment activities, estimation of the damage area is of primary importance in order to draw up proper safety guidelines. To do this, loss prevention specialists use quick and well-established numerical tools (i.e., integral models) in their daily activities. However, the presence of an obstacle in the flow field of the jet (e.g., the ground) is a more probable situation to deal with. It is known that integral models fail in this kind of scenario, leading to unreliable predictions. Hence, the present work investigates how an industrial ground surface influences the LFL cloud size of a horizontal high-pressure methane jet. An innovative quick procedure is proposed allowing to determine the height below which the ground begins to influence the LFL cloud size and the extent of such influence. Therefore, this procedure allows practitioners to establish when integral models can be used and when not to use them, and also provides a simple and reliable alternative to their use. These analytical instruments are derived from an extensive computational fluid dynamics analysis performed with Ansys Fluent 19.0.