A product analysis-based study on the mechanism of inflammable gas explosion suppression

To study the mechanism of the suppressing effect of Expanded Aluminium (EA) on the premixed gas explosion, premixed methane-air and propane-air gases were undergone explosion reaction in the presence of EA in a self-designed closed pipeline with the overpressures and the compositions, rates and sensitivities of products analyzed. The results showed that the 9.5% methane-air and 5% propane-air explosions produced peak pressures decreased by 79.3% and 65.6%, and residual methane and propane contents increased by 270% and 560% respectively than without EA. In addition, the results revealed that the explosions of propane in the presence of EA produced less methane and carbon oxides contents, but more ethylene and propylene contents. The simulation showed that H, O, and OH are the key factors affecting the rate of products. The product compositions, together with other parameters, suggested that EA decreased temperature, inhibited chain initiation and propagation reaction, but facilitated chain termination reaction by advancing and accelerating the gas phase and wall destruction reaction of radicals, especially collisions and concentration of key free radicals. This new research method based on the analysis of explosion products can be used for in-depth research into gas explosion features and shed light on the suppressing mechanism of EA in flammable gas explosion.     

Determination of 27 pharmaceuticals and personal care products (PPCPs) in water: The benefit of isotope dilution

• Isotope dilution method was developed for the determination of 27 PPCPs in water. • The established method was successfully applied to different types of water samples. • The correction effect of corresponding 27 ILSs over 70 d was investigated. • Benefit of isotopic dilution method was illustrated for three examples. Pharmaceuticals and personal care products (PPCPs) are a unique group of emerging and non-persistent contaminants. In this study, 27 PPCPs in various water samples were extracted by solid phase extraction (SPE), and determined by isotope dilution method using liquid chromatography coupled to tandem triple quadruple mass spectrometer (LC-MS/MS). A total of 27 isotopically labeled standards (ILSs) were applied to correct the concentration of PPCPs in spiked ultrapure water, drinking water, river, effluent and influent sewage. The corrected recoveries were 73%–122% with the relative standard deviation (RSD)<16%, except for acetaminophen. The matrix effect for all kinds of water samples was<22% and the method quantitation limits (MQLs) were 0.45–8.6 ng/L. The developed method was successfully applied on environmental water samples. The SPE extracts of spiked ultrapure water, drinking water, river and wastewater effluent were stored for 70 days, and the ILSs-corrected recoveries of 27 PPCPs were obtained to evaluate the correction ability of ILSs in the presence of variety interferences. The recoveries of 27 PPCPs over 70 days were within the scope of 72%–140% with the recovery variation<37% in all cases. The isotope dilution method seems to be of benefit when the extract has to be stored for long time before the instrument analysis.     

Fuzzy experts on recreational vessels, a risk modelling approach for marine invasions

Understanding risks from the human-mediated spread of non-indigenous species (NIS) is a critical component of marine biosecurity management programmes. Recreational boating is well-recognised as a NIS pathway, especially at a regional scale. Assessment of risks from this pathway is therefore desirable for coastal environments where recreational boating occurs. However, formal or quantitative risk assessment for the recreational vessel pathway is often hampered by lack of data, hence often relies on expert opinion. The use of expert opinion itself is sometimes limited by its inherent vagueness, which can be an important source of uncertainty that reduces the validity and applicability of the assessment. Fuzzy logic, specifically interval type-2 fuzzy logic, is able to model and propagate this type of uncertainty, and is a useful technique in risk assessment where expert opinion is relied upon. The present paper describes the implementation of a NIS fuzzy expert system (FES) for assessing the risk of invasion in marine environments via recreational vessels. The FES was based on expert opinion gathered through systematic elicitation exercises, designed to acknowledge important uncertainty sources (e.g., underspecificity and ambiguity). The FES, using interval type-2 fuzzy logic, calculated an invasion risk value (integrating NIS infection and detection probabilities) for a range of invasion scenarios. These scenarios were defined by all possible combinations of two vessel types (moored and trailered), five vessel components (hull, deck, internal spaces, anchor, fishing gear), two infection modes (fouling, water/sediment retention) and six frequently visited marine habitats (marina, mooring, farm, ramp, wharf, anchorage). Although invasion risk values determined using the FES approach was scenario-specific, general patterns were identified. Moored vessels consistently showed higher invasion risk values than trailered vessels. Invasion risk values were higher for anchorages, moorings and wharves. Similarly, hull-fouling was revealed as the highest infection risk mode after pooling results across all habitats. The NIS fuzzy expert system presented here appears as a valuable prioritising and decision-making tool for NIS research, prevention and control activities. Its easy implementation and wide applicability should encourage the development and application of this type of system as an integral part of biosecurity, and other environmental management plans.     

碱活化过一硫酸盐降解水中环丙沙星

采用碱活化过一硫酸盐(peroxymonosulfate,PMS)对环丙沙星(ciprofloxacin,CIP)的去除进行了系统地研究.结果表明,碱活化PMS体系能够高效地去除CIP.通过自由基捕获实验确定了单线态氧(~1O_2)和超氧自由基(O_2~-·)是反应体系中的主要活性物种.NaOH浓度、PMS浓度、反应温度和共存阴离子等对CIP在碱活化PMS体系中的去除均有一定影响.随着NaOH和PMS浓度的增加,CIP的降解均呈现出先增加后降低的趋势.提高反应温度能够加大CIP的反应速率,经过阿伦尼乌斯方程拟合得到的反应活化能为5.09 k J·mol~(-1).不同的阴离子对CIP的去除呈现不同的影响:Cl~-、SO_4~(2-)和NO_3~-对CIP的降解没有呈现明显的作用,H_2PO_4~(2-)能够有效地抑制环丙沙星的去除,而CO_3~(2-)极大地促进了反应进程.通过UPLC-MS/MS可检测到10种降解产物,CIP分子结构中的哌嗪环易于受到活性物种的攻击.     

Research on the degradation mechanism of pyridine in drinking water by dielectric barrier discharge

Pyridine, an important chemical raw material, is widely used in industry, for example in textiles,leather, printing, dyeing, etc. In this research, a dielectric barrier discharge(DBD) system was developed to remove pyridine, as a representative type of nitrogen heterocyclic compound in drinking water. First, the influence of the active species inhibitors tertiary butanol alcohol(TBA),HCO_3~-, and CO_3~(2-)on the degradation rate of pyridine was investigated to verify the existence of active species produced by the strong ionization discharge in the system. The intermediate and final products generated in the degradation process of pyridine were confirmed and analyzed through a series of analytical techniques, including liquid chromatography–mass spectrometry(LC–MS), high performance liquid chromatography(HPLC), ion chromatography(IC), total organic carbon(TOC) analysis, ultraviolet(UV) spectroscopy, etc. The results showed that the degradation of pyridine was mainly due to the strong oxidizing power of ozone and hydroxyl radical produced by the DBD system. Several intermediate products including 3-hydroxyl pyridine, fumaric acid, 2, 3-dihydroxypyridine, and oxalic acid were detected. Nitrogen was removed from the pyridine molecule to form nitrate. Through analysis of the degradation mechanism of pyridine, the oxidation pathway was deduced. The study provided a theoretical and experimental basis for the application of DBD strong ionization discharge in treatment of nitrogen heterocyclic compounds in drinking water.     

Bioaccumulation and the expression of hepatic cytochrome P450 genes in marine medaka (Oryzias melastigma) exposed to difenoconazole

This study was conducted to assess the effects of difenoconazole (DFZ), a triazole fungicide, on the hepatic biotransformation system and its bioaccumulation in marine medaka (Oryzias melastigma). Fish were exposed to DFZ (1, 10, 100, 1000 ng/L) for 180 days. The results showed that: (1) The mRNA levels of hepatic CYP1A1, CYP1B, CYP1C1, CYP27B and CYP3A40 were up-regulated, but those of CYP3A38 and CYP27A1 were down-regulated. (2) The activity of ethoxyresorufin-O-deethylase (EROD) and the content of reduced glutathione (GSH) in the liver were increased in the DFZ-treated groups, and glutathione S-transferase (GST) activity was increased in the 100 and 1000 ng/L groups. (3) DFZ was accumulated in the muscle and the biological concentration factors in the 10, 100, and 1000 ng/L groups were respectively 149, 81 and 25. These results suggested that long-term exposure to DFZ at low concentrations would result in a bioaccumulation of this compound and disturb the biotransformation system.     

城市污水处理厂及其受纳水体中5种典型PPCPs的赋存特征和生态风险

以5种药品及个人护理用品(pharmaceuticals and personal care products,PPCPs)包括氯贝酸、酮洛芬、萘普生、双氯芬酸和布洛芬为目标物,初步研究了它们在上海某生活污水处理厂不同污水处理单元中的赋存特征和去除特性,探讨了污水处理厂受纳河流中5种PPCPs的分布情况,并对其在受纳水体中的生态风险进行了初步评估.结果表明,5种PPCPs在污水处理厂进水中均被检出,表明生活污水是污水处理厂中PPCPs的来源之一.5种PPCPs在整个污水处理工艺中不能全部去除,微生物转化/降解是主要降解机制.受纳污水河流中5种PPCPs的分布特征与污水处理厂出水中的相似,且排污口下游水体中目标物浓度普遍高于上游,反映出污水处理厂排放可能是其受纳水体中PPCPs的主要来源之一.初步风险评估结果表明,受纳水体中双氯芬酸存在高生态风险,而酮洛芬、萘普生、氯贝酸和布洛芬的生态风险相对较低.     

单光子/光电子在线质谱实时分析聚氯乙烯热分解/燃烧产物

实验室研制了低能光电子磁场增强电离(MEPEI)和单光子电离(SPI)复合电离源,该电离源具有电离化合物范围宽、碎片离子少、质谱图简单等优点,结合飞行时间质谱(TOF-MS)实现了聚氯乙烯(PVC)热分解/燃烧产物的在线分析.针对不同的目标化合物,MEPEI/SPI复合电离源通过调节电离区电场强度,可以快速在SPI和SPI-MEPEI之间切换.PVC热分解/燃烧产物中电离能大于光子能量(10.60 eV)的HCl和CO2(12.74 eV、13.77 eV)利用MEPEI模式电离;而烯烃、二氯乙烯、苯系物、氯苯、苯乙烯、茚满及萘系物等可通过SPI-MEPEI复合模式电离.通过实时监测PVC主要燃烧产物的信号强度随温度的变化趋势可推断出,PVC燃烧产物主要是通过两种机制生成:①250～370℃时,PVC发生脱氯及分子内环化反应,产生大量的HCl、苯和萘;②380～510℃时,PVC发生分子间交联反应,生成烷基芳烃,如甲苯和二甲苯/乙苯等.实验结果表明,SPI/SPI-MEPEI复合离子源TOF-MS分析速度快,应用范围广,在在线分析中具有广泛的应用前景.     

浅议环境法的绿色专利

人们通常强调新颖性和经济效用的一个创新,而忽略了对环境造成的影响。这一思想体现到制度设计专利制度。一般来说,如果能够通过三个条件：新颖性、实用性和创新性,可授予专利。这种制度设计制约思维过程中创新者的回报,他们努力发明一件新颖的且有利可图的专利,但是忽略了对环境造成的影响。因此,牺牲的最终是环境。在这项研究中,试图探索一种体制上的补救。在为了改变科技发展的方向,建议完善政策背景下的创新,特别是专利制度。引进一个新的考核标准,绿色专利制度,并探讨其可行性和可能带来的影响。通过把这项环保的关注到专利审查,专利制度可以鼓励创新发明的＂创新,实用和绿色＂的产品以及程序,称之为＂绿色专利＂。     

海水鱼类网箱养殖的环境效应及多营养层次的综合养殖

海水鱼类网箱养殖是世界主要渔业国家(如挪威、日本等)广泛开展的一种高密度、集约化的养鱼方式,这种养殖方式在给广大从业者带来巨大经济、社会效益的同时,对环境也造成了不可忽视的负面影响。开展多营养层次的综合养殖(IMTA)是缓解这一环境压力的有效途径,鱼类养殖过程中释放出的二氧化碳、氮、磷等物质,由无机提取单元(大型藻类)来吸收,粪便和残饵等微小颗粒则成为有机提取单元(滤食性贝类)的饵料,较大的颗粒物质沉到海底后,可以为腐食性单元(海参等)提供食物,通过这种养殖模式,最大限度地实现系统内营养物质的高效利用,在减轻养殖对环境压力的同时,使系统具有较高的容纳量和食物产出能力。