Cercaricidal activity of some essential oils of plants from Brazil

Extended screening tests on the cercaricidal activity of various plants from northeast Brazil have shown that the extracts of the leaves and fruits ofPiper marginatum,Protium heptaphyllum, andCapsicum annuum show a remarkable effect on the cercaria ofSchistosoma mansoni. In the case of the oils ofPiper marginatum andCapsicum annuum, 90–96% of the cercaria ofSchistosoma mansoni were killed within 15 min. According to the NMR spectra, the active principles of the extracts seem to be water-soluble unsaturated compounds from the oils or their hydrolysis products. Natural substances provide an attractive alternative for preventive actions against schistosomiasis, as the perturbation of the ecological equilibrium of natural waters can be avoided in this manner.     

珠江口海洋生物体中脂肪烃组分的气相色谱指纹特征分析

采用毛细管气相色谱法分析了珠江口鱼类（蓝圆）、虾类（长毛对虾）、头足类（火枪乌贼）和贝类（近江牡蛎）样品的脂肪烃组分。组分特征参数表明,珠江口海洋生物体中的脂肪烃类主要来自石油源,少量来自海洋生源烃。生物体内的石油烃已经经历了一定程度的降解和代谢,反应出低浓度持续性石油污染的特点。在４种海洋生物中,近江牡蛎表现出较弱的降解和代谢石油烃的能力。     

稻田生态系统气体调节功能及其价值

论文以2002年在上海五四农场稻田生态系统田间实验为基础,运用造林成本法、碳税法和工业制氧法对稻田生态系统气体调节功能及其价值进行研究。研究表明:①稻田生态系统O2释放物理量变化范围为16518～38517kg·hm-2,其价值量也有相同的变化趋势,变化范围是6217～11873元·hm-2;②稻田生态系统对温室气体(CO2、N2O和CH4)调节基本上起着抑制作用,而不是促进作用,在水稻生育期内,稻田温室气体调节物理量的变化范围为-997～2787kgCO2-C·hm-2,价值量变化范围为-751～2098元·hm-2;③稻田生态系统气体调节功能的综合价值变化范围为5467～12842元·hm-2。可见,除了粮食生产和提供秸秆外,农田生态系统还为人类社会提供包括气体调节、养分转化、供观赏的景观等在内的服务功能,共同为人类福利服务。     

南海区平台石油的特征荧光光谱分析

通过对南海区平台石油进行普通荧光光谱、同步扫描荧光光谱、导数荧光技术和三维荧光技术扫描,立体地了解各原 油样品荧光光谱特征,为科学鉴别濒发的海上溢油来源提供科学的依据。实验中综合分析了6个平台原油样品,并与标准原油 进行光谱对比,找出了这些样品的光谱数字化特征。     

Process conditions of preparing methanol from cornstalk gas

The low-heat-value cornstalk gas produced in the down-flow fixed bed gasifier was tentatively used for methanol synthesis. The cornstalk gas was purified and the technical procedures such as deoxygenation, desulfurization, catalytic cracking of tar, purification and hydrogenation were studied. The catalytic experiments of methanol synthesis with cornstalk syngas were carried out in a tubular-flow integral and isothermal reactor. The effect of reaction temperature, pressure, catalysttypes, catalyst particle size, syngas flow at entering end and composition of syngas was investigated. The optimum process conditions and yield of methanol from cornstalk syngas were obtained. The experimental results indicated that the proper catalyst of the synthetic reaction was C301 and the optimum catalyst size (φ) was 0.833 mm×0.351 mm. The optimum operating temperature and pressure were found to be 235℃ and 5 Mpa, respectively. The suitable syngas flow 0.9-1.10 mol/h at entering end was selected and the best composition of syngas were CO 10.49%, CO2 8.8%, N2 37.32%, CnHm 0.95% and H2 40.49%. The best methanol yield is 0.418 g/g cornstalk. The study provided the technical support for the industrial test of methanol production from biomass (cornstalk)gas.     

粪便源指纹及其鉴别研究

利用气相色谱-质谱联用仪检测了人和32种动物粪便中以及5个不同排污口表层沉积物中10种粪固醇,以10种粪固醇含量和9个粪固醇比值为指标,分别应用层次聚类分析法对人和32种动物粪便以及5个沉积物的粪便污染来源进行了鉴别,结果表明:草食动物粪便中主要含C29-甾醇,5β-甾醇比5α-甾醇含量多,草食动物粪便的主要指示物是24-乙基粪醇和谷甾醇;肉食动物粪便中主要含C27-甾醇,胆固醇是肉食动物的主要指示物;杂食粪便中粪固醇组成多变;人粪便中主要含粪醇,占总粪固醇的51.5%;应用10种粪固醇含量和9个粪固醇比值以及层次聚类分析法,可以准确地鉴别人和32种动物粪便以及5个沉积物样品的粪便污染来源。     

渤海海上原油油指纹库建设

参照国际先进的油指纹分析、溢油鉴别技术以及油指纹库建设方法,建立一套先进的油指纹库建设技术体系,开展了渤海不同区块9个原油油指纹库建设工作。通过本课题的研究,使我国的油指纹库建设技术体系更趋完备,全面提高了溢油鉴别工作的科学性。     

Removal of PCDD/Fs and PCBs from flue gas using a pilot gas cleaning system

A 100 Nm3 /hr capacity pilot scale dual bag filter (DBF) system was tested on the flue gas from an actual hazardous waste incinerator (HWI), the removal efficiency of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) was also studied. The first filter collected most of the fly ash and associated chlorinated organic; then activated carbon (AC) was injected and used to collect phase chlorinated organic from the gas. Concentrations of PCDD/Fs and PCBs after the DBF system were 0.07 and 0.01 ng TEQ/Nm3 , respectively, which were both far below the national emission standard. Comparing with the original single bag filter system, the PCDD/Fs concentration dropped a lot from 0.36 to 0.07 ng TEQ/Nm3 . Increasing AC feeding rate enhanced their collection efficiency, yet reduced the AC utilization efficiency, and it still needs further study to select an appropriate feeding rate in the system. These results will be useful for industrial application and assist in controlling emissions of PCDD/Fs and other persistent organic pollutions from stationary sources in China.     

Production and emission of phosphine gas from wetland ecosystems

Phosphine is a part of an atmospheric link of phosphorus cycle on earth, which could be an important pathway for phosphorus transport in environment.Wetland ecosystems are important locations for global biogeochemical phosphorus cycle.In this study, production and emission fluxes of free phosphine from four wetlands types in southern China were observed in different seasons.The results showed that the concentration of phosphine liberated from wetlands was at pg/m3-ng/m3 level.The emission concentrations of different wetlands followed the sequence:paddy field(51.83 ± 3.06) ng/m3 marsh(46.54 ± 20.55) ng/m3 lake(37.05 ± 22.74) ng/m3 coastal wetland(1.71 ± 0.73) ng/m3, the positive phosphine emission flux occurred in rice paddy field(6.67 ± 5.18) ng/(m2·hr) and marsh(6.23 ± 26.9) ng/(m2·hr), while a negative phosphine flux of(-13.11 ± 35.04) ng/(m2·hr) was observed on the water-air interface of Lake Taihu, suggesting that paddy field and marsh may be important sources for phosphine gas in atmosphere, while lake may be a sink of atmospheric phosphine gas during the sampling period.Atmospheric phosphine levels and emission flux from Yancheng marsh and rice paddy field varied in different seasons and vegetational zones.Both diffusion resistance in aqueous phase and temperature were dominating factors for the production and transportation of phosphine to atmosphere.     

机动车尾流区CO2扩散特征的数值分析

为了研究车辆运动过程中尾流区排放污染物的扩散情况,通过CFD软件FLUENT 6.1.22TM中湍流模型和组分输运方程对单辆货车尾流区内的气流速度、湍流动能和排气管排放的CO2浓度的分布进行了模拟.通过模拟结果与风洞实验的数据对比验证了模拟结果的适用性.分析了车速,排气管出口温度和湍流动能对货车尾流区内CO2扩散过程的影响,结果表明,由于出口直径和流速相对较小,排气管射流对尾流区流场的影响不明显;在排气管出口处CO2的浓度梯度最大,且随着与车尾距离的增加浓度迅速减小;尾流区内CO2在x、y、z3个方向上的浓度变化速度均随车速的增加而增加;且在尾流区内相同位置处.车速越大CO2浓度越低;排气管出口与外部环境温差对污染物扩散的影响仅局限于距离车尾0.75倍车长范围内;湍流动能最大值出现在尾流区内,有利于CO2的稀释和扩散.     

不同农地整治模式对耕地生产价值和生态价值的影响——基于天门、潜江部分农户的实证分析

基于耕地生产价值和生态价值理论及其评估方法,构建农地整治背景下耕地生产价值和生态价值的分析框架,利用湖北省天门市和潜江市的农户问卷调查数据,采用DID模型和OLS模型,分析不同农地整治模式影响耕地生产价值和生态价值的作用机理。研究发现： （1）农地整治能较大促进耕地生产价值的提高,且新型经营主体主导模式的促进作用要优于政府主导模式;（2）农地整治能显著促进耕地生态价值的提高,但两种模式的促进效应没有明显不同;（3）耕地生产价值的提升有助于耕地生态价值的提高。基于此,今后不仅要继续加大农地综合整治的投资力度,还要在农地综合整治中重视生态整治,更要创新农地整治实施模式。     

Process conditions for preparing methanol from cornstalk gas

The low-heat-value cornstalk gas produced in the down-flow fixed bed gasifier was tentatively used for methanol synthesis. The cornstalk gas was purified and the technical procedures such as deoxygenation, desulfurization, catalytic cracking of tar, purification and hydrogenation were studied. The catalytic experiments of methanol synthesis with cornstalk syngas were carried out in a tubular-flow integral and isothermal reactor. The effect of reaction temperature, pressure, catalyst types, catalyst particle size, syngas flow at entering end and composition of syngas was investigated. The optimum process conditions and yield of methanol from cornstalk syngas were obtained. The experimental results indicated that the proper catalyst for the synthetic reaction was C301 and the optimum catalyst size was 0.833 mm x 0.351 mm. The optimum operating temperature and pressure were found to be 235癈 and 5 MPa, respectively. The suitable syngas flow 0.9-1.10 mol/h at entering end was selected and the best composition of syngas were CO 10.49%, CO2 8.8%, N2 37.32%, CnHm 0.95% and H2 40.49%. The best methanol yield was 0.418 g/g cornstalk. This study provided the technical support for the industrial test of methanol production from biomass (cornstalk) gas.     

Greenhouse gas emissions from rubber industry in Thailand

Rubber production has been taking place in Thailand for many decades. Thailand is currently the world's largest natural rubber producer. We present emissions of greenhouse gases associated with the production of fresh latex, and three primary rubber products, including concentrated latex, block rubber (STR 20), and ribbed smoked sheet (RSS) in Thailand. Besides industrial activities in the rubber mills, the agricultural activities in rubber tree plantation are taken into account. The overall emissions from the production of concentrated latex, STR 20, and RSS amount to 0.54, 0.70, and 0.64 ton CO₂-eq/ton product, respectively. This is for the case that rubber plantations have been located on cultivated lands for more than 60 years, which is current practice in most of Thailand. Emissions are largely associated with energy use and the use of synthetic fertilizers. We also quantify emissions for the case that tropical forests have been converted to rubber plantations relatively recently, which is a recent trend in Thailand. In this case the emissions are much higher because of carbon loss from land conversion: 13, 13, and 21 ton CO₂-eq/ton product for concentrated latex, STR 20, and RSS, respectively. We discuss the implications of our results for strategies to reduce greenhouse gas emissions from rubber production.     

Reducing greenhouse gas emissions from magnesium die casting

The U.S. magnesium industry uses sulfur hexafluoride (SF₆) as a cover gas to prevent the rapid and hazardous oxidation of molten magnesium. While this gas is considered to be safe and effective in this application, it is one of the most potent and persistent greenhouse gases (GHG) found in the atmosphere. The U.S. Environmental Protection Agency (EPA) launched a collaborative initiative called the SF₆ Emission Reduction Partnership for the Magnesium Industry in 1999 to identify and implement practical technologies for improving the industry's environmental profile. EPA's Partners, joined by the International Magnesium Association (IMA), have voluntarily committed to eliminate the use of SF₆ by 2010. The Partnership and IMA's commitment sent a clear signal to industry suppliers and has precipitated the exploration of alternate cover gases that are just as effective as SF₆ but greatly reduce the process's climate impact. The focus of this study is to assess byproducts, degradation levels, and GHG emission factors for three different fluorinated cover gases (SF₆, AM-cover™, and Novec™ 612) in cold chamber die casting applications. The results of this study are used to describe two approaches that modify current Intergovernmental Panel on Climate Change (IPCC) Good Practice Guidance for estimating cover gas emissions from the magnesium industry.     

Simulation and life cycle assessment of process design alternatives for biodiesel production from waste vegetable oils

This study uses the process simulator ASPEN Plus^® and Life Cycle Assessment (LCA) to compare three process design alternatives for biodiesel production from waste vegetable oils that are: the conventional alkali-catalyzed process including a free fatty acids (FFAs) pre-treatment, the acid-catalyzed process, and the supercritical methanol process using propane as co-solvent. Results show that the supercritical methanol process using propane as co-solvent is the most environmentally favorable alternative. Its smaller steam consumption in comparison with the other process design alternatives leads to a lower contribution to the potential environmental impacts (PEI’s). The acid-catalyzed process generally shows the highest PEI’s, in particular due to the high energy requirements associated with methanol recovery operations.