FCC催化剂实验室循环污染老化的方法

采用固定流化床装置对FCC催化剂进行重金属污染,并对污染后的催化剂进行水热老化,建立了有机重金属盐循环污染老化方法;比较了不同污染老化方法对催化剂性能的影响。实验结果表明,在循环污染过程中重金属沉积率与剂油比、循环污染次数有关,并建立了相应的函数关系式;利用函数关系式可确定有机重金属盐循环污染老化实验方案;与无机、有机盐浸渍污染老化的催化剂相比,有机重金属盐循环污染老化的催化剂上的重金属分散状态较好;有机重金属盐循环污染老化方法的实验过程简单。

渗透作用下多孔介质中循环浓度污染物的迁移过程研究

根据饱和多孔介质中考虑释放效应的一维渗透作用的可溶性污染物的迁移控制方程,通过Laplace变换和Fourier变换及其逆变换求得相应的通解形式。根据半无限体表面可溶性污染物点源注入情形下的基本解,通过积分方法得到半无限体表面圆形区域上作用循环浓度污染物后,在多孔介质内部污染物迁移过程的求解方法。作为一个典型算例,对渗透作用下循环浓度污染源引起的多孔介质中的迁移过程进行分析。算例表明,当污染源浓度为周期变化时,多孔介质内部污染物的浓度随时间增长由不稳定的周期变化过程逐渐过渡到稳定的循环过程,而某一深度处污染物浓度的相位则相应滞后。此时,稳定后的污染物浓度周期与污染源浓度周期相同。实际上,随多孔介质表面污染源浓度的周期变化,在靠近多孔介质表面一定深度范围内的污染物浓度在深度方向也呈增大或减小的交替变化过程。另一方面,在污染源循环变化过程中污染物不断向深处推进,而最终其影响范围限定在某一深度内。

塔里木河干流农田盐分排灌污染循环与调控研究

通过调查监测研究发现 ,在塔里木河干流 ,随着排水系统的初步完善 ,农田排水进入了河流 ,造成流域农田盐分上灌下排的污染循环。污染循环的影响枯水期最大 ,影响严重的区域在干流的上游下段和中游 ,其水化学类型以Cl·SO4-Na为主。提出只有采用多途径排水措施和通过开发地下水解决枯水期的用水 ,才能缓解和削弱它的影响。

富营养化对海底系统污染物循环的影响

本文研究了有机物质输入对波罗的海和卡特加特海峡海底生态系统疏水性有机污染物(HOC)生物利用度和循环的影响。通过实验,我们研究了由于紫胎贝(Mytilus edulis)、蛇尾虫(Amphiura filiformis)及多毛目环节动物(Nereis diversicolor)所引起的微藻增加对HOC(PCB和PAH)生物积累的影响。和平衡分配理论相反,生物积累与海藻和有机碳的浓度成正比。这是由海藻有机碳中营养质量高所造成的,同时也表明是取食而不是平衡分配控制了这些物种的生物积累。通过实地研究,我们估计了紫贻贝和蛇尾虫体内每年PCB的流通总量和每年转移到更高营养级的污染物的总量。研究结果指出:①富营养化能促进底栖生物体内HOC的积累。②在评价海底系统污染时,必需考虑有机碳质量和数量在时间上的变化。③大型动物的取食活动对海底和深海结合IIOC很重要。④生物扰动促进了HOC从沉积物向水面的释放。

基于“入湖水质监控+循环处理”的流域面源污染治理方法及应用研究——以异龙湖流域面源污染治理为例

流域面源污染已成为湖泊水环境治理过程中的重点和难点。本课题围绕湖泊流域面源污染治理问题,开展了面源污染末端拦截收集(前置水体污染物沉淀库+调蓄带)、湿地工程净化和“入湖水质监控+循环处理”等多种措施组合应用的面源污染末端治理模式研究,并应用于异龙湖流域的面源污染治理工程。研究发现:该措施组合在异龙湖流域面源污染治理中起到积极的作用,是一种有效的面源污染末端治理措施,尤其是“入湖水质监控+循环处理”措施有效得保障了入湖水质的净化效果,能为其他流域湖泊水环境治理提供有益的借鉴。

循环水系统去除氨氮及氯根的经验措施

以中盐昆山有限公司成功解决联碱循环水中氨氮和氯根离子浓度偏高的经验为例,介绍了其处理方法及流程,为后续其他联碱企业遇到类似突发情况提供参考依据。

土壤环境的生物地球化学过程、质量演变和风险管理研究展望

结合国内外研究现状和发展趋势分析,提出开展土壤环境的生物地球化学过程、质量演变和风险管理研究。认为将土壤环境划分为内部、界面和外部三部分,有助于认识土壤环境中污染物的交换与循环规律及其相互影响。强调了开展土壤环境的物理-化学-生物学-地学交叉、综合研究的必要性,并从土壤颗粒表面-溶液、土壤-生物、土壤-植物、土壤-大气、土壤-水体等土壤环境子系统探讨了科学问题,展望了未来研究方向,旨在促进不同尺度土壤环境的质量变化规律与修复调控研究。

气候变化与持久性有机污染物全球循环

作为全球变化的主要表现之一,气候变暖对人类赖以生存的地球环境已经产生了不可磨灭的影响.其中,气候变暖如何影响污染物传播引起了科学家的广泛关注.持久性有机污染物(POPs)是可以进行全球传输的污染物.揭示气候变暖对POPs全球循环的影响机制对于准确理解POPs循环的过程和相关政策的制定具有重要的指导意义.本文综述了此领域近十年来的主要研究工作,总结了气候变暖对POPs排放、迁移、储存、降解和毒性的影响,简述了相关模型的特点和主要应用,并指出目前研究中存在的问题以及未来研究的主要方向.在气候变暖条件下,POPs全球循环的变化主要体现在以下几个方面:(1)全球变暖直接促进了POPs的二次排放,升温将导致POPs从土壤和海洋中挥发出来,而冰川融化、冻土退化则可以将POPs二次释放进入淡水生态系统;(2)全球极端气候(干旱和洪水)通过剧烈的地表侵蚀过程,将土壤所负载的POPs重新释放进入环境,进而改变了POPs的全球分布;(3)气候变暖条件下大气与海洋环流的变化将显著改变全球POPs的迁移路径;(4)气候变暖改变了海洋生物生产力,进而改变了海洋对POPs的储存能力;(5)部分地区水生及陆地食物链结构在气候变暖的情景下发生了明显变化,这种变化可以导致POPs在生态系统中毒性的放大;(6)尽管气候变暖在促使POPs再挥发的同时也加速着其降解的过程,但是总体上气候变暖增加了环境中POPs的总量;(7)各种模型的耦合应用对未来气候变暖情景下POPs环境行为的反馈与响应进行了预测,这些工作有助于政策和法律制定者在POPs控制措施中全面考虑气候变暖对POPs环境载荷的影响.在未来,气候变暖与全球变化的其他表现协同影响POPs的循环将是下一步的研究重点,POPs与碳循环、水循环互相关联耦合,其相互作用机制将是生态系统对气候变化适应性研究的一个新方向.

N Cycle, N Flow Trends in Japan, and Strategies for Reducing N_2O Emission and NO_3^- Pollution

To feed an increasing population, large amounts of chemical nitrogen fertilizer have been used to produce much of our food, feed and fiber thereby increasing nitrogen levels in soils, natural waters, crop residues, livestock wastes,and municipal and agricultural wastes, with national and international concern about its potential adverse effects on environmental quality and public health. To understand these phenomena and problems, first the nitrogen cycle and the environment are described. Then recent trends for nitrogen cycling through the food and feed system, N2O emissions from fertilized upland and paddy soils, and NO-3 pollution in ground water in Japan are reported. Finally, mitigation strategies in Japan for reducing N2O emission and NO-3 pollution are proposed, including nitrification inhibitors, controlled release fertilizers, utilization of plant species that could suppress nitrification, utilizing the toposequence, government policy, and appropriate agricultural practices. Of all the technologies presented, use of nitrification inhibitors and controlled release fertilizers are deemed the most important with further development of these aspects of technologies being expected. These practices, if employed worldwide, could help reduce the load, or environmental deterioration, on the Earth's biosphere.

Bifunctional S-scheme g-C3N4/Bi/BiVO4 hybrid photocatalysts toward artificial carbon cycling

Although both the aerobic photocatalytic oxidation of organic pollutants into CO2 and the anaerobic photocatalytic reduction of CO2 into solar fuels have been intensively studied,few efforts have been devoted to combining these carbon-involved photocatalytic oxidation-reduction processes together,by which an artificial photocatalytic carbon cycling process can be established.The key challenge lies in the exploitation of efficient bifunctional photocatalysts,capable of triggering both aerobic oxidation and anaerobic reduction reactions.In this work,a bifunctional ternary g-C3N4/Bi/BiVO4 hybrid photocatalyst is successfully constructed,which not only demonstrates superior aerobic photocatalytic oxidation performance in degrading an organic pollutant(using the dye,Rhodamine B as a model),but also exhibits impressive photocatalytic CO2 reduction performance under anaerobic conditions.Moreover,a direct conversion of Rhodamine B to solar fuels in a one-pot anaerobic reactor can be achieved with the as-prepared ternary g-C3N4/Bi/BiVO4 hybrid photocatalyst.The excellent bifunctional photocatalytic performance of the g-C3N4/Bi/BiVO4 photocatalyst is associated with the formation of efficient S-scheme hybrid junctions,which contribute to promoting the appropriate charge dynamics,and sustaining favorable charge potentials.The formation of the S-scheme heterojunction is supported by scavenger studies and density functional theory calculations.Moreover,the in-situ formed plasmonic metallic Bi nanoparticles in the S-scheme hybrid g-C3N4/Bi/BiVO4 photocatalyst enhances vectorial interfacial electron transfer.This novel bifunctional S-scheme g-C3N4/Bi/BiVO4 hybrid photocatalyst system provides new insights for the further development of an integrated aerobic-anaerobic reaction system for photocatalytic carbon cycling.

Dynamics of Microbial Activity Related to N Cycling in Cd-Contaminated Soil During Growth of Soybean

The potential influences of cadmium (Cd) on the biochemical processes of the soil nitrogen (N) cycle, along with the dynamics of ammonification, nitrification, and denitrification processes in the rhizosphere and non-rhizosphere (bulk soil), respectively, were investigated in a Cd-stressed system during an entire soybean growing season. In terms of Cd pollution at the seedling stage, the ammonifying bacteria proved to be the most sensitive microorganisms, whereas the effects of Cd on denitrification were not obvious. Following the growth of soybeans, the influences of Cd on ammonification in the bulk soil were: toxic impacts at the seedling stage, stimulatory effects during the early flowering stage, and adaptation to the pollutant during the podding and ripening stages. Although nitrification and denitrification in the bulk soil decreased throughout the entire growth cycle, positive adaptation to Cd stress was observed during the ripening stage. Moreover, during the ripening stage, denitrification in the bulk soil under high Cd treatment (20 mg kg-1) was even higher than that in the control, indicating a probable change in the ecology of the denitrifying microbes in the Cd-stressed system. Changes in the activity of microbes in the rhizosphere following plant growth were similar to those in the non-rhizosphere in Cd treatments; however, the tendency of change in the rhizosphere seemed to be more moderate. This suggested that there was some mitigation of Cd stress in the rhizosphere.

Effects of Nutrients on Biofouling Formation and Preponderant Bacteria Diversity in Recirculating Cooling Water System

A series of orthogonal array experiments were conducted using carbon source, ammonia nitrogen and total phosphorus （TP） as major influencing factors to investigate the effects of nutrients on biofouling formation and preponderant bacteria diversity in the recirculatiug cooling water system. Carbon source was demonstrated to be the most significant determinant affecting the biofouling formation. A minimum biofouling outcome was obtained when BOD2, NHa＋-N and TP were 25, 10, and 1 mg/L, respectively. Then the preponderant bacteria strains in biofouling mass under two typical culture conditions （negative and favorable） were identified applying both traditional biochemical methods and further molecular biology technology with phylogenetic affiliation analysis, which indicated that Enterobacteriaceae Enterobacter, Micrococcaceae Staphylococcus, Bacillaceae Bacillus, Enterobacteriaceae Proteus, Neisseriaceae Neisseria and Pseudomonadaceae Pseudomonas were dominant under negative condition, while Enterobacteriaceae Klebsiella, Enterobacteriaceae Enterobacter and Microbacterium - under favorable one.

Effect of cyclic drying and wetting on engineering properties of heavy metal contaminated soils solidified/stabilized with fly ash

Solidification/stabilization （S/S） is one of the most effective methods of dealing with heavy metal contaminated soils. The effects of cyclic wetting and drying on solidified/stabilized contaminated soils were investigated. A series of test program, unconfined compressive strength （UCS） test, TCLP leaching test and scanning electron microscopy （SEM） test, were performed on lead and zinc contaminated soils solidified/stabilized by fly ash. Test results show that UCS and the leaching characteristics of heavy metal ions of S/S contaminated soils are significantly improved with the increase of fly ash content. UCS of S/S soils firstly increases with the increase of the times of drying and wetting cycles, after reaching the peak, it decreases with it. When the pollutant content is lower （1 000 mg/kg）, the TCLP concentration first slightly decreases under cyclic drying and wetting, then increases, but the change is minor. The TCLP concentration is higher under a high pollutant content of 5 000 mg/kg, and increases with the increase of the times of drying and wetting cycles. The results of scanning electron microscopy （SEM） test are consistent with UCS tests and TCLP leaching tests, which reveals the micro-mechanism of the variations of engineering properties of stabilized contaminated soils after drying and wetting cycles.

Presence of Contaminants in Refrigerant and Their Effect on Refrigeration Cycle

Refrigerant is a medium used in refrigeration cycle. Until now in thermodynamic models calculations of refrigerant is not considered with lubricant and moist air but as an ideal pure gas （without any contaminants）. This is also the case in refrigeration cycle where the refrigerant is very often considered as an ideal one. Lubricant, air and water vapour are not considered in thermodynamic calculations in spite of their existence. The problems in the existing research are summarized. A further study is suggested on refrigerant systems. This circulation of such calculations is at the origin of a deviation from a theoretical behaviour. This article aims at reviewing the researches of oil-refrigerant, air-refrigerant, moist air-refrigerant or oil-moist air-refrigerant mixtures and focuses particularly on mixture enthalpy calculation. This paper deals with the description of the real mixture of refrigerant and contaminants （lubricant, water, moist air and other remains of refrigerants at elevated pressures and temperatures） which flow in a refrigerating cycle and the main point of this paper is to appoint thermodynamic parameters of such a mixture using the thermodynamic formulas.

Cutting Techniques for Facilities Dismantling in Decommissioning Projects

Fuel cycle related activities were accomplished in IPEN-CNEN/SP in laboratory and pilot plant scale and most facilities were built in the 70-80 years. Nevertheless, radical changes of the Brazilian nuclear policy in the beginning of 90＇s determined the interruption of several fuel cycle activities and facilities shutdown. Some laboratory and pilot plant decommissioning activities have been performed in IPEN in the last years. During the operational activities in the decommissioning of old nuclear fuel cycle facilities, the personnel involved in the task had to face several problems. In old facilities, the need of large components dismantling and material removal use to present some difficulties, such as lack of available and near electricity supply. Besides this, the spread out of the superficial contamination in the form of dust or aerosols and the exposure of workers should be as much as possible avoided. Then, the selection and availability of suitable tools for the task, mainly those employed for cutting and segmentation of different materials is of significant importance. Slight hand tools, mainly those powered by rechargeable batteries, facilitate the work, especially in areas where the access is difficult. Based on the experience in the dismantling of some old nuclear facilities of IPEN-CNEN/SP, some tools that would have facilitated the operations were identified and their availability could have improved the quality and efficiency of different individual tasks. In this paper, different cutting problems and techniques, as well as some available commercial hand tools, are presented as suggestion for future activities.

第三世界城市的环境问题

伦敦1992年最新出版的《Environmental Problems in Third Woeld Cities》一书,从多个方面描述了第三世界城市所面临的环境问题及起源。作者Jorge E Hardor是世界环境和发展委员会顾问。他认为,在第三世界国家的城市每年都有上百万人受环境污染的影响而患病。

Characteristics of Heavy Metal Circulation in Biosphere

In order to control heavy metal pollution effectively, this paper reviews heavy metal source and transport characteristics in heavy metal circulation in bio- sphere, including geochemical cycle and biological cycle of heavy metals. The inter- body of geochemical cycle of heavy metals includes soil, gas as well as water body, and the interbody of biological cycle of heavy metals includes environment, plant, microorganisms and animals. As to macro-cycle, transportation character in each interbody is different. Heavy metal circulation in different interbody interacts with each other and is in dynamic balance. Heavy metals in soil include two parts, i.e. active and inert forms, which are in dynamic equilibrium. This equilibrium may be affected by different physicochemical factors. Heavy metal content at different soil depth reflects historical accumulation level of heavy metal. In contrast to agri- cultural eco-system itself, industrial and urban activities are of great menace. Fluvial transport and atmospheric input are significant pathways of heavy metal circulation. Sludge plays an accumulative role of heavy metals, and can release its heavy met- als to water body causing secondary pollution. Balance of heavy metal immobiliza- tion and release is interrupted by physicochemical characters and microbial activity. Temperature can influence atmospheric heavy metal content, and volatile heavy meal precipitation is an indLspensable source in soil and water body. In regard to micro-cycle, plants is the main part in heavy metal cycle, microorganisms play roles in accelerator and animals in recipient. Specific transportation and assigned location of heavy metal in plants are adopted to keep internal heavy metal equilibrium.

Including Co-benefits in the CDM of the Power Sector： A Case Study for India

This study examines the effects of the inclusion of co-benefits on the potential capacity of advanced thermal plants with a linear programming model in the CDM （clean development mechanism） in India＇s power sector. It investigates how different marginal damage costs of air pollutants affect the potential capacity of NGCC （natural gas combined cycle） and IGCC （integrated gasification combined cycle） by CDM projects with a scenario analysis. Three results are found from this analysis. First, IGCC and NGCC are installed at lower CER （certified emission reductions） prices when the marginal damage costs of air pollutants are added to the CER prices. Second, the CER prices of $1/tCO2 correspond with the sum of marginal damage costs of air pollutants of $150/t for NGCC and $30/t for IGCC in India＇s power sector. Thus, including the co-benefits into CDM attracts developing countries such as India where coal resource is redundant. Third, the SOx and NOx reduction benefits attained from the CDM projects become large in a grid where IGCC is installed.