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1.
国外食物系统研究综述及借鉴   总被引:3,自引:0,他引:3  
郭华  王灵恩 《自然资源学报》2018,33(6):992-1002
食物关系到国计民生,食物的高效供给取决于食物系统的高效运转。目前国内食物系统视角的研究不足,系统梳理国外研究进展对我国食物系统研究具有积极的借鉴意义。为了更好地把握食物系统的研究脉络,论文通过对国外食物系统研究文献进行研读,在总结分析食物系统研究相关理论和方法的基础上,着重对食物系统的全球化与本地化、食物系统规划、食物系统的资源环境效应、食物安全与政策研究等问题进行了系统梳理。在借鉴国外食物系统研究的基础上,结合已有的研究基础和社会需求,提出未来我国食物系统领域的研究展望,包括开展不同尺度的食物系统实证研究、开展跨学科多领域的共同研究、食物系统定量指标体系设计问题研究、食物系统的利益相关者研究以及加强技术创新对食物系统的影响研究等。  相似文献   

2.
大型气候环境实验室空气处理系统方案探讨   总被引:5,自引:5,他引:0       下载免费PDF全文
目的探讨适用于大型气候环境实验室的空气处理系统方案。方法从大型气候环境实验室空气处理系统的功能出发,探讨循环风系统、新风系统和空气补偿系统方案,并对各系统的工作流程和优劣进行分析,在此基础上提出优化的集成空气处理系统方案。结果循环风系统采用串联风道比并联风道能更好地保证极限温湿度指标和均匀性指标,循环风系统与空气补偿系统集成方案优于两个个独立系统方案、具备可行性。结论该空气处理系统方案适用于大型气候环境实验室。  相似文献   

3.
改良型SBR系统处理染料废水的研究   总被引:3,自引:0,他引:3       下载免费PDF全文
通过试验考察了两种改良型序批式间歇反应器-SBR-系统——“厌氧、好氧”交替运行系统-系统1-和“厌氧+好氧”串联二级系统-系统2-的运行过程,分析了影响系统运行效果的因素,比较了两个系统厌氧阶段、好氧阶段及全过程处理效果的差异,并分析了造成差异的原因.结果表明,两个系统均具有适应能力强、稳定性能好、能够有效地降解污染物的特点;污泥浓度、碳源数量、环境温度均影响系统的运行效果;系统1的厌氧阶段比系统2更有效,系统2的好氧阶段比系统1更有效,系统2的全过程处理效率更高;分析认为生物相组成情况的不同是导致两个系统处理效果差异的主要原因.  相似文献   

4.
李靖 《环境》1999,(4):43-44
大亚湾核电站放射性废物的处理技术放射性废气的处理对放射性废气的控制、收集、处理、输送、暂存和排放由废气系统承担。废气系统包括:废气处理系统(TEG)和厂房通风系统(反应堆厂房通风系统、核辅助厂房通风系统、燃料厂房通风系统)。  相似文献   

5.
在这个固体废弃物填埋场中,有完整的地下水收集系统、污水收集处理系统、沼气收集系统、闭路电视监控系统、电脑网络系统和环境监测系统。  相似文献   

6.
分析了选择自动喷淋系统应考虑的因素,在考虑备选系统使用期间资金时间价值的前提下,构造系统选择模型,通过对备选系统年均值的计算和比较,选择出最优系统,使系统使用年均总费用达到最小化。  相似文献   

7.
水资源开发利用与区域经济协调管理的一种交互式模式   总被引:1,自引:0,他引:1  
本文据大系统多级递阶优化控制理论,将水资源系统分解成地面水资源系统与地下水资源系统。在地面水系统中,给出了多目标开发利用管理模型;在地下水系统中,提出了地下水资源开发利用经济管理模型。区域经济涉及区域内的各种工农业和城镇生活用水部门──用水系统。对该用水系统提出了分解──协调优化管理模型。据水资源开发利用和用水系统的特点,在最高级设置总协调器来协调水资源开发利用系统与用水系统,进而提出了水资源开发利用与区域经济协调管理的一种交互式模式。  相似文献   

8.
信息化监管系统由现地信息采集系统和应用系统组成.前者由闸控现地监控系统、视频监控系统、水量水质监测系统、水雨情监测系统和便携式水质仪组成;后者由一体化平台软件、数据接收处理软件、应用服务系统软件、移动服务软件等组成.尾水导流工程信息化监管系统的建设,能提升尾水导流项目运行维护能力,满足徐州市水务局系统维护便捷、测量精度一致、信息共享的需求,满足江苏省南水北调尾水导流水质监管系统网络的需求,适应后期尾水导流工程的监督管理工作.  相似文献   

9.
介绍了世界上第一个包装废弃物利用系统--绿色-德国回收利用系统股份有限公司成立的背景,法律基础,回收利用系统绿点标志,系统运作方式及通过该系统的运作取得的初步成果及该系统向欧洲和亚洲推广的计划。  相似文献   

10.
一个完整的LIMS系统必需包九大层面,其核心为样件管理系统,向外延伸为八个系统,分别是管理审查系统、药品管理系统、矫正管理系统、接单派工系统、数据报表管理系统、文件管理系统、仪器设备管理系统及仪器设备联机系统。但其中最重要的部份为中间层的三大系统接单派工系统、样件管理系统及数据报表管理系统,本研究将针对这中间层三大系统为核心,以Web-based为基础架构成环境监测信息管理系统。  相似文献   

11.
The mechanism of flow turbulence, sediment supply conditions, and sediment transport patterns that affect the adsorption of cadmium ions onto sediment particles in natural waters are experimentally simulated and studied in this study both in batch reactors and in a turbulence simulation tank. By changing the agitation conditions, the sediment transport in batch reactors can be categorized into bottom sediment-dominated sediment and suspended sediment-dominated sediment. It is found that the adsorption rate of bottom sediment is much less than that of suspended sediment, but the sediment transport pattern does not affect the final (equilibrium) concentration of dissolved cadmium. This result indicates that the parameters of an adsorption isotherm are the same regardless of the sediment transport pattern. In the turbulence simulation tank, the turbulence is generated by harmonic grid-stirred motions, and the turbulence intensity is quantified in terms of eddy diffusivity, which is equal to 9.84F(F is the harmonic vibration frequency) and is comparable to natural surface water conditions.When the turbulence intensity of flow is low and sediment particles stay as bottom sediment, the adsorption rate is significantly low, and the adsorption quantity compared with that of suspended sediment is negligible in the 6 h duration of the experiment. This result greatly favors the simplification of the numerical modeling of heavy metal pollutant transformation in natural rivers. When the turbulence intensity is high but bottom sediment persists, the rate and extent of descent of the dissolved cadmium concentration in the tank noticeably increase, and the time that is required to reach adsorption equilibrium also increases considerably due to the continuous exchange that occurs between the suspended sediment and the bottom sediment.A comparison of the results of the experiments in the batch reactor and those in the turbulence simulation tank reveals that the adsorption ability of the sediment, and in particular the adsorption rate, is greatly over-estimated in the batch reactor.  相似文献   

12.
Two novel polymers (NJ-1 and N J-2) were synthesized by chemically modified a hypercrosslinked polymer NJ-0 with dimethylamine and trimethylamine, respectively. The comparison of the adsorption properties of the three polymers toward phenol, resorcin and phloroglucin was made. The study focused on the static equilibrium adsorption behaviors and the adsorption thermodynamics. Freundlich equation was found to fit the adsorption results well. The effect of amino groups introduced onto the surface of the resin and the structure of phenolic compounds on the adsorption were also studied. The hydrogen-bonding interaction and electrostatic interaction could happen between the amino groups and the adsorbates. The adsorption impetus increased as quantity of hydroxyl groups increased, but the adsorption capacity decreased due to the drop of the matching degree of the aperture of resins and the diameter of adsorbate molecules.  相似文献   

13.
厌氧氨氧化过程中COD及pH与基质浓度之间的关系   总被引:8,自引:3,他引:5  
田智勇  李冬  张杰 《环境科学》2009,30(11):3342-3346
分析了上向流厌氧氨氧化生物滤池中氮素化合物浓度、COD和pH变化规律以及ANAMMOX活性和生物量的分布规律,利用数理统计的方法研究了厌氧氨氧化过程中COD和pH与氮素基质浓度之间的关系.结果表明,溶解氧和氮负荷的共同作用使得ANAMMOX活性和生物量的分布沿滤层深度呈"山脊"状不均匀分布;异养反硝化的存在和H+的消耗使得厌氧氨氧化过程中COD和pH分别呈降低和升高趋势;100 mg/L以下的有机物浓度对厌氧氨氧化菌的影响不大,且COD和pH与基质NH4+-N浓度之间呈良好的线性相关关系.本试验中COD-NH4+-N和pH-NH4+-N拟合直线的斜率分别为1.113 8±0.052 2和-0.111 3±0.001 2,置信度为95%,平均相关系数R2分别为0.982 3和0.985 0.  相似文献   

14.
To evaluate the influence of lactic acid on the methanogenesis, anaerobic digestion of kitchen wastes was firstly conducted in a two-phase anaerobic digestion process, and performance of two digesters fed with lactic acid and glucose was subsequently compared. The results showed that the lactic acid was the main fermentation products of hydrolysis-acidification stage in the two-phase anaerobic digestion process for kitchen wastes. The lactic acid concentration constituted approximately 50% of the chemical oxygen demand (COD) concentration in the hydrolysis-acidification liquid. The maximum organic loading rate was lower in the digester fed with lactic acid than that fed with glucose. Volatile fatty acids (VFAs) and COD removal were deteriorated in the methanogenic reactor fed with lactic acid compared to that fed with glucose. The specific methanogenic activity (SMA) declined to 0.343 g COD/(gVSS-d) when the COD loading were designated as 18.8 g/(L-d) in the digester fed with lactic acid. The propionic acid accumulation occurred due to the high concentration of lactic acid fed. It could be concluded that avoiding the presence of the lactic acid is necessary in the hydrolysis-acidification process for the improvement of the two-phase anaerobic digestion process of kitchen wastes.  相似文献   

15.
Taihu Lake is one of the five biggest lakes in China. Surface water samples from 26 sampling sites of Taihu Lake were collected. Furthermore wet chemical analysis (CODCr and BOD5) and measurement of three dimensional excitation-emission matrix (3DEEM) spectra in the laboratory have been conducted. Using parallel factor analysis (PARAFAC) model, three components of colored dissolved organic matter (CDOM) have been identified successfully, based on the analysis of 3DEEM data. The characteristics of the three components also have been described by comparing them to some components of CDOM, identified in earlier researches. Meanwhile, spatial variations of concentration for the three components in Taihu Lake have been analyzed, and the result indicates that the concentration of component 1 depends more on the situation of wastewater pollution and can be used as the indicator of wastewater pollution. The relationship between the concentrations of the three components and results of the wet chemical analysis show that none of the three components can be used as indicators of gross organic matter in water. However, the concentrations of all the three components have obvious linear relationships with the BOD5 value, especially for component 1 (r = 0.72878). Finally, the potential applications of the composition analysis based on 3DEEM and PARAFAC model in water quality monitoring have been illuminated.  相似文献   

16.
Sorption and cosorption of the nonionic herbicide mefenacet and two typical metals (copper and silver) on black soil and its components (kaolinite and humic acid) were investigated. It was found that because of their different valences and properties, Cu2+and Ag+ presented different effects on the sorption of mefenacet. Due to the competition of Cu2+, along with the shells of dense water formed by its surface complexation, for sorption surface area with mefenacet, the addition of Cu2+ decreased the sorption amount of mefenacet on soil and its components, especially on humic acid. However, the addition of Ag+ significantly enhanced the sorption of mefenacet, which was attributed to the softness of the cation that weakened the hydrophilicity of the local region around Ag+-complexed functionalities, and thus mitigated the competitive sorption of water. In addition, the sorption of mefenacet on soil with or without the two metals was generally decreased with increasing pH, which was caused by the hydrolysis of carbonyl and carboxyl groups on the surface of the sorbents, π-π interaction between mefenacet and the soil organic matter, and so on. On the other hand, the presence of mefenacet seemed to have little effect on the sorption of Cu2+ and Ag+, indicating that Cu2+ and Ag+ might be sorbed strongly on the tested sorbents and the mefenacet added was too low in concentration to affect the sorption of the metals.  相似文献   

17.
田秀英  蔡强  刘锐  张永明 《环境科学》2013,34(2):462-467
根据上海某土壤与地下水污染修复现场情况,应用自主研发的电子鼻系统(iSA-M1)分别对未修复及修复过程中的土壤和地下水、修复场地上空及周边空气中的VOCs和恶臭类气体进行检测.结合前期研究所得TPI和OPI公式,求得各点的值,并将其用图表示.结果表明:①修复后TVOC和恶臭的浓度总体呈下降趋势;②在土壤和地下水修复过程中,VOCs和恶臭的挥发受气象要素和作业的影响,其浓度在总体下降的过程中伴随着阶段性上升现象;③结合GIS技术,电子鼻能初步用于评估土壤和地下水修复现场造成的空间污染情况及对周围居民产生的影响.但造成影响程度的具体细化分级还需要进一步研究.  相似文献   

18.
The purpose of this study is to understand the effect and mechanism of preventing membrane fouling, by coagulation pretreatment, in terms of fractional component and molecular weight of natural organic matter (NOM). A relatively higher molecular weight (MW) of hydrophobic compounds was responsible for a rapid decline in the ultrafiltration flux. Coagulation could effectively remove the hydrophobic organics, resulting in the increase of flux. It was found that a lower MW of neutral hydrophilic compounds, which could remove inadequately by coagulation, was responsible for the slow declining flux. The fluxes in the filtration of coagulated water and supernatant water were compared and the results showed that a lower MW of neutral hydrophilic compounds remained in the supernatant water after coagulation could be rejected by a membrane, resulting in fouling. It was also found that the coagulated flocs could absorb neutral hydrophilic compounds effectively. Therefore, with the coagulated flocs formed on the membrane surface, the flux decline could be improved.  相似文献   

19.
Black carbon (BC) can strongly adsorb hydrophobic organic compounds (HOCs).The HOC sorption to coated BC could be attenuated in soil and sediment compared with that of the parent BC.To study the potential causes of the sorption attenuation,humic acid (HA) and BC were isolated.Phenanthrene (PHE) was selected as the representative of HOCs.BC was coated with the precipitated HA.The PHE sorption to the HA-coated BC was determined.The HA coatings on BC could result in the significant sorption attenuation of PHE to BC.The attenuation varied in different HA origin and was positively correlated to the aromaticity of HA.The attenuation could be explained by the direct competition between HA and PHE for the available sorption sites on BC and the reduction of the available sorption sites as a result of the pore blockage of BC caused by the HA coatings.Therefore,the HA coatings on BC was one potential cause of the attenuation of HOC sorption to BC in soil and sediment.  相似文献   

20.
Spatial distribution of dissolved Pb, Hg, Cd, Cu and As in the Bohai Sea   总被引:11,自引:0,他引:11  
Characteristics of the spatial distribution of selected dissolved heavy metals were analyzed during large scale surveys from August 12 to 25,2003 in the Bohai Sea.Dissolved Pb was the only element with average concentrations higher than the grade-one sea water quality standard of China.The spatial distribution of dissolved Pb in surface water was similar to those of Cd,Cu and As,where the isopleths generally indicated decreasing values from the bays to the central areas.Only for Hg did the high concentrations not only appear in Liaodong Bay,Bohai Bay and Laizhou Bay,but also in the Central Area,viz.not only in inshore but also in offshore areas. Vertical distributions of dissolved Pb,Cd,Cu and As were largely uniform,while that of dissolved Hg increased with depth.We infer that the input of pollutants from land was the main influencing factor for the detected distribution patterns of dissolved heavy metals, followed by the dynamics of sea water,release from bottom sediments and biochemical processes.Comparing with historical data, average concentrations of dissolved heavy metals appear to decline in recent years.  相似文献   

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