共查询到20条相似文献，搜索用时 31 毫秒
1.
In the last decade, with the development of environmental science, the studies on water quality models have developed rapidly at home and abroad. The water quality models are mainly used for simulating, assessing and predicting water quality and expounding the transport and transformation of pollutants in aquatic environment, the common models in literature such as fugacity approach, transport model of pollutants in multimedia environment, pollutant exposure model, and water quality management model and so on are discussed. The current situation, history and future trend of the research on aquatic environmental model are summarized. The theories, methodology and application problems which are involved with in this field are analyzed. Several leading objects for study are advanced also in this paper. 相似文献
2.
A two-dimension,steady-state,multi-component transport model is presented to investigate the cathode performance of a proton exchange membrane fuel cell with an interdigitated gas distributor.Darcy law is used to describe the flow in the porous media.Subsequently,the model is applied to predict the pressure,velocity and mass fraction distributions in the electrode and explore the effect of the change of differential pressure between the inlet and the outlet,electrode thickness and rib width on the performance of fuel cell.The results show that: current density creases with the higher differential pressure between the inlet and outlet,but the increment is diminishing;electrode thickness has an optimum value which depends on the electrode morphology and the gas distributor design parameters;using narrower electrode rib can improve the performance of fuel cell. 相似文献
3.
原生动物在环境毒理学研究中的应用 总被引：1，自引：0，他引：1
环境毒理学一直是环境科学的重要分支,其研究成果对于确定污染物生物效应、作用机理以及制定环境监测指标都有重要意义。原生动物在环境毒理学研究中具有特殊的地位和作用。本文概述了原生动物在水体监测,污水净化及土壤环境评价等方面的应用,以及作为环境毒理学研究模式生物的独特优势,对原生动物在毒理学研究中的发展前景进行了展望。 相似文献
4.
Spill of volatile poisons into natural water bodies causes water pollution and then air pollution arises from water pollution because of volatilization. In order to explain the coupling of water pollution and air pollution, the dimensionless Henry constant of volatile poisons was used to establish coupling diffusion model based on compressed VOF method and the double film theory explained for volatilization. A high resolution bounded differencing scheme for arbitrarily unstructured meshes was applied to simulate coupling diffusion of trichloroethylene and tribromoethylene. The simulation results are in good agreement with those from single phase model. The influence of environmental temperature, wind velocity and the dimensionless Henry constant on the mass transfer across gas liquid interface was analysed. 相似文献
5.
为了研究积水入渗土壤水盐运移规律,通过室内土柱试验,分析不同灌水量条件下土壤水盐分布状态。应用饱和-非饱和土壤水分及溶质运动理论构建数学模型,利用Hydrus-1D软件进行水盐运移数值模拟,并将模拟结果与实测结果进行对比分析。结果表明：灌水量为1.4 L、2.8 L、4.2 L处理的积盐区位置分别20 cm、30 cm、40 cm,积盐区积盐率分别为49.2%、57.6%、100%,表层土脱盐率分别为87.2%、93.7%、96.8%;积盐区在湿润锋以上5 cm左右处。HYDRUS-1D模型可以较好对土壤水盐运移规律进行模拟。 相似文献
6.
《Soil Technology》1997,10(2):133-153
Soil and groundwater resources in many parts of the world are threatened by spilled petroleum products. These products generally consist of complex mixtures of volatile hydrocarbons with different vapor pressures. The volatilization of light hydrocarbon fractions leads to changes in viscosity and density of the residual nonaqueous liquid. This may cause changes in the transport characteristics of the porous matrix and of the residual liquid. Differing volatilization and solubility characteristics result in differential distribution of released hydrocarbon components in air, soil, and water environmental compartments. Soil frequently serves as the site of petroleum spills and hence the capacity of the soil to filter, retain, or release hydrocarbons is fundamental in determining the type and extent of environmental contamination. Retention, volatilization, and transport of hydrocarbons as affected by soil physical and chemical properties is reviewed. 相似文献
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有机农业是遵循自然发展规律和适应生态发展的新型农业生产方式。有机农业是我国遵循可持续发展战略、适应当前资源供需严峻形势的重要措施。有机茶更是有机农业的典型代表,因此研究有机茶的发展将对我国有机农业的发展具有重要的指导意义。而通过对有机茶的相关研究综述,可以充分了解我国有机茶将面对的问题、机遇和有关措施,这将对我国有机茶的发展研究方向提供较有价值的参考。 相似文献
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Based on the static liquefaction of granular materials, an elastoplastic static liquefaction constitutive model was proposed in the framework of critical state soil mechanics. The yielding surface and hardening rules were obtained by integrating the contact force of the model proposed by Chang and a non-associate flow rule was adopted as well. The model has taken the state dependent dialatency law and the effect of initial density to the stress-strain relationship into consideration. The parameters of the model are simple and have certain physical meanings. The predicted results obtained by the model have a good agreement with the undrained triaxial test of Toyoura sand and sand-silt mixture. 相似文献
9.
多溴联苯醚污染现状研究进展 总被引：1，自引：1，他引：0
多溴联苯醚(PBDEs)是一种新增的环境持久性有机污染物,作为一种溴代阻燃剂被广泛地应用于日常生活中。近年来在世界各地区多种环境介质和人体中均检测到PBDEs的存在,其中电子垃圾拆解区、污水处理厂排水口处及大型工业区附近PBDEs污染最为严重。由于PBDEs具有生物累积性、环境持久性及生物毒性等特性,其引起的环境及健康问题受到广泛的关注。笔者沿着水体-沉积物-食用动物-人体和大气-人体这两条链,综述了近年来环境介质和人体中多溴联苯醚的污染现状、污染来源、生物富集特征以及人类膳食和日常生活中PBDEs的暴露情况,并进行了国内外污染水平对比,从而分析了中国目前所存在的问题,提出相应对策建议,以期为中国深入开展PBDEs环境毒理学和生态风险评估等研究工作提供参考。 相似文献
10.
华北地区有机及常规草莓生产对环境影响的生命周期评价 总被引：1，自引：0，他引：1
有机农业与农产品质量安全和生态环境安全密切相关,其环境影响效应也越来越受到人们的广泛关注,系统全面评价有机农产品生产过程对环境的影响,对促进有机农业健康发展具有重要应用价值。本研究采用生命周期评价方法(Life Cycle Assessment, LCA),分析和比较了山东省淄博市博山区有机草莓和北京市昌平区常规草莓生产过程及其对环境的影响。研究结果表明,在各项环境影响指标中,常规草莓生产带来的全球变暖、环境酸化、富营养化和土壤毒性的潜在环境影响分别是全球人均基准值的 3.45%、 2.11%、 27.09%和 280.16%,而有机草莓生产带来的全球变暖、环境酸化、富营养化和土壤毒性的潜在环境影响分别是全球人均基准值的 1.22%、 0.44%、 15.17%和 202.76%,均低于常规草莓。常规草莓生产中生命周期环境影响较大的是富营养化、水体毒性和土壤毒性,造成常规草莓水体毒性危害严重的原因是种植阶段农药残留迁移至水体所致,而土壤毒性是由于化肥和有机肥所携带的重金属残留所致。有机草莓生产中生命周期环境影响较大的是富营养化和土壤毒性,主要是由于有机草莓农作阶段施肥过程中的磷流失和重金属残留所引起的。总体上看,有机草莓生命周期环境影响综合指数为 0.22,而常规草莓为 0.43,说明常规草莓对环境的负面影响明显高于有机草莓。因此,施用生物源农药与优质有机肥是控制草莓生命周期负面环境影响的关键措施。 相似文献
11.
ZHAO Guang-ming~ 《保鲜与加工》2006,(4):54-57
As a new type of meshless method which has appeared in recent years, the Reproducing Kernel Particle Method has such meshless features as the need for nodes only without classified units, and is advantageous in the process of calculation. The present study introduces the Reproducing Kernel Particle Method and applies it to the research of nonlinear dynamic mechanics. The dynamic process involves different kinds of nonlinearity. The study assumes that deformation of dynamic analysis belongs to small one and that the material nonlinearity has been taken into account. When under small strain, the increment constitutive law and the total Lagrangian model of calculation are adopted to deduce the dynamic control equation by the Reproducing Kernel Particle Method. The instances of calculation demonstrate that this method is effective in the analysis of dynamic problems. 相似文献
12.
有机肥改良农产品品质的科学探索 总被引：11，自引：0，他引：11
滥用化肥栽培的农产品品质下降,而使用有机肥栽培的农产品品质好是一个公认的事实,但却一直缺少系统的研究。此文考查了国内外有关有机肥与农产品品质关系研究的成果,从土壤学、肥料学、植物营养生理学以及食品科学的不同视角进行归纳、分析。研究结果对于深入了解控制农产品质量的科学基础具有重要意义。 相似文献
13.
非点源污染河流水环境容量研究 总被引：1，自引：1，他引：0
为探索适合非点源污染河流水环境容量计算的模型,为水环境容量的合理利用提供科学依据,针对中国东部地区典型河流-曹娥江的污染情况,选其上游以非点源污染为主的支流进行了水环境容量研究。根据该河段的水流特性和水文、污染源的调查资料及水质实测资料,选用适当的数学模型,研究了该河段各月的水环境容量。结果表明这种方法简单、实用,适用于非点源情形下河流氨氮、总磷及CODcr的容量问题研究。 相似文献
14.
调查和测定了拜泉县上升乡进步小流域内的土壤养分、重金属以及水质pH值、氟化物、氰化物、重金属等的含量,并对土壤质量和水质量进行了分析和评价,以期为在实际生产中为绿色肉鹅食品的生产基地的选择提供理论依据和数据支撑。研究结果表明：本区域的土壤肥力高,为1等级别;土壤重金属含量均符合绿色食品产地的土壤环境质量标准,综合指数P综≤0.7,属于安全等级,达到了1级标准;水质量符合绿色食品产地环境质量中的禽畜用水质量的标准,水质单项污染指数均＜1.0,综合污染指数≤0.5,水质量等级为1级。因此,在典型调查区域内,利用不同的土地利用类型推行肉鹅的放牧式散养模式,是发展寒地绿色肉鹅食品的理想场所。 相似文献
15.
[目的]持久性有机污染物(POPs)是导致环境污染的重要原因,其中多溴联苯醚(PBDEs)又是POPs中的一种,所以全面了解多溴联苯醚在环境中的残留及其对生物体的毒理学效应对于环境的治理和人的健康至关重要。[内容]本文简要归纳了多溴联苯醚在土壤、水体中的残留和相互之间的迁移、转化,总结了多溴联苯醚对生物体的急性毒性和生理生化毒性,并分析了多溴联苯醚对生物体抗氧化系统、机体组织器官的和生物遗传的影响,对接下来进一步的研究提供了依据。[建议]针对多溴联苯醚在环境和生物体中具有高毒性的问题,提出了通过制定更加严格的法律法规来限制多溴联苯醚的使用、加强对含多溴联苯醚废弃物的处理,禁止进口电子垃圾,选取距离居民区较远的地方进行生产等措施,并对发展新型溴代阻燃剂进行了展望。 相似文献
16.
In recent years, more and more people pay attention to the pollution and destruction of water resources. Due to lack of administrative law and civil law, it is necessary for the criminal law to deal with the water problems. In this paper, the necessity and shortage of protection of water resources by the criminal law is discussed. Then, based on the current criminal law, in this paper, some beneficial suggestions with the water liability principle are proposed. The criterion by which to decide whether a person violates the criminal law or not as well as the water criminal object and the water criminal objective conditions are proposed. 相似文献
17.
Debris flow is a kind of typical water ruins to highways, and it is a dynamic load for highway water ruin. The authors, following the moving law of debris flow and characteristics of highway ruin, put forward reasonable section shape of high - speed drainage trough. Then, according to the energy conservation principle and horizontal throwing theory, the authors established a calculation formula for the throwing distance. The results of the calculation formula given in this paper offer a solution for load calculation and control effect evaluation problems and provide theoretical foundation i to structure design and disease control of debris flow along the highways. 相似文献
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三峡库区次级河流污染现状与对策研究 总被引：1，自引：1，他引：1
沉水植物金鱼藻和黑藻在治理三峡库区次级河流水体污染具有广阔前景,对保护三峡水库的水环境贡献很大,在库区水体中可以发挥强大的环境生态功能。本文通过分析三峡库区次级河流的环境问题,预测了金鱼藻和黑藻在库区的应用前景,即防止水体富营养化、有机物污染、重金属污染、抑制藻类生长,以及维持生物多样性、生态完整性和稳定性。 相似文献