铜川斜坡变形与作用因素分析

斜坡变形与失稳活动是黄土高原突出的地质地貌现象．它有较强的致灾性。本文通过陕西铜川斜坡变形的现场实际调查，研究了该地斜坡的形态、物质组成、变形形式以及作用因素等。本研究对厚层黄土区斜坡变形灾害的防治有较重要意义。     

污染土壤的微波辐照技术研究进展

简要介绍了土壤污染的状况,总结了国外学者对重金属和有机物两大类污染土壤所进行的微波修复工作,探讨了修复机理及影响因素,最后展望了微波修复污染土壤的研究重点.     

Quantitative structure - activity study on the reductivedehalogenation potency of the halogenated aromatics

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Identification of key factors governing chemistry in groundwater near the water course recharged by reclaimed water at Miyun County, Northern China

Reclaimed water was successfully used to recover the dry Chaobai River in Northern China, but groundwater may be polluted. To ensure groundwater protection, it is therefore critical to identify the governing factors of groundwater chemistry. Samples of reclaimed water, river and groundwater were collected monthly at Chaobai River from January to September in 2010. Fifteen water parameters were analyzed. Two kinds of reclaimed water were different in type (Na-Ca-Mg-Cl-HCO3 or Na-Ca-Cl-HCO3 ) and concentration of nitrogen. The ionic concentration and type in river were similar to reclaimed water. Some shallow wells near the river bed had the same type (Na-Ca-Mg-Cl-HCO3 ) and high concentration as reclaimed water, but others were consistent with the deep wells (Ca-Mg-HCO3 ). Using cluster analysis, the 9 months were divided into two periods (dry and wet seasons), and all samples were grouped into several spatial clusters, indicating different controlling mechanisms. Principal component analysis and conventional ionic plots showed that calcium, magnesium and bicarbonate were controlled by water-rock interaction in all deep and some shallow wells. This included the dissolution of calcite and carbonate weathering. Sodium, potassium, chloride and sulfate in river and some shallow wells recharged by river were governed by evaporation crystallization and mixing of reclaimed water. But groundwater chemistry was not controlled by precipitation. During the infiltration of reclaimed water, cation exchange took place between (sodium, potassium) and (calcium, magnesium). Nitrification and denitrification both happened in most shallow groundwater, but only denitrification in deep groundwater.     

黄淮海平原水浇地、旱地不同熟制的气候资源利用

为了合理利用气候资源,提高土地生产力,探索适合我国国情与黄淮海平原的种植制度,1980—1984年期间在平原北部(北京)水浇地上连续进行了五年田间试验,1983年和1984年两年又增加了水浇地与旱地对比,并在平原中部黑龙港地区的北京农业大学曲周试验站及平原南部属黄淮平原的河南省淮阳县增加了两个点。试验设水浇地和旱地两部分,各有一年一熟(冬小麦、春玉米和春大豆)和一年两熟(冬小麦复播玉米、冬小麦套播玉米和冬小麦复播大豆)。栽培管理按当地中上水平进行。     

考虑非线性吸附时溶质在有限厚度粘土中的一维扩散解

在采用非线性分段式吸附等温模式的基础上,建立了溶质在粘土中的一维扩散模型,在考虑有限厚度边界及土中溶质背景浓度的条件下得到了相应的解.模型引入了移动边界以说明当溶质在粘土孔隙水中的浓度达到某一较高值后,阻滞因子将发生显著变化.算例分析表明,该模型和考虑经典非线性吸附等温线得到的结果相差不大,这进一步说明了该模型的合理性.考虑非线性吸附效应对溶质迁移有重要影响.在较高溶质浓度下采用线性吸附等温模式会得到偏不安全的结果.该解相对较简单,并可用于验证各种数值模型、拟合试验数据等.     

Combination of biodiesel-ethanol-diesel fuel blend and SCR catalyst assembly to reduce emissions from a heavy-duty diesel engine

In this study, the efforts to reduce NOx and particulate matter （PM） emissions from a diesel engine using both ethanol-selective catalytic reduction （SCR） of NOx over an Ag/Al2O3 catalyst and a biodiesel-ethanol-diesel fuel blend （BE-diesel） on an engine bench test are discussed. Compared with diesel fuel, use of BE-diesel increased PM emissions by 14% due to the increase in the soluble organic fraction （SOF） of PM, but it greatly reduced the Bosch smoke number by 60%-80% according to the results from 13-mode test of European Stationary Cycle （ESC） test. The SCR catalyst was effective in NOx reduction by ethanol, and the NOx conversion was approximately 73%. Total hydrocarbons （THC） and CO emissions increased significantly during the SCR of NOx process. Two diesel oxidation catalyst （DOC） assemblies were used after Ag/Al2O3 converter to remove CO and HC. Different oxidation catalyst showed opposite effect on PM emission. The PM composition analysis revealed that the net effect of oxidation catalyst on total PM was an integrative effect on SOF reduction and sulfate formation of PM. The engine bench test results indicated that the combination of BE-diesel and a SCR catalyst assembly could provide benefits for NOx and PM emissions control even without using diesel particle filters （DPFs）.     

4,4'-DDT全生命周期暴露对大型溞(Daphnia mag-na)生长、生殖、心率、行为、存活及基因转录的影响

大型溞(Daphnia magna)慢性毒性测试的毒理学数据是美国环境保护局水质基准(water quality criteria,WQC)制定中非常重要的数据来源,用以推导能有效保护水生生物的化学污染物浓度阈值.以往的研究表明,在部分生命周期暴露的基础上得出的最低观察效应浓度(lowest observed effe...     

微型生物在水质监测中的作用和意义

水污染仍是中国水环境面临的突出问题.生物监测是常用水质监测的有效方法之一,它是利用水生生物在污染环境下所发生的信息来判断水体污染状况的一种手段.而微型生物群落是水生态系统中一个完整的生态单元,具有对胁迫反应敏感以及胁迫过后自身恢复迅速等特性,在水质监测中起着重要的作用.水生微型生物主要包括藻类、原生动物、细菌、真菌、轮虫等.本文阐述它们在水生生态系统中具有的各自地位、作用和微型生物监测水质成为生物监测的重要手段的原因.     

液态聚合氯化铝铁深度除磷的优化研究

以北京市生活废水为研究对象,考察了液态聚合氯化铝铁及与聚丙烯酰胺(PAM)协同作用下除磷效果及其影响因素。结果表明,液态聚合氯化铝铁与PAM复合作用时对除磷效果有一定的提高,明确了PAM的最佳投加量、最佳搅拌强度、最佳搅拌时间和pH,并得出了影响混凝效果因素的主次顺序为:pH值搅拌时间搅拌强度投加量。