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281.
282.
We performed a sensibility analysis of model selection in modeling the reactive transport of cesium in crushed granite through model calibration and validation. Based on some solid phase analysis data and kinetic batch experimental results, we hypothesized three two-site sorption models in the LEHGC reactive transport model to fit the breakthrough curves (BTCs) from the corresponding column experiments. The analysis of breakthrough curves shows that both the empirical two-site kinetic linear sorption model and the semi-mechanistic/semi-empirical two-site kinetic surface complexation model, regardless of their complexity, can match our experimental data fairly well under given test conditions. A numerical experiment to further compare the two models shows that they behave differently when the pore velocity is not of the same order of magnitude as our test velocities. This result indicates that further investigations to help determine a better model are needed. We suggest that a multistage column experiment, which tests over the whole range of practical flow velocities, should be conducted to help alleviate inadequate hypothesized models. 相似文献
283.
284.
将脉冲电源和直流电源分别作为废水电解处理的电源,试验探明其对废水电解处理的电能消耗和COD去除率的影响,并分析废水脉冲电解处理节能高效的原因。试验结果表明,脉冲电流相对直流电流能够更加有效减缓电极的极化,降低电极过电位,使电能消耗降低15%-35%;在脉冲电解处理废水过程中电流效率稳定、Fe^2+能够有效扩散到废水中,使去污效果增强5%-7%。 相似文献
285.
城市化的加速,促进了经济社会的快速发展,但同时也带来了城市发展模式的思考和城中村改造的问题。对于目前中国多数的大中城市来说,建设生态城市和改造城中村是当前城市建设工作的两项重要内容。从这两项工作的理论研究入手,阐述了城中村改造与生态城市建设的关系,论证了城中村改造遵循生态城市建设要求的重要性,论述了城中村改造中的生态保护措施,力求促使城中村改造与生态城市建设有机衔接,加速生态城市建设进程。 相似文献
286.
Fe(Ⅲ)水解过程中无机阴离子的影响作用 总被引:18,自引:5,他引:18
本文通过PO^3- 4,F^-,SO^2- 4,Cl^-,NO^- 3和ClO^- 4存在时,0.1mol/1 FeCl3溶液的碱中和曲线的分析对比,说明了用曲线斜率区分滴定曲线为三个区域:(A)自发水解反应;(B)聚合反应;(C)沉淀反应,以及阴离子对中和曲线的影响及其规律,指出阴子子对Fe(Ⅲ)浓度中和反应影响为不同程度的竞争配位,参与聚合及电中和脱稳,使沉淀反应提前等。并与OH^-共同形成F 相似文献
287.
武汉市“三废”排放的库兹涅茨特征及原因探析 总被引:24,自引:0,他引:24
通过分析武汉市1985-2001年近16年的“三废”排放量变化情况,发现武汉市“三废”的排放总量在波动中呈现上升趋势,但各类排放的时间规律相差明显。建立模型,将其人均GDP与“三废”排放的标准化值进行拟合,其计算结果显示:武汉市“三废”排放与人均GDP之间存在比较明显的三次曲线特征,在1985-1994年曲线呈持续下降趋势,而1995-2001年曲线初步显现出标准的环境库兹涅茨曲线。理论计算表明:武汉市“三废”排放的环境库兹涅茨曲线的转折点为人均GDP为12338.46元左右。通过环境经济学分析发现武汉市的经济发展、产业结构变动、能源结构变动和环境政策等4项因素是武汉市出现非标准环境库兹涅茨曲线的主要原因。 相似文献
288.
In order to enhance the sensitivity and the speed of the yeast estrogen screen (YES)-assay, which has been established in many laboratories for the determination of estrogenic activity of compounds and environmental samples, the LYES-assay, a modified version of the YES-assay including a digestion step with the enzyme lyticase, was developed. With the LYES-assay the estrogenic activities of natural (17β-estradiol E2 and estrone), synthetic (17-ethinylestradiol EE2) and pharmaceutical estrogens (diethylstilbestrol DES) as well as xenoestrogens (4-nonylphenol NP and five parabens) were determined and compared with the results obtained by other in vitro-assays namely the conventional YES-assay, the E-Screen-assay (MCF-7 breast tumor cell proliferation) and a receptor binding-assay (RB) with human estrogen receptors hER- and hER-β. In the case of E2 the LYES-assay had a significantly lower limit of quantification (LOQ) than the conventional YES-assay and even two orders of magnitude lower than the RB-assay. Compared to the E-Screen-assay the LOQ of the LYES-assay was almost one order of magnitude higher. The time required to perform the LYES-assay was as little as seven hours compared to three to five days for the conventional YES-assay. Thus, the LYES-assay is a very good alternative to existing estrogenic in vitro-assays, since it has a good sensitivity, is cheap and much faster than the other assays. 相似文献
289.
A.C.D. Ertsen 《Environmental Modeling and Assessment》1999,4(1):13-22
In the Netherlands the increasing demand for ecohydrological models on a regional (provincial) scale has resulted in the development
of an empirical statistical impact–assessment model for semi-natural terrestrial herbaceous ecosystems. This model, called
ITORS, describes the relationship between plant species and site factors such as soil, groundwater and management. The model,
developed for the region of Noord-Holland, is applied to support provincial policy on soil and water management.
The empirical statistical approach required the collection of a large set of field data, describing the biotic and environmental
variation of a variety of semi-natural terrestrial ecosystems in Noord-Holland. These data were used to calculate species
response models with help of logistic regression, resulting in significant models for 130 out of 144 species.
Significant species response models were incorporated in the computer program ITORS. With help of ITORS the effect of various
management scenarios can be easily evaluated, which is demonstrated by an example.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
290.
目的 探究镍基合金925和抗硫油管管材110SS在不同面积比下耦接后的电偶腐蚀行为和电偶腐蚀效应,模拟国内某油气田高温高酸性腐蚀环境。方法 采用浸泡腐蚀试验和电化学测试技术,评价电偶腐蚀的阴阳极过程对腐蚀进程的影响,并利用扫描电子显微镜(SEM)、X射线能谱仪(EDS)与X射线衍射仪(XRD)对腐蚀试样的表面形貌及腐蚀产物成分进行分析。结果 110SS的自腐蚀电位远远低于925,阴阳极分别以1:1、1:5、1:10、1:30四种面积比耦接后,均发生电偶腐蚀。耦接后110SS的腐蚀速率分别为:0.7564、0.7032、0.6457、0.6289 mm/a,均为极严重腐蚀。结论 电偶腐蚀速率和电偶腐蚀效应均随着阴阳极面积比的增大而增加。镍基合金与碳钢油管耦接主要对材料在腐蚀环境下的腐蚀进程有影响,而对腐蚀产物和腐蚀机理的影响不大。 相似文献