Assessment of alternative adsorption models and global sensitivity analysis to characterize hexavalent chromium loss from soil to surface runoff          下载免费PDF全文

Chuan‐An Xia  Juxiu Tong  Bill X. Hu  Xiujie Wu  Alberto Guadagnini 《水文研究》2018,32(20):3140-3157

We investigate our ability to assess transfer of hexavalent chromium, Cr(VI), from the soil to surface runoff by considering the effect of coupling diverse adsorption models with a two‐layer solute transfer model. Our analyses are grounded on a set of two experiments associated with soils characterized by diverse particle size distributions. Our study is motivated by the observation that Cr(VI) is receiving much attention for the assessment of environmental risks due to its high solubility, mobility, and toxicological significance. Adsorption of Cr(VI) is considered to be at equilibrium in the mixing layer under our experimental conditions. Four adsorption models, that is, the Langmuir, Freundlich, Temkin, and linear models, constitute our set of alternative (competing) mathematical formulations. Experimental results reveal that the soil samples characterized by the finest grain sizes are associated with the highest release of Cr(VI) to runoff. We compare the relative abilities of the four models to interpret experimental results through maximum likelihood model calibration and four model identification criteria (i.e., the Akaike information criteria [AIC and AIC_C] and the Bayesian and Kashyap information criteria). Our study results enable us to rank the tested models on the basis of a set of posterior weights assigned to each of them. A classical variance‐based global sensitivity analysis is then performed to assess the relative importance of the uncertain parameters associated with each of the models considered, within subregions of the parameter space. In this context, the modelling strategy resulting from coupling the Langmuir isotherm with a two‐layer solute transfer model is then evaluated as the most skilful for the overall interpretation of both sets of experiments. Our results document that (a) the depth of the mixing layer is the most influential factor for all models tested, with the exception of the Freundlich isotherm, and (b) the total sensitivity of the adsorption parameters varies in time, with a trend to increase as time progresses for all of the models. These results suggest that adsorption has a significant effect on the uncertainty associated with the release of Cr(VI) from the soil to the surface runoff component.  相似文献   

Optical flashes and very early afterglows in wind environments     

X. F. Wu  Z. G. Dai  Y. F. Huang  T. Lu 《Monthly notices of the Royal Astronomical Society》2003,342(4):1131-1138

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An approximate method for evaluating the shear band thickness in saturated soils     

X. B. Lu  Wang Shuyun  Wang Yihua  Peng Cui 《国际地质力学数值与分析法杂志》2004,28(15):1533-1541

A formula for the thickness of a shear band formed in saturated soils under a simple shear or a combined stress state has been proposed. It is shown that the shear band thickness is dependent on the pore pressure properties of the material and the dilatancy rate, but is independent of the details of the combined stress state. This is in accordance with some separate experimental observations. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

长江上游洪涝暴雨环流形势中期演变趋势分析     

郁淑华  骆红  芮良生 《成都信息工程学院学报》1990,(1)

本文通过对1980年以来长江上游10次洪涝过程的500hpa环流形势分析,并用车比雪夫多项式对500hpa高度场进行展开,研究了各类洪涝过程的中期演变特征,发现代表不同洪涝过程环流形势变化的不同的车氏系数值都有明显的特征变化,结合欧洲中心中期数值预告96小时500hpa高度场的车氏系数分析,可为洪涝暴雨的中期预报提供一种新的思路。  相似文献   

Observational constraints on the radio and γ-ray emission regions of PSR B1055−52     

H. G. Wang  G. J. Qiao  R. X. Xu  Y. Liu 《Monthly notices of the Royal Astronomical Society》2006,366(3):945-952

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P‐wave transmission across fractures with nonlinear deformational behaviour     

X. B. Zhao  J. Zhao  J. G. Cai 《国际地质力学数值与分析法杂志》2006,30(11):1097-1112

Stress wave attenuation across fractured rock masses is a great concern of underground structure safety. When the wave amplitude is large, fractures experience nonlinear deformation during the wave propagation. This paper presents a study on normal transmission of P‐wave across parallel fractures with nonlinear deformational behaviour (static Barton–Bandis model). The results show that the magnitude of transmission coefficient is a function of incident wave amplitude, nondimensional fracture spacing and number of fractures. Two important indices of nondimensional fracture spacing are identified, and they divide the area of nondimensional fracture spacing into three parts (individual fracture area, transition area and small spacing area). In the different areas, the magnitude of transmission coefficient has different trends with nondimensional fracture spacing and number of fractures. In addition, the study reveals that under some circumstances, the magnitude of transmission coefficient increases with increasing number of fractures, and is larger than 1. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

On signal–noise decomposition of time-series using the continuous wavelet transform: application to sunspot index     

J. Polygiannakis  P. Preka-Papadema  X. Moussas 《Monthly notices of the Royal Astronomical Society》2003,343(3):725-734

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A critical state model for sands dependent on stress and density     

Y.P. Yao  D.A. Sun  T. Luo 《国际地质力学数值与分析法杂志》2004,28(4):323-337

An elastoplastic model for sands is presented in this paper, which can describe stress–strain behaviour dependent on mean effective stress level and void ratio. The main features of the proposed model are: (a) a new state parameter, which is dependent on the initial void ratio and initial mean stress, is proposed and applied to the yield function in order to predict the plastic deformation for very loose sands; and (b) another new state parameter, which is used to determine the peak strength and describe the critical state behaviour of sands during shearing, is proposed in order to predict simply negative/positive dilatancy and the hardening/softening behaviour of medium or dense sands. In addition, the proposed model can also predict the stress–strain behaviour of sands under three-dimensional stress conditions by using a transformed stress tensor instead of ordinary stress tensor. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

行星磁场与卫星引力及其相对运动的统计关系     

罗葆荣 《天文研究与技术》1997,(3)

从知道某些天体具有磁场起，人们就对其磁场的起源提出种种解释，例如有电池说，转子说，化石说，发电机说等等。但由于这些学说都分别与某些观测事实相抵触而未被公认，因此星球磁场的起源一直是未能解决的命题。余先河先生提出，星球的磁场起源可能与所受的引力有关，行星的磁场强度正比于其所受卫星的引力；正比于卫星与行星的引力连线转动的相对角速度。本文对这两方面的命题分别进行了相关分析，得到其相关系数分别为：ｒ＝０．８４８１和ｒ＝０．８４２５，它们都在ａ＝０．０１的信度水平上相关。结果表明余新河关于行星磁场起源的设想是有基础的。本文还对其统计结果和可能机制进行了讨论。  相似文献   

The range-averaged intensity model: a tool for underwater acousticfield analysis     

Lurton  X. 《Oceanic Engineering, IEEE Journal of》1992,17(1):138-149

The range-averaged intensity model (RAIM) long known as a powerful method for transmission loss estimation in waveguides, is extended to other aspects of the acoustic field: impulse response and angular pattern estimations at a receiver, general time spreading in a waveguide, signal fluctuations, reverberation levels, and ambient noise structure. An example of its application to a SOFAR propagation and detection case is presented. This method appears to be a very efficient and reliable analysis tool for many underwater acoustics configurations: particularly long-range horizontal telemetry and shallow-water sonar  相似文献