Assessment of alternative adsorption models and global sensitivity analysis to characterize hexavalent chromium loss from soil to surface runoff

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.     

太阳发电机理论研究进展

太阳发电机理论主要解释太阳磁场的起源和演化，是太阳物理中最基本、最重要的问题之一．对它的研究不仅具有重要的科学价值，而且对空间天气的预测和空间技术的发展有一定的影响．随着日震学的发展，该理论也得到了很大改进。从相关观测入手，综述了发电机理论需解释的观测事实，以及为发电机理论提供约束的太阳内部动力学结构；介绍了基本理论和近来的主流模型，并指出尚待解决的问题和进一步的努力方向。     

对"数字地球"的几点认识

自“数字地球”的概念被提出以来，已引起全球的广泛关注和积极响应。然而，数字地球在目前还仅仅是一个概念。为了逐步建立“数字地球”，需要就“数字地球”的理论、技术以及实现进行深入地探讨。从“数字地球”的产生背景、基本概念、研究内容、构成框架、关键技术、实施难点和发展战略等方面谈了对“数字地球”的一些认识。     

彗星等离子体某些特征的讨论

本文讨论了彗星中尘埃粒子的充电机制 ,带电特性和平衡电势的变化规律 ,分析了彗星尘埃的破碎特性和临界半径 ,得出了很有意义的结果     

STRATEGY OF MAIZE′S CONCENTRATING TO ADVANTAGE AREAS IN JILIN PROVINCE

WiththedevelopmentofagricultureandChina'sentryintoWTO,thesituationofsupplyanddemandinmaizemarkethaschangedgreatly.Facingtherelativesurplusofmaizeandtheformationofbuyer'smarket,weshouldfullydeveloprelativeadvantages,carryouttheunevenstrategyofsupportingthesuperior inmaizeproduction andcultivateadvantagedareasofmaize.Theabovestrategicmeasurescanrapidlyim-provetheinternationally competitiveabilityandpro-ductivityofmaizeinJilinProvince,getoutofthea-griculturalpredicamentandmaketheagriculturalde-…     

中国大陆科学钻探先导孔零偏VSP资料解释

用六级三分量检波器在中国大陆科学钻探先导孔中实施了零偏VSP测量.数据处理结果表明,中国大陆科学钻探孔区超高压变质岩石的地震波速度主要介于4500～7000m/s之间,显著高于一般的沉积岩地区,而且随深度变化不明显.声波测井速度系统地稍低于VSP层速度,可能是由于井壁处岩石的完整性受到破坏而造成的.地震波速度与岩石密度和岩性存在明确的对应关系,榴辉岩的密度和地震波速度均显著高于片麻岩类岩石;由榴辉岩退变生成的斜长角闪岩类岩石,其密度和地震波速度均呈现出较大的变化,主要与其退变质程度有关;超基性岩中的裂隙系统导致其密度和地震波速度大幅度下降.由于榴辉岩与其他岩石类型之间存在较大的波阻抗差异,因此用零偏VSP资料标定该区地震波的地质层位是有效的.关于地震波反射的原因,通过综合研究地震波(包括反射纵波、上行转换横波、井筒波)的特征、岩石速度和密度分布以及井径变化,认为主要是岩性分界面、韧性剪切带和断裂(带),但还有一些因素尚待进一步研究.     

彗木碰撞期间3.6和12cm射电观测

本文介绍了1994年7月SL－9彗星撞击木星期间3．6cm和12cm射电连续谱观测的结果．在3．6cm波长上，撞击事件无明显的视效应，在12cm波长上，木星的射电平均视流量增加约20％．     

成都及附近地区旅游气候资源研究

通过对成都及附近等7个地区多年气候资源及人体舒适指数进行分级比较，得出了7个地区的人体舒适指数的时间分布特征及对当地旅游的影响。     

APPLICATION OF MAP AND FILE INFORMATIONVISUALIZATION SYSTEM TO COMPREHENSIVEDIVISION OF NATURAL DISASTERS- Takingthe ChangjiangValleg as an Example

In recent years，scholars at home and abroad have method，and that vanous disasters would be analyzed assynthetically studied natural dlsaste‘theoretically and an Integral．SHI Peilun（1991）putforwad a scientificmethodologlcally，as well as its cases analys。s（CND，term—regional disaster system，which Indicates that1987； MA et al，1990； MARBLE，1990； NE et al，the situation of a disaster（calamity loss）results from1999； PATAK et al，1982； SHI，1991；VAN et al，h…