Measuring and modeling the surface charge of clays, and more especially smectites, has become an important issue in the use of bentonites as a waste confinement material aimed at retarding migration of water and solutes. Therefore, many studies of the acid-base properties of montmorillonite have appeared recently in the literature, following older studies principally devoted to cation exchange....

Introduction: Over 13 years after landing at Meridiani Planum and in her 10 extended mission, Mars Exploration Rover Opportunity continues to explore the rim of ~22 km diameter Endeavour crater [1]. The rim exposes material that is older than the S-rich, layered sedimentary rock covering the Meridiani plains and filling much of the interior of Endeavour. Clay mineral exposures at the rim have b...

The Boltysh crater has an entire suite of crater-fill impactites preserved, including two impact meltbearing breccias. Smectite occurrence in the breccias suggests two stages of alteration; an early hydrothermal mineralization, and a later, low temperature weathering. δD and δO of smectite separates are currently being measured and will be presented.

Electron beam techniques namely Scanning Electron Microscopy (SEM), the closely related Electron Probe Microanalysis (EPMA) and Transmission Electron Microscopy (TEM) find ample applications on the characterization of various types of geological materials including clays. They provide morphological, structural and chemical information down to the atomic scale. The principal advantage of the ele...

small amounts of water to soil reduced the sorption of organic compounds relative to the sorption by the In soils, organic matter and minerals are often associated such that dehydrated soil in hexane, and that organic vapor adit is unclear how the presence of the former component influences sorption by soil was significantly depressed by increasing the sorptive properties of the latter one. In ...

We characterize the topographic evolution of Pacific Northwest, United States, during Cenozoic. New paleosol carbonate stable isotope (δ 18 O) results from central Oregon are presented, along with published proxy data, including fossil teeth, smectites, and concretions. interpret a polygenetic history Cascade Mountain uplift along-strike, characterized by: 1) Steady Washington Cascades through ...

In aqueous suspension, the affinity of many pesticides for smectites is influenced by the clay properties such as surface area, surface charge density and location, exchangeable cations, and hydration status of exchangeable cations in clay interlayers. The amount and the type of salts present in the aqueous phase influence clay quasicrystal structures and hydration status, which we hypothesize ...

The adsorption of polymers on clay is important in many applications. However the mechanisms of poly(ethylene oxide) (PEO) adsorption n smectite and its effect on suspension rheology are not well elucidated at present. The aim of this study was to investigate the mechanisms esponsible for PEO sorption on smectite and how this impacts on dispersive behavior of smectite suspension. The results in...