Due to its low permeability, a clay liner is the main material used in solid waste disposal landfills. It is exposed there to various chemical, biological, and physical events, and the clay liner is affected by the resulting leachate. For this reason, when attempting to define the geotechnical characteristics of clay liners, the use of distilled water or tap water is far from being representati...

One of soil microbiology's most intriguing puzzles is how so many different bacterial species can coexist in small volumes of soil when competition theory predicts that less competitive species should decline and eventually disappear. We provide evidence supporting the theory that low pore connectivity caused by low water potential (and therefore low water content) increases the diversity of a ...

Clay with free gas bubbles can be frequently encountered in the seabed. Gassy clay is an unsaturated soil, but its mechanical behavior cannot described using conventional soil mechanics because it has a composite internal structure saturated matrix and bubbles. The have either detrimental or beneficial effect on undrained shear strength of clay. New lower upper bounds for gassy are derived by c...

Long ago, people must have realised that clay could be used to take imprints of simple objects like a leaf, or later, a coin. Carefully withdrawing the clay gave a negative of the object or a mold in which other materials like plaster could be cast to reproduce the original. Clay is still used today to make molds, particularly to reproduce museum pieces like statues, not only because it is inex...

The spatial organisation of swelling clay platelets in a suspension depends on the chemical composition of the equilibration solution. Individual clay platelets can be well dispersed, with surfaces entirely in contact with the external solution, or be stacked in tactoids, where part of the surfaces forms parallel alignments embedding interlayer water and cations. External and interlayer surface...

The Chaco leaf-cutting ant Atta vollenweideri is native to the clay-heavy soils of the Gran Chaco region in South America. Because of seasonal floods, colonies are regularly exposed to varying moisture across the soil profile, a factor that not only strongly influences workers' digging performance during nest building, but also determines the suitability of the soil for the rearing of the colon...

Manure-borne bacteria can be transported in runoff as free cells, cells attached to soil particles, and cells attached to manure particles. The objectives of this work were to compare the attachment of fecal coliforms (FC) to different soils and soil fractions and to assess the effect of bovine manure on FC attachment to soil and soil fractions. Three sand fractions of different sizes, the silt...

Many impurities in waters and wastewaters are present as colloidal dispersions, i.e. they occur in particulate form within the approximate size range 1 to 10 -3 μm (refer Fig 1.3). Examples of this type of suspension include clays, substances of biological origin such as natural colour, proteins, carbohydrates and their natural or industrial derivatives. Invariably suspensions of this type poss...

Geochemical models for Mars predict carbonate formation during aqueous alteration. Carbonate-bearing rocks had not previously been detected on Mars' surface, but Mars Reconnaissance Orbiter mapping reveals a regional rock layer with near-infrared spectral characteristics that are consistent with the presence of magnesium carbonate in the Nili Fossae region. The carbonate is closely associated w...