Rocks, Sediments, and Soils

Suspensions, and to some degree emulsions and foams, play crucial roles in the evolution of the earth s rocks, rivers, streams, lakes, oceans, and soils. Table 9.1 lists some examples. In many cases their role is somewhat disguised in that these colloidal dispersions are the precursors to the ultimate products, the latter having very different final appearances, such as many rocks, sediments, and soils. 

Foams Free gas bubbles in oceans, lakes and rivers G/W 

Within the earth are hot, fluid precursors to lava, called magmas. These magmas can contain hot liquids, gases, and solids in all proportions and combinations, and they have an extremely variable rheology [511,512]. As such, magmas can represent 

Emulsions, Foams, and Suspensions Fundamentals and Applications. Laurier L. Schramm Copyright 2005 WILEY-VCH Veriag GmbH Co. KGaA, Weinheim ISBN 3-527-30743-5 

Particle type Diameter (gm) Sedimentation velocity (cm/s) Time to sediment 4 km 

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The pathway of plutonium dissolved in natural water, from a source such as a nuclear facility, to man, may be quite complicated. During the transport, the plutonium atoms encounter dissolved and particulate inorganic and organic matter, as well as minerals in rocks, sediment and soil, and living organisms which may metabolize the plutonium. Figure 1 depicts some of the more essential routes for plutonium between the point of emission and the plutonium consuming man. The overall effect of these pathways is that plutonium is slowly eliminated from the water, so that only a minor fraction of it reaches man. An example of this is that of the 4.2 tonnes of plutonium deposited on the earth after... 

Elemental abundances in various types of geological media such as rocks, sediments and soils of China have been studied since 1980s. These data were published in many literatures (Chi Yan 2007 Yan Chi 1997, 2005 Ren et al. 1998 Zhao Yan 1994 Zhu et al. 2006). To provide readers with a general overview and convenient use, the authors collected these published data and compiled a concise data set in this paper. 

Mineral A naturally occurring and well-crystallized inorganic and nonbiological solid substance. Minerals are major components of most rocks, sediments, and soils. 

Direct analysis of solids for selenium by XRF has a detection limit of —0.5 mgkg and so is often insufficiently sensitive. Rock, sediment, and soil samples can be dissolved using wet chemical methods (HF-HCl-etc.) followed by La(OH)3 co-precipitation to separate hydride-forming elements including selenium. This is present as Se(IV) following acid dissolution (Hall and Pelchat, 1997). The methods described above for aqueous samples can then be used. 

Smith, J. D. Spectrophotometric determination of traces of tin in rocks, sediments and soils. Anal. Chim. Acta57, 371 (1971)... 

The category of PBTs, as defined by U.S. EPA, includes mercury, lead, dioxins, and several dozen other substances. Mercury and lead have so far been the most widely targeted of these substances because, like other heavy metals (naturally occurring elements contained in rocks, sediments, and soils), they do not degrade at all. Polychlorinated dioxins are also PBTs, and while normally they are not purposefully manufactured, they are often generated as byproducts during the manufacture of chlorinated compounds and during incineration or combustion.3... 

Terrestrial environments consist of solid (rocks, sediments and soils), liquid (rivers, lakes and groundwater) and biological (plants and animals) components. The chemistry of terrestrial environments is dominated by reactions between the Earth s crust and fluids in the hydrosphere and atmosphere. 

Antimony has geochemical behavior similar to arsenic, as it occurs most commonly in the +3 (antimonite) and +5 (antimonate) oxidation states and also tends to associate with sulfides in rocks, sediments, and soils. In soil solutions, the Sb and Sb oxidation states are stable under reducing and oxidizing conditions, respectively. 

Arsenic is ubiquitous in nature and is found in detectable concentrations in all environmental matrices. The occurrence of As in the continental crust of Earth is usually given as 1.5 to 2.0 mg/1. The distribution of arsenic in nature is extremely variable, showing little correlation with geological formation, climate, or soil. Numerous minerals, rocks, sediments and soils contain arsenic partly as constituent of sulfide minerals or complex sulfides of metal cations and partly as a constituent retained by soils and/or sediments in occluded or adsorbed forms. The latter is manifested primarily by the adsorption or occlusion of As on hydrous A1 and Fe oxides, but these are not necessarily the only source. Arsenic is also adsorbed on clay colloid, is bound to organic matter and may form slightly water soluble compounds with Al, Fe, Ca and Mg in the soil matrix. Some of the more common minerals in soils are arsenopyrite (FeAsS), Orpiment (AsgSg) etc. 

The present-day flux of solids eroded from exposed rocks, sediments, and soils carries four to five times more mass than the flux of solutes in rivers, as reported by a number of investigators over a period of years. Physical erosion is favored over chemical weathering by a combination of such factors as existence of a high... 

In precipitation, water falls onto the land surface and comes in contact with rocks, sediments, and soils and the animal and plant inhabitants of the land surface. Chemical reactions take place that further modify the composition of the water. The reactions can be viewed in general terms as a giant global acid-base titration in which the acids of the rainwater CO2, SO2, and NOx) titrate the bases of the rocks. Since the composition of the land surface and the extent and nature of biological activity (including man s activity) vary from one place to another, we can expect that waters of a variety of compositions will result from these reactions. The time and intimacy of contact between water and rocks also influences the composition of the solution. 

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