Arsenic movement

Robson SG. 1981. Computer simulation of movement of DIMP-contaminated groundwater near the Rocky Mountain Arsenal, Colorado. ASTM Special Technical Publication 746 209-220. 

The type is cast in a mould that can be opened and shut very quickly. The metal, which is ladled into it, consists of lead, arsenic and regulus of antimony. At the same time as the metal enters the mould... a rapid movement is made by the hand holding the mould, which increases the pressure on the bottom where the actual letter is formed. 

The potential of live cell imaging to address mechanisms of cellular biology is ever expanding. Directed protein-tagging techniques have been used to visualize nascent versus mature protein in vivo (Rodriguez et al., 2006). This technique involves the use of arsenic-based dyes, such as FiAsH or ReAsH, which bind to tetracysteine (TC) tags (Zhang et al, 2002). In addition, photo-activatable variants of GFP have been shown to determine the kinetics of protein movement in live cells (Patterson and Lippincott-Schwarz, 2002). Furthermore, techniques such as FRET and the... 

Boron and arsenic are natural components of soil and are both present as oxyanions. Boron is present as boric acid or borate polymers, and arsenic is present as arsenate. While boron is weakly held by soil, arsenic is similar to phosphate in its interactions with soil constituents. Boron is an essential nutrient for plants however, it is also toxic to plants at relatively low levels. Arsenic is toxic. The laboratory chemistry of both of these elements is well understood, but their environmental chemistry, speciation and movement, is less well understood [23-27],... 

Heat Transfer The movement and dispersion of heat by conduction, convection, or radiation. Heavy Metals High-density metallic elements generally toxic to plant and animal life in low concentrations (e.g. mercury, chromium, cadmium, arsenic, and lead). 

Precipitation refers to dissolved species (such as As(V) oxyanions) in water or other liquids reacting with other dissolved species (such as Ca2+, Fe3+, or manganese cations) to form solid insoluble reaction products. Precipitation may result from evaporation, oxidation, reduction, changes in pH, or the mixing of chemicals into an aqueous solution. For example, As(V) oxyanions in acid mine drainage could flow into a nearby pond and react with Ca2+ to precipitate calcium arsenates. The resulting precipitates may settle out of the host liquid, remain suspended, or possibly form colloids. Like sorption, precipitation is an important process that affects the movement of arsenic in natural environments and in removing arsenic from contaminated water (Chapters 3 and 7). 

Movement of arsenic from mining wastes and into the environment... 

Peryea, F.J. and Kammereck, R. (1997) Phosphate-enhanced movement of arsenic out of lead arsenate-contaminated topsoil and through uncontaminated subsoil. Water Air and Soil Pollution, 93(1-4), 243-54. 

There are few observations of arsenic transport in aquifers, and its rate of movement is poorly understood. The transport of arsenic, as that of many other chemicals, is closely related to adsorption-desorption reactions (Appelo and Postma, 1993). Arsenate and arsenite have different adsorption isotherms. They, therefore, travel through aquifers at different velocities, and tend to be separated. 

Several acidic solvent systems and types of supports work with varying efficiency (Table 23). Cellulose and silica gel H (with organic binder) allow the movement of arsenite, but arsenate and disodium methanearsonate (DSMA) remain on the origin. DSMA, arsenate and arsenite separate best on thin-layer plates coated with silica gel G (calcium sulphate binder). 

There is much speculation about the reasons for the high arsenic concentrations in groundwaters in Bangladesh and elsewhere. It is useful in these discussions to consider three aspects of the problem the source of the arsenic, its mobilization and the extent of its present and past transport or movement in the groundwater flow. 

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