Atmospheric Weathering

Kump LR, Brantley SL, Arthur MA (2000) Chemical weathering, atmospheric COj and climate. Atm Rev Earth Planet Sci 28 611-667... 

Inorganic constituents are present in major, minor, and trace concentrations in aquatic environments as a result of weathering, atmospheric, and biogeochemical processes, and also as a consequence of industrial pollution. Inorganic constituents in aquatic ecosystems are a group of chemical species that are characterized by... 

Continental crust is the ultimate source of trace elements in hydrologic systems. Trace elements are introduced in the river basin by rock weathering, atmospheric dry and wet deposition and by anthropogenic activities. The sketch diagram of Figure 8 summarizes the natural and anthropogenic sources of elements in aquatic environments (modified after Foster and Charles worth, 1996). 

This simple device, called a barometer, works like a balance, one arm of which is loaded with the mass of mercury in the tube and the other with a colnmn of air of the same cross-sectional area that extends to the top of the Earth s atmosphere, approximately 150 km above the surface of the earth, (see Fig. 9.2b). The height of the mercury column adjusts itself so that its mass and that of the air colnmn become equal. This means that the two forces on the surface of the mercury in the dish are balanced. Day-to-day changes in the height of the column occur as the force exerted by the atmosphere varies with the weather. Atmospheric pressure varies strongly with altitude it is lower at higher altitudes because the column of air pressing down is shorter and, therefore, has less mass. 

Weathering, atmospheric deposition, and the fixation of atmospheric gases are the ultimate sources of the material transported by rivers. These... 

The three main natural sources of soil salinity are mineral weathering, atmospheric precipitation, and fossil salts (those remaining from former marine or lacustrine environments). The human activities that add salts to soil include irrigation and saline industrial wastes. Seawater encroachment can also harm soils. 

TABLE 1. Electrical Parameters of the Clear (Fair-Weather) Atmosphere, Pertinent to the Classical Picture of... 

Epoxy and polyester polyols, though more expensive than the acrylic polyols, are more chemically and moisture resistant. However, the acrylic polyol, when suitably reacted to form a urethane coating, is satisfactory for weathering atmospheres. 

Almost everyone has a concept of pressure from weather reports of tlie pressure of the atmosphere around us. In this context, high pressure is a sign of good weather while very low pressures occur at the eyes of cyclones and hurricanes. In elementary discussions of mechanics, hydrostatics of fluids and the gas laws, most scientists leam to compute pressures in static systems as force per unit area, often treated as a scalar quantity. They also leam that unbalanced pressures cause fluids to flow. Winds are the flow of the atmosphere from regions of high to low... 

Weathering is defined as corrosion by atmospheric-bome gases and vapors. 

Environmental Impact of Ambient Ozone. Ozone can be toxic to plants, animals, and fish. The lethal dose, LD q, for albino mice is 3.8 ppmv for a 4-h exposure (156) the 96-h LC q for striped bass, channel catfish, and rainbow trout is 80, 30, and 9.3 ppb, respectively. Small, natural, and anthropogenic atmospheric ozone concentrations can increase the weathering and aging of materials such as plastics, paint, textiles, and mbber. For example, mbber is degraded by reaction of ozone with carbon—carbon double bonds of the mbber polymer, requiring the addition of aromatic amines as ozone scavengers (see Antioxidants Antiozonants). An ozone decomposing polymer (noXon) has been developed that destroys ozone in air or water (157). 

Ilmenite is more abundant than mtile. Ilmenite world suppHes are estimated to meet the requirements of the Ti02 industry into the twenty-second century. The largest sources of ilmenite are in AustraHa, Canada, South Africa, Russia, and the United States. Large, unexplored sources also exist in China. About 9 million metric tons of ilmenite are mined aimuaHy. Long-term atmospheric effects weather ilmenite into leucoxene [1358-95-8], which contains most of its iron as Fe " . The majority of the world s supply of mtile comes from the beach sands of AustraHa, Florida, India, Bra2H, and South Africa. The total worldwide supply is estimated to be about 50 million metric tons. About 0.5 million tons are mined a year. The supply should last at least until the end of the twenty-first century. 

Aluminum and aluminum alloys are employed in many appHcations because of the abiHty to resist corrosion. Corrosion resistance is attributable to the tightly adherent, protective oxide film present on the surface of the products. This film is 5 —10 nm thick when formed in air if dismpted it begins to form immediately in most environments. The weathering characteristics of several common aluminum alloy sheet products used for architectural appHcations are shown in Eigure 30. The loss in strength as a result of atmospheric weathering and corrosion is small, and the rate decreases with time. The amount of... 

Al—Mg—Si types have excehent corrosion resistance in most weathering exposures including industrial and seacoast atmospheres. Ahoys based on additions... 

It has been shown (20,21) that siUcate weathering is more important than carbonate mineral weathering as a longterm control on atmospheric CO2. The HCO3 and ions produced by weathering of CaCO precipitate in the... 

Dynamic meteorological models, much like air pollution models, strive to describe the physics and thermodynamics of atmospheric motions as accurately as is feasible. Besides being used in conjunction with air quaHty models, they ate also used for weather forecasting. Like air quaHty models, dynamic meteorological models solve a set of partial differential equations (also called primitive equations). This set of equations, which ate fundamental to the fluid mechanics of the atmosphere, ate referred to as the Navier-Stokes equations, and describe the conservation of mass and momentum. They ate combined with equations describing energy conservation and thermodynamics in a moving fluid (72) ... 

Dipped Goods. Gloves with and without cloth support are a typical example. Unsupported appUcations involve specialty medical gloves and weather balloons. Eor CR to compete with less expensive natural mbber, it must provide added value. Natural mbber medical examination gloves contain proteins that can cause an allergic reaction in both patients and medical personnel. Polychloroprene gloves avoid the problem for those individuals, but are too expensive for general use. Natural mbber weather balloons have less lift than CR balloons and are rapidly attacked by ozone in the upper atmosphere. 

---