Weathering processes biological

Weathering and transportation is followed by the sedimentation of material. The depositional environment can be defined as an area with a typical set of physical, chemical and biological processes which result in a specific type of rock. The characteristics of the resulting sediment package are dependent on the intensity and duration of these processes. The physical, chemical, biological and geomorphic variables... 

Carbon dioxide plays a key role in climate, in biological processes, in weathering reactions, and in marine chemistry. I shall next describe how the partial pressure of this gas in the atmosphere may be calculated. Because there is a rapid exchange of carbon dioxide between ocean and atmosphere, we must consider the fate of dissolved carbon. 

However, under dry-weather conditions that may occur around 95% of the time in many countries, chemical and biological sewer processes may exert pronounced effects on sewer performance and on the interaction between the sewer and subsequent treatment processes. Possibly, because researchers and operators interests have been devoted to wet-weather conditions, the biological and chemical performances of a sewer, i.e., the sewer as a chemical and biological reactor, have not been of great concern. It is, however, apparent that the sewer cannot be neglected as a chemical and biological process system. These processes may have impacts on the sewer itself, the treatment plant, the environment and the humans in direct or indirect contact with the sewer. 

In Table 5.4 the contributions of the individual weathering reactions were assigned and combined in such a way as to yield the concentrations of Ca2+, Mg2+, Na+, K+, and H+ measured in these lakes the amounts of silicic acid and aluminum hydroxide produced and the hydrogen ions consumed were calculated stoichiometrically from the quantity of minerals assumed to have reacted. Corrections must be made for biological processes, such as ammonium assimilation and nitrification and the uptake of silicic acid by diatoms. Some of the H4Si04 was apparently lost by adsorption on aluminum hydroxide and Fe(III)(hydr)oxides, but the extent of these reactions was difficult to assess. 

Surficial processes that affect the redox composition of Earth materials include weathering, drainage, groundwater movement, mechanical mixing and dispersion of rock material, soil formation, the accumulation of organic material and biological processes. There is an almost unlimited number of ways in which these factors can combine to affect the composition of Earth materials and therefore to affect local redox conditions. However, the processes that are most likely to affect redox locally can be simplified. 

Mud, silt and sandy sediments form mainly by weathering—the breakdown and alteration of solid rock. Usually, these sedimentary particles are transported by rivers to the oceans, where they sink onto the seabed. Here, physical and biological processes and chemical reactions (collectively known as diagenesis) convert sediment into sedimentary rock. Eventually these rocks become land again, usually during mountain building (orogenesis). 

Soil is a special kind of sedimentary deposit produced in situ by the weathering of the earth s surface. Weathering refers to the chemical and biological processes that operate to breakdown and change the surface of the earth, altering its color, texture, or composition. These processes include rainfall, frost, and plant and animal activity as major forces of change. Soils are not only found on the surface of the ground. Old soils can be buried by later deposits. Buried soils provide a useful marker of the location of former land surfaces. 

Many geologists and soil scientists have repeatedly suggested the important influences of biological processes on the weathering reactions. The synthesis of terrestrial biomass is accompanied by acidification of the surrounding soil. This... 

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