Lake effect

Hessen, D. O. 1992. Dissolved organic carbon in a humic lake effects on bacterial production and respiration. Hydrobiologia 229 115—123. 

Zabik ME, Zabik MJ, Booren AM, et al. (1995) Pesticides and total polychlorinated biphenyls in Chinook salmon and carp harvested from the Great Lakes effects of skin-on and skin-off processing and selected cooking methods. Journal of Agricultural and Food Chemistry 43 993-1001. 

With more than 2V2 million people, Chicago is America s third-largest city and one of its most important. It has been called the most American of cities, with all the vitality of a New York, San Francisco or Los Angeles, but without all the attitude accompanying their specialized industries. Chicago is also a tough city. It s had it share of struggles over the decades, with fires, issues of race and poverty, and those lake-effect snows that constantly blanket the city in winter. 

N.M. Scully, D.R.S. Lean, D.J. McQueen, W.J. Cooper (1995). Photochemical formation of hydrogen peroxide in lakes Effects of dissolved organic carbon and ultraviolet radiation. Can. J. Fish. Aquat. Sci., 52,2675-2681. 

In many common chemical operations, the liquid phase is in contact with another vapor, and a portion of the liquid will vaporize and mix with the vapor phase. We frequently want to know how much liquid can be contained in the vapor stream, or the saturation condition for the vapor. We define a gas as being saturated when it contains as much of a liquid substance as possible. For example, water evaporating from a pond increases the moisture content in the air above the pond. During the winter, this creates lake effect snow, as saturated air is carried back across the land, experiences a temperature decrease, and loses excess moisture in the form of snow. 

Many molecular mechanics potentials were developed at a time when it was computationally impractical to add large numbers of discrete water m olecules to ih e calcu la Lion to sim ulate th e effect of ac ueous media. As such, tech n iq ties cam e into place that were intended to Lake into account the effect of solvent in some fashion. These tech niqiieswcre difficult to justify physically but they were used n cvcrth eless. 

A few studies have found potential surfaces with a stable minimum at the transition point, with two very small barriers then going toward the reactants and products. This phenomenon is referred to as Lake Eyring Henry Eyring, one of the inventors of transition state theory, suggested that such a situation, analogous to a lake in a mountain cleft, could occur. In a study by Schlegel and coworkers, it was determined that this energy minimum can occur as an artifact of the MP2 wave function. This was found to be a mathematical quirk of the MP2 wave function, and to a lesser extent MP3, that does not correspond to reality. The same effect was not observed for MP4 or any other levels of theory. 

Residue Disposal. The major environmental problem in the Bayer process is disposal of bauxite residue which is effected by marine disposal, lagooning, use of underdrain lakes, or semidry disposal. Marine disposal in oceans or rivers, diluting the alkaline residue by large quantities of water, is environmentally unacceptable. Lagooning behind retaining dikes built around clay-sealed ground is commonly used, but there have been isolated leaks into aquifers. This has motivated installation of underdrains between the residue and clay-sealed, plastic-lined, lake bottom. This design removes the hydraulic head from the lake bottom and improves consoHdation of the residue. 

Air. Studies have shown that 2500 years ago lead pollution caused by Greek and Roman silver smelters was a significant problem (4). Based on analysis of lake sediments and Greenland s ice, it was found that lead contamination from smelters in southern and central Europe was carried throughout the northern hemisphere. As long ago as the thirteenth century, air pollution has been linked to the burning of coal (4). The main concern was the smell from the sulfur in the coal and the effects of the soot. It was not until many years later that the effects of air pollution on people s health were discovered. 

Processing at Sead.es Lake, California, by North American Chemical is similar to that of Texas brines. Brine is cooled to 16°C to remove borax crystals, then cooled to 4°C which precipitates Glauber s salt. This salt is then separated from its mother Hquor, melted in multi-effect vacuum crystallizers to form anhydrous sodium sulfate, and dried. Both processes produce crystals that are 99.3—99.7% pure (9). 

An accompanyiag effect of eutrophication that is more readily observable ia Table 1 is a decrease ia siUca coaceatratioa ia Lake Oatario. Some decliae ia dissolved siUca appareatiy has occurred ia all of the lakes except Lake Superior. This decliae is brought about by the growth of diatoms, a species of aquatic microorganisms ia the upper layers of lake water that is widespread ia all types of water impouadmeats where the water is clear and exposed to the sun. The siUca is used by these microorganisms to form their skeletons and is later precipitated and becomes part of the bed sediment. 

Agricultural mnoff is a large contributor to etrophication in lakes and other natural bodies of water. Effective control measures have yet to be developed for this problem. Runoff of pesticides is also receiving increasing attention. 

Properties of lakes that enhance their usefiilness iaclude their opacity, their abiUty to be iacorporated iato products ia the dry state, their relative iasolubihty, and their superior stabiUty toward heat and light. Such properties have made possible the more effective and more efficient preparation of candy and tablet coatings, and often eliminate the need to remove moisture from dry products before coloring them. Lakes have also made possible the coloring of certain products that, because of their nature, method of preparation, or method of storage, caimot be colored with ordinary color additives. 

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