Stream natural

Hydrometallurigcal Processes. In hydrometaHurgical processes, metal values and by-products are recovered from aqueous solution by chemical or electrolytic processes. Values are solubilized by treating waste, ore, or concentrates. Leaching of copper ores in place by rain or natural streams and the subsequent recovery of copper from mnoff mine water as impure cement copper have been practiced since Roman times. Most hydrometaHurgical treatments have been appHed to ores or overburden in which the copper was present as oxide, mixed oxide—sulfide, or native copper. PyrometaHurgical and hydrometaHurgical processes are compared in Reference 34. 

Traditionally, French fishermen have used the male sex attractant of the sea lamprey, Petromyzon marinus. They bait a trap with an adult male and catch numerous females at night. Land-locked sea lamprey such as those in the Great Lakes of North America spawn in streams. Males arrive before the females and build nests. In laboratory choice experiments, ovulating females selected water from spermiating males and increased their searching behavior there. In a natural stream, females responded to male odors from as far as 65 m. The active... 

Chang, H.-W. (1999) Apparent solubilities of schwertmannite and ferrihydrite in natural stream waters polluted by mine drainage. Geochim. Cosmochim. Acta 63 3407—3416... 

The question that we need to ask ourselves is whether the longitudinal dispersion can be predicted accurately for these rivers. Equation (6.35), which predicts that >l/(m+/i) = constant, is shown in Table 6.4 to have a large range of constants, probably because of the variations in cross section and morphology seen in natural streams. Fisher (1973) observed that this constant seemed to depend on mean surface width, W, and substituted W for h in the numerator of equation (6.34) to develop the following empirical equation to characterize longitudinal dispersion coefficient in rivers ... 

Drying up of natural streams, springs, and/or lowering of the water table in adjoining aquifers... 

The polished powder is dried at 50°C to 0.5-1.0% moisture content (in countries with a damp climate the permissible moisture content is higher and in countries with a dry climate—lower). Shelf driers with a natural stream of warm air are usually employed. The use of a pressurized air stream is permissible provided that it is... 

Winding sluggish canals Dredged earth channels Natural-stream channels 0.025 0.021... 

The principal types of open channels are natural streams or rivers artificial canals and sewers, tunnels, or pipelines not completely filled. Artificial canals may be built to convey water for purposes of water power development, irrigation or city water supply, drainage or flood control, and numerous others. While there are examples of open channels carrying liquids other than water, there exist few experimental data for such, and the numerical coefficients given here apply only to water at natural temperatures. 

Rock cuts, jagged and irregular Natural streams 0.035 0.045... 

As a rule, uniform flow is found only in artificial channels of constant shape and slope, although even under these conditions the flow for some distance may be nonuniform. But with a natural stream the slope of the bed and the shape and size of the cross section usually vary to such an extent that true uniform flow is rare. Hence the application of the equations given to natural streams can be expected to yield results that are only approximations of the truth. In order to apply these equations at all, the stream must be divided into lengths within which the conditions are approximately the same. 

In the case of artificial channels that are free from the irregularities found in natural streams, it is possible to apply analytical methods to the various problems of nonuniform flow. In many instances, however, the formulas developed are merely approximations, and we must often resort to trial solutions and even purely empirical methods. For the treatment of many types of flow, see Bakhmeteff [35],... 

The qualitative analysis of backwater scenarios has been restricted to rectangular sections of great width. These equations are, however, applicable to any channel of uniform cross section, if y0 is the depth for uniform flow andyc is the depth that satisfies Eq. (10.118). The surface profiles can even be used qualitatively in the analysis of natural stream surfaces as well, provided that local variations in slope, shape, roughness of cross section, etc., are taken into account. The step-by-step integration method for the solution of nonuniform flow problems is not restricted to uniform channels and is therefore suited to backwater computations for any stream whatever. 

The M1 scenario. This is a mild slope case. The most common case of backwater is where the depth is already above the critical and is increased still further by a dam. Referring to the specific energy equation, Eq. (10.116), as the depth increases, the velocity diminishes without any abrupt transitions, so that a smooth water surface plane is obtained. In the case of flow in an artificial channel with a constant bed slope, the backwater curve would be asymptotic at infinity to the surface for uniform flow, as noted before. But the problems that are usually of more important interest are those concerned with the effect of a dam on a natural stream and the extent to which it raises the water surface at various points upstream. 

For a natural stream, the solution is not so direct, because the form and dimensions of a cross section cannot be assumed and then the distance to its location computed. As there exist various slopes and cross sections at different distances upstream, the value of L in Eq. (10.123) must be assumed and then the depth of stream at this section can be computed by trial. 

Gustavson K, Mphlenberg F, Schliiter L. 2003. Effects of exposure duration of herbicides on natural stream periphyton communities and recovery. Arch Environ Contam Toxicol 45 48-58. 

Since these bacteria are aerobic, this scheme implies that an important function of oxygen is to provide oxic conditions for adequate respiration. These half-reactions (3 and 4) need not be in equilibrium with each other only a small amount of oxygen, enough for respiration, is necessary to drive this process. In this study, we are chiefly concerned with the reactions occurring in the effluent water after it has left the mines and has entered natural streams. 

It is for this reason that a version of the double-layer model of cation adsorption shall be used here in attempting to reconcile pH-dependent adsorption of lead on a fraction of a natural stream-bed sediment. 

Altmann, D., Stief, P., Amann, R., and de Beer, D. (2004). Distribution and activity of nitrifying bacteria in natural stream sediment versus laboratory sediment microcosms. Aquatic Microbial Ecology... 

Winding natural streams and canals in poor condition—considerable moss 0.035... 

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