Turbidity flows

Most of the solid matter found in the sediments of the open ocean was transported to the seafloor via the slow sinking of small particles through the water column. This process is termed pelagic sedimentation. Other types of sedimentation are discussed in the next chapter and include turbidity flows, hydrothermal deposits, and deposition of large animal carcasses, e.g. whales, squid, and fish. 

Virtually over its entire extension, the continental slope of the Black Sea is dissected by numerous faults and underwater canyons. These canyons, confined to tectonic dislocations (fracture zones or grabens), are later transformed by turbidity flows, which use them as channels for the transport of mineral particulate matter from the near-shore zone to the foot of the continental slope. At the places of discharge of turbidity flows, alluvial fans are formed, which may be cut by runoff channels [10]. 

Wave action, currents, and gravity processes define the particular features of the redistribution of the bottom sediments, their zonation, and the existence of coarse-grained matter in the near-shore zone subjected to wave action, and of the fine-grained fraction beyond this zone at greater depths. Unusual features in the bottom sediment distribution may be caused by the activity of turbidity flows and landslide processes, which distort the general regularities of the lithological zonation. 

The continental slope represents a transit zone of the sediment fluxes supplied in the form of detrital matter from the rivers and the products of abrasion, as well as the sediments carried by turbidity flows. The continental slope is covered with compacted clayey oozes (grain-size fractions of 0.001-0.01 mm). At selected places on steeper parts of the slope, remains of mollusk fauna such as shells of Dreissena rostriformis have been encountered. At sites with gentle sloping, they are overlain by the Holocene and recent sediments [11]. 

A special type of sediment is formed at the foot of the continental slope of the Black Sea in the zone of discharge of turbidity flows. In the western part of the sea and in the Crimean sector, the sediments of the base of the continental slope are represented by finely stratified biogenic or organogenic oozes. In the eastern and southern parts of the basin, a terrigenous component of clayey sediments becomes more significant [6,14]. 

The escape of the trace elements back to the water column could be prevented by burial, thereby preserving a sediment record. However, such fossilized enrichments might be difficult to detect the surface sediments commonly have extremely low densities, and thus comprise very little material. On burial, we can expect that any enrichment will be strongly diluted by the normal underlying and overlying sediment. There are, however, some potential examples in the sediment of Lake Baikal (Boyle et al., 1998), where frequent small turbidity flows provide an ideal mechanism for burying the surface enrichments. 

Submarine flow slide initiated landslides on HoKsh and shore and turbidity flows traveling several Hendron... 

Pantin, H.M. 1979. Interaction between velocity and effective density in turbidity flow Phase-plane analysis, with criteria for autosuspension. Marine Geology, 31(1/2) 59-100. 

Kishan B. Mathur and Norman Epstein, Dynamics of Spouted Beds W. C. Reynolds, Recent Advances in the Confutation of Turbident Flows R. E. Peck and D. T. Wasan, Drying of Solid Particles and Steets... 

Eanning friction at transition between laminar and turbident flow Laminar component of fanning friction factor... 

Foam rheology has been a challenging area of research of interest for the yield behavior and stick-slip flow behavior (see the review by Kraynik [229]). Recent studies by Durian and co-workers combine simulations [230] and a dynamic light scattering technique suited to turbid systems [231], diffusing wave spectroscopy (DWS), to characterize coarsening and shear-induced rearrangements in foams. The dynamics follow stick-slip behavior similar to that found in earthquake faults and friction (see Section XU-2D). 

The trend in the use of deep bed filters in water treatment is to eliminate conventional flocculators and sedimentation tanks, and to employ the filter as a flocculation reactor for direct filtration of low turbidity waters. The constraints of batch operation can be removed by using one of the available continuous filters which provide continuous backwashing of a portion of the medium. Such systems include moving bed filters, radial flow filters, or traveling backwash filters. Further development of continuous deep bed filters is likely. Besides clarification of Hquids, which is the most frequent use, deep bed filters can also be used to concentrate soflds into a much smaller volume of backwash, or even to wash the soflds by using a different Hquid for the backwash. Deep bed filtration has a much more limited use in the chemical industry than cake filtration (see Water, Industrial water treatment Water, Municipal WATERTREATiffiNT Water Water, pollution and Water, reuse). 

Both vacuum and pressure filters are used. Turbidity is more easily removed by vacuum filters, usually at 85% efficiency. Flow rates are low, ca 4 mL/(cm -min) [1 gal/(ft -min)] these filters are not practical for treating large volumes. 

The common indices of the physical environment are temperature, pressure, shaft power input, impeller speed, foam level, gas flow rate, liquid feed rates, broth viscosity, turbidity, pH, oxidation-reduction potential, dissolved oxygen, and exit gas concentrations. A wide variety of chemical assays can be performed product concentration, nutrient concentration, and product precursor concentration are important. Indices of respiration were mentioned with regard to oxygen transfer and are particularly useful in tracking fermentation behavior. Computer control schemes for fermentation can focus on high productiv-... 

Water from cooling tower pump suction, pH 8.6-8.8, pressure 20-30 psi (140-210 kPa), flow 2-5 ft/s (0.2 to 1.5 m/s). Dispersant, 1-3 ppm tolyltriazole, sodium hypochlorite 2 hr/day to 0.8 free residual chlorine 0.6-0.8 ppm total zinc and 0.1-0.2 ppm soluble zinc. Free chlorine maintained at 1 ppm for 5 consecutive days/month during the summer. Chemical treatment started after 2 years of no treatment. Water conductivity -612 ( imhos/cm), turbidity 27 NTU (nephelometric turbidity units), chloride 110 ppm, sulfate 50 ppm, carbonate alkalinity (CaCOa) 27 ppm, bicarbonate alkalinity (CaCOs) 118 ppm... 

Biostat. This is also known as a turbidostat. It is a system where cell growth is controlled and remains constant while the flow rate of fresh media does not remain constant. Cell density is controlled based on set value for turbidity, which is created by the cell population while fresh media is continuously supplied. A turbidostat is shown in Figure 5.8. 

Operating near the washout point maximizes the production rate of cells. A feedback control system is needed to ensure that the limit is not exceeded. The easiest approach is to measure cell mass—e.g., by measuring turbidity— and to use the signal to control the flow rate. Figure 12.5 shows how cell mass varies as a function of t for the system of Examples 12.7 and 12.8. The minimum value for t is 2.05 h. Cell production is maximized at F=2.37h. 

In the one phase region, when the sample was seen to flow easily, it was said that the system was still a sol. When the meniscus was seen not to deform under it own weight, the system was considered a gel. The sol-gel transition was taken at the onset of meniscus deformation when the tube is held horizontal. Syneresis and precipitation were detected by the presence of water at the gel surface or by the existence of large turbid aggregates which could be centrifugated. 

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