Sand drift

Wind velocities in winter markedly exceed the summer ones (Fig. 2d). Practically everywhere in the Aral region their mean monthly values exceed 3 ms reaching in some places even 5 ms and more, which makes these territories rather attractive in terms of small-scale wind energy development. Strong winds and loose soils -the consequence of the Aral desiccation - create a serious environmental problem as salt and sand drift from the exposed seabed in addition to transfer of chemicals that were once brought into the sea from the fields with river waters. Every year from coastal areas that were up to quite recently at the bottom of the Aral Sea the wind puts adrift more then 75,000 tons of sand and salts [5] and transports them hundreds of kilometers. This causes progressive soil salinization in the Aral Region. 

About one-fifth of the land surface of the Earth is desert. Approximately four-fifths of this desert area consists of exposed bedrock or weathered rock waste. The rest is mainly covered with deposits of sand. Bagnold (1941) recognized five main types of sand accumulations, namely, sand drifts and sand shadows, whalebacks, low-scale undulations, sand sheets and true dunes. He further distinguished two kinds of true dunes, the barkhan and the seif (Fig. 3.33a and b). 

Several factors control the form that an accumulation of sand adopts. Firstly, there is the rate at which sand is supplied secondly, there is wind speed, frequency and constancy of direction thirdly, there is the size and shape of the sand grains and fourthly, there is the nature of the surface across which the sand is moved. Sand drifts accumulate at the exits of the gaps in the landscape through which wind is channelled and are extended downwind. 

Al-Awadi J, Gemak J (1998) Sand traps for measurement of eolian sand drift rate. In Omm SAS, Misak R, Al-Ajmi D (eds) Sustainable development of arid zones assessment, vol 1, pp 177-188... 

Erosion of a landfill by wind is generally not significant in terms of volume loss of material. However, effects like dust and sand drift can be annoying, detrimental to equipment, structures, industrial processes and crop (abrasiveness) or even hazardous to safety and health (low visibility, respiratory distress) of construction workers on the reclaimed area and drivers, residents and other people downwind of the fill area (see Figure 10.5). 

For fill material on those parts of the reclamation where the delivery height is reached measures shall be taken in case the top layer dries up in order to prevent discomfort caused by dust and sand drift until the time of handover. 

The results of simulation have been confirmed by determination of Fe traces in quai tz sand, Cu and Mo in flotation tails and Ag in waste fixing waters on BRA-17-02 analyzer based on X-ray gas-filled electroluminescent detector and on BRA-18 analyzer based on Si-drift detector. The results of the simulation conform satisfactory with the experimental data in the mentioned cases the optimum filtration results in 2 to 5 times lowering of the detection limit. 

Dr. Kellogg, who approved the condemnation on March 30. Among the items discarded from the Hall collection were "minerals," "shot," "cross bar ," "quartzite," "iron pyrites," and "quartz rock," as well as "pebbles," "sand stone rock," "one lot sea shells," "drift wood," "plumbago used by natives," and "rib of spotted seal."... 

If the drift-weed were to be burnt to a loose ash, it would furnish 25 to 30 lbs. of iodine per ton in practice, it rarely contains more than 12 lbs. per ton. The low yield is due to faulty treatment in calcination-—e.g. (i) burning at too high a temp, which causes the volatilization of part of the iodine, and the fusion or fluxing of the ash with sand and pebbles and (ii) imperfect protection of the kelp-ash from the weather whereby some of the soluble iodides are washed out by rain. High temp, burning also reduces some of the sulphates to sulphides, which later causes a high consumption of acid per unit of iodine. 

The high percent of unaccounted spray is likely due to filtration of the spray by foliage, and not to drift or evaporation. The effect was pronounced in the Ocala sand pine, a more densely foliated species than the slash pine. Dense foliage acts as fibers in a filter. As the number of fibers increase there are fewer open spaces for drops to penetrate without colliding with a fiber, in this case a needle. As the foliage collects drops at the upper crown there are fewer available to the lower crown levels. These results suggest that pines, even with their sparse foliage compared to spruce and fir, are efficient collectors of spray drops. 

Occurrence and History.—Osmium occurs in nature alloyed with iridium as iridosmine or osmiridium, which is found as irregular flattened grains and, more rarely, as hexagonal prisms. It has a metallic lustre, tin-white to light steel-grey in appearance hardness 6-7 density 19-3 to 21-12.1 It occurs in Choco, South America in the Urals in auriferous and other drifts in New South Wales in auriferous beach-sands of North California and also in gold washings of certain Canadian rivers.1... 

During the aquatic phase plants are detached from the sediments and drift with the current. They contribute to the carbon pool of the main channel of the Amazon River and also accelerate the colonization of newly created open areas formed by the deposition of sediments. Quick colonization creates a range of different stages of allogenic succession in the floodplains. The velocity of the successional process will depend upon the stability of the habitat. Isolated floodplain lakes, where deposition rates of sediments are small, show a slow but gradual colonization process while, processes on sand bars and mud flats in the river channel are more dynamic and often reversible (Junk and Piedade 1997). 

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