Sediments/sedimentation cycle

Garrels R.M. (1988) Sediment cycling during Earth history. In Physical and Chemical Weathering in Geochemical Cycles (eds. A. Lerman and M. Meybeck), pp. 341-356. Kluwer Academic Publishers, Boston. 

Perlmutter M. A., Radovich B. J., Matthews M. D., and Kendall C. G. St. c (1998) The impact of high-frequency sedimentation cycles on stratigraphic interpretation. In Sequence Stratigraphy—Concepts and Application. Special PubU-cation 8 (eds. F. M. Gradstein, K. O. Sandvik, and... 

GLACIALLY-INFLUENCED SEDIMENT CYCLES IN THE LIME CREEK KARST, EAGLE COUNTY, COLORADO... 

The role of calcification in the cycling of carbon has been discussed in Chapter 2,1, and its importance can be gauged from calculations by Li (1972) that the ratios, by weight, of sedimentary rocks are 71 12 15 2 for shales, sandstones, carbonates and evaporites, respectively. This implies that the carbonate cycle accounts for 15% of the total sediment cycle which has been estimated to have a turnover time of 300 My. 

Rutile from Tiwest The original powder contained sand and alumina. Sand was removed by a few dispersion-sedimentation cycles. Alumina was removed with hot 1.5 M HCL... 

Some important biogenic elements, such as phosphorus,caIcium and magnesium, have their own characteristic sedimentation cycle. In this type of cycle, elements from biological systems are continuously lost due to erosion and excessive use in economic activities (e.g. phosphorus in the form of industrial fertilizers, detergents, etc.) and they axe finally stored in the sea. 

The return of such elements into the earth s biological systems is rather complex and depends on processes such as, for example, erosion. The sedimentation cycles are less perfect than others (e.g. the cycles of carbon or nitrogen) and, therefore, they are more easily disturbed by man for example, he accelerates the losses of phosphorus to such an extent that this element may become a decisive factor in the functioning of the biosphere in the future. 

By the end of the Late Carboniferous period, when the sedimentation cycle was entering its final stage, the highest paleotemperatures were recorded in the south and south-west of the region, reaching 80 °C at the top and 125 °C at the bottom of the Gedinnian sediments. The lowest temperatures were observed in the north of the region 80 C at the Ordovician bottom and 50 °C at the Silurian bottom. By the end of the Cenomanian age, the paleotemperatures rose from 100 to 125 °C at the Silurian bottom and from 80 to no °C at the Devonian. At the present time, the temperature remains at the same level, except for the north-western and south-western areas where it reaches 130-150 °C. 

Modem practice is to maintain the white water system as closed as possible, ie, as much water as is compatible with efficient machine operation is recycled. The loss of fibers and inert furnish components, particularly clay, has been gready reduced. Eiber losses, however, stiU occur into the white water, and greater economy of operation may be achieved if these fibers could be recovered. Thus, it is common to design a fiber-recovery system into the white water cycle. The three general types of save-all fiber recovery are based on filtration (qv), dotation (qv), and sedimentation (qv). If these are operated efficiendy, the net fiber loss can be less than 1%. 

Fig. 1. Natural water environments. Water links essential cycles of the atmosphere with those of the sediments.

Removal of Particulate Matter. The amount of particulate entering a cooling system with the makeup water can be reduced by filtration and/or sedimentation processes. Particulate removal can also be accompHshed by filtration of recirculating cooling water. These methods do not remove all of the suspended matter from the cooling water. The level of fouling experienced is influenced by the effectiveness of the particular removal scheme employed, the water velocities in the process equipment, and the cycles of concentration maintained in the cooling tower. 

Joly observed elevated "Ra activities in deep-sea sediments that he attributed to water column scavenging and removal processes. This hypothesis was later challenged with the hrst seawater °Th measurements (parent of "Ra), and these new results conhrmed that radium was instead actively migrating across the marine sediment-water interface. This seabed source stimulated much activity to use radium as a tracer for ocean circulation. Unfortunately, the utility of Ra as a deep ocean circulation tracer never came to full fruition as biological cycling has been repeatedly shown to have a strong and unpredictable effect on the vertical distribution of this isotope. 

It is becoming increasingly clear that, in shallow lakes which have high rates of phosphorus sediment re-cycling, bio-manipulation is an essential element of successful restoration. 

AVT Barg BD BDHR BF BOF BOOM BOP BS W BSI BTA Btu/lb BW BWR BX CA CANDUR CDI CFH CFR CHA CHF CHZ Cl CIP CMC CMC CMC COC All-Volatile treatment bar (pressure), gravity blowdown blowdown and heat recovery system blast furnace basic oxygen furnace boiler build, own, operate, maintain balance of plant basic sediment and water British Standards Institution benzotriazole British thermal unit(s) per pound boiler water boiling water reactor base-exchange water softener cellulose acetate Canadian deuterium reactor continuous deionization critical heat flux Code of Federal Regulations cyclohexylamine critical heat-flux carbohydrazide cast iron boiler clean-in-place carboxymethylcellulose (sodium) carboxy-methylcellulose critical miscelle concentration cycle of concentration... 

For Pond 3513, the cycle of 2 3 8U and 239,2 °pu concentrations in water (filtered with a 0.22y membrane) is out of phase with the cycle of plutonium concentrations in Lake Michigan. In this shallow pond, the concentrations of the two actinides peak in summer and decline in winter. An explanation for this cycle of plutonium is that photosynthetic activity depletes dissolved CO2 which results in an increase in pH and this in turn shifts the oxidation state in favor of Pu(V) which is desorbed from the sediments(26). 

The annual cycle depicted in Figure 3 could, therefore, be due to a redox cycle whose kinetics are controlled by pH, decay processes in the sediment, and temperature. 

The shallow nature of Pond 3513 makes chemical processes occurring In the sediment extremely Important. More work will be needed, however, to elucidate the redox cycle. 

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