Coral deposition

Corals deposit skeleton below the basal epidermis. Typically, corals deposit one high-density and one low-density band of skeleton each year. The high-density band has thicker skeletal elements than the low-density band. Each band is often composed of several finer bands called dissepiments, deposited directly at the base of the coral tissue. At discrete intervals, the polyp presumably detaches from the dissepiment, and begins to lay down a new skeletal dissepiment. Some evidence suggests that dissepiments may form on a lunar cycle. 

Bridge foundations are often constructed in difficult ground conditions such as landslide areas, hq-uefiable soil, collapsible soil, soft and highly compressible soil, swelling soil, coral deposits, and underground caves. Special foundation types and designs maybe needed under these circumstances. 

A unique condition encountered on land that has been built up from coral deposits is the presence of blowholes, fissures and caves, which augments the penetration of seawater to areas remote from the actual seashore. Knowing that seawater makes for a very extensive, uniform, low resistivity "ground bed" for cathodic protection anodes, the above condition facilitates the design of unique cathodic protection systems. 

The ocean is host to a variety and quantity of inorganic raw materials equal to or surpassiag the resources of these materials available on land. Inorganic raw materials are defined here as any mineral deposit found ia the marine environment. The mineral resources are classified generally as iadustrial minerals, mineral sands, phosphorites, metalliferous oxides, metalliferous sulfides, and dissolved minerals and iaclude geothermal resources, precious corals, and some algae. The resources are mosdy unconsoHdated, consoHdated, or fluid materials which are chemically enriched ia certain elements and are found ia or upon the seabeds of the continental shelves and ocean basias. These may be classified according to the environment and form ia which they occur (Table 1) and with few exceptions are similar to traditional mineral deposits on land. 

Aragonite. Calcium carbonate is a common deposit in shallow tropical waters as a constituent of muds, or in the upper part of coral reefs where it precipitates from carbon dioxide-rich waters supersaturated with carbonate from intense biological photosynthesis and solar heating. Deposits of ooHtic aragonite, CaCO, extending over 250,000 km in water less than 5 m deep ate mined for industrial purposes in the Bahamas for export to the United States (19). 

A major biological sink for CO9 that is often overlooked is the calcium carbonate shells of corals, molluscs, and Crustacea. These invertebrate animals deposit CaCOa in the form of protective exoskeletons. In some invertebrates, such as the sderaetinians (hard corals) of tropical seas, photosynthetic dinoflagellates (kingdom Protoctista) known as zooxanthellae live within the ani-... 

Despite the inherent problems associated with in speleothems, recent work by Beck et al. (2001) has focused attention on this topic because they demonstrated that in certain circumstances the dcp correction may be sufficiently well constrained that calibration of the radiocarbon timescale might be possible. Speleothems have an advantage over marine corals (e g., Bard et al. 1990, 1998 Edwards et al. 1993), which have been used to extend the calibration curve, because they provide continuous records and are less likely to be affected by post-depositional alteration. Beck et al. (2001)... 

Vinegar is recommended for cleaning a variety of appliances and other items that may be stained by hard water deposits. Automatic coffee makers, steam irons, dishwashers, teapots, faucet heads, and shower heads — over time, all accumulate calcium deposits from hard water. Groundwater, that is, water that travels through soil and rocks, accumulates dissolved calcium ions as a consequence of the natural weathering of minerals that contain calcium such as limestone and calcite, shells, and coral. At the same time, carbon dioxide in the air dissolves in water to form carbonate ions that combine with calcium ions to form a white solid, calcium... 

In addition to climate change, the increased atmospheric concentration of C02 is likely to have wide-spread ecological effects in various environments, since C02 is a physiologically active gas, in plants as well as animals. The acidic nature of C02 will also lead to changes in the chemistry of the ocean s surface, which is in equilibrium with the atmosphere. Once the shift in the oceanic chemical balance becomes significant, it will affect ecosystems. It has been shown, for example, that doubling C02 concentration in the atmosphere will reduce the rate of calcium carbonate deposition in coral reefs by 30-40% (Langdon et al., 2000). 

Where the waves and currents weaken, resuspended sediment settles back down to the seafloor. Given the small particle sizes of the suspended material (mostly 3 to 10 pm), redeposition can take many years. The resulting redistribution of sediments creates patches of clay, mud, and exposed rock on the continental margins. In other words, resuspension from waves and currents can cause some sediments to become reUct deposits. Hard bottoms can serve as good habitats for some members of the benthos as they promote the formation of coral reefs. For paleoceanographers, relict deposits are problematic because they represent gaps, or imconformities, in the sedimentary record. 

Platform carbonates Massive concretions of calcium carbonate in neritic sediments deposited by corals, corraUne algae and other organisms that deposit calcareous hard parts. 

J. G. Forchhammer found in 1865 that Baryta occurs both in seaweeds and in sea animals, but the ashes of seaweeds contain more of it than the corals and shells. It can even be determined directly in sea water and in the deposits of the boilers of the Transatlantic steamers (106). 

Calcium Carbonate (CaC03) Speleothem, Shell and Coral. - 3.1.1 Paramagnetic Impurities Field-swept ESE and Out-of-phase Measurements. Carbonate dissolution and the back reaction of its deposition are described as follows... 

Biological calcification processes are widely distributed in nature. They can be found in microorganisms, in plants, in the animal kingdom and in humans. Under physiological conditions, the results of mineral deposition in biological systems can be represented by the formation of bones, teeth and shell material as well as coccoliths, corals, pearls etc. The variety of biomineralisates can best be expressed by the fact that approximately 128,000 species of molluscs636 are known. The majority of them (Conchifera) form shells of different kinds of size and shape as well as of color. 

Goreau, T. F. Problems of growth and calcium deposition in reef corals. Endeavour 20, 32 (1961)... 

Goreau, T. F. The physiology of skeleton formation in corals. 1. A method for measuring the rate of calcium deposition by corals under different conditions. Biol. Bull. mar. biol. 

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