Sediments/sedimentation ocean

Species Upper Mantle Oceanic Continental Crust Crust Earth Surface Sediments Ocean Atmosphere ... 

A variety of methods have been described for the detection of tetryl in environmental samples, including air, fresh water and sea water, soil, sediment, ocean floor fauna, and explosives. Table 6-2 is a summary of several representative methods for determining tetryl in environmental media. 

Continental interiors are thought to be constructed from welded pieces of island arcs, metamorphosed sediments, oceanic plateaux and continental fragments (e.g. Hoffinan 1989). Modern-day analogues for this include the convergent zones of the Western Pacific (Hamilton 1979), and the South American-Caribbean plate boundary, where the Leeward Antilles arc is colliding with South America (Ave Lallemant 1997). To what extent these processes were occurring... 

Fig. 2. Comparison of volatile abundance data in protosolar nebula (PSN), primitive chondrites, terrestrial mantle and atmosphere (atmosphere sensu stricto, crust, sediments, oceans). Data are normalized to Ne and PSN, so that the PSN pattern is flat. The choice of Ne as a normalizing isotope is based on the observation that recycling of atmospheric neon in the mantle is limited as indicated by its isotopic composition. Data sources Mazor et al. (1970), Marty Jambon (1987), Anders Grevesse (1989), Pepin (1991), Moreira et al. (1998), Ozima et al. (1998), Marty Zimmermann (1999).

The second major section describes the characteristics of some of the major domains or "spheres" of the system. We define these subspaces as lithosphere, pedosphere, sediments, oceans, and atmosphere, and they are examined in Chapters 6 through... 

Individual chapters are devoted to tectonic processes (lithosphere), soils (pedosphere), sediments, oceans (hydrosphere), and atmosphere. Most biologists, chemists, and physicists will see most of this as new material. 

Th 1600y deep-sea sediments ocean circulation, ground-water inputs... 

Floodwater Flooded soils Freshwater sediments Ocean sediments Marsh soils... 

Deep water and sediment Ocean bottom Very slow biodegradation —... 

Sediments from the bottom of streams, rivers, lakes, estuaries, and oceans are collected with a bottom grab sampler or with a corer. Grab samplers are equipped with a pair of jaws that close when they contact the sediment, scooping up sediment in the process (Figure 7.5). Their principal advantages are ease of use and the ability to collect a large sample. 

Sinks, chemical species, or method OH, reaction with OH radical S, sedimentation P, precipitation scavenging NO, reaction with NO radical uv, photolysis by ultraviolet radiation Sr, destmction at surfaces O, adsorption or destmction at oceanic surface. 

Biogenic Ma.teria.ls, Deep ocean calcareous or siUceous oo2es are sediments containing >30% of biogenic material. Foraminifera, the skeletal remains of calcareous plankton, are found extensively in deep equatorial waters above the calcium carbonate compensation depth of 4000 to 5000 m. 

Authigenic barium sulfate or barite [13462-86-7] is found in relatively high concentrations in sediments covering active diverging oceanic plate boundaries. It occurs as rounded masses containing up to 75% BaSO or as a dispersed constituent of the sediment. Its origins are uncertain, but it is likely that it is associated with hydrothermal actions. 

In hydrological studies, the transfer of water between reservoirs is of primary interest. The magnitudes of the main reservoirs and fluxes (volume per time) are given in Figure 7. The oceans hold ca 76% of all the earth s water. Most of the remainder, ie, ca 21%, is contained in pores of sediments and in sedimentary rocks. A Httle more than 1% (or 73% of freshwater) is locked up in ice. The other freshwater reservoir of significant size is groundwater. Lakes, rivers, and the atmosphere hold a surprisingly small fraction of the earth s water. 

Fig. 12. The relationship between the mean oceanic residence time, T, yr, and the seawater—cmstal rock partition ratio,, of the elements adapted from Ref. 29. , Pretransition metals I, transition metals , B-metals , nonmetals. Open symbols indicate T-values estimated from sedimentation rates. The sohd line indicates the linear regression fit, and the dashed curves show the Working-Hotelling confidence band at the 0.1% significance level. The horizontal broken line indicates the time required for one stirring revolution of the ocean, T. ...

Most commercial marine diatomite deposits exploit accumulations resulting from large blooms of diatoms that occurred ia the oceans during the Miocene geological epoch. Diatomite sediments older than the Jurassic period are rare in the fossil record. Commercial deposits of diatomite are accumulations of the fossil skeletons, which can occur in beds as thick as 900 m in some locations (5). Marine deposits must have been formed on the bottom of protected basins or other bodies of quiet water, undisturbed by strong currents, in an environment similar to the existing Santa Barbara Channel or Gulf of California (3,6). 

Owing to the stability of the uranyl carbonate complex, uranium is universally present in seawater at an average concentration of ca. 3.2/rgL with a daughter/parent activity ratio U) of 1.14. " In particulate matter and bottom sediments that are roughly 1 x 10 " years old, the ratio should approach unity (secular equilibrium). The principal source of dissolved uranium to the ocean is from physicochemical weathering on the continents and subsequent transport by rivers. Potentially significant oceanic U sinks include anoxic basins, organic rich sediments, phosphorites and oceanic basalts, metalliferous sediments, carbonate sediments, and saltwater marshes. " ... 

This removal may also include diffusion of soluble U(VI) from seawater into the sediment via pore water. Uranium-organic matter complexes are also prevalent in the marine environment. Organically bound uranium was found to make up to 20% of the dissolved U concentration in the open ocean." ° Uranium may also be enriched in estuarine colloids and in suspended organic matter within the surface ocean. " Scott" and Maeda and Windom" have suggested the possibility that humic acids can efficiently scavenge uranium in low salinity regions of some estuaries. Finally, sedimentary organic matter can also efficiently complex or adsorb uranium and other radionuclides. 

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