Sediment chemical sediments

H. L. Windom, "Lithogenous Matedal in Marine Sediments," Chemical Oceanography, Academic Press, Inc., New York, 1976. 

Font, R. and Laveda, M.L., 1996. Design method of continuous thickeners from semibatch tests of sedimentation. Chemical Engineering Science, 51, 5007-5015. 

Precipitation involves the alteration of the ionic equilibrium to produce insoluble precipitates. To remove the sediment, chemical precipitation is allied with solids separation processes such as filtration. Undesirable metal ions and anions are commonly removed from waste streams by converting them to an insoluble form. The process is sometimes preceded by chemical reduction of the metal ions to a form that can be precipitated more easily. Chemical equilibrium can be affected by a variety of means to change the solubility of certain compounds. For e.xample, precipitation can be induced by alkaline agents, sulfides, sulfates, and carbonates. Precipitation with chemicals is a common waste stream treatment process and is effective and reliable. The treatment of sludges is covered next. 

Sediment Analysis. Sediment is the most chemically and biologically active component of the aquatic environment. Benthic invertebrate and microbial life concentrate in the sediment, a natural sink for precipitated metal forms, and an excellent sorbent for many metal species. TTie extent to which potentially toxic trace element forms bind to sediment is determined by the sediment s binding intensity and capacity and various solution parameters, as well as the concentration and nature of the metal forms of interest. Under some conditions sediment analyses can readily indicate sources of discharged trace elements. 

By far the most important ores of iron come from Precambrian banded iron formations (BIF), which are essentially chemical sediments of alternating siliceous and iron-rich bands. The most notable occurrences are those at Hamersley in Australia, Lake Superior in USA and Canada, Transvaal in South Africa, and Bihar and Karnataka in India. The important manganese deposits of the world are associated with sedimentary deposits the manganese nodules on the ocean floor are also chemically precipitated from solutions. Phosphorites, the main source of phosphates, are special types of sedimentary deposits formed under marine conditions. Bedded iron sulfide deposits are formed by sulfate reducing bacteria in sedimentary environments. Similarly uranium-vanadium in sandstone-type uranium deposits and stratiform lead and zinc concentrations associated with carbonate rocks owe their origin to syngenetic chemical precipitation. 

Parkinson D-R, Dust JM (2010) Overview of the current status of sediment chemical analysis trends in analytical techniques. Environ Rev 18(NA) 37-59... 

Runnells, D. D., 1969, Diagenesis, chemical sediments, and the mixing of natural waters. Journal of Sedimentary Petrology 39, 1188-1201. 

System 15. bottom sediments (X) sediment organisms and their biological reactions (XI). The invertebrates of bottom sediment are important in biogeochemical migration of many chemical species in aquatic ecosystems. 

System 17. bottom sediments (X) sediment organisms and their biological reactions (XI) waters (II) aquatic plants and their biological reactions (XII) atmosphere air (17a, 30, 31). The chemical interactions between aquatic and gaseous phases play an extremely important role in the composition of both water and air. These interactions determine the development of aquatic ecosystems. The example of oxygen content in the water is the most characteristic one. 

Leppanen, H. and Kukkonen, V.K. 2000, Effect of sediment-chemical contact time on availability of sediment-associated pyrene and benzo[a]pyrene to oligochaete worms and semipermeable membrane devices. Aquat. Toxicol. 49 227-241. 

The groundwater must also be treated to remove contamination. The costs of this may run as high as 160 per cubic meter. This is based on a figure of. 16 per liter for highly contaminated water. The estimate includes equipment costs and amortization. Equipment needed may include filtration, centrifuges, sedimentation, chemical treatment and any materials disposal. 

Sinking particles transport trace elements to the sediments. Once in the sediments, chemical reactions can resolubilize a significant fraction of the particulate metals. This process is termed diagenetic remobilization and is the subject of the next chapter. The resolubilized elements can diffuse across the sediment-water interface into the deep zone. 

Only a few evaporites have been found that are more than 800 miUion years old, indicating that most of the salt formed prior to this period has been recycled via uplift and weathering. No evaporites of Archean age have as yet been discovered. The oldest known chemical sediments were deposited 3.45 bybp in what is now western Australia. They appear to have precipitated as shallow-water carbonates. This suggests that sulfate concentrations during the Archean were much lower than present day, probably because of limited oxygenation of the atmosphere and ocean. 

JOHANNESSON, K.H., HAWKINS JR., D.L. Cortes, A., 2006. Do Archean chemical sediments record ancient seawater rare earth element patterns Geochimica et Cosmochmica Acta, 70, 871-890. 

Bodies of Water and the Chemical Sediments ,— The chemistry of the deposition of salts from sea-water has already been made the subject of special research, and van t Hoff s results in this field are already familiar. The deposition of calcium carbonate awaits a similar thorough study. Allied questions are the formation of dolomite, the deposition of various salts from inclosed bodies of water, the deposition of phosphate rocks, the precipitation of colloidal suspensions of clay and other substances, and the origin of the great deposits of sedimentary iron ore. 

One of the most sensitive tracers recording the composition of ancient sea water is the isotopic composition of chemical sediments precipitated from sea water. The following discussion concentrates on the stable isotope composition of oxygen, carbon, and sulfur, but in recent years other isotope systems have been included such as Ca (De La Rocha and De Paolo 2000 Schmitt et al. 2003 Fantle and de Paolo 2005 Farkas et al. 2007) and B (Lemarchand et al. 2000, 2002 Joachimski et al. 2005) and Li (Hoefs and Sywall 1997). One of the fundamental questions in all these approaches is which kind of sample provides the necessary information, in the sense that it represents the ocean water composition at its time of formation and has not been modified subsequently by diagenetic reactions. 

The sample locations are shown on the map in Figure 1. Euromonding (Port of Rotterdam) and the North Sea Canal (Port of Amsterdam) are well-known polluted areas. The sites in the North Sea are situated at the end of the estuarine harbour areas, except for Noordwijk (site 6), which is a t5 ical coastal location. Two relatively clean sites, the Oesterput in the Eastern Scheldt estuary (site 14) and Ussehneer near Enkhuizen (site 12), were also sampled and used as saltwater and freshwater reference sites respectively. In the Port of Rotterdam transect the salinity gradient is continuous whilst in the Port of Amsterdam transect the salinity gradient is interrupted and more complex due to canalisation. The numbers of the sampling sites correspond with the site numbers reported previously for the results of the chemical sediment and flounder liver analyses (De Boer 2001). The transects were sampled from 19 to 26 September 1996. 

This thesis focuses on the applicability of in vitro and in vivo bioassays and bioindicators as tools for evaluating the effects of complex chemical sediment contaminants in the process of deciding whether dredged harbour sediments can be safely disposed of at sea. To this end three objectives have been defined ... 

Aerobic microbial oxidation Beggiatoa mat Coastal marine sediment Coastal marine sediment Estuarine sediments Thiobacilli in water of L. Faro S oxidation in water of Big Soda L, Chemical oxidation by oxygen0 Black Sea Calculated Hypolimnetic Sediment... 

With waters containing large amounts of coarse, easily settled, suspended matter, sedimentation (plain sedimentation) is ofien of value in reducing the load on the filters and effecting economies in amounts of chemicals used for coagulabon, Sedimentation may be earned out in sedimentation tanks or basins or in reservoirs. Detention periods vary over a wide range—from a few hours up to one or more months. 

Belzile, N. and Lebel, J. (1986) Capture of arsenic by pyrite in near-shore marine sediments. Chemical Geology, 54(3-4), 279-81. 

Polizzotto, M.L., Harvey, C.F., Li, G. et al. (2006) Solid-phases and desorption processes of arsenic within Bangladesh sediments. Chemical Geology, 228(Special Issue 1-3), 97-111. 

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