Trace elements occurrence

Comparative Media Evaluation. Table 4 is a summary of trace element occurrences for water, sediment, fish and rocks in Oregon as compared with concentrations measured elsewhere in the world. Details of the comparison parameters are provided in the footnotes to Table 4. The table indicates that no excessively high concentrations of potentially toxic trace elements exist in Willamette River water relative to "uncontaminated sites. 

Table 4. Summary of Trace Element Occurrences for Water, Sediment, Fish and Rocks in Oregon and Elsewhere with Comparisons...

BGS (British Geological Survey) (1989) Trace Element Occurrence in British Groundwaters. Research Report SD/89/3, British Geological Survey (BGS), Key worth. 

A final section draws attention to the human alteration of river chemistry during the past hundred years, particularly for Na, K, Cl, and it is important to differentiate anthropogenic from natural inputs. Trace element occurrence is covered by Gaillardet (see Chapter 5.09). 

Occurrence. Indium is widely spread in nature, generally in very low concentrations (0.1 ppm, earth s crust). Indium is present as a trace element in many minerals, such as sphalerite. 

Table 5.61 summarizes synthetically the observed occurrences of various trace elements in feldspars, based mainly on the indications of Smith (1983). 

Pets, L. 1999. Probable modes of occurrence of trace elements in oil shale ashes of power plant. Oil Shale, 16, 464-472. 

Wang, J., Sharma, A. Tomita, A. 2003. Determination of the modes of occurrence of trace elements in coal by leaching coal and coal ashes. Energy and Fuels, 17, 29-37. 

Davidson, R. M. 2000. Modes of Occurrence of Trace Elements in Coal. IEA Coal Research, London, pp. 36. 

This circular reviews the occurrence of 34 trace elements in coal and the occurrence and distribution of chlorine, phosphorus, titanium, and manganese, which are not considered rare in coal. Separate chapters are devoted to germanium, gallium, and uranium in coal. 

This review contains sections on the occurrence of 13 trace elements in coals and a summary of trace element distribution in coals. 

There is, therefore, much interest in determining the concentration of various trace elements in coal. The Illinois State Geological Survey recently concluded a study of the occurrence and distribution of potentially volatile trace elements in coal sponsored by the U. S. Environmental... 

Nickel has long been suspected to be an essential trace element for living organisms, but the identification of its functions in molecular terms is relatively recent. The first nickel protein to be identified was urease (urea ammonia hydrolase) (i). This was demonstrated 49 years after the original isolation and crystallization of the enzyme by Sumner (2). This enzyme is of widespread occurrence, and the specific requirement for nickel explains many of the effects of nickel deficiency in plants (3, 4). 

The occurrence of sulfide strongly affects the speciation and solubility of numerous trace elements. Solid sulfide phases may be precipitated, and dissolved sulfide and polysulfide complexes may be formed (21-23). The influence of sulfide on trace... 

The oxidation state of redox-sensitive trace elements such as As(III)/ As(V) and Cr(III)/Cr(VI) is thus affected by the redox conditions, as indicated by the occurrence of major reduced species. Kinetic control of the redox reactions plays an important role. As(III) appears in the anoxic hypolimnion in agreement with the thermodynamic redox sequence together with Fe(II) and sulfide, although the reduction of As(V) is incomplete under these conditions. Whereas the reduced As(III) species can clearly be observed in the... 

Cases involving human toxicity from heavy trace elements, such as Pb. Hf . As. and Cd. are much more common bul are almost exclusively traced to accidental contamination rather than true natural occurrences. 

Kopp JF. 1969. The occurrence of trace elements in water. Proc Univ MO Annu Conf Trace Subst Environ Health. 3 59-73. 

Apodaca, L.E., Driver, N.E. and Bails, J.B. (2000) Occurrence, transport, and fate of trace elements, blue river basin, Summit County, Colorado an integrated approach. Environmental Geology, 39(8), 901-13. 

Diehl, S.F., Goldhaber, M.B. and Hatch, J.R. (2004) Modes of occurrence of mercury and other trace elements in coals from the warrior field, Black Warrior Basin, northwestern Alabama. International Journal of Coal Geology, 59(3-4), 193-208. 

Huggins, F.E. and Huffman, G.P. (1996) Modes of occurrence of trace elements in coal from XAFS spectroscopy. International Journal of Coal Geology, 32(1-4), 31-53. 

Ren, D., Xu, D. and Zhao, F. (2004) A preliminary study on the enrichment mechanism and occurrence of hazardous trace elements in the Tertiary lignite from the Shenbei coalfield, China. International Journal of Coal Geology, 57(3-4), 187-96. 

Taylor, H.E., Antweiler, R.C., Roth, D.A. et al. (2001) The occurrence and distribution of selected trace elements in the Upper Rio Grande and tributaries in Colorado and northern New Mexico. Archives of Environmental Contamination and Toxicology, 41, 410-26. 

Wagner, N.J. and Hlatshwayo, B. (2005) The occurrence of potentially hazardous trace elements in five Highveld coals, South Africa. International Journal of Coal Geology, 63(3-4), 228-46. 

Recent reviews on chemical speciation are published by e.g. Stumm and Brauner (1975), Florence and Batley (1980) and Leppard (1983) sometimes, with special reference to metal-organic interactions (Mantoura, 1982) or complexation in natural waters (Kramer and Duinker, 1984b). Bruland (1983) summarized the distribution and behaviour of trace elements in ocean waters. The occurrence of certain species is largely dependent on the environmental conditions. There exists a strong competition of trace metals with H+ or major cations like Ca2+ and Mg2+ in seawater, but also with other trace metals which might form more stable complexes with the ligand in question on the other side, many potential ligands or chelators compete for one trace element. 

C60 has not yet been detected in primitive meteorites, a finding that could demonstrate its existence in the early solar nebular or as a component of presolar dust. However, other allotropes of carbon, diamond and graphite, have been isolated from numerous chondritic samples. Studies of the isotopic composition and trace element content and these forms of carbon suggest that they condensed in circumstellar environments. Diamond may also have been produced in the early solar nebula and meteorite parent bodies by both low-temperature-low-pressure processes and shock events. Evidence for the occurrence of another carbon allotrope, with sp hybridized bonding, commonly known as carbyne, is presented. 

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