Seawater element contents

Electro-active labile metal contents have also been measured by using a combination of electro-deposition and analysis by graphite furnace AAS (Batley and Matousek, 1977). Metals (e.g. Pb, Co, Ni, Cr from seawater) are plated on to a short graphite tube by application of a suitable potential. At the end of the electrolysis period, the graphite cell (plus pre-concentrated metal) is placed in an electro-thermal atomiser attached to an AAS spectrometer, and the element content determined. 

The wide range of 8180 values for post-Mississippian Zone 5 cements reflects, in part, precipitation of these cements at elevated temperatures. The trace element contents indicate little seawater influence on water chemistry. The values are variable but intermediate and suggest intraformational or extraformational cement carbon sources owing to pressure solution in conjunction with stylolitization during progressive burial of the formation to a depth of about 1000 m (Meyers and Lohmann, 1985 Moore, 1989). 

Drinking water and seawater (Halifax), water and biological CRMs Cd Co Cu Hg Mn Th U V Zn Precipitate with TAN, cupferron and APDC in PE irradiation vial. [SEP/CONC] Irradiate in reactor, determine elemental contents using different schemes of irradiation, decay and counting [SEP/CONC-INAA] [SEP/CONC- INAA] Rao and Chatt (1993)... 

Zinc, like most metals, is found in all natural waters and soils as well as the atmosphere and is an important trace element in plant and animal life (see Mineral nutrients). Rocks of various kinds contain 20—200 ppm zinc and normal soils 10—30 ppm (average ca 50 ppm) in uncontaminated areas. The average zinc content of coal is 33 ppm. Seawater contains 1—27 )-lg/L (median ca 8 p.g/L), and uncontaminated freshwater usually <10 / g/L. 

Orren [663] used atomic absorption spectrometry to determine these elements in seawater in both their soluble and insoluble forms. The alkali metals are determined directly, but the other elements are first concentrated by solvent extraction. The particulate matter content is derived by dissolving the membranes used to filter the sample and determine the metals in the resulting solution. For organic standards of known metal content, the efficiency of the technique was almost 100%. 

Because of their role as an elemental sink, the formation and weathering of evaporites has the potential to affect the salinity of seawater. This can in turn alter climate, because the heat capacity of seawater is a function of its salt content. Changes in the salt content of seawater also have the potential to affect survival of marine biota, particularly the calcifiers. 

Because of its high organic content, the marine snow acts as a microhabitat that supports enhanced rates of heterotrophic microbial activity. The associated nutrient remineralization causes the seawater within and aroimd the marine snow to be characterized by elevated nitrogen and phosphorus concentrations and low levels of O2. The importance of these suboxic and anoxic microzones to the marine cycling of the biolimiting elements is unknown but potentially significant. 

There are three naturally occurring isotopes, 39K through 41K, of which 40K is radioactive with a half-life of 1.3 109 years. Tn ordinary potassium, this isotope represents only 0.0119% of the content. There are four other known isotopes, all radioactive. 33 K and 42K through 44K, all with relatively short half-lives measured in minutes and hours. In terms of abundance, potassium ranks seventh among the elements occurring in the earth s crust. In terms of content in seawater, the element ranks eighth, with an estimated 1,800,000 tons of potassium per cubic mile (388,000 metric tons per cubic kilometer) of seawater, First ionization potential 4,339 eV ... 

Zinc ranks 27th in order of abundance of the chemical elements in the earth s crust, an estimated 0.004% content of igneous rocks on an average basis. Tt is estimated that a cubic mile of seawater contains about 48 tons of zinc. First ionization potential 9.39L eV second, 17.89 eV. Oxidation... 

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