Seawater barium concentration

Polarography has also been applied to the determination of potassium in seawater [535]. The sample (1 ml) is heated to 70 °C and treated with 0.1 M sodium tetraphenylborate (1 ml). The precipitated potassium tetraphenylborate is filtered off, washed with 1% acetic acid, and dissolved in 5 ml acetone. This solution is treated with 3 ml 0.1 M thallium nitrate and 1.25 ml 2M sodium hydroxide, and the precipitate of thallium tetraphenylborate is filtered off. The filtrate is made up to 25 ml, and after de-aeration with nitrogen, unconsumed thallium is determined polarographically. There is no interference from 60 mg sodium, 0.2 mg calcium or magnesium, 20 pg barium, or 2.5 pg strontium. Standard eviations at concentrations of 375, 750, and 1125 pg potassium per ml were 26.4, 26.9, and 30.5, respectively. Results agreed with those obtained by flame photometry. 

Early work was based on concentrating the radium from the seawater sample by adding barium and coprecipitating with barium sulfate. This concentration procedure has been replaced by one involving the extraction of radium from seawater on acrylic fibre coated with manganese dioxide [19,20] (Mn fibres). By use of this technique, volumes of 200-2000 litres may be sampled routinely. 

Pillai and Ganguly [286] have concentrated the nucleic acids from seawater by adsorption on homogeneously precipitated barium sulfate, then hydrolysed with 0.02 M hydrochloric acid and analysed for the constituents. 

Average Concentrations of Rubidium, Strontium and Barium in Seawater (3)... 

The distribution coefficients determined for strontium (at U c) and for barium (at ll C for 3 0 < -log < U.5 and at for all other values of -log Ci) are summarized in Figure 2. Due to the relatively high concentration of strontium in seawater (and hence the relatively high concentration initially in the clay-phase) only limited data for strontium were obtained. The distribution coefficients which were obtained appear to behave similarly to the respective coefficients for barium but are somewhat smaller in magnitude. For solution-phase concentrations on the order of 10"3 mg-atom/ml, the barium coefficients appear to be between 10 and 100 ml/gm, and for solution-phase concentrations on the order of 10 ", the barium coefficients appear to be on the order of 10, as was expected. Furthermore, the coefficients for both strontium and barium are generally consistent with the corresponding data obtained for similar oceanic sediments and related clay minerals found within the continental United States (6,758 13) The... 

Not only are accurate data for trace metals in rivers sparse, there are complications that exist at the river-sea interface. The increase in salinity occurring at the river-sea water interface, with its concomitant increase in the concentrations of the major seawater cations, can lead to flocculation and sedimentation of trace metals such as iron (Boyle et al., 1978 Sholkovitz and Copeland, 1983) or to desorption from suspended riverine particles of trace metals such as barium (Edmond et al., 1978). In organic-rich rivers a major fraction of dissolved trace metals can exist in physiochemical association with colloidal humic acids. Sholkovitz and Copeland (1983) used product-mode mixing experiments on filtered Scottish river water, and observed that iron removal was almost complete due to the flocculation of strongly associated iron-humic acid colloids in the presence of the increased... 

The biological pump influences, to varying degrees, the distribution of many elements in seawater besides carbon, nitrogen, phosphorus, and silicon. Barium, cadmium, germanium, zinc, nickel, iron, selenium, yttrium, and many of the REEs show depth distributions that very closely resemble profiles of the major nutrients. Additionally, beryllium, scandium, titanium, copper, zirconium, and radium have profiles where concentrations increase with depth, although the correspondence of these profiles with nutrient profiles is not as tight (Nozaki, 1997). 

Barium sulf ate scales form in situations where production of reservoir fluids causes mixing of incompatible aqueous fluids. For example, in North Sea (UK) offshore hydrocarbon production, seawater is injected into reservoirs to displace oil, and maintain reservoir pressure. When seawater, high in sulfate, contacts reservoir fluids that have high concentrations of Ba +, BaS04 scales result. Barium sulfate is an especially intractable scale mineral because of its physical hardness and very low solubility (i-6). 

The strontium content in the lithosphere is ca. 370 mg/kg (i.e., ppm wt.), but, owing to its chemical reactivity, the metal does not occur free in nature. The chief strontium containing minerals are the sulfate celestite or celestine [SrSO, orthorhombic] and the carbonate strontianite [SrCOj, orthorhombic], but strontium traces can also be found in calcium and barium-containing minerals. Nevertheless, strontium minerals rarely concentrate in large ore deposits, and the chief ore is only represented by celestite because there are no known economically workable strontianite deposits. However, strontium occurs widely dispersed in seawater and in igneous rocks as a minor constituent of rock-forming minerals. 

Transfer about 50 mL of a seawater sample into a 600 mL beaker covered with a watch-glass and weigh to + 0.02 g. Dilute with 235 mL of distilled water and add 10 mL of saturated picric acid solution and 5 mL of concentrated hydrochloric acid. Heat the solution to about 90 °C, taking care to prevent boiling and add 10 mL of a hot 10 % solution of barium chloride while stirring vigorously. Allow the precipitate to settle whilst the solution is kept hot. 

Sulphate concentrations may also be determined accurately by potentiometric back-titration of excess Ba + with a mercury electrode following the precipitation of BaS04 Mucci, 1991). The seawater sample is freed from most seasalt cations with an ion-exchange-column. Then the eluate is reacted with an excess of barium, and after filtration of precipitated BaS04, the solution is titrated potentiometrically with an EGTA solution (see also Section 11.2) to the endpoint. The method applies over a wide range of salinities and sulphate concentrations in 1 mL or less of seawater and marine pore water samples, however, it is somewhat less precise (c.v. of about 0.6 %) than the simple gravimetric procedure described. 

The Michigan Basin brines very low pH helps to explain their ability to leach and react with other rocks, as is indicated by their high contents of strontium, barium and other metals, although much of the Sr and Ba probably came from the reaction with calcite. Geothermal water also probably mixed with some of the formations, as indicated by the variable presence of iodine, boron, lithium, cesium, rubidium and other rare metals. With most of the brines, the calcium concentration is somewhat higher than its magnesium equivalent in seawater end liquor from a potash deposit, and the potassium a little lower. Wilson and Long (1993) speculated that this occurred by the conversion of the clays kaolinite and smectite to illite ... 

Source water quality has a key influence on the suitability of using seawater desalination for industrial water supply. The water quality parameters that have a significant impact on the desalination system design, operations, and cost of water production are the concentration of TDS, chlorides, turbidity, silt density index (SDl), organic content, nutrients, algae, bacteria, temperature, boron, sUica, barium, calcium, and magnesium. 

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