Barium distribution

One should not conclude that trace analysis of water systems is a hopeless undertaking. It is possible to get results which are consistent and which seem to be reliable, but it does involve much effort and attention. One does not get satisfactory results without careful, critical appraisal of all conceivable variables involved. An example of the approach which is necessary is the recent work by Andersen in our laboratory on strontium and barium distribution in the Atlantic Ocean (I, 2). 

Studies in humans indicate that barium distributes predominantly to the skeleton and teeth. The route of exposure is not always known, but it is presumed to be mostly oral therefore, the studies are discussed below in Section 2.3.2.2. 

Lea D. W. and Boyle E. A. (1990) Foraminiferal reconstmc-tions of barium distributions in water masses of the glacial oceans. Paleoceanography 5, 719-742. 

Fig. 6.16 Barium distribution in a Catalhoyuk house floor which reflects deposition of food...

Barium. The results of the barium analyses [Tables I-VI and (3)] show that the range of the barium content of sea water, analyzed in this work, ranges from 0.8 to 37.0 p.p.b. in the equatorial region and from <0.04 to 22.8 p.p.b. in the North Atlantic, with average values of 6.5 p.p.b. and 7.6 p.p.b., respectively. In the North Atlantic, the station at 41°33 N 50°03 W has a maximum barium content of 281 meters, minimum values at 489 meters and 1006 meters, and the barium concentration increasing below this depth to the next to highest value in the profile at 2098 meters. This distribution is similar to a North Atlantic profile constructed from the results of the barium analysis of sea water from 21 unfiltered samples collected at various locations, dates and depths reported recently (22) and a profile near Bermuda (9). There is little correlation with the profile of the barium distribution at the indicated locations with that of a station at 41°33 N 29°43 W. In the former station a maximum barium concentration was observed at 93 meters with no detectable amounts below 683 meters to 1579 meters. 

On Saturday, December 17, the day after Hahn stormed the revenue office on behalf of Meitner s furniture, he and Strassmann carried out a further heroic check. They mixed Ra-III with dilute mesothorium and precipitated and fractionated the two substances together. Then the chemical evidence was certain, whatever it might mean in physical terms the mesothorium remained in solution when the barium carrier crystallized out but Ra-III went off with the barium, distributing itself uniformly and indi-visibly throughout the small pure crystals. Hahn wrote an enthusiastic note in his pocket appointment book to mark the day Exciting fractionation of radium/barium/mesothorium. ... 

Neanderthal children were weaned when they were a year old. .. C. Austin et al. Barium distributions in teeth reveal early-life dietary transitions In primates. 2013. Nature 498(7453), p. 216. DOl 10.1038/naturel2169. 

Calcium—Silicon. Calcium—silicon and calcium—barium—siUcon are made in the submerged-arc electric furnace by carbon reduction of lime, sihca rock, and barites. Commercial calcium—silicon contains 28—32% calcium, 60—65% siUcon, and 3% iron (max). Barium-bearing alloys contains 16—20% calcium, 9—12% barium, and 53—59% sihcon. Calcium can also be added as an ahoy containing 10—13% calcium, 14—18% barium, 19—21% aluminum, and 38—40% shicon These ahoys are used to deoxidize and degasify steel. They produce complex calcium shicate inclusions that are minimally harm fill to physical properties and prevent the formation of alumina-type inclusions, a principal source of fatigue failure in highly stressed ahoy steels. As a sulfide former, they promote random distribution of sulfides, thereby minimizing chain-type inclusions. In cast iron, they are used as an inoculant. 

Zirconium occurs naturally as a siUcate in zircon [1490-68-2] the oxide baddeleyite [12036-23-6] and in other oxide compounds. Zircon is an almost ubiquitous mineral, occurring ia granular limestone, gneiss, syenite, granite, sandstone, and many other minerals, albeit in small proportion, so that zircon is widely distributed in the earth s cmst. The average concentration of zirconium ia the earth s cmst is estimated at 220 ppm, about the same abundance as barium (250 ppm) and chromium (200 ppm) (2). 

Barium [7440-39-3] Ba, is a member of Group 2 (IIA) of the periodic table where it Hes between strontium and radium. Along with calcium and strontium, barium is classed as an alkaline earth metal, and is the densest of the three. Barium metal does not occur free in nature however, its compounds occur in small but widely distributed amounts in the earth s cmst, especially in igneous rocks, sandstone, and shale. The principal barium minerals are barytes [13462-86-7] (barium sulfate) and witherite [14941-39-0] (barium carbonate) which is also known as heavy spar. The latter mineral can be readily decomposed via calcination to form barium oxide [1304-28-5] BaO, which is the ore used commercially for the preparation of barium metal. 

Barite [13462-86-7], natural barium sulfate, BaSO, commonly known as barytes, and sometimes as heavy spar, tiU, or cawk, occurs in many geological environments in sedimentary, igneous, and metamorphic rocks. Commercial deposits are of three types vein and cavity filling deposits residual deposits and bedded deposits. Most commercial sources are replacement deposits in limestone, dolomitic sandstone, and shales, or residual deposits caused by differential weathering that result in lumps of barite enclosed in clay. Barite is widely distributed and has minable deposits in many countries. 

The average adult human body contains 22 mg Ba, of which 93% is present in bone (47). The remainder is widely distributed throughout the soft tissues of the body in very low concentrations. Accumulation of barium also takes place in the pigmented parts of the eyes. 

Figure 8.10 Predicted and measured (averaged) crystal size distributions for barium sulphate (Re = 30,000, C o = 0.015 kmol Cbo = 1-500 kmol Rii = 1).

For code R8 it commences with a solid with the help of AFNOR standards NF T 20-035 . Handling consists in preparing mixtures of variable compositions of an oxidant to be classified as cellulose. Both substances have to have a definite particle size distribution. The composition which gives the fastest combustion on a moulding of the mixture at a distance of 20 cm is established. This speed is compared with the one of the mixture used as a reference, which has an imposed composition of barium nitrate and cellulose. If the combustion speed of the particular substance is higher than that of the reference, it will bear R8. 

Endoscopic approaches are typically used and may include colonoscopy, proctosigmoidoscopy, or possibly upper GI endoscopy in patients with suspected CD. Endoscopy is useful for determining the disease distribution, pattern and depth of inflammation, and to obtain mucosal biopsy specimens. Supplemental information from imaging procedures, such as computed tomography (CT), abdominal x-ray, abdominal ultrasound, or intestinal barium studies may provide evidence of complications such as obstruction, abscess, perforation, or colonic dilation.3... 

Yttrium—barium—copper oxide, 3 343, 369 Yttrium—barium—copper—oxide ceramics superconductivity in, 5 603-605 Yttrium distribution, in mineral sources, 14 637t... 

Stalder, M. Rozendaal, A. 2005. Distribution and geochemical characteristics of barite and barium-rich rocks associated with the Broken Hill-type Gamsberg Zn-Pb deposit, Namaqua Province, South Africa. South African Journai of Geoiogy, 108, 35-50. 

Beyond iron lies a first population of so-called s-process nuclei, which includes among others barium and lead. This population has an abundance distribution with peaks around mass numbers 87, 138 and 208. These nuclei are produced by slow neutron capture, referred to as the s process. A second population, slightly shifted from the first, including gold, platinum and uranium, is imputed to the process of rapid neutron capture, referred to as the r process. 

---