Total Mn concentration

The total Mn concentration in Israeli soils varies from 52.6-810 mg/kg and averages 367 259.8 mg/kg (Han, 1998). The average total Co content is 9.45 4.88 mg/ kg, varying from 3.35 mg/kg in a very sandy soil to 15.9 mg/kg in alluvial soil samples (Han et al., 2002b). In soils on alluvions and derived from aeolian deposits, the Co concentration is 8 mg/kg, and soils from hard limestone contain 10 mg/kg Co. The B concentration in alluvial soils is in the range of 25-85 mg/kg, while brown isohumic soils formed on alluvions contain 25-40 mg/kg B. Mediterranean red soils on limestone are rich in B (190 mg/kg). In soils on calcareous sandstone, alluvions, and aeolian deposits, total Mo content ranges from 4.6-6 mg/kg (Aubert and Pinta, 1977). 

Profiles of total Mn concentrations indicate that the high Mn content in the settling material must be reduced within months. The Mn concentration in the top 5 mm of the sediment was only about 20% of the average Mn content of settling particles at depths of 81 m. Within 2 years the Mn con-... 

Figure 5. Total Mn concentration in three sediment cores from the deepest site of Lake Sempach (86-m depth). Arrows at the top indicate the average Mn concentration in settling material at depths of 20 and 81 m. The time scale is calculated from 137Cs dating and is valid for the two cores from 1991 only. Key , concentrations in a core from 1988 Q and +, concentrations in two cores from...

From these characterizations, a picture of the Pd-Mn samples can be given. They are made up of both alloy particles, the size of which is about 5 nm and of small MnOx particles (s 1 nm) on the silica support. The Mn content in the bulk of the alloy particles depends on the total Mn concentration in the material and significant segregation of Mn occurs on the outermost layer of the bimetallic particles. 

The map of total Mn concentrations obtained by Synchrotron XRF is presented in Fig. 4(a). Relative concentrations are presented with lighter colours indicating higher metal concentrations. As for TOF-SIMS, there is clearly a higher relative content of Mn at the soil-root interface. Similar results were also obtained for other metals (e.g. Cu and Fe) (Naftel et al, 2002). 

In Fig. 5 we have gathered the experimental data on the total Mn concentration in the form of a first-order plot. The experiments carried out in the presence of silica (U30, U31 and U34) give rise to a linear relationship in Fig. 5, which supports the idea that the overall precipitation process in the presence of silica can be described by first-order kinetics. For experiment U33 (no carrier), too, a linear plot is obtained, but we hesitate to conclude from this that the precipitation kinetics are first-order in this case. This hesitation arises from (i) the low levels of manganese conversion attained in experiment U33, and (il) the linear relationship obtained in Fig. 4 for this experiment, which suggests zero-order kinetics. 

Kase and Horiuchi (1996) obtained a large number of analytical data on sphalerites from sixteen Besshi-type deposits, mainly at Besshi and its vicinity, Hitachi, and Shimokawa. They revealed that (1) the Mn/Zn and Co/Zn ratios of sphalerite may have markedly increased during contact metamorphism, while the Cd/Zn ratios remained unchanged (2) the Emco/ lwzn (2/n total dissolved concentration in ore fluids) and Emco/S/wzn ratios in the initial ore solutions responsible for the mineralizations at Besshi which was calculated ba.sed on the equilibrium fractionation model between hydrothermal solution and sphalerite and analytical data on sphalerites are quite similar to the ratios of hydrothermal solutions at EPR 21 °N (3) however, these ratios for the Hitachi solutions are very low and different from those of the Besshi-subtype solution. 

In chernozems formed on serpentinite diluvium, Co content is in the range of 10-30 mg/kg, while in chestnut and chestnut vertic soils, Co concentrations vary from 3-15 and 15-45 mg/kg, respectively. Soils on basalt, andesite and gabbro contain 15-68 mg/kg total Cu. Total Mn in chernozems is in the range of 520-850 mg/kg. Chestnut soils have 42-106 mg/kg Zn content. Total Zn in saline alkali soils is in the range of 40-60 mg/kg Zn. Bioavailable Zn (ammonium acetate-extractable Zn) in chernozems, chestnut soils and saline alkali soils of the steppe zones varies from trace amounts to 3.8 mg/kg (1-8.3% of total Zn). In chernozems of Northern Bulgaria, total B is in the range of 25-53 mg/kg. Boron increases in saline soils and saline alkali soils. 

Adsorption Experiments. The adsorption experiments were performed at 25 0.2 C in 0.1 M NaClO. Mn adsorption experiments were performed under a nitrogen atmosphere at a total Mn(II) concentration of 50pM. Filterable concentrations were determined by analyzing 0.22 micron (Mi 11 ipore Type GWSP) filtered samples. The first 5 mL of the filtrate was discarded. Adsorbed concentrations were determined by difference (i.e. adsorbed = total- filterable). 

Vertical profiles of O2 and particulate and dissolved trace metal concentrations at 32.5°E and 44.5°N in the Black Sea. (a) Temperature, salinity, fluorescence, and O2 (b) ammonium, silica, nitrate+nitrite, and phosphate (c) Fe (d) Mn (e) Co (f) Pb (g) Cu (h) Zn (I) Cd and Ni. In the trace metal profiles, the dissolved concentrations are represented as solid circles, the total particulate concentrations by open circles, the acid-leachable particulate concentrations by open squares, and the suspended particulate matter concentrations by the solid triangles. Source-. After Tankere, S. P. C., et al. (2001). Continental Shelf Research, 21, 1501-1532. 

Mn2+ increased severalfold in concert with these changes. As in the water column, there was no significant difference in Mn2+ determined by ESR spectroscopy and total Mn determined by AA spectrophotometry after acidification. Similarly, there was no difference in Mn concentration between filtered and whole-water samples. All the Mn released into the water column was present as soluble-colloidal Mn2+ species. Although surprising when it occurred, the mobilization of Mn2+ under oxygen actually is in accord with the reports of other groups, who have observed accumulation of Mn2+ under oxic conditions. 

Nowadays, not only Fe but other trace metals as well, for example, Mn, Co, or Cu, are thought to limit primary production. It is thus a real challenge for oceanographers not just to assess correctly the very low levels of Fe and Mn in the oceans but also to carry out the speciation of these elements (total dissolved concentrations are at the nM level, labile forms oxidation states in natural aquatic systems Fe(II), which is readily soluble, and Fe(III), which is almost insoluble. Flowever, both Fe ions can form diverse complexes with organic ligands with different labilities and solubilities, and colloidal particles, which are also considered part of the dissolved phase. Manganese also exists in two oxidation states in aquatic systems soluble Mn(II) and insoluble Mn(IV) both are present in a dynamic cycle in seawater. The nonlabile Mn pool consists of oxidized Mn(IV) species, but these can be photochemically reduced and thus solubilized.23... 

Figure 3. Plot for determining the association constant K for the interaction of a-MDG with Mn-Con A. F the fraction of Ca2 -Mn2 -Con A molecules with saccharide, is determined from observation of the solvent-proton relaxation rate at 0.04 MHz, as discussed in the text. PT is the total Ca2 -Mn2 -Con A concentration, mM (monomer), and ST the total saccharide concentration, mM. The slope of the line through the data give a K of 1.1 X 10s M"1. Measurements were made at 25° in pH 5.6,0.1 M potassium acetate buffer, n = 1.0 in KCl.

Manganese is found in much higher concentrations in infant formulas than in breast milk. In fact, soy-based formulas were shown to contain about 80 times more Mn than breast milk [11]. Also, animal protein-based formulas contained also about 30 times more Mn than human milk. Infants are not able to absorb and excrete excess Mn during their first year of life, a period of rapid development. As Mn is neurotoxic and impairs intestinal Fe absorption, it would be desirable to reduce Mn levels in infant formulas down to those found in human milk (4-8 p,g l-1). Coni et al. [12] reported that in formulas more than 25 percent of total Mn is bound to caseins. On the other hand, Mn present in soy- and in cow s milk-based formula whey is mainly associated with LMW components (< 10 kDa), as is the case with human milk whey [15, 18, 34, 72],... 

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