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  • Author or Editor: R. Fujiyoshi x
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Abstract  

Uptake of manganese(II) and zinc(II) by chlorophylla (Chl) was investigated using a radiotracer technique in order to elucidate its ability of scavenging metals released into the soil environment. Two possibilities were considered for the metal uptake: (1) substitutional complexation with Chl and (2) inclusion of the metals into Chl aggregates. It was found that manganese(II) was not trapped appreciably by both Chl itself and its aggregates. Magnesium of Chl was exchanged with zinc(II) in aqueous phase giving Zn−Chl at pH values higher than 7. Zinc(II) was found to be trapped by Chl aggregates depending on the pH of the aqueous phase.

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Abstract  

The uptake of manganese(II) and zinc(II) by humic acids (HA) was investigated using a radiotracer technique in order to elucidate their ability of scavenging heavy metals released into the soil environment. Metal uptake by HA was affected by aqueous pH, in which the amounts of Mn(II) and Zn(II) associated with HA showed a similar pattern against pH. These facts indicate that interactions of Mn(II) and Zn(II) with HA would be ionic in character, and affected by properties of the carboxyl groups in HA.

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Abstract  

A metal exchange reaction between*Zn-EDTA and Mn-PAN complexes has been investigated to evaluate the possibility of Mn determination in geological samples radiometrically. Exchange ratios (E) of Mn(II) to Zn(II) were obtained from measuring the activity of65ZnPAN2 extracted into an organic phase. Values of E increased rapidly with increasing pH of the aqueous solution. Suitable conditions for the determination of Mn(II) in soil samples are considered.

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Abstract  

Ligand exchange reaction of Zn(II)-acetylacetonate complex (Zn-acac2) with 5,10,15,20-tetraphenyl-21H,23H-porphinetetrasulfonic acid (H2TPPS) has been investigated spectrophotometrically and radiometrically. The exchange reaction was observed by spectral change from H2TPPS to Zn-TPPS or activity of65Zn(acac)2 extracted into the chloroform phase. The 2nd order rate constants (k 2) for the exchange reaction at 70 °C and at pH 7.8 were found to be 32.8±2.3 and 31.2±3.2 M–1·s–1 from the spectrometric and radiotracer experiments, respectively. For the direct complexation of Zn(II) with H2TPPS, a similar 2nd order rate constant (k=32.4±4.7 M–1·s–1) was obtained as that in the ligand exchange reaction. The activation energies (E) for the exchange and the formation of Zn-TPPS were found to be 69.3±0.2 and 69.4±0.2 kJ·mol–1, respectively, in the temperature range from 40 to 70 °C.

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Abstract  

The sorption of manganese(II) and zinc(II) on soil samples collected from Sapporo (Japan) and Tiksi (Russia) was investigated using a radiotracer technique to elucidate the abilities of soil organic matter as a scavenger of heavy metals released to the soil environment. The sorbed amounts of both manganese and zinc metals to organic soil components were estimated to be different on different soils, depending on the pH of aqueous phase. The degree of humification of pertinent soils was suggested as a parameter which could describe the properties of the organic soil matter in complexing with heavy metals.

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Abstract  

Environmental radionuclides (40K, 137Cs, 210Pb, 226Ra) were determined in soils under semi-arid stands, a transition area from thorn to deciduous forest in El Angolo, and heath stands in the Alto Mayo in Northern Peru in order to elucidate their activity level in soil, and to trace underground environment in remote areas of little anthropogenic intervention. Anthropogenic 137Cs was only found in the uppermost portion of the soils in small amount, whereas the 210Pb activity was exceptionally high at the soil surfaces in a tropical stand of Alto Mayo. The results suggest a fallout nuclide, 210Pb, having been transported from local source(s) not to be specified yet.

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