| Based on the current evidence, Germanium (Ge) has been suspected as an essential trace element for the normal biological function. But Ge, over certain limits, also has adverse effects on the biological function. Soil, as a major pool of Ge, will incessantly offer Ge to various life forms in the terrestrial ecosystems and eventually to human bodies through food chains. On the other hand, soil is a potential recipient of Ge pollution and Ge-containing wastes discharged from such sources as electronics and aeronautics industries, coal use, and so on. So study on soil Ge becomes etwironmentally and ecologically significant. By far, however, there is little knowledge of soil Ge since very few researches involved in soil Ge have been made. It is the objectives of this study to set up a po!arographic method for determining soil Ge, and then investigate the background values and distribution characteristics of Ge in purple soils in Chongqing areas. In a supporting solution containing 0.OI2mol/L KCI, 0.OImolIL Vanadium(IV), 6X l0~ mol/L Alizarin red, at acidity of 0.24molIL H2S04, a sensitive second derivative catalytic polarographic wave of Germanium could be obtained by cathodized single-sweeping polarograph . The peak potential volt was -0.54V (vs.SCE) during scan starting at-0.3V. The concentration of Germanium was correlated to peak height in the range of 1.0 X i05 ?6.0 X101 iigGe/mL; the detection limit was l.OX iO~5 ~ g Ge/mL. The RSDQ/o) was <2.0% for relatively pure solutions with Ge in 0.003---0.3 I.?g/mL, but was 2?% for soil samples with Ge in 2.65 -~ 5.38mg/kg.The solution of soil samples digested by H:1POrH2SOcHNO3 could be used directly to determine Germanium in presence of EDTA-Vc as masking agent, and the recovery was 90.9?.4%. 4 The above polarographic method was used to determine Ge contents in 261 purple soil samples which were obtained from 6 counties in Chongqing during the middle I 980s?and analyzed for the background values of nine elements ,including Hg.. Cd Pb.. As.. Cu Zn.. Ni.. Mn.. Cr. Results were as the following: Ge contents in purple soils complied with the logarithmic-normal distribution pattern, ranged from 0.28 to 2.0mg/kg, most of which concentrated on the range of 0.43 ~?1.0 mg/kg, and their geometric mean value was 0. 67*! + 1. 4mg/kg which is slightly lower than the world-averaged soil Ge of 1.0 mg/kg. It was observed that Ge contents in purple soils was obviously affected by the deposition environment and Iithofaces of the soil-forming rocks and/or parent materials. The sequence for Ge concentrations of several major purple soil gqnus developed from different soil-forming rocks was reddish-brown purple soil>reddish purple soil>brown purple soil>grey-brown purple soil>dark purple soil. In General, the purple soils originated from rocks with higher percentage of mud stone or from river-lake sedimentary rocks deposited during the arid climates tended to have higher Ge contents than those from rocks with lower percentage of mud stone or from river-lake sedimentary rocks deposited during the humid climates, and those from neritic scdimentazy rocks. Analyses of Pearson correlation coefficients showed that the correlations between soil Ge contents and soil pH, soil organic matter, contents of soil clay and carbonate, and contents of soil Hg, Cd, Zn, Al203, Fe203, K20, Na20, CaO, MgO, Mn, Cr, Ni, 1102 were weak, but there existed significant negative correlation between soil Ge and soil CEC and Cu, and... |
PDF Full Text Request