| Summary: | 碩士 === 國立中興大學 === 土壤環境科學系所 === 96 === Mercury is one of the most toxic elements in the environment. The pollution of soil by mercury through its high reactivity, volitility and solubility, which will cause serious threat to the human health. The aims of this study are to search a quick and effective method of detecting mercury ions in soils and to understand the mobility of mercury ions in soils by the selected leaching solutions. The optimum conditions for mercury analysis using gold plated screen-printed electrode in electrolyte of 0.1 M HCl are 0 mV for plating potential, 2 min. for deposition time, 25 mV for amplitude of square-wave voltammetry and 15 Hz for frequency of square-wave voltammetry. The peak current of mercury is liner with concentration in the range of 0-100 μg/L (R2 = 0.9997), and detection limit is 5 μg/L. The results of the extracted experiments using 0.1 M HCl and 0.1 M HNO3 indicated the following sequence for extracted percentage of mercury from three selected soils : Shiushui series ( 40.08 %, 37.02 % ) > Wutso series ( 27.20 %, 22.23 % ) > Tali series ( 6.60 %, 4.63 % ) ; for using 0.05 M CaCl¬2 , 0.1 M NH4Cl and 0.1 M KCl : Wutso series ( 21.87 %, 19.03 % and 23.37 % ) > Shiushui series ( 8.87 %, 5.62 % and 9.16 % ) > Tali series ( all < 1 % ) ; and for 0.05 M CaNO3, 0.1 M NH4NO3 and 0.1 M KNO3 : all < 1.5 %. The results showed a a significant distinction of extracted effect among acid, chloride and nitrite solutions. The results of column leaching experiments indicated that Ca(H2PO4)2 enhances the mobility of mercury in Tali series and Wutso series leached by both 0.1 M HCl and 0.5 M KCl ; CaCO3 reduces the mobility of mercury in Wutso series leached by both 0.1 M HCl and 0.5 M HCl. In the presence of humic acid, no effect on transportation of mercury ions was observed in three soils leached by both 0.1 M HCl and 0.5 M KCl.
|
|---|
