外加Se(Ⅵ)在土壤溶液中的价态转化研究

Valence State Transformation of Added Selenate in Soil Solution

以熟红黄泥为试验材料 ,研究了在淹水培养过程中不同氧化还原条件下外加 Se( )在土壤溶液中的价态转化 .结果表明 ,在两种土壤 Eh培养条件下 ,外加的 Se( )约有 2 0 %进入土壤固相 ,80 %进入土壤溶液 .在低 Eh值 (175 m V)条件下 ,进入土壤溶液的硒约有 90 %呈有机态 ,且较稳定 ;10 %左右的 Se( )还原为 Se( ) ,此还原反应符合动力学一级方程 ,半衰期为 3.7d.在高 Eh值 (4 5 0 m V)条件下 ,进入土壤溶液的硒在第一天 70 .9%呈Se( )态 ,且稳定 ;2 9.0 %呈有机态 ,并在培养过程中先氧化成 Se( ) ,然后 Se( )再氧化成 Se( )

Valence state transformation of added selenate in soil solution was studied by flooding incubation under the different redox potential conditions. The results show that 20 per cent of added selenate is transformed into soil solid and 80 per cent added selenate remains in soil solution under two redox potential conditions. At low redox potential (175 mV),90 per cent of selenium in soil solution exists as organic form,and is the stable species present in soil solution.About 10 per cent of selenate is reduced to selenite,at the first day which is a first order reaction with a half life of 3.7 days. At high redox potential (450 mV),70.9 per cent of selenium in soil solution exists as selenate at the first day,which is the stable species.29.0 per cent of selenium exists as organic form.As incubation proceeding,organic selenium is oxidized to selenite and selenite is rapidly oxidized to selenate.