中国几种土壤中的有机态硒及其分布特征

采用0.1mol/L NaOH-0.1mol/L Na_4P_2O_7浸提,活性碳分离技术研究了中国湿润半湿润地区几种土壤中有机态硒的化学特征.供试土壤有机态硒占全硒含量的百分数变幅为3.46％—59.86％,平均28.42％.影响有机硒含量的主要因素有全硒含量(r=0.8033)、有机碳含量(r=0.6618)、土壤交换性酸(r=0.6136)和pH(r=-0.5248)。土壤有机质的C/Se为0.58×10~6-42.93×10~6,平均为6.38×10~6.低硒环境土壤有机质的C/Se显著高于正常硒含量土壤.以平均计,胡敏酸结合态硒约占有机态硒的34％,富啡酸结合态硒占66％.缺硒土壤有机态硒中,胡敏酸结合态硒的比例一般都较高.

ORGANIC SELENIUM AND ITS DISTRIBUTION IN SOILS

Organic selenium and its distribution in soils of typical groups in China were studied using 0.1 mol L^-1NaOH+0.1 mol L^-1Na₄P₂O₇ extraction techniques. Organic selenium accounts for 3.46 %-59.86%, on average, 28.6% of the total Se for 16 soils tested. Factors affecting organic Se content in soils include total Se content, organic carbon, exchangeable acidity, and pH. The C/S eratio of organic matter extracted by the NaOH-Na₄P₂O₇ mixture ranges from 0.58 × 10⁶ to 42.93×10⁶, on average, 6.38×10⁶. Soils from low Se areas where Kashan and Kaschin-Beck disease once happened, have much higher C/Se ratio than those from areas without Se deficiency. Of the organic selenium, 66% (the average) was associated with fulvic acid (FA-Se) and 34% with humic acid fraction (HA-Se). The percentage of HA-Se is, in general, higher in Se deficient soil than in normal soil.