若尔盖高原湿地土壤性质对硒有效性的影响

Effect of Wetland Soil Properties on Selenium Availability in Ruoergai Plateau

用等温吸附的方法研究了若尔盖高原广泛分布的泥炭土、沼泽土和风沙土对硒的吸附与解吸,以探讨湿地土壤因素对硒有效性的影响。结果表明,3种土壤还原状态下硒的吸附量均大于氧化态,水溶性硒和交换态硒的解吸量均为氧化态高于还原态,潜在有效硒与此相反,氧化状态有助于提高土壤硒的有效性。土壤pH升高,泥炭土对SeO_3^(2-)-Se的吸附量降低,水溶态硒增加,交换态硒降低,潜在有效硒变化不明显。土壤有机质能大量吸持硒降低其有效性,泥炭土去有机质后对硒的吸附量大幅度下降,水溶性硒和交换态硒量增加,潜在有效性硒量则明显降低。

The absorption and desorption of selenium in three kinds of soil (peat soil, bog soil and aeolian sandy soil) were studied using an isothermal adsorption approach in order to explore the effect of wetland soil properties on Se availability in Ruoergai Plateau. The results showed that SeO^2_3-Se adsorbing capacity of the reduced soil was more than that of the oxic soil, the desorbing capacity of water selenium (W-Se) and exchangeable selenium (E-Se) was higher in oxidation state than that in reduction state, but on the contrary the desorbing capacity of la- tent available selenium (LA-Se) in three kinds of soil. Soil oxidation state was helpful to improve the availability of soil Se. With the raising of pH value, SeO^2_3-Se adsorbing capacity decreased, the desorbing capacity of W-Se increased and that of E-Se decreased, but the desorbing capacity change of LA-Se was not obvious in peat soil. Soil organic matter adsorbed Se in large quantities and weakened the availability of soil Se, SeO^2_3-Se adsorbing capacity of peat soil reduced greatly, the amount of W-Se and E-Se enhanced and that of LA-Se diminished obvi- ously after getting rid of soil organic matters.