若尔盖高原湿地土壤硒的数量、形态与分布

Contents,Species and Distributions of Se in Wetland Soils in Ruoergai Plateau

用连续浸提的方法研究了若尔盖高原4种湿地土壤(风沙土、草甸土、沼泽土和泥炭土)中硒的含量、形态、剖面分布及其影响因素,以期为该区人、畜缺硒症的防治积累科学资料。结果表明,该区土壤属于低硒环境,表层土壤全硒含量范围为65～260μg/kg。在各种形态硒中,水溶性硒仅占土壤全硒含量的1.12%～3.08%,交换态硒占2.91%～6.03%,有机态硒占10.28%～45.63%,酸溶态硒、硫化态硒和残余态硒3种无效态硒共占60%以上。在土壤有机态硒组成中,胡敏酸结合态硒(HA-Se)占有机态硒的57.84%,富里酸结合态硒(FA-Se)占42.16%。土壤总硒和有机态硒的含量与分布主要受土壤有机碳的影响,且其影响程度随着深度的不同而改变,湿地土壤丰富的有机碳有利于土壤有机态硒和总硒的积累。土壤总硒含量低、有机态硒的比例较高以及胡敏酸结合态硒占优势导致硒的生物利用率低,可能是该区域人、畜硒缺乏症发生的重要原因。

This paper studied the amounts, species and distribution of Se in four kinds of wetland soil (aeolian sandy soil, meadow soil, bog soil and peat soil) by a method of successive extraction in order to accumulate scientific data for preventing and curing the selenium response symptom of people and livestock in Ruoergai Plateau. The results showed that the content range of total Se(T-Se) in surface soil layer was 65～260μg/kg in ten sampling sites and the low Se circumstance existed because of soil Se deficiency. Among several kinds of Se forms, water soluble Se(W-Se),exchangeable Se(E-Se),Organic Se(O-Se) accounted for 1.12%～3.08%,2.91%～6.03%,10.28%～45.6% of total Se respectively, unavailable Se(U-Se) including acid soluble Se(A-Se),sulphide Se(S-Se) and residual Se(R-Se) accounted for more than 60% of total Se. Of the soil O-Se, (57.84)%(the average) was associated with the humic acid fraction(HA-Se) and 42.16% with the fulvic acid fraction (FA-Se) in surface soil layer. The soil organic matter was the most important factor affecting the content and profile distribution of soil T-Se and O-Se, the influence to them changed with the soil depth, and the rich soil organic matter was helpful to the accumulation of soil T-Se and O-Se. It was clear that the lower utilization ratio of Se due to the low content of soil T-Se, the higher portion of O-Se and HA-Se were the main reasons for the selenium response system in Ruoergai plateau.