摘要:
通过对福州市土壤和岩石中Se形态的分析研究结果表明,表层土壤中强有机态Se、腐殖酸结合态Se约占全量的57.44%,残渣态Se占28.77%,残渣态Se是土壤Se的重要储备库源,三者均与表层土壤Se全量呈极显著的线性正相关关系.表层土壤Se含量随土壤酸性的加强而增加,随有机质含量加大而增加的幅度较小;深层土壤Se受pH值的影响不明显,但受有机质含量的影响很大,两者线性回归关系达到极显著水平;不同岩石类型对土壤含Se量没有明显的影响规律,各介质中Se含量表层土壤＞深层土壤＞岩石,并且差幅巨大.这些研究结果揭示了在岩石风化、土壤发育(熟化)过程中有机质和黏土矿物吸附Se,致使Se较其他元素流失比例少,从而造成从深部到表层土壤Se相对富集的结果.同时,提出了利用全量来推导Se形态值的方法.建立了土壤Se全量与形态间的关系模型以及决定土壤有效态Se的公式,建议在评价土壤Se时只要考虑有机结合态Se、残渣态Se、离子交换态Se和全量Se.
Abstract:
Selenium speciation in soil and rock samples taken from Fuzhou City was investigated in this work. The results showed a significantly positive correlation between species and total amount of selenium in topsoil. The residue species of selenium occupied 28.77% of total selenium, the species of strong bound in organic compounds and the species of humic acid bound approximately accounted for 57.44% of total amount of selenium in topsoil. Meanwhile, the selenium abundance between top soil and sub-soil also displayed a significant positive correlation. Selenium abundance in topsoil increased with the acidity increase but no obvious increase with the increase of content of organic substances. While selenium abundance in deep soil insignificantly varied with the change of pH value but significantly influenced by organic substance content. Moreover, the abundance of selenium dramatically deviated from the samples with different materials except the types of rocks, which decreased in the order of topsoil＞deepsoil＞rock. The results suggested that the process of selenium adsorption in soil organic substance and clay mineral caused selenium enrichment in topsoil in the process of rock weathering and soil development. This paper has proposed a method to estimate speciation concentration of selenium according to the total selenium and established a formula to calculate available selenium content with given data of selenium abundance and speciation in soils. And a suggestion that only selenium species of organic bound, residue, ion exchangeable and total amount of selenium be considered in soil selenium assessment has put forward.
Keywords:
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selenium
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speciation
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analysis
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transformation
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enrichment
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soi
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