土壤中钒的化学结合形态与转化条件的研究

Studies on chemical forms of vanadium in soil and their transformation

为了利用和控制土壤条件，改善土壤供钒特征，为农业生产和环境保护服务，综合参考国内外对土壤中其他微量元素形态划分的方法，初步区分出土壤中的钒以５种主要的化学结合形态存在。其含量多少依次为残留态＞无定形氧化铁结合态＞有机质结合态＞易还原锰结合态＞可溶态。通常，残留态钒占土壤全钒含量的９０％以上，而可溶态钒的含量常低于１μｇ／ｇ。一般而言，在较高的温度，较强的还原条件以及酸性土壤条件下，土壤中其它化学结合态钒更多地向可溶态钒转化；除有机质结合态钒外，其它形态钒的含量都与土壤全铁含量间有着显著或极显著的正相关。外源钒在酸性红壤中的形态转化速率较慢，在石灰性的栗钙土中的形态转化速率较快。酸性土壤对钒的缓冲能力强，缓冲容量大，不容易产生钒污染。

Vanadium in soil could be fractionated into five forms, namely, soluble, organic matter bound, easily reduced Mn oxide bound, amorphous Fe oxide bound, and residual. It may be concluded that more than 90% of the total vanadium content remain as residual form in soil; but soluble vanadium content averages usually less than 1μg/g. Besides the organic matter bound form. thecontents of the other chemical forms have marked of very significant positive correlation with the total iron content of soil, which indicats that different ranadium forms are able to be closely bound with the iron oxides through complex mechanism in soil. Generally, in higher temperature and stronger reduction conditions, larger amount of other forms in soil could transform into soluble vanadium. When soluble vanadium is added into soil, the rate of the transformation is lower in acid red earth than in calcareous chestnut soil. The acid soil has stronger buffer power nad larger buffer capacity, so it could not be easily polluted by vanadium.