铁铝盐基离子对土壤中水溶性氟环境效应的影响

Effects of Fe/Al chlorides on soluble fluorine in soil environment

氧化物或粘土矿物可吸附氟离子,但磷酸根离子与氟离子存在竞争吸附效应,造成氟的环境存在量、存在形态及生物效应更加复杂,影响了环境中氟污染的治理。试验选用典型贵州黄壤和石灰土,通过向模拟高氟污染土壤中添加铁铝盐基离子和磷酸盐,采用两因素最优设计,研究外源物质对土壤中水溶性氟的影响。结果表明,FeCl3.6H2O或AlCl3.6H2O都能降低土壤中水溶性氟,而KH2PO4使土壤中水溶性氟增加,对黄壤和石灰土中水溶性氟影响效果大小依次为FeCl3.6H2O(AlCl3.6H2O)、KH2PO4。同时表明,采用铁铝盐基离子改变黄壤性质,达到降氟效果仍有很大潜力,而石灰土环境在高添加铁铝盐基离子水平下继续添加FeCl3.6H2O或AlCl3.6H2O降低土壤中水溶性氟的作用较弱。从土壤pH看,黄壤水溶性氟受试验因子影响复杂,土壤pH低水溶性氟不一定低,pH在4～6时,氟元素的形态及有效性尤其复杂,而石灰土中水溶性氟基本随pH降低而降低。

Fluoride ion can be absorbed by oxide and mineral ingredients of soil; however, the soil＇s capacity for fluoride is reduced by the presence of phosphate due to its competition for the adsorption sites on soil surface. Series of batch experiments were conducted to determine the effects of soil additives （for pH control） FeCl3 · 6H2O, AlCl3 · 6H2O, and KH2PO4 on soluble fluorine content of the yellow soil and the calcareous soil samples of Guizhou Province. The soil soluble fluorine contents were reduced by adding FeCl3 · 6H2O and, to a lesser extent, by AlCl3 · 6H2O; it was increased by KH2 PO4. Adding FeCl3· 6H2O or AlCl3 · 6H2O with KH2 PO4 in the soil to neutralize its acidity/alkalinity was effective to reduce its release of fluoride. The soil＇s soluble fluorine content was correlated with the additive doses by second order bi-variable regression equations.