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首页> 外文期刊>日本土壤肥料学雑誌 >Short-term reaction of apatite in fresh Pinatubo volcanic ash with reactive components in the soil-plant system.
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Short-term reaction of apatite in fresh Pinatubo volcanic ash with reactive components in the soil-plant system.

机译：新鲜Pinatubo火山灰中磷灰石与土壤-植物系统中的活性成分的短期反应。

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The reactivity of the apatite in the volcanic ash from Mt. Pinatubo, Philippines, to various soil components (Al, Fe and organic acids) was examined. The heavy fraction (specific gravity>2.8) of the volcanic ash having the diameter of 0.044-0.2 mm was first separated by sieving in water, and then by centrifugation. The content of P2O5 in the heavy fraction thus obtained was 6.5 gthinkg-1. One-hundred mg of the heavy fraction was shaken with 500 mg of four soils containing different amounts of active Al and Fe, four model materials (Al-gel, Al-Si-gel, Fe-gel and goethite), organic acids (10 mM of citrate and oxalate), and dilute HCl (0-4 mM) in 25 ml of aqueous solution for 16 h. The pH values of the solution ranged from 3 to 7 when the experimentswere completed. The amounts of dissolved apatite P increased with the decrease in the final pH of the solutions. For all soil samples, Al-gel, and Al-Si-gel, the amounts of dissolved apatite P became noticeable only when the final pH values were <4.5. By contrast, the reactivity of active Fe with apatite was higher than that of active Al. Substantial reactions between Fe-gel and goethite and apatite were observed under the final pH ranges of 3-7. The amounts of apatite P reacted with Fe-gel increased with the amount added, suggesting that the amount of active Fe contained in the soil samples examined were not sufficient to react with the apatite. It was suggested that apatite does not react with active Al immediately under normal soil pH conditions, although active Fe reacts with apatite and reactivity is affected by the form and amount of active Fe. The amounts of apatite P dissolved by organic acids were also dependent on solution pH. Although the dissolution of apatite by organic acids was observed even at the final pH of 5-6, dissolution with dilute HCl was not observed under the above pH range. This can be attributed to the ability of those organic acids to form chelate compounds with Ca in apatite, resulting in the release of P in the apatiteinto the liquid phase. The mode of dissolution by oxalate solution was different from that by citrate solution. In lower pH conditions (final pH<4.5), the amount of dissolved P by oxalate solution did not increase with reduction in final pH. This might result from the formation of a coated layer due to precipitated Ca oxalate at the surface of apatite, which prevents further reaction of oxalate and apatite.
机译：火山灰中磷灰石的反应性。考察了菲律宾皮纳图博（Pinatubo）对各种土壤成分（铝，铁和有机酸）的影响。首先通过在水中筛分，然后通过离心分离直径为0.044-0.2 mm的火山灰的重质馏分（比重> 2.8）。这样得到的重质馏分中的P 2 O 5的含量为6.5gthinkg-1。将100 mg的重质馏分与500 mg的四种含有不同量的活性Al和Fe的土壤，四种模型材料（Al-gel，Al-Si-gel，Fe-gel和针铁矿），有机酸（10）一起摇动mM的柠檬酸盐和草酸盐）和HCl（0-4 mM）在25 ml的水溶液中稀释16小时。实验完成后，溶液的pH值范围为3至7。随着溶液最终pH值的降低，磷灰石P的溶解量增加。对于所有土壤样品（铝凝胶和铝硅凝胶），只有当最终pH值<4.5时，磷灰石P的溶解量才变得明显。相反，活性铁与磷灰石的反应性高于活性铝。在最终pH范围3-7下，观察到Fe-凝胶与针铁矿和磷灰石之间的大量反应。与Fe-凝胶反应的磷灰石P的数量随添加量的增加而增加，这表明所检查的土壤样品中所含的活性Fe的量不足以与磷灰石反应。有人指出，尽管活性铁与磷灰石反应且活性受活性铁的形式和含量影响，但在正常的土壤pH条件下，磷灰石不会立即与活性铝反应。有机酸溶解的磷灰石P的量也取决于溶液的pH值。尽管即使在最终pH为5-6时也观察到磷灰石被有机酸溶解，但在上述pH范围内未观察到用稀HCl溶解。这可以归因于那些有机酸与磷灰石中的Ca形成螯合物的能力，从而导致磷灰石中P释放到液相中。草酸盐溶液的溶解方式与柠檬酸盐溶液的溶解方式不同。在较低的pH条件下（最终pH <4.​​5），草酸溶液中溶解的P的量不会随着最终pH的降低而增加。这可能是由于在磷灰石表面沉淀草酸钙而形成的涂层所致，从而阻止了草酸盐与磷灰石的进一步反应。

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