Aluminum species in soil solution and their formation conditions.

为了研究酸性土壤中铝对植物的毒害作用及其浓度特征，对农田和森林土壤中提取的土壤溶液进行了分析。采用亚当斯（1971）提出的逐次逼近法计算铝的形态及其浓度。在本文中，我们通过以下质量平衡方程计算Al物种，假设在使用铝盐溶液的几项研究中强烈建议的四种多核Al物种可以共存。（总Al）=[Al^&lt;3+&gt;]+[AlOH^&lt;2+&gt;]+[Al（OH）_2^+]+[Al（OH）_3 ^o]+[AlSO_4^+]+[AlHPO_4^+]+[AlH_2PO_4^2+&gt;]+2 Al_2（OH）_2^4+&gt;]+3 Al_3（OH）_4^5+&gt;]+13[Al_<13>（OH）<24>_7 +&gt;]+6 Al_6（OH）<15>_3 +&gt;]结果表明：（1）当土壤溶液的pH值在4.7 ~ 3.0之间，pAlt值在4.5 ~ 2.3之间时，Al^&lt;3+&gt;为Al的主要形态;（2）当土壤溶液的pH值在4.5 ~ 2.3之间时，Al &lt;3+&gt;为Al的主要形态 ...更多信息 m 7.3 ~ 5.3，pAlt值为5 ~ 2.3时，Al（OH）_3 <15>~（3+）为Al的主要形态。3）pH值为7.3 ~ 5.3，pAlt值为7.5 ~ 4.5时，Al（OH）_3 ~（3+）为Al的主要形态。4）pH值为7.31 ~ 3.0，pAlt值为7.31 ~ 2.3时，Al_2（OH）_2^&lt;4+&gt;和Al_3（OH）_4^&lt;5+&gt;都不是Al的主要形态，它们的浓度比Al的浓度低百分之一。在pH值为5 ~ 6.5、Al_O_4（OH）_7 ~+浓度大于10 μ mol/L的铝盐溶液中，这些多核形态可成为铝的优势形态<-2><-1>。Al_O_4<13>（OH）<24>_7 ~+浓度与Al_2浓度的比值约为1：1亿，因此可以认为它们的存在。那么Al（OH）_2^+形态在Alt.7中占几十个百分比。在施用大量磷肥的耕地土壤中，AlHPO_4^+是Al的主要存在形态，在pH和pAlt范围内，Al^&lt;3+&gt;、Al（OH）_2^+、Al（OH）_3 ^o、Al_6（OH）_<15>（3+）和AlHPO_4^+中的一种是Al的主要存在形态。少

In order to examine characteristics of aluminum species toxic to plants and their concentrations in acid soils, soil solution extracted from soils of crop fields and forests was examined. Al species and their concentrations were calculated by applying the method of successive approximation reported by Adams (1971). In the present paper, we calculated Al species through the following mass balance equation, assuming that four kinds of polynuclear Al species which have been strongly suggested in several studies using aluminum salt solution can coexist.Alt (total Al) =[Al^<3+>]+[AlOH^<2+>]+[Al(OH)_2^+]+[Al(OH)_3^o]+[AlSO_4^+]+[AlHPO_4^+]+[AlH_2PO_4^<2+>]+2[Al_2(OH)_2^<4+>]+3[Al_3(OH)_4^<5+>]+13[Al_<13>(OH)_<24>^<7+>]+6[Al_6(OH)_<15>^<3+>]The following results were obtained.1) If the pH value of soil solution pH is in the most acid range of 4.7 through 3.0 and the pAlt value ranges from 4.5 through 2.3, Al^<3+> became dominant Al species in Alt.2) If the pH value of soil solution ranges fro … More m 7.3 to 5.3 and the pAlt value ranges from 5 to 2.3, then polynuclear species, Al_6(OH)_<15>^<3+>, becomes dominant Al species in Alt.3) If the pH value of soil solution ranges from 7.3 to 5.3 and the pAlt value ranges from 7.5 to 4.5, then Al(OH)_3^o becomes dominant Al species in Alt.4) In the pH value of range from 7.31 through 3.0 and in the pAlt value range from 7.31 through 2.3, neither Al_2(OH)_2^<4+> nor Al_3(OH)_4^<5+> becomes dominant Al species and the concentration of these species was one hundredth less than the Alt concentration. It is inferred that these polynuclear species can become dominant Al species in alminum salt solution where Alt concentration is larger than 10^<-2> molL^<-1> and the pH value ranges from 5 to 6.5) The ratio of Al_<13>O_4(OH)_<24>^<7+> concentration to Alt concentration is about one to hundred million, and thus the existence can be ignored.6) If the pH value of soil solution ranges from 6.5 through 5 and the pAlt value ranges from 7 through 4 and the pAlt value is almost equal to the pH value, then Al(OH)_2^+ species amounts to dozens of percentages in Alt.7) In the case of cultivated field soils amended by high amounts of phosphate fertilizers, AlHPO_4^+ is recognized as dominant Al species.Based on these results, it is assumed that one of Al^<3+>, Al(OH)_2^+, Al(OH)_3^o, Al_6(OH)_<15>^<3+>, and AlHPO_4^+ becomes dominant Al species in Alt in the pH and pAlt ranges examined. Less