Genesis and Classification of A-Type Humic Acids in Ando Soils

a.对两种提取腐殖酸的方法进行了试验和比较.一种常用的方法是使用0.5% NaOH预处理的土壤，然后浸泡在100 ℃的沸水浴中。另一种方法使用相同的预处理并在室温下振荡1小时。结果表明，后一种方法更有效，因为方法简单，结果趋势清晰。用△ log K、色密度、黑素指数和Pg指数对胡敏酸的性质进行了测定，将胡敏酸分为5种类型，其中4种为A型胡敏酸。用红外光谱和核磁共振方法测定了不同色密度下A型胡敏酸的脂肪族和芳香族化合物。脂肪族峰在低颜色密度时最强，芳香族峰在高颜色密度时最强。可以说，色密度是判断腐殖酸性质的一个很好的光学指标。薄片显微镜法已被用来确定土壤的性质。目前用此法测定腐殖质结构的研究或调查工作正在进行中，土壤薄片的有效尺寸仍在用试错法确定中。正在测试25 x 40 mm、50 x 70 mm和80 x 100 mm的尺寸。土壤微形态与A型胡敏酸性质的相关性是今后研究的重点。

a. Two methods of extracting humic acids were tested an compared for efficiency. One method, which is commonly practiced, made use of soil pre-treated with 0.5% NaOH and then soaked in boiling water bath at 100ﾟC. The other method made use of the same pre-treatment and shaken for one hour at room temperature. It was found out that the latter method was more effective because of the simplicity of the method and clear trend of results produced.b. Properties of humic acids were determined using the following indices : DELTA log K, color density, melanic index and Pg index to identify 5 types of humic acids, four of which are A-type humic acids.C. IR and NMR methods were used to determine the aliphatic and aromatic compounds of the A-type humic acids at varying color densities. Aliphatic peaks were strongest at low color densities and aromatic peaks were strongest at higher color densities.d. It can be said that color density is a good optical index of determining the properties of humic acids.e. Thin section microscopy method has been used to determine the properties of soil. Present study or investigation to determine the structure of humus using the said method is being conducted by the researcher.Effective size of soil thin section is still being determined through trial and error method. Sizes of 25 x 40 mm, 50 x 70 mm and 80 x 100 mm are being tested. Correlation of soil micromorphology with A-type humic acid properties are being considered to be taken in future studies.