On the chemical structure and plant growth-promotion effects of environmental humic acids.

第四种腐植酸样品是从不同类型的土壤中提取的，包括水生沉积物。分析了腐植酸的每个来源的元素组成和羧基、低pKA羧基、羰基、酚羟基和醇羟基的含量。从各种腐植酸的可见光谱和~1H-核磁共振谱中，比较了各种腐植酸的光学性质和质子组成(芳香族、甲氧基、内酯、脂肪族-lt；α&gt；、-&lt；β&gt；、-&lt；γ&gt；)。因子分析表明，胡敏酸的光学性质首先是脂肪链和含氮组分的含量，其次是官能团含量和光学性质。通过对上述特征的判别分析，可以判断腐植酸来源的土类。对煤化学中发展起来的结构分析进行了改进，使之适用于腐植酸。由元素组成、官能团组成和质子组成计算了平均分子结构参数(f_aH_&lt；Au&gt；/Ca，&lt；sigma&gt；，n)。腐殖化程度越高，缩合度越大，侧链长度越短，腐殖化程度较高的腐殖酸的数均分子量低于腐殖化程度较低的腐殖酸。测定了腐植酸溶液的表面张力。高相对分子质量组分和具有高数均相对分子质量的腐植酸具有较高的表面活性。为了测试腐植酸对植物生长的影响，在含营养的水培条件下培养水稻。通过对渗出液和植物顶端的分析来估计离子吸收。腐植酸对镁的吸收有促进作用。从Entisol中提取出最有效的腐植酸，其特征如下：芳环缩合程度低、侧链长、数均相对分子质量高、表面活性高。

Forth humic acid samples were extracted from various types of soils, including aquatic sediment. Each source of humic acid was analysed for elemental conpositions and contents of carboxyl, low pka carboxyl, carbonyl, phenolic and alcoholic hydroxyl groups. From the visible and ^1H-NMR spectra of various types of humic acids, optical properties and proton compositions (aromatic, methoxyl, lactone, aliphatic-<alpha>, -<beta>, -<gamma>) were compared.Factor analysis clarified that the humic acid was first characterized by the contents of aliphatic chains and nitrogenous components, followed by functional groups contents and optical properties. Soil groups of the source of humic acids could be judged by discriminant analysis on the above characteristics.Structural analysis developed in coal chemistry was modified to apply to humic acids. Average molecular structure parameters (f_a H_<au>/C_a, <sigma>, n) were calculated from elemental composition, functional groups composition and proton composition. The higher the humification digrees were, the larger the condensation degrees were and the shorter the side chain lengths were.Number-average molecular weight of well humified humic acids were lower than low humified ones. Surface tension of humic acids solution were measured. High molecular weight fraction and the humic acids holding high number-average molecular weight exhibit high surface activity.To test the effect of humic acids on plant growth, rice was cultivated in water aculture containing nutrients. Ion uptake was estimated by the analysis of exudate and plant tops. The uptake of magnesium was enhanced by humic acids. Most effective humic acid was extracted from Entisol and characterized by the followings; low condensation of aromatic rings, long side chain, high number-average molecular weight and high surface activity.