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

第四，从不同类型的土壤中提取腐植酸样品，包括水生沉积物。分析了各来源腐植酸的元素组成和羧基、低pka羧基、羰基、酚基和醇羟基的含量。通过不同类型腐植酸的可见光和核磁共振光谱，比较了其光学性质和质子组成（芳香族、甲氧基、内酯、脂肪族-< α >、-< β >、-< γ >）。因子分析表明，腐植酸首先以脂肪链和含氮组分含量表征，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壤类群。在煤化学中发展起来的结构分析被改进为适用于腐植酸。根据元素组成、官能团组成和质子组成计算平均分子结构参数（f_a H_<au>/C_a, <sigma>, n）。腐殖化度越高，缩聚度越大，侧链长度越短。腐殖酸的数平均分子量低于腐殖酸的数平均分子量。测定了腐植酸溶液的表面张力。高分子量组分和具有高数平均分子量的腐植酸具有较高的表面活性。为研究腐植酸对水稻生长的影响，在含营养物的水培条件下栽培水稻。离子吸收是通过分析渗出液和植株顶部来估计的。腐植酸对镁的吸收有促进作用。从Entisol中提取的腐植酸最有效，其特征如下：芳烃环缩合率低，侧链长，数均分子量高，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.