Humic substances can be considered as polyelectrolytes with supramolecular character and complicated behaviour in water environment. The fractions of humic substances dissolved in water are the most active ones and determinative for their functioning in nature, where the proton-binding and dissociation ability play a crucial role. The dissociation behaviour of humic and fulvic acids can be affected by different circumstances including their concentration which is directly connected with the molecular organization of humic particles in solution and the accessibility of their ionizable functional groups. This study is focused just on these active fractions and their dissociation behaviour in the dependence on their content in studied system. Standards and reference samples of International Humic Substances Society were used. Flow-through coulometry was used to determine the total content of acidic functional groups in fulvic solutions and humic leachates. The amount of dissociated acidic groups was determined on the basis of potentiometry. Several differences between the behaviour of humic and fulvic acids were found. While whole samples of fulvic acids including the weakest functional groups were analysed, only the active dissolved humic fractions containing stronger acidic functional groups were characterized. The fractions containing higher amounts of the weakest functional groups remained insoluble. The dissociation degree of fulvic acids decreased with their increasing content, but a maximum on its concentration dependence obtained for humic acids was observed. Two different values of dissociation constants were determined for each sample. The first was determined on the basis of the extrapolation of infinite dilution, second was determined as their average value in the region of high concentrations in which it was constant. Obtained values characterize the functioning of dissolved humic substances from point of view of their dissociation ability. The results obtained by this approach can help to predict the acid–base behaviour of dissolved organic carbon in soil and generally in nature. The acid–base behaviour of dissolved organic carbon depends on its ratio to water. It behaves differently in soil which is dry and in soil which is wet or saturated by water.

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表征超分子电解质解离行为的新可能性：通过库仑法为国际腐殖质协会标准和参考样品获得的结果

腐殖质可以被认为是具有超分子特性和在水环境中复杂行为的聚电解质。溶解在水中的腐殖质部分是最活跃的部分，并且决定了它们在自然界中的功能，其中质子结合和解离能力起着至关重要的作用。腐殖酸和富里酸的解离行为会受到不同环境的影响，包括它们的浓度与溶液中腐殖质颗粒的分子结构及其可电离官能团的可及性直接相关。本研究仅关注这些活性部分及其离解行为，这取决于它们在研究系统中的含量。使用国际腐殖质协会的标准和参考样品。流通库仑法用于测定富里酸溶液和腐殖质渗滤液中酸性官能团的总含量。基于电位测定法测定解离的酸性基团的量。发现腐植酸和富里酸的行为之间存在一些差异。虽然分析了包括最弱官能团的整个富里酸样品，但仅表征了含有较强酸性官能团的活性溶解腐殖质部分。含有较高量最弱官能团的级分仍然不溶。黄腐酸的解离度随着其含量的增加而降低，但观察到腐殖酸的浓度依赖性最大。每个样品测定两个不同的解离常数值。第一个是根据无限稀释的外推法确定的，第二个确定为它们在恒定的高浓度区域中的平均值。获得的值从分解能力的角度表征溶解的腐殖质的功能。通过这种方法获得的结果有助于预测土壤和自然界中溶解有机碳的酸碱行为。溶解有机碳的酸碱行为取决于它与水的比例。它在干燥的土壤和潮湿或被水饱和的土壤中表现不同。获得的值从分解能力的角度表征溶解的腐殖质的功能。通过这种方法获得的结果有助于预测土壤和自然界中溶解有机碳的酸碱行为。溶解有机碳的酸碱行为取决于它与水的比例。它在干燥的土壤和潮湿或被水饱和的土壤中表现不同。获得的值从分解能力的角度表征溶解的腐殖质的功能。通过这种方法获得的结果有助于预测土壤和自然界中溶解有机碳的酸碱行为。溶解有机碳的酸碱行为取决于它与水的比例。它在干燥的土壤和潮湿或被水饱和的土壤中表现不同。