Conceptualization of definition and classification for humic substances

doi:10.1515/ci-2022-0216

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Conceptualization of definition and classification for humic substances

Published/Copyright: April 14, 2022

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From the journal Chemistry International Volume 44 Issue 2

Carbon accounting is crucial for reliable estimates of anthropogenic impact on climate change. Organic carbon is the most labile carbon pool composed predominantly of humified non-living organic matter. It is the major natural emitter of carbon dioxide and methane. At the same time, ill-defined isolation protocols and a lack of rigorous chemical definition of the humic systems provide for large uncertainties in assessing the rate of natural degradation and turnover of non-living organic matter. The humic systems exist both in soils, water, and organic rocks. While in all solid substrates, such as soil, coal, peat, etc., they are referred to as humic substances (HS), the non-living organic matter in waters is referred to as natural organic matter (NOM). Both HS and NOM play crucial ecological roles, in particular, under conditions of global climate change and represent different varieties of humic systems. The development of molecular systematics for these complex chemical systems is a prerequisite for reliable carbon accounting on different scales. The major problem is that in contrast to living systems, the synthesis of humic systems has no genetic code. It proceeds stochastically being constrained by the specific environmental parameters such as temperature, pressure, concentration of oxygen, humidity, the presence of aqueous, mineral, or organic matrices, etc. As a result, both definition and classification of humic systems are operationally defined according to the protocols of their isolation and fractionation. There is ample experimental evidence that behind this operational classification are structural regularities governing this behavior. However, they are not used yet for developing molecular systematics of HS and NOM, which are the different varieties of humic systems.

photo by Johannes Plenio/Unsplash

The specific objectives of this project are as follows:

critical evaluation of recent developments in the field of systems chemistry aimed at conceptualization of HS and NOM as complex chemical system
critical evaluation of existing analytical methodologies for investigation structural and molecular space of humic systems
critical evaluation of existing approaches to classification of non-living organic matter (e.g., humic substances, natural organic matter, dissolved organic matter, soil continuum, soil organic matter, aquatic continuum)
evaluation of recent developments in the field of quantitative description of structure of HS and NOM aimed at recommendations of best structural descriptors
elaboration of algorithm to compile the existing (reported) data on molecular composition of HS and NOM into chemical library of humic systems
elaboration of principles of molecular systematics of humic systems
elaboration of chemical definition and classification of humic substances
clear descriptions of relatively simple and inexpensive analytical measurements by which a sample could be properly classified for a use by small industrial companies – humate producers.

A Thematic session is planned for at the 21st International Conference of the International Humic Substances Society – Sept 17-22, 2022. <http://www.humus.ru/ihss-21/>

For more information and comments, contact Task Group Chair Irina Perminova <iperm@org.chem.msu.ru>

https://iupac.org/project/2021-032-3-600

Online erschienen: 2022-04-14

Erschienen im Druck: 2022-04-01

©2022 IUPAC & De Gruyter. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. For more information, please visit: http://creativecommons.org/licenses/by-nc-nd/4.0/

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https://doi.org/10.1515/ci-2022-0216