Role of polar and apolar moieties in water adsorption by humic acids under arid conditions


In arid soils, humic acids (HAs) are used as amendments to improve water uptake from the atmosphere. This method of harvesting water involves several steps depending on the relative humidity (RH). At low RH, water is adsorbed solely on primary sorption sites such as polar groups. As RH increases, more water is adsorbed on polar groups forming secondary sorption sites, which grow as the RH increases. As a result, the neighboring sorption sites can connect to form water molecule bridges (WaMBs). The WaMBs are responsible for the transport of water in the form of clusters into hydrophobic pores resulting in an increase in water content in organic matter (OM), swelling of OM and formation of phase water. HA being a complex mixture complicates the understanding of the relationship between the proportion of polar groups and properties of water. The understanding of these relationships can guide the design of humic-based amendments applicable in arid systems. To address this issue, seven HAs were characterized by nuclear magnetic resonance followed by the investigation of the properties of water (water content, strength of WaMBs and strength of water binding) on the HAs. Results showed that the content of polar groups positively correlated with the amount of water adsorbed by HA and the stability of WaMBs. It was found that presumably apolar moieties such as aromatics and phenols increased the binding energy of water to HA thereby appearing to be responsible for preventing the desiccation. In addition, between 44 and 76% RH, the WaMB stability positively correlated with O-alkyl and peptides moieties. Therefore, both polar and apolar domains influence water properties depending on RH. We conclude that this synergism is an advantage in systems composed of hydrophobic and hydrophilic molecules held together by weak interactions providing high flexibility to the system under arid conditions.

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  1. 1.

    Schimel DS. Drylands in the earth system. Science (80-). 2010;327(5964):418–9.

    CAS  Article  Google Scholar 

  2. 2.

    McHugh TA, Morrissey EM, Reed SC, Hungate BA, Schwartz E. Water from air: an overlooked source of moisture in arid and semiarid regions. Sci Rep. 2015;5:13767.

    Article  Google Scholar 

  3. 3.

    Agam N, Berliner PR. Dew formation and water vapor adsorption in semi-arid environments—a review. J Arid Environ. 2006;65(4):572–90.

    Article  Google Scholar 

  4. 4.

    Xu S, Zhang L, Zhou L, Mi J, Mclaughlin NB, Liu J. Effects of water absorbing soil amendments on potato growth and soil chemical properties in a semi-arid region. Agric Eng Int CIGR J. 2018;20(2):9–18.

    Google Scholar 

  5. 5.

    David J, et al. The physico-chemical properties and biostimulative activities of humic substances regenerated from lignite. Springerplus. 2014;3(1):156.

    Article  Google Scholar 

  6. 6.

    Ctvrtnickova A, Drastik M, David J, Kucerik J. Surface and solution behavior of surfactants produced from lignite humic acids. Fresenius Environ Bull. 2011;20(7A):1764–71.

    CAS  Google Scholar 

  7. 7.

    Fashina TB, Adesanwo OO, Adebiyi FM. Influence of humic acid on biodegradation of petroleum hydrocarbons in oil-contaminated soils. Energy Sources Part A Recover Util Environ Eff. 2016;38(17):2624–32.

    CAS  Article  Google Scholar 

  8. 8.

    Piccolo A. The supramolecular structure of humic substances. Soil Sci. 2001;166(11):810–32.

    CAS  Article  Google Scholar 

  9. 9.

    Schaumann G. Soil organic matter beyond molecular structure part II: amorphous nature and physical aging. J Plant Nutr Soil Sci. 2006;169(2):157–67.

    CAS  Article  Google Scholar 

  10. 10.

    Chilom G, Rice JA. Structural organization of humic acid in the solid state. Langmuir. 2009;25(16):9012–5.

    CAS  Article  Google Scholar 

  11. 11.

    Borisover M. The effect of organic sorbates on water associated with environmentally important sorbents: estimating and the LFER analysis. Adsorption. 2013;2–4:241–50.

    Article  Google Scholar 

  12. 12.

    Aquino AJA, Tunega D, Schaumann GE, Haberhauer G, Gerzabek MH, Lischka H. Stabilizing capacity of water bridges in nanopore segments of humic substances: a theoretical investigation. J Phys Chem C. 2009;113(37):16468–75.

    CAS  Article  Google Scholar 

  13. 13.

    Schaumann GE, Bertmer M. Do water molecules bridge soil organic matter molecule segments? Eur J Soil Sci. 2008;59(3):423–9.

    CAS  Article  Google Scholar 

  14. 14.

    Lu Y, Pignatello JJ. Sorption of apolar aromatic compounds to soil humic acid particles affected by aluminum(III) ion cross-linking. J Environ Qual. 2004;33(4):1314.

    CAS  Article  Google Scholar 

  15. 15.

    Scheel T, Jansen B, van Wijk AJ, Verstraten JM, Kalbitz K. Stabilization of dissolved organic matter by aluminium: a toxic effect or stabilization through precipitation? Eur J Soil Sci. 2008;59(6):1122–32.

    CAS  Article  Google Scholar 

  16. 16.

    Brennan JK, Bandosz TJ, Thomson KT, Gubbins KE. Water in porous carbons. Colloids Surf A Physicochem Eng Asp. 2001;187:539–68.

    Article  Google Scholar 

  17. 17.

    Aquino AJA, et al. Molecular dynamics simulations of water molecule-bridges in polar domains of humic acids. Environ Sci Technol. 2011;45(19):8411–9.

    CAS  Article  Google Scholar 

  18. 18.

    Kučerík J, Schwarz J, Jäger A, Bertmer M, Schaumann GE. Character of transitions causing the physicochemical aging of a sapric histosol. J Therm Anal Calorim. 2014;118(2):1169–82.

    Article  Google Scholar 

  19. 19.

    Jäger A, Schwarz J, Mouvenchery YK, Schaumann GE, Bertmer M. Physical long-term regeneration dynamics of soil organic matter as followed by 1H solid-state NMR methods. Environ Chem. 2016;13(1):50.

    Article  Google Scholar 

  20. 20.

    Schaumann GE, Gildemeister D, Kunhi Mouvenchery Y, Spielvogel S, Diehl D. Interactions between cations and water molecule bridges in soil organic matter. J Soils Sediments. 2013;13(9):1579–88.

    CAS  Article  Google Scholar 

  21. 21.

    Ondruch P. Soil organic matter aging processes and their contribution to the sequestration of pollutants in soil. Mainz: University of Koblenz-Landau; 2018.

    Google Scholar 

  22. 22.

    Do D, Junpirom S, Do H. A new adsorption–desorption model for water adsorption in activated carbon. Carbon N Y. 2009;47(6):1466–73.

    CAS  Article  Google Scholar 

  23. 23.

    Kučerík J, Ondruch P, Kunhi Mouvenchery Y, Schaumann GE. Formation of water molecule bridges governs water sorption mechanisms in soil organic matter. Langmuir. 2018;34(40):12174–82.

    Article  Google Scholar 

  24. 24.

    Swift RS. Organic matter characterization. Methods Soil Anal: Part 3 Chem Methods. 1996;5:1011–69.

    Google Scholar 

  25. 25.

    Amer AMA. Water vapor adsorption and soil wetting. London: InTech; 2015.

    Google Scholar 

  26. 26.

    Novák F, Hrabal R. Quantitative 13C NMR spectroscopy of humic acids. Chem List. 2011;105(10):752–60.

    Google Scholar 

  27. 27.

    Jat ML, Bhakar SR, Sharma SK, Kothari AK. Dryland technology. Jodhpur: Scientific Publishers; 2013.

    Google Scholar 

  28. 28.

    Schaumann GE, LeBoeuf EJ. Glass transitions in peat: their relevance and the impact of water. Environ Sci Technol. 2005;39(3):800–6.

    CAS  Article  Google Scholar 

  29. 29.

    Průšová A, Šmejkalová D, Chytil M, Velebný V, Kučerík J. An alternative DSC approach to study hydration of hyaluronan. Carbohydr Polym. 2010;82(2):498–503.

    Article  Google Scholar 

  30. 30.

    Cihlář Z, Vojtová L, Michlovská L, Kučerík J. Preparation and hydration characteristics of carbodiimide crosslinked lignite humic acids. Geoderma. 2016;274:10–7.

    Article  Google Scholar 

  31. 31.

    Ondruch P, Kucerik J, Steinmetz Z, Schaumann GE. Influence of organic chemicals on water molecule bridges in soil organic matter of a sapric histosol. J Phys Chem A. 2017;121(12):2367–76.

    CAS  Article  Google Scholar 

  32. 32.

    Starostová A. Water-cation bridges in soil organic matter. Brno: Brno University of Technology; 2018.

    Google Scholar 

  33. 33.

    Hurrass J, Schaumann GE. Is glassiness a common characteristic of soil organic matter? Environ Sci Technol. 2005;39:9534–40.

    CAS  Article  Google Scholar 

  34. 34.

    Schaumann GE, Thiele-Bruhn S. Molecular modeling of soil organic matter: squaring the circle? Geoderma. 2011;166(1):1–14.

    CAS  Article  Google Scholar 

  35. 35.

    Schulten H-R, Leinweber P. New insights into organic-mineral particles: composition, properties and models of molecular structure. Biol Fertil Soils. 2000;30(5–6):399–432.

    CAS  Article  Google Scholar 

  36. 36.

    Sasaki O, Kanai I, Yazawa Y, Yamaguchi T. Relationship between the chemical structure of humic substances and their hygroscopic properties. Ann Environ Sci. 2007;1:17–22.

    CAS  Google Scholar 

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We are thankful for the financial support of the International Humic Substances Society (IHSS) (Grant No. IHSS2017TRAINING), Project FCH-S-20-6446 and LO1211 of the Ministry of Education, Youth and Sports of the Czech Republic (Grant No. FCH-S-18-5331) and the Department of Soil and Crop Sciences, Texas A&M University, USA.

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Correspondence to Bidemi Fashina.

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Fashina, B., Novák, F. & Kučerík, J. Role of polar and apolar moieties in water adsorption by humic acids under arid conditions. J Therm Anal Calorim (2020).

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  • Humic acid
  • Hydration
  • Desiccation
  • 13C NMR
  • DSC
  • Water molecule bridges