Formation of Water Molecule Bridges Governs Water Sorption Mechanisms in Soil Organic Matter

Langmuir ◽  
2018 ◽  
Vol 34 (40) ◽  
pp. 12174-12182 ◽  
Author(s):  
Jiří Kučerík ◽  
Pavel Ondruch ◽  
Yamuna Kunhi Mouvenchery ◽  
Gabriele E. Schaumann
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Water Molecule ◽  
Water Sorption ◽  
Sorption Mechanisms

Sorption of hydrophobic pesticides to aliphatic components of soil organic matter

2003 ◽  
Author(s):  
Benny Chefetz ◽  
Baoshan Xing
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Organic Pollutants ◽  
Agricultural Soils ◽  
Hydrophobic Interactions ◽  
Spectroscopic Techniques ◽  
Plant Materials ◽  
Hydrophobic Compounds ◽  
High Sorption ◽  
Sorption Mechanisms

Sorption of hydrophobic compounds to aliphatic components of soil organic matter (SOM) is poorly understood even though these aliphatic carbons are a major fraction of SOM. The main source of aliphatic compounds in SOM is above- and below-ground plant cuticular materials (cutin, cutan and suberin). As decomposition proceeds, these aliphatic moieties tend to accumulate in soils. Therefore, if we consider that cuticular material contributes significantly to SOM, we can hypothesize that the cuticular materials play an important role in the sorption processes of hydrophobic compounds (including pesticides) in soils, which has not yet been studied. The overall goal of this research was to illustrate the mechanism and significance of the refractory aliphatic structures of SOM in sorbing hydrophobic compounds (nonionic and weakly polar pesticides). The importance of this study is related to our ability to demonstrate the sorption relationship between key pesticides and an important fraction of SOM. The specific objectives of the project were: (1) To isolate and characterize cuticular fractions from selected plants; (2) To investigate the sorption mechanism of key hydrophobic pesticides and model compounds to cuticular plant materials; (3) To examine the sorption mechanisms at the molecular level using spectroscopic techniques; (4) To investigate the sorption of key hydrophobic pesticides to synthetic polymers; (5) To evaluate the content of cuticular materials in agricultural soils; and (6) To study the effect of incubation of plant cuticular materials in soils on their sorptive capabilities. This project demonstrates the markedly high sorption capacity of various plant cuticular fractions for hydrophobic organic compounds (HOCs) and polar organic pollutants. Both cutin (the main polymer of the cuticle) and cutan biopolymers exhibit high sorption capability even though both sorbents are highly aliphatic in nature. Sorption by plant cuticular matter occurs via hydrophobic interactions and H-bonding interactions with polar sorbates. The cutin biopolymer seems to facilitate reversible and noncompetitive sorption, probably due to its rubbery nature. On the other hand, the epicuticular waxes facilitate enhance desorption in a bi-solute system. These processes are possibly related to phase transition (melting) of the waxes that occur in the presence of high solute loading. Moreover, our data highlight the significance of polarity and accessibility of organic matter in the uptake of nonpolar and polar organic pollutants by regulating the compatibility of sorbate to sorbent. In summary, our data collected in the BARD project suggest that both cutin and cutan play important roles in the sorption of HOCs in soils; however, with decomposition the more condensed structure of the cutin and mainly the cutan biopolymer dominated sorption to the cuticle residues. Since cutin and cutan have been identified as part of SOM and humic substances, it is suggested that retention of HOCs in soils is also controlled by these aliphatic domains and not only by the aromaticrich fractions of SOM.

Influence of water molecule bridges on sequestration of phenol in soil organic matter of sapric histosol

2019 ◽  
Vol 16 (7) ◽  
pp. 541 ◽  
Author(s):  
Pavel Ondruch ◽  
Jiri Kucerik ◽  
Daniel Tunega ◽  
Nadeesha J. Silva ◽  
Adelia J. A. Aquino ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Water Molecule ◽  
Organic Molecules ◽  
Desorption Kinetics ◽  
Modulated Differential Scanning Calorimetry ◽  
Time Constants ◽  
Oh Groups ◽  
Solvation Energies ◽  
Kinetics Of

Environmental contextImmobilisation of organic chemicals in soil organic matter can strongly influence their availability in the environment. We show that the presence of water clusters, called water molecule bridges, hampers the release of organic molecules from soil organic matter. Moreover, water molecule bridges are sensitive to changes in environmental conditions (e.g., temperature or moisture) which affect the release of organic molecules into the environment. AbstractWater molecule bridges (WaMB) can stabilise the supramolecular structure of soil organic matter (SOM) by connecting individual SOM molecular units. WaMB are hypothesised to act as a desorption barrier and thus to physically immobilise molecules in SOM. To test this hypothesis, we prepared two sets of soil samples – aged samples with WaMB developed, and vacuumed samples, in which WaMB were disrupted. The samples were spiked with phenol and then stored under controlled humidity. The degree of phenol immobilisation in SOM was assessed by desorption kinetics of phenol into a gas phase. This was compared with the thermal stability (T*) of WaMB obtained by modulated differential scanning calorimetry (MDSC) and the results were related to computer modelling, which provided the stability and solvation energies of phenol-WaMB-SOM models. The desorption kinetics of phenol was best described by a first-order model with two time constants ranging between 1 and 10h. In aged samples, the time constants correlated with T*, which showed that the desorption time increased with increasing WaMB stability. Molecular modelling proposed that phenol molecules are preferentially locked in nanovoids with polar OH groups pointed to WaMB in the most stable configurations. Both findings support the hypothesis that WaMB can act as a desorption barrier for phenol.

Influence of Organic Chemicals on Water Molecule Bridges in Soil Organic Matter of a Sapric Histosol

2017 ◽  
Vol 121 (12) ◽  
pp. 2367-2376 ◽  
Author(s):  
Pavel Ondruch ◽  
Jiri Kucerik ◽  
Zacharias Steinmetz ◽  
Gabriele E. Schaumann
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Water Molecule ◽  
Organic Chemicals

Experimentally Determined Soil Organic Matter–Water Sorption Coefficients for Different Classes of Natural Toxins and Comparison with Estimated Numbers

2012 ◽  
Vol 46 (11) ◽  
pp. 6118-6126 ◽  
Author(s):  
Judith Schenzel ◽  
Kai-Uwe Goss ◽  
René P. Schwarzenbach ◽  
Thomas D. Bucheli ◽  
Steven T. J. Droge
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Water Sorption ◽  
Natural Toxins

Interactions between cations and water molecule bridges in soil organic matter

2013 ◽  
Vol 13 (9) ◽  
pp. 1579-1588 ◽  
Author(s):  
Gabriele E. Schaumann ◽  
Daniela Gildemeister ◽  
Yamuna Kunhi Mouvenchery ◽  
Sandra Spielvogel ◽  
Dörte Diehl
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Water Molecule

Sorption of anthropogenic organic compounds by soil organic matter: a mechanistic consideration

2001 ◽  
Vol 81 (3) ◽  
pp. 317-323 ◽  
Author(s):  
Baoshan Xing
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Organic Compounds ◽  
High Surface ◽  
High Surface Area ◽  
Fate And Transport ◽  
Dual Mode ◽  
Subsurface Environments ◽  
Desorption Hysteresis ◽  
Sorption Mechanisms

Sorption experiments with apolar organic compounds (naphthalene and 1,2-dichorobenzene) were conducted to evaluate sorption mechanisms in soil organic matter (SOM). All isotherms were nonlinear and competition between solutes was observed. Nonlinearity and competition increased in an order of peat humic acid (HA) < peat < peat humin. Isotherms of Al-saturated HA (Al-HA) were more nonlinear than untreated HA and Ca-HA, and sorption/desorption hysteresis occurred only in Al-HA. These results are not consistent with partitioning theory or the presence of high-surface-area carbonaceous materials (HSACM) in soil. But the results are consistent with dual-mode sorption, where SOM is postulated to have both condensed (rigid) and expanded (flexible) domains, and adsorption takes place only in the condensed domains and partitioning in both domains. These non-ideal sorptive behaviors need to be incorporated into predictive models to more accurately describe the fate and transport of organics in soil and subsurface environments. Key words: sorption, organic compounds, organic matter, dual-mode, partition, mechanisms

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