Allochthonous and autochthonous organic matter in natural waters: Kinetic and thermodynamic patterns of transformation and quantitative and qualitative compositions

<p>The reactions of toxicants with organic substances of a humic nature are complex and depend on many geochemical factors. Differences in the mechanisms of the selected toxicants binding with organic natural substances of various natural waters - atmospheric precipitation, lake waters (acidic and alkaline), lysimetric waters are especially interesting. Due to significant concentration differences, features of functional groups and size distribution of components, the inactivation features of humic substances are selective and highly variable. We studied the waters of an acid lake near the city of Valday (Valday National Park, conditionally a background lake) and alkaline lake Valday (city of Valday, local technogenic influence). Near each lake there was a sediment collector (a container for collecting atmospheric precipitation) and a lysimeter (a container under the soil for collecting soil moisture) under the humus horizon (about 20 cm). Particular attention was paid to soil (lysimetric) waters with varying degrees of anthropogenic impact. We considered the behavior of a large group of heavy metals, as well as benzopyrene. To assess the composition and qualitative features of organic substances, gas chromatography-mass spectrometric methods of analysis were used. Chromatographic methods were used to assess the molecular weight distribution of the components. Possible reaction mechanisms were studied by IR spectral methods. Evaluation of the reactivity of organic substances was carried out by the methods of dynamic light scattering (zeta potential, MM, size) using the "Zeta-sizer nano". In addition to humic substances in the waters, the contents of autochthonous organic matter were estimated, especially in an alkaline lake, which in some periods prevailed over humic ones. In addition to humic substances in the waters, the contents of autochthonous organic matter were estimated, especially in an alkaline lake, which in some periods prevailed over humic ones. For separation, exchange technique and fluorometric evaluations were used. We conducted research in the period 2015-2020, sampling was carried out in spring, summer, autumn. Thus, we studied the circulation (in miniature) of changes in the protective properties of humic substances, depending on a large number of factors.</p>

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Photochemical effects on the interaction of enzymes and dissolved organic matter in natural waters

Limnology and Oceanography ◽

10.4319/lo.2003.48.5.1818 ◽

2003 ◽

Vol 48 (5) ◽

pp. 1818-1824 ◽

Cited By ~ 23

Author(s):

Norman M. Scully ◽

Lars J. Tranvik ◽

William J. Cooper

Keyword(s):

Organic Matter ◽

Dissolved Organic Matter ◽

Natural Waters

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Optical Properties of Dissolved Organic Matter in Finnish and Estonian Lakes

Hydrology Research ◽

10.2166/nh.2003.0012 ◽

2003 ◽

Vol 34 (4) ◽

pp. 361-386 ◽

Cited By ~ 14

Author(s):

L. Sipelgas ◽

H. Arst ◽

K. Kallio ◽

A. Erm ◽

P. Oja ◽

...

Keyword(s):

Organic Matter ◽

Dissolved Organic Matter ◽

Natural Waters ◽

Mean Value ◽

Published Data ◽

Optical Parameters ◽

Exponential Approximation ◽

Absorption Coefficients ◽

Specific Absorption ◽

The Mean

The main objective of the present study is to test various methods for describing the absorption spectra of coloured dissolved organic matter (CDOM) and to determine the numerical values of some optical parameters of CDOM in lakes with diverse water quality. First, the parameters of an exponential model in different spectral intervals were determined. In addition, the suitability of some other models for the approximation of CDOM spectra was estimated. Specific absorption coefficients of CDOM were calculated from the absorption coefficients and dissolved organic carbon (DOC) concentrations. The experimental initial data were differences between spectral attenuation coefficients of filtered and distilled water. Two datasets were used: 1) for 13 Estonian and 7 Finnish lakes (altogether 404 spectra between 350 and 700 nm) measured by the Estonian Marine Institute (EMI); 2) for 10 Finnish lakes (73 spectra) measured by the Finnish Environment Institute (FEI). The spectra of CDOM absorption coefficients (aCDOM) were calculated from experimental data taking into account the correction due to scattering properties of colloids in the filtered water. The total content of CDOM in natural waters of Estonian and Finnish lakes was expressed by means of aCDOM at the wavelength of 380 nm. It varied significantly, from 0.71 to 19.5 m−1, the mean value (of all the investigated lakes) being around 6.6 m−1. Slopes of the exponential approximation varied widely, from 0.006 to 0.03 nm−1. Averaged over all lakes values of slope for the interval 380-500 nm obtained from the EMI dataset are close to those obtained from the FEI dataset: from 0.014 nm−1 (without correction) to 0.016-0.017 nm-1 (with different types of correction). These results are in good correspondence with most published data. Attempts to describe the spectra in the region of 350-700 nm by means of hyperexponential functions (∽ exp(-αλη)) show that: (1) η < 1 (in the case of traditional exponential approximation η = 1); (2) a promising idea is to seek the best fit only for wavelengths λ > λ1, where λ1 will be chosen taking into account the real shape of aCDOM spectra. The mean value of the specific absorption coefficient (a*CDOM) at the wavelength 380 nm obtained in this study (0.44 L mg−1 m−1) is close to the values published in the literature, if we assume that a*CDOM (380) is calculated using the data of dissolved organic matter (DOM). The optically non-active fraction of DOM in our study was high and therefore a*CDOM (380) was considerably higher (1.01 L mg−1 m−1) than a*CDOM (380). The results of the present work could be used in the modeling of underwater light field as well as in the interpretation of radiation measurements and optical remote sensing results.

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Complexation of Dissolved Organic Matter with Trace Metal Ions in Natural Waters

Photobiogeochemistry of Organic Matter - Environmental Science and Engineering ◽

10.1007/978-3-642-32223-5_9 ◽

2012 ◽

pp. 769-849 ◽

Cited By ~ 7

Author(s):

Khan M. G. Mostofa ◽

Cong-qiang Liu ◽

Xinbin Feng ◽

Takahito Yoshioka ◽

Davide Vione ◽

...

Keyword(s):

Organic Matter ◽

Dissolved Organic Matter ◽

Trace Metal ◽

Metal Ions ◽

Natural Waters ◽

Trace Metal Ions

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Organo-Mineral Interactions Are More Important for Organic Matter Retention in Subsoil Than Topsoil

Soil Systems ◽

10.3390/soilsystems4010004 ◽

2020 ◽

Vol 4 (1) ◽

pp. 4 ◽

Cited By ~ 2

Author(s):

Vincent Poirier ◽

Isabelle Basile-Doelsch ◽

Jérôme Balesdent ◽

Daniel Borschneck ◽

Joann K. Whalen ◽

...

Keyword(s):

Organic Matter ◽

Crop Residue ◽

Crop Residues ◽

Clay Content ◽

X Ray Diffraction ◽

Density Fractions ◽

Organic Matter Concentration ◽

Fractionation Procedure ◽

Autochthonous Organic Matter ◽

C And N

Decomposing crop residues contribute to soil organic matter (SOM) accrual; however, the factors driving the fate of carbon (C) and nitrogen (N) in soil fractions are still largely unknown, especially the influence of soil mineralogy and autochthonous organic matter concentration. The objectives of this work were (1) to evaluate the retention of C and N from crop residue in the form of occluded and mineral-associated SOM in topsoil (0–20 cm) and subsoil (30–70 cm) previously incubated for 51 days with 13C-15N-labelled corn residues, and (2) to explore if specific minerals preferentially control the retention of residue-derived C and N in topsoil and subsoil. We used topsoil and subsoil having similar texture and mineralogy as proxies for soils being rich (i.e., topsoil) and poor (i.e., subsoil) in autochthonous organic matter. We performed a sequential density fractionation procedure and measured residue-derived C and N in occluded and mineral-associated SOM fractions, and used X-ray diffraction analysis of soil density fractions to investigate their mineralogy. In accordance with our hypothesis, the retention of C and N from crop residue through organo-mineral interactions was greater in subsoil than topsoil. The same minerals were involved in the retention of residue-derived organic matter in topsoil and subsoil, but the residue-derived organic matter was associated with a denser fraction in the subsoil (i.e., 2.5–2.6 g cm−3) than in the topsoil (i.e., 2.3–2.5 g cm−3). In soils and soil horizons with high clay content and reactive minerals, we find that a low SOM concentration leads to the rapid stabilization of C and N from newly added crop residues.

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