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Aquatic humic substances : influence on fate and treatment of pollutants by I. H Suffet Book 13 editions published between and in English and held by WorldCat member libraries worldwide. Humic substances : nature's most versatile materials by Geoffrey Davies Book 6 editions published between and in English and held by WorldCat member libraries worldwide Contains a compilation of papers presented at the Humic Substances Seminar and will keep humic substances scientists current with the latest research.
Humic substances in soil and crop sciences : selected readings : proceedings of a symposium cosponsored by the International Humic Substances Society An introduction to soil humic substances. Variations between humic substances isolated from soils, stream waters, and groundwaters as revealed by 13C-NMR spectroscopy. Synthesis and degradation of natural and synthetic humic material in soil.
Selected methods for the characterization of soil humic substances. Nitrogen in humic substances as related to soil fertility. Roles of organic matter, minerals, and moisture in sorption of nonionic compounds and pesticides by soil. Effects of humic substances on plant growth. Ecological aspects of soil organic matter in tropical land use. Humic and fulvic acid fractions from sewage sludges and sludge-amended soils. Application of nuclear magnetic resonance spectroscopy to whole soils.
Humic substances in soil and crop sciences: an overview. Aquatic humic substances : influence on fate and treatment of pollutants ; developed from a symposium sponsored by the Division of Environmental Chemistry of the American Chemical Society and the International Humic Substances Society at the rd National Meeting of the American Chemical Society, Denver, Colorado, April , Book 1 edition published in in English and held by 17 WorldCat member libraries worldwide. Humic substances II : in search of structure by M. B Hayes Book 4 editions published in in English and held by 11 WorldCat member libraries worldwide Based on the Second International Conference of the International Humic Substances Society held in Birmingham, England, in , this compendium reviews ways of studying the structure and function of humic substances, including the use of both degradative and nondegradative processes.
The results indicated that the most important factor determining the biological activity of South-Moravian lignite potassium humates is related to the nature of self-assemblies, while the chemical composition had no direct connection with the root growth of Zea mays seedlings.
It was demonstrated a controlled processing that provided humic substances with different chemical and physicochemical properties and variable biological activity. Humic substances humics, HS are refractory, dark-colored heterogeneous organic compounds produced in the decay of the total biota in the environment Stevenson From the chemical point of view, they are a heterogeneous mixture of fragments of lignins, cellulose, suberins and cutins.
Their unique structure makes them a versatile material with applications in industry, medicine, environmental protection, and agriculture. It is becoming clearer, that the presence of humics in soil is necessary for sustainable agriculture, due to their ability to condition the soil, enhance its stability and increase its resistance to erosion Laker et al.
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In addition, humics have the ability to sequestrate soil pollutants Evdokimov and von Wandruszka ; Sanjay et al. The biological activity of humics has been recognized in Bottomley , while their hormone—like nature was reported later Canellas et al. Aguirre et al. Mora et al. Piccolo et al. In contrast, neither the aliphatic nor the aromatic content of the extracts appeared to play a role in the biological activity Nardi et al. In contrast, Canellas et al. Lignite, i. The content of humics can be increased by regeneration processes with nitric acid, potassium manganate VII , sulfuric acid, or hydrogen peroxide Berkowitz , Rausa et al.
However, understanding the influence of lignite regeneration on the physicochemical and biological behavior is still incomplete. The same holds true for optimization of the regeneration processes e. The aims of this work, therefore, are: i to elucidate the pertinent processes in South-Moravian lignite treatment; ii to test the obtained products from both chemical and physico-chemical perspectives; and iii to assess the influence of regeneration on their biological activity in vitro. All the chemicals were obtained from LachNer Ltd. The mixture was filtered and the filtration cake of treated lignite was used for extraction of regenerated humate.
It involved an alkaline extraction with a mixture of 0. After extraction and dialysis, each humic sample was divided into two parts. The first part was freeze dried as such, yielding solid humic acid of low solubility. The second part was titrated with 0. This yielded water soluble potassium humate.
Freeze drying was carried out with Freezone 4.
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The products obtained were crushed in an agate mortar, weighed, and stored in sealed vials in a dry, dark location. The oxygen percentage was calculated as a difference between the sample weight and the C, H, and N content, taking into account the moisture and ash contents determined by thermogravimetry see below. The influence of regeneration on the thermooxidative stability of humics products was assessed by thermogravimetry.
The spectra were processed using the Nicolet Omnic 8 software. Dynamic light scattering measurements were obtained with a N4 Plus Submicron Particle Sizer equipped with He-Ne red laser of wavelength of Outlying values were excluded according to the Dean-Dixon test Dean and Dixon The flow rate was set at 0. Samples were prepared as 0. The calibration of the column was performed using poly styrenesulphonate standards of The weight averaged M W and number averaged M N molecular weights of the humates were calculated according to the Mori and Barth Calibration was carried out using polysaccharide standards of , , , In order to determine the amount of water of hydration bound by the humics, a high resolution ultrasonic spectrometer HRUS , Sonas Technologies Ltd.
The system was kept at The instrument was calibrated with deionized water at High resolution density measurements were performed for the same solutions, in triplicates, with a DMA density meter Anton Paar Ltd. The seeds were treated for 5 min in a 50 mM sodium hypochlorite NaClO solution and then washed and immersed in deionized water for 4 h to precondition them for germination. For the purpose of comparison, a commercial nitrophenolate growth promoter AtonikPro, ArystaLifeScience, Czech Republic was also included in the testing regimen.
This solution contained 0.
This resulted in a light intensity of — lux. All the experiments were performed in duplicate. Similarly, the stress tests on the plants have not been applied, since the plants seemed to present uniform leave numbers, lengths and areas and these would be far beyond the scope of this work. Placing the germs in testing polystyrene containers, with 30 germs per container and each 5 of them placed in a marked position on a floating styrofoam bed to be observed later for root length and division.
The germinated seeds and grown plants were weighed and the differences were recorded in terms of total mass increment. The scanned images were saved as bitmaps and subjected to 2D Wavelet Analysis. The root growth increments for the particular 15 samples were statistically compared using a one-way analysis of variance ANOVA. Rather than plants stress tests, we focused on the determination of sugars and protein in the seedlings. The total dry mass was divided for determination of sugars and proteins. The sugar content was determined polarimetrically using the customary Ewers polarimetric method Kennedy et al.
The proteins were determined by the Kjeldahl method McClements for the determination of total nitrogen. Regarding the hydrogen peroxide treated lignites, only the 20P sample gave a greater HA yield than direct extraction from parental lignite. The reason for this discrepancy is not entirely clear; it might be related to variation of humics from batch to batch within the same source. Since the O content was calculated as a difference, the determined value may include traces of S and P. The regenerated humic acids were characterized by thermogravimetry and results were compared with humics extracted from parental lignite parental HA.
These decomposition curves were comparable to results obtained by other groups and they were typical for lignitic humic substances Gonet and Cieslewicz It is worth to mention that the onset temperatures represent a measure of the thermo-oxidative stability. The lower onset temperatures and steeper degradation curves of regenerated HA samples indicate a relative enhancement of aliphatic structures and polar functionalities, which are generally less thermo-oxidative stable than aromatic moieties Plante et al.
In view of the pseudomicellar model of humic aggregation and when compared to the DLS results of Palmer and von Wandruszka , the humate samples showed abnormal behavior. From this perspective, the regeneration brought more soil-humic-acid-like behavior to the samples. High performance size exclusion chromatography HPSEC experiments were conducted with refractive index detector RID and diode array detector DAD in order to avoid the underestimation of a variety of molecular fractions absorbing in the visible range.
The great differences were found between potassium humates obtained from parental and treated lignites, the HNO 3 treatment of lignite caused an increased unsaturated content in the humates. This indicates that the oxidation of lignite had a major impact on the aliphatic moieties, while affecting the aromatic ones to a lesser extent.
The irregular behavior of KRHA40N was probably due to inhomogeneities in the lignite fraction used in the preparation of this sample. The RID results indicate that nitric acid treatment decreased the molecular mass of extracted humic acids, while peroxide had the opposite effect.
Humic substances in surface waters of the Ukraine
The hydration of humates was studied by means of high resolution ultrasonic velocimetry and density measurements. The hydration values of the humates e. Up: hydration left axis, triangles and compressibility right axis, hexagons chart; down: ultrasound velocity U12 left axis, squares and density right axis, circles chart.