Wyniki wyszukiwania - AGRO

1

Characteristics of humic acids extracted from soils by the capillary electrophoresis

100%

Grzelakowska A., Christy A.

Polish Journal of Soil Science

|

2003

|

tom 36

|

nr 2

145-152

Humic acids have an important role in the soils. When specific structures of which little is known, are studied, one should use the latest analitycal methods. So far the method of fractionation by electrophoretic mobility has not been very popular in the research studies on humic substances. However, it seems that it is possible to study humification processes and subtle changes in the structure of the material investigated using capillary electrophoresis. On the basis of our experience, some soils representing various types were selected as study material. Electrophoretic separation (by means of buffer solutions with various pH-values) was carried out for the humic acids extracted from the soils selected. The results obtained allowed for the determination of differences in the humic acids structures due to their origin.

2

Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik

Considerations on the degradation of hydrophobic organic chemicals in humic acid solutions

88%

Badora A.

Zeszyty Problemowe Postępów Nauk Rolniczych

|

2001

|

tom 476

The aim of this research was to show, that sorption and desorption processes of organic hydrophobic compounds on humic acid fraction can influence the microbial degradation rates of contaminants. This study was carried out in the Netherlands in 1996. Chlorinated benzene (pentachlorobenzene QCB) and a polychlorinated biphenyl (2.5-dichlorobiphenyl) were used as a model compounds.

3

Synthesis and properties of model humic substances derived from gallic acid

88%

Slawinska D., Polewski K., Rolewski P., Slawinski J.

International Agrophysics

|

2007

|

tom 21

|

nr 2

4

Content of phenolic compounds in humus acids of forest soil

88%

Banach-Szott M.

Polish Journal of Soil Science

|

2007

|

tom 40

|

nr 1

Theaimof the present paper was to define the qualitative and quantitative composition of phenolic compounds in the extracts of fulvic acids and hydrolyzates of humic acids isolated from forest soil. Forest soil was sampled from the organic horizon (5-3.5 cm – sub-horizon Ol and 3.5-0 cm– sub-horizon Ofh) and mineral horizon every 10 cm (0-50 cm). Phenoliccompounds in fulvic acids (FAs) extracts and humic acids (HAs) hydrolyzates were identified by high performance liquid chromatography (HPLC). The recorded chromatograms showed differences in the composition of phenolic compounds between humic and fulvic acids fractions. The content of those compounds both in extracts of fulvic acids and hydrolyzates of humic acids and V+S+C parameter values decreased together with the sampling depth. The highest values of V+S+C parameter were calculated for extracts of fulvic acids and humic acids hydrolyzates isolated from the organic horizon of forest soil. The share of the vanillyl type in the extracts of humus acids (HAs+FAs) of the subhorizon Ol was close to that of the sum share of the syringyl and cinnamyl type. The greater the depth, the greater the share of vanillyl compounds in the pool of the share of syringyl, cinnamyl and vanillyl compounds.

5

The comparison of the structure of humic acids from soil amended with different sources of organic matter

75%

Kwiatkowska-Malina J.

Polish Journal of Soil Science

|

2015

|

tom 48

|

nr 1

Soil organic matter (SOM) is an essential soil constituent. The deficiency of SOM is an essential problem in many regions in Poland. Diversity of organic matter and the environment create varying structures and compositions, and thus differences in properties of humic substances (HS) especially humic acids (HAs). It was found that soil amendment with organic matter resulted in improving of soil and HAs properties compared with non-treatment ones. The results obtained provided the following evidences. With respect to HAs: an increasing content of carboxylic groups in HAs from amended soils; a major content of aromatic ring systems; higher carbon, nitrogen, hydrogen, and sulphur and lower oxygen contents comparing to the control; the addition of straw caused an increase of carbon content in HAs particles and, consequently a decrease of the C:H ratio; higher content of oxygen functional groups compared with non-treated ones. Organic matter from straw is more resistant to fast decomposition as compared to compost and it shows higher long-term sorption capacity. Therefore, straw may be an equivalent to natural sources of SOM in terms of agriculture and ecosystems protection.

6

The effect of humic acid on metal accumulation by Unio tumidus

75%

Formicki G., Stawarz R., Guzik M., Gal A., Kuczkowska-Kuzniar A., Ciaglo A.

Folia Malacologica

|

2012

|

tom 20

|

nr 1

7

Changes in iron(II) and iron(III) content in a solution of humic acids during coagulation by means of monomeric iron(III) salts

75%

Libecki B., Dziejowski J.

Polish Journal of Environmental Studies

|

2010

|

tom 19

|

nr 5

This study discusses the results of laboratory analyses investigating the chemical coagulation of a model of humic acid solution with the use of monomeric iron(III) salts – chloride and sulfate – in a standard coagulation test environment. The objective of the study was to determine changes in iron compound concentrations in the tested solution as a result of coagulation. The following parameters were analyzed in solution samples: changes in COD, colour, turbidity, suspended solids, pH, and streaming potential in relation to the applied coagulant dose. The content of total iron (Fetotal) and iron(II) was determined in solution samples after coagulation. The lowest Fetotal concentrations were observed following the use of optimal coagulant doses, and higher doses led to a repeated increase in total iron levels. In purified solution samples, iron(III) was partially reduced to iron(II) with an 8-42% share of Fetotal, depending on salt type and the applied dose.

8

Chemical composition of compost from municipal waste in the context of use as fertiliser

75%

Becher M., Symanowicz B., Jaremko D., Trzcinska E.

Acta Agrophysica

|

2018

|

tom 25

|

nr 3

9

The characteristics of the properties of humic acids extracted from sewage sludge

75%

Flis-Bujak M., Zukowska G.

Polish Journal of Soil Science

|

2002

|

tom 35

|

nr 2

10

Properties of humic acids of light soil fertilized with sewage sludge

75%

Zukowska G., Flis-Bujak M.

Polish Journal of Soil Science

|

2002

|

tom 35

|

nr 2

11

Share of hydrophilic and hydrophobic fractions in humic acids formed as a result of post-harvest residue decomposition

75%

Debska B., Gonet I.

Polish Journal of Soil Science

|

2007

|

tom 40

|

nr 1

The importance of humus in the environment is related to its quantity and quality, and hence there is a constant search for parameters that define the properties of humus. One of the indicators determining sorption capacity and solubility of humic substances, and so their susceptibility to biodegradation, is the share of hydrophilic and hydrophobic fractions. The hydrophilic and hydrophobic properties were determined for humic acids formed in the process of post-harvest residue decomposition under soil conditions and outside the soil. It was demonstrated that the share of hydrophilic and hydrophobic fractions in the molecules of humic acids depends on the plant species of incubated plant residue and the incubation time. The changes in the share of hydrophilic, and thus also the hydrophobic fractions, result in a change in the value of the HIL/HOB ratio. This ratio can be used as an indicator of the degree of transformation of organic matter of soils.

12

Effect of the soil type on the molecular structure, properties and conditions of occurrence of humous acids

75%

Ksiezopolska A.

Acta Agrophysica

|

2000

|

tom 35

The study presented here concentrates on the characteristics of the humous compounds of humic and fulvic acid fractions of ß-humus, originating from the typologically differentiated soils (podzolic soil and chernozem). The soils were chosen so as to emphasize differences between chemical structure and degree of aromatic nucleus condensation in the humous acids isolated from them. It was found that the structure of the humous substances isolated from the podzolic soil is characterised by the lowest degree of condensation of the aromatic nucleus and the lowest polymerisation, while the humous acids from the chernozem are characterised by the highest degree of condensation of the aromatic nucleus and the strongest polymerisation.

13

Characteristics of humic acids from under crop rotations with differentiated cereal share

75%

Flis-Bujak M., Zukowska G.

Acta Agrophysica

|

2001

|

tom 52

This paper presents the results of studies carried out to estimate the influence of crop rotation, with diversified cereal shares on the humic acid characteristics. The tested range covered humic acids separated from the following soil types: degraded chernozem developed from loess, Orthic Luvisol developed from boulder clay, Orthic Luvisol developed from loess. Samples"were taken from the soil arable layer being under many-year crop rotation with a differentiated share of cereals (50 and 100%). The results obtained show that soil use affected quality indices of humic acids. In the lessive soils under cereal monocultures, an increase of the atomic H:C ratio was observed in humic acids. This allows for a conclusion that the monoculture system causes an increase in the content of aliphatic structures in humic acid molecules or a decrease in the condensation degree of their nuclei. Moreover, a decrease in the optic density of humin solutions given in A465 values was found in the humic acids under cereal monocultures which proves a marked direction of changes. In the case of humic acids extracted from chernozem, an analysis of elemental composition did not show any clear differentiation in the crop rotation with a 50% cereal share and a monoculture of cereal plants. The analysis of optic properties indicates a growth of the optic density (value of the E4:E6 ratio decreases) in the variant with a cereal plant monoculture which may suggest growth in the humification of individual humic acids.

14

Adhesion of humic acids to nonreactive surfaces: effect on surface free energy and wettability of glass

75%

Jozefaciuk G., Hajnos M., Sokolowska Z., Stawinski J., Polubesova T., Ponizovskij A.

International Agrophysics

|

1993

|

tom 07

|

nr 4

15

Integration studies of humic acids structure by the electron microscopy [TEM] and elemental analyses

75%

Drozd J.

Polish Journal of Soil Science

|

1997

|

tom 30

|

nr 1

16

Effect of oxygen on UV-induced photodegradation of humic acid obtained from composted hulls of Juglans regia walnut

75%

Slawinska D., Polewski K., Rolewski P., Slawinski J.

International Agrophysics

|

2004

|

tom 18

|

nr 2

17

Statistical relationship between selected physicochemical properties of peaty-muck soils and their fraction of humic acids

63%

Boguta P., Sokolowska Z.

International Agrophysics

|

2014

|

tom 28

|

nr 3

Influence of humic acids on soil environment is still subject of scientific discussions. The aim of above studies was to investigate the relationships between selected physicochemical properties of eleven peaty-muck soils and properties of humic acids isolated from these soils. The following parameters were determined for soils: total and organic carbon, density, ash, humifi- cation, and the water absorption index. Humic acids were described by: absorbance at 280 nm, absorbance ratios at 465 and 665 nm, at 260 and 665 nm, elemental composition and atomic ratios: H/C, O/H, O/C, C/N, the degree of internal oxidation, and the content of carboxylic and phenolic groups. Statistical analyses showed that an increase in density, humification, and water absorption indices of soils caused a significant increase in the humic acid parameters: absorbance at 280 nm, the oxygen content, O/H, O/C ratios, inter- nal oxidation degree, and functional groups. Statistically signifi- cant negative correlations were found for the same parameters of soils and for the hydrogen and carbon content as well as the H/C ratio of humic acids. The relationships showed that there was a pos- sibility to express the properties of humic acids on the basis of more simple parameters measured for soil and without time-consuming isolation of humic acids.

18

Optimization of humic acids coagulation with aluminum and iron [III] salts

63%

Libecki B., Dziejowski J.

Polish Journal of Environmental Studies

|

2008

|

tom 17

|

nr 3

397-403

Humic substances contained in ground and surface waters increase the degree of their pollution, give it a specific colour and contribute to the formation of toxic disinfection by-products in the process of water treatment. Coagulation is an effective method of removing organic compounds, including humic acids (HA), from water and wastewater. The proper selection of coagulants and optimization of such parameters as coagulant dose and the pH of the solution enable improvement of coagulation efficiency. The objective of the present study was to determine the efficiency of humic acids removal by coagulation, depending on the dose of Al and Fe(III) salts and pH of the analyzed solutions. A model alkaline solution and 0.2 M solutions of Al₂ (SO₄)₃ and Fe₂ (SO₄)₃ were used. The experiment was performed with and without pH adjustment, by a standard jar test procedure. COD-Cr [mg O₂ ·dm⁻³], colour – PtCo [mg·dm⁻³], turbidity – FTU [mg·dm⁻³], suspended solids – SS [mg·dm⁻³], pH and streaming potential – SP [mV] were determined during coagulation tests. In the solutions coagulated without pH adjustment and with the optimum doses of Al₂ (SO₄)₃ and Fe₂ (SO₄)₃ ,COD was at a level of 0.1 to 3% of the initial value and colour was removed almost completely. Iron(III) sulfate was found to be slightly more effective as a coagulant, in respect to COD removal. The results of electrokinetic measurements showed that the charge of molecules of humic colloids depends on the type and concentration of coagulating salt, as well as on the pH of the solution. The analysis of coagulation with pH adjustment revealed that there exists the optimum value of pH for each of the salt doses applied in the experiment. Coagulation with the use of Al₂ (SO₄)₃ and Fe₂ (SO₄)₃ proceeded at pH < 5.8 and pH < 4.2, respectively. A decrease in the pH of an HA solution allowed us to considerably (even eight-fold) reduce the dose of coagulants, maintaining high (above 94%) efficiency of humic acid removal by coagulation.

19

Effect of water regimes on sorptivity and organic matter humic components of soil

63%

Raut S., Sahoo N., Chakraborty H.

International Agrophysics

|

2012

|

tom 26

|

nr 1

The aim of the study was to find the effect of water regimes on soil sorptivity and humic components of organic matter. Physicochemical parameters were also determined. Steady state cumulative infiltration was the highest (60-100 mm) in non-irrigated upland soil and the lowest (8-10 mm) in waterlogged soil. The highest sorptivity of 4.0-4.5mmmin-1/2 was found in nonirrigated upland soil and the lowest in seasonally waterlogged soil (1.0-1.5 mm min-1/2). Organic carbon content of all soils was low (<1%), EC values were also low (< 4 dS m-1). Saturated moisture was high in waterlogged soil. The non-irrigated upland soils had a higher fraction of fulvic acid (0.15-0.2%), due to which they were more capable of infiltration, whereas waterlogged soils had a greater fraction of insoluble humic acid (0.29-0.35%) and exhibited less cumulative infiltration. Sorptivity decreased as the clay content, pH, EC, porosity and humic acid content of the soil increased.

20

Characteristics of humic acids isolated from soils under various farming systems

63%

Szombathova N., Debska B., Lacko-Bartosova M., Zaujec A., Gonet S. S.

Acta Scientiarum Polonorum. Agricultura

|

2004

|

tom 03

|

nr 2

Farming systems strongly affect soil humus. In this study some humus characteristics were used to compare the humus quantity and quality under two different farming systems. The field experiment was established in 1990 on an Orthic Luvisols in Slovakia. A higher content of organic carbon (CT) in topsoil (13.1 g‧kg⁻¹) was recorded in soil under ecological farming where only organic manures were applied rather than in topsoil from integrated farming (12.5 g‧kg⁻¹) where both organic and inorganic fertilisers were applied. The quality of humus (HA : FA ratio) was similar in soils under both farming systems. Humic acids (HA) were isolated and analyzed for elemental composition, UV-VIS spectra and thermal properties. HA extracted from soil under ecological farming, as compared with HA from soil under integrated system, were characterised by a lower value of the H : C ratio and by a higher degree of internal oxidation. It shows that HA from ecological farming have higher aromaticity, humification degree and therefore are of a higher quality than HA from integrated farming. A higher aromaticity of humic acids from soil under ecological farming was confirmed by lower values of absorbance ratios (A2/6, A2/4 and A4/6) compared with the other HAs analyzed. The degree of aliphaticity determined thermogravimetrically was lower in HA from ecological farming, as compared with the integrated one, and it confirmed the results of spectral and elemental analyses referring to a higher humic acids quality in ecological farming.

Ograniczanie wyników