Revisiting molecular characteristics responsive for the aromaticity of soil humic acids

Tinoco, Pilar; Almendros, G.; González-Vila, Francisco Javier; Sanz, J.; González‐Pérez, José Antonío

doi:10.1007/s11368-014-1033-y

Cited by 40 publications

(37 citation statements)

References 20 publications

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“…In many studies, a significant relationship has been found between the optical density of HA solutions and the aromaticity of HA (Tinoco et al 2015). HA solutions containing more aromatic components are more condensed and characterized by higher optical density compared to acid solutions, where aliphatic chains are more abundant in the structure.…”

Section: Discussionmentioning

confidence: 99%

The impact of different land uses in urban area on humus quality

2018

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Purpose In urban areas, humus quantity and quality depend less on natural environmental factors than on anthropogenic ones. The aim of the study was to assess the impact of different land use types of urban soils on the properties of soil organic matter (SOM). Materials and methods Thirty-five sites involving four ways of soil use were examined: lawns, allotment gardens, fallows, and arable lands. The study was conducted in Pruszków Town in the Warsaw Agglomeration, Central Poland. Lawns and allotment gardens were located in the central part of the town, whereas fallows and arable lands were in the peripheral zones. Humus horizons, to a depth of 0-20 cm, were analyzed. Using Na-pyrophosphate extraction, we determined the soluble SOM compounds (PY), and the organic matter in the extraction residue, considered as humins (HM). In a separate extraction (with 0.05 M H 2 SO 4 ), low molecular weight (LMW) humus compounds were determined. The quantity of humic acids (HA) precipitated during Na-pyrophosphate extraction was determined as well. A spectroscopic method (UV-Vis) was used to characterize HA properties. The absorption coefficients E4/E6 were calculated based on the results of absorbance measurements involving 465-and 665-nm wavelengths of UV-Vis light. Statistical analyses were performed to find similarities and differences between soils differently used in Pruszków. Results and discussion The dominant part of the humus in the studied soils were humins HMs. There were two times more HM in the central part of the town than that in the peripheral zones. The same observation was made for soluble humus compounds (PY). The amount of LMW fractions was similar in soils of all uses. The degree of humification was small and averaged about 30% for all soils. Fulvic acid (FA) concentrations predominated over HA concentrations in all soils. The least condensed HA occurred in the allotment gardens with an E4/E6 ratio of 5.7, whereas the most condensed HAs were present in soil on arable lands (E4/E6 ratio of 4.7). Conclusions The studies have shown that the type of land use affects humus properties. The main differences were found to be in the quantity of humus compounds. Soils from the central part of the town contained more stable (HM) and soluble (PY) compounds than soils in the outskirts of town. PY compounds were characterized by a simple structure. Fulvic acids (FA) dominated in all of the studied soils (low HA/FA ratio). A high E4/E6 ratio indicates low maturity of humic fractions with low molecular weight compounds.

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Section: Discussionmentioning

confidence: 99%

The impact of different land uses in urban area on humus quality

2018

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“…The optical densities at 465 nm (E ) and 665 (E 6 ) nm of HAs were determined from solutions of 200 mg C L -1 of HA in 0.02 M NaHCO 3 [19] with a Shimadzu UV-240 spectrophotometer. The E 4 is classically considered to be related with the aromaticity of HAs [20,21], whereas the E 4 /E 6 ratio gives information about the polydispersity of the HAs [22].…”

Section: Spectroscopic Characteristics Of the Humic Acidsmentioning

confidence: 99%

Response of humic acid structure to soil tillage management as revealed by analytical pyrolysis

Dorado

Almendros

González-Vila

2016

Journal of Analytical and Applied Pyrolysis

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The effects on the structural features of humic acids (HA) from dryland farming soils under long term management practices have been approached by analytical pyrolysis (Curie-point pyrolysis-gas chromatography/mass spectrometry, Py-GC/MS). The field experiments (started in 1987) include conventional, minimum and no-tillage plots, as well as non cultivated plots. The HA isolated from the various plots showed significant differences in their pyrolytic behaviour, in particular regarding the total abundances of alkyl pyrolysis compounds (fatty acids, alkenes and alkanes). The occurrence of very short-chain fatty acids (C 5 to C 11) in uncultivated plots could be indicative of constitutional alkyl structures in the relictual HA from undisturbed soil. The effect of soil tillage managements substantially increased total abundances of fatty acids in plots under conservation practices (mainly notillage). The HAs from uncultivated soils showed the greatest percentages of alkanes and alkenes. This was associated to the increased proportions of even C-numbered alkene homologues from C 12 to C 18 , possibly related to the incorporation of microbial compounds during the humification process. High percentage of alkylbenzenes and catechols were also characteristic of the uncultivated plots. The increased proportions of methoxyphenols, in special of the syringyl (dimethoxyphenyl) type compounds, in HAs from plots subjected to conventional tillage pointed out to humification processes based on progressive alteration of plant lignins. From the viewpoint of soil quality, the results suggest comparatively advanced 2 transformation stages of the HA from uncultivated plots, which means that conservation tillage practices seems to lead to increasing soil C levels, at expenses of the accumulation of comparatively recent organic matter derived either from altered lignins and/or microbial biomass.

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“…They can be considered as indicators of pedogenetic processes [2] because their composition and properties are determined by conditions of soil genesis [3]. Difference in quantity and chemical composition of humic and fulvic acids depends on many variables, such as: parent material, altitude, slope gradient, climate, vegetation type and soil management [4,5,6]. Dominant effect of annual precipitation and temperature on the composition of humic acids was also reported by [7].…”

Section: Introductionmentioning

confidence: 99%

Humic Acids Optical Properties of Rendzina Soils in Diverse Environmental Conditions of Serbia

Radmanović¹,

Nikolić²,

Đorđević³

2018

AFST

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This study examined the impact of climate, altitude and landforms on humic acids (HA) opticalproperties (E4/E6, ΔlogK, RF indexes) in Serbian Rendzina soils. HA humification degree of calcareousand decarbonated Rendzinas under natural vegetation (forest and grassland, separately) decreased withaltitude increasing. This particular rule was not manifested in arable Rendzinas. HA humificationdegree in Rendzinas on flat positions (hilltop and footslope) is significantly higher than in Rendzinas onslope sides. Humification degree of HA is the highest in Rendzinas in eastern Serbia (in the vicinity ofNegotin), followed by central Serbia (Sumadija) and Srem, southeast and finally, southeast andsouthwest Serbia. With respect to the climate change foreseen for the end of this century, i.e. increase ofprecipitation and temperature variance among the regions in Serbia, also an increase in variance ofquality of humic acids in Rendzinas on different altitudes and regions can be expected.

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Revisiting molecular characteristics responsive for the aromaticity of soil humic acids

Cited by 40 publications

References 20 publications

The impact of different land uses in urban area on humus quality

The impact of different land uses in urban area on humus quality

Response of humic acid structure to soil tillage management as revealed by analytical pyrolysis

Humic Acids Optical Properties of Rendzina Soils in Diverse Environmental Conditions of Serbia

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