scholarly journals Metal Binding and Sources of Humic Substances in Recent Sediments from the Cananéia-Iguape Estuarine-Lagoon Complex (South-Eastern Brazil)

2021 ◽  
Vol 11 (18) ◽  
pp. 8466
Author(s):  
Christian Millo ◽  
Carlo Bravo ◽  
Stefano Covelli ◽  
Elena Pavoni ◽  
Elisa Petranich ◽  
...  
Keyword(s):  
Organic Matter ◽  
Trace Metals ◽  
Humic Substances ◽  
Humic Acids ◽  
Metal Binding ◽  
Binding Capacity ◽  
Stable Carbon Isotope ◽  
Fulvic Acids ◽  
Freshwater Environment ◽  
Estuarine Lagoon

The Cananéia-Iguape estuarine–lagoon complex (São Paulo state, Brazil) is a natural laboratory to study metal binding by humic substances (HS) in subtropical settings. This transitional environment is evolving into a freshwater environment due to water input from the Ribeira River, funneled through the Valo Grande Canal (Iguape). Past mining activities in the Ribeira River basin and maritime traffic are suspected to be potential sources of trace metals in the system. In this study, the trace metal contents of Free Humic Acids (FHA), Bound Humic Acids (BHA), and Fulvic Acids (FA) extracted from sedimentary organic matter were investigated. Moreover, the sources of HS were traced using their stable carbon isotope compositions and C/N ratios. The results suggested a mixed marine–terrestrial source of FHA, BHA, and FA. Copper and Cr were the most abundant trace metals bound to HS. On average, Cu showed concentrations of 176, 115, and 37.9 μg g−1 in FHA, BHA, and FA, respectively, whereas Cr showed average concentrations of 47.4, 86.3, and 43.9 μg g−1 in FHA, BHA, and FA, respectively. Marine FHA showed the highest binding capacity for trace metals, whereas terrestrial FA derived from the decay of mangrove organic matter showed the lowest binding capacity.

scholarly journals Characterization of Soil Organic Matter Individual Fractions (Fulvic Acids, Humic Acids, and Humins) by Spectroscopic and Electrochemical Techniques in Agricultural Soils

Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1067
Author(s):  
Aleksandra Ukalska-Jaruga ◽  
Romualda Bejger ◽  
Guillaume Debaene ◽  
Bożena Smreczak
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Humic Substances ◽  
Humic Acids ◽  
Agricultural Soils ◽  
Fulvic Acids ◽  
Sorption Properties ◽  
Aliphatic Chains

The objective of this paper was to investigate the molecular characterization of soil organic matter fractions (humic substances (HS): fulvic acids-FAs, humic acids-HAs, and humins-HNs), which are the most reactive soil components. A wide spectrum of spectroscopic (UV–VIS and VIS–nearIR), as well as electrochemical (zeta potential, particle size diameter, and polydispersity index), methods were applied to find the relevant differences in the behavior, formation, composition, and sorption properties of HS fractions derived from various soils. Soil material (n = 30) used for the study were sampled from the surface layer (0–30 cm) of agricultural soils. FAs and HAs were isolated by sequential extraction in alkaline and acidic solutions, according to the International Humic Substances Society method, while HNs was determined in the soil residue (after FAs and HAs extraction) by mineral fraction digestion using a 0.1M HCL/0.3M HF mixture and DMSO. Our study showed that significant differences in the molecular structures of FAs, Has, and HNs occurred. Optical analysis confirmed the lower molecular weight of FAs with high amount of lignin-like compounds and the higher weighted aliphatic–aromatic structure of HAs. The HNs were characterized by a very pronounced and strong condensed structure associated with the highest molecular weight. HAs and HNs molecules exhibited an abundance of acidic, phenolic, and amine functional groups at the aromatic ring and aliphatic chains, while FAs mainly showed the presence of methyl, methylene, ethenyl, and carboxyl reactive groups. HS was characterized by high polydispersity related with their structure. FAs were characterized by ellipsoidal shape as being associated to the long aliphatic chains, while HAs and HNs revealed a smaller particle diameter and a more spherical shape caused by the higher intermolecular forcing between the particles. The observed trends directly indicate that individual HS fractions differ in behavior, formation, composition, and sorption properties, which reflects their binding potential to other molecules depending on soil properties resulting from their type. The determined properties of individual HS fractions are presented as averaged characteristics over the examined soils with different physico-chemical properties.

scholarly journals Sustainability/resilience of soil organic matter components in an Argentinean arid region .

2014 ◽  
Vol 2 ◽  
Author(s):  
Carolina Vázquez ◽  
Laura Noe ◽  
Adriana Abril ◽  
Carolina Merlo ◽  
Carlos Romero ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Humic Substances ◽  
Humic Acids ◽  
Arid Region ◽  
Management Practices ◽  
Agricultural Soils ◽  
Fulvic Acids ◽  
Soil Sustainability ◽  
Undisturbed Site

This short communication presents a novel approach to determining the soil sustainability of productive practices in an Argentinean arid region, using the resilience degree of soil organic matter components. The study was conducted in four sites of the Arid Chaco region of the Cordoba province: one undisturbed site, two sites with livestock (with total and with selective clearing) and one site with agriculture. In each site three soil samples were taken and total soil organic matter, fulvic and humic acids, and non-humic substances were analyzed. Variations of each component (%) between each productive practice and the undisturbed site were calculated in order to establish the resilience degree. The livestock soils showed: a) moderate resilience for non-humic substances, b) low resilience for organic matter and humic acids, and c) no resilience for fulvic acids. The agricultural soils showed: a) low resilience for total organic matter and non-humic substances, and b) no resilience for fulvic and humic acids. We conclude that this approach is a powerful tool for establishing management practices according to each particular situation, allowing improved productivity in arid regions.

scholarly journals Chemical and structural characterization of soil humic substances under agroforestry and conventional systems

2011 ◽  
Vol 35 (5) ◽  
pp. 1597-1608 ◽  
Author(s):  
Gislane M. de Moraes ◽  
Francisco Alisson da Silva Xavier ◽  
Eduardo de Sá Mendonça ◽  
João Ambrósio de Araújo Filho ◽  
Teógenes Senna de Oliveira
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Humic Substances ◽  
Humic Acids ◽  
Arid Region ◽  
Fulvic Acids ◽  
Native Forest ◽  
Aromatic Character ◽  
Semi Arid Region ◽  
Semi Arid

Studies have proven that the agroforestry systems in the semi-arid region of the State of Ceará, Brazil, induce an increase in soil organic C levels. Notwithstanding, there is no information if this increase also results in qualitative changes in different pools of soil organic matter. The objective of this study was to verify the possible chemical and structural alterations in fulvic and humic acids of a Luvisol in areas adopting agroforestry, traditional intensive cultivation and native forest in a long-term experiment conducted in the semi-arid region of Ceará State, Brazil. The study was conducted in an experimental area of the National Goat Research Center (Embrapa) in Sobral, CE. The following treatments were evaluated: agrosilvopasture (AGP), silvopasture (SILV), intensive cultivation under fallow (ICF), and areas with native forest (NF). Soil fulvic and humic acids fractions were extracted from the 0-6 and 6-12 cm layers and characterized by elemental composition, thermogravimetry and infrared spectroscopy analyses. The elemental composition analysis of humic acids confirmed the data found for fulvic acids, showing reduction in the C, H and N levels, followed by an increase in O contents in the AGP and ICF treatments over SILV and NF. In all treatments, except to SILV in the 0-6 cm layer, the percentage of mass loss was highest (300-600 °C) for humic acids in the thermally most stable region. Despite the similarity between infrared spectra, soil fulvic acids in the SILV treatment extracted from 6-12 cm depth decrease the absorption bands at 1708 and 1408 cm-1 followed by an increase in the absorption band at 1608 cm-1 attributed to aromatic C=C groups. This behavior suggests an increase in the aromatic character of the structure. The AGP and ICF treatments, which increase the soil tilling, favored the maintenance of humic substances with a more aromatic character in the soil than SILV and NF. The less aromatic humic substances in the SILV treatment resulted in an increase of exchange sites of soil organic matter, indicating improved nutrient cycling and maintenance of productivity in the system.

scholarly journals Characterization of wastewater from landfills - amount and type of humic substances extracted from leachate

2019 ◽  
Vol 80 ◽  
pp. 03002
Author(s):  
Maria Elisabete Silva ◽  
Marlene Santos ◽  
Isabel Brás
Keyword(s):  
Organic Matter ◽  
Humic Substances ◽  
Functional Groups ◽  
Humic Acids ◽  
Fulvic Acids ◽  
Organic Fertilizers ◽  
Structural Composition ◽  
Carboxylic Groups ◽  
Humification Degree

This study aimed to characterize the humic substances (HS) extracted from landfills wastewater – leachates, with different ages of exploration. To reach the objective it was applied spectroscopy techniques, UV-Vis and FTIR spectra, as well as the ratio between the absorbance analysed. First, the HS were extracted, then fractionated in fulvic acids (FA) and humic acids (HA) and it was evaluated the phytotoxicity. HS content in the leachates were higher than the typical values found in the natural aquatic humic sources. It has been identified that the leachate HS, HA and FA aromatic fractions increased with the increase of the landfilling age, suggesting that the degree of humification increased with the landfilling age. All the HS showed a high aromaticity and humification degree. The HS extracts irrespective of their source presents similar structural composition. The functional groups found are in agreement with the literature: phenols, alcohols, carboxylic groups, aliphatic structures, among others. It was found that HA are mainly organic matter with a higher aromatic degree than FA. The HS and HA showed absence of phytotoxicity, testing by germination index, suggesting that may be used to produce liquid organic fertilizers.

scholarly journals Study Into the Changes in Soil Organic Matter, Caused By Laboratory Simulated Fires in Four Slovak Soils 1. UV-VIS Spectrum Analysis

2021 ◽  
Vol 29 (48) ◽  
pp. 131-142
Author(s):  
Maroš Sirotiak ◽  
Alica Pastierová ◽  
Lenka Blinová
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Humic Substances ◽  
Humic Acids ◽  
Spectrum Analysis ◽  
Fulvic Acids ◽  
Natural Fires ◽  
Visible Spectra ◽  
External Conditions ◽  
Soil Behaviour

Abstract The study was focused on describing ultraviolet-visible spectra of the humic substances, humic acids and fulvic acids isolated from four Slovak soils. The samples were heated in a laboratory furnace, to simulate soil behaviour during fires. The absorbances at the wavelengths corresponding to the selected chromophores and specific wavelength for groups of substances were compared. Analysis of the UV -VIS spectra of the extracted humic substances may indicate the directions of interest in the changes in soil organic matter, along with the changes in external conditions, such as natural fires.

scholarly journals Contribution of humic substances from different composts to the synthesis of humin in a tropical soil

2010 ◽  
Vol 34 (4) ◽  
pp. 1041-1048 ◽  
Author(s):  
Claudivan Costa Lima ◽  
Eduardo de Sá Mendonça ◽  
Asunción Roig
Keyword(s):  
Organic Matter ◽  
Humic Substances ◽  
Humic Acids ◽  
13C Nmr ◽  
Fulvic Acids ◽  
Tropical Soil ◽  
Organic Components ◽  
Soil Fraction ◽  
Alkyl Groups ◽  
Castor Cake

The contribution of humic substances of different composts to the synthesis of humin in a tropical soil was evaluated. Increasing doses (0, 13, 26, 52, and 104 Mg ha-1) of five different composts consisting of agroinpowderrial residues were applied to a Red-Yellow Latosol. These composts were chemically characterized and 13C NMR determined and the quantity of the functional alkyl groups of humic acids applied to the soil as compost was estimated. Thirty days after application of the treatments, organic matter samples were collected for fractionation of humic acids (HA), fulvic acids (FA) and humin (HU), from which the ratios HA/FA and (HA + FA)/HU were calculated. The application of the composts based on castor cake resulted in the highest HU levels in the soil; alkyl groups of the HA fraction of the composts were predominant in the organic components added to the HU soil fraction.

scholarly journals Transformations of phenolic compounds in meadow soils

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Anna Ziolkowska ◽  
Bozena Debska ◽  
Magdalena Banach-Szott
Keyword(s):  
Organic Matter ◽  
Chemical Composition ◽  
Phenolic Compounds ◽  
Humic Substances ◽  
Humic Acids ◽  
Plant Material ◽  
Fulvic Acids ◽  
Humic And Fulvic Acids

Abstract The aim of the research has been to determine the role of phenolic compounds in the processes of transformations of organic matter in meadow soils, leading to the formation of humic substances. The research has been performed based on the plant material and soil sampled from Europe’s unique complex of permanent grasslands irrigated continuously for 150 years applying the slope-and-flooding system, the Czerskie Meadows. Phenolic compounds were isolated from the plant material samples (hay, sward and roots) and soils (horizon A, AE and Bsv) and from the fraction of humic and fulvic acids. It was found that the contents of phenolic compounds decrease in the following order: hay > sward > roots > A horizon soil > AE horizon soil > Bsv horizon soil > A horizon fulvic acids > AE horizon fulvic acids > Bsv horizon fulvic acids > A horizon fulvic acids > AE horizon fulvic acids > Bsv horizon fulvic acids. A significantly higher share of cinnamyl than vanillyl and syringyl compounds in the extracts of fulvic acids and slightly higher in the hydrolysates of humic acids confirms the effect of the chemical composition of the plant material undergoing decomposition on the properties of the emerging humic substances.

Metal ion binding by humic substances as emergent functions of labile supramolecular assemblies

2020 ◽  
Vol 17 (3) ◽  
pp. 252 ◽  
Author(s):  
Elena A. Vialykh ◽  
Dennis R. Salahub ◽  
Gopal Achari
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Humic Substances ◽  
Metal Binding ◽  
Metal Ion ◽  
Computational Modelling ◽  
Intermolecular Forces ◽  
Metal Complexation ◽  
Emergent Properties ◽  
Metal Availability

Environmental contextThe fundamental basis for the high flexibility of humic substances is still unclear, though it is crucial for the understanding of metal bioavailability and toxicity in soil and aqueous environments. We show at the molecular level how characteristics of organic matter affect metal binding depending on the environmental conditions. Such understanding will help in the modulation of metal availability in soil and water in changing environmental situations. AbstractIn this work, we explore the hypothesis that humic substances (HS) can be perceived as labile supramolecular assemblages, the functioning of which is mainly determined by chemical composition and characteristics, the size of molecular units and weak intermolecular forces, rather than the exact primary structure of molecular moieties and their spatial configuration. To test the hypothesis, 72 computational models of three different organic mixtures were composed. The formation of inner and outer sphere metal–ligand complexes, metal binding sites, complex configurations, binding energies and aggregation/dissolution as emergent properties of HS were determined under various conditions. The results of computational modelling revealed that: (i) the highest Cu2+ binding (55.6%) was by the SRFA-22 organic model, which represents low-molecular-weight fulvic acids. In contrast, the highest amount of inner-sphere Mg–organic matter complex (63.4%) was formed in SRHA-6, which has higher-molecular-weight constituents. Therefore, a correlation between the type of cation, the system aromaticity and the extent of metal complexation is proposed. (ii) Increase of metal ion concentration and decrease of water content resulted in an increase in the number of hydrogen bonds and more compact and stable aggregates with lower hydrophilic and higher hydrophobic surface areas in SRFA-22. However, in SRHA-6, the results varied owing to the competition between metal binding, H-bonding and non-polar interactions in the structural arrangement of the aggregates. In general, the aggregation process, driven by metal complexation and water removal, resulted in the formation of more stable conformers, with lower potential energy, with the only exception of SRHA-6–Cu.

scholarly journals Impact of expected global warming on C mineralization in maritime Antarctic soils: results of laboratory experiments

2010 ◽  
Vol 22 (5) ◽  
pp. 485-493 ◽  
Author(s):  
Juliana Vanir de Souza Carvalho ◽  
Eduardo de Sá Mendonça ◽  
Rui Tarcísio Barbosa ◽  
Efrain Lázaro Reis ◽  
Paulo Negrais Seabra ◽  
...  
Keyword(s):  
Organic Matter ◽  
Humic Substances ◽  
Humic Acids ◽  
Incubation Temperature ◽  
Structural Characteristics ◽  
Maritime Antarctic ◽  
Organic C ◽  
Antarctic Soils ◽  
Mineral Soils ◽  
Increasing Temperature

AbstractThis study concerned the fragility of maritime Antarctic soils under increasing temperature, using the C dynamics and structural characteristics of humic substances as indicators. Working with four representative soils from King George Island (Lithic Thiomorphic Cryosol (LTC1 and LTC2), Ornithogenic Cryosol (OG) and Gelic Organosol (ORG)) we evaluated the total organic C and nitrogen contents, the oxidizable C and humic substances. Soil samples were incubated to assess the amount of C potentially mineralizable at temperatures typical of an Antarctic summer (5–14°C). Humic acids showed a higher aliphatic character and a smaller number of condensed aromatic groups, which suggests that these molecules from Antarctic soils are generally less resistant to microbial degradation than humic acids molecules from other regions. Based on 13C NMR spectra of MAS and CP/MAS, samples of soil humic acids of mineral soils (LTC1 and LTC2) have a higher content of aliphatic C, and heteroatom C, with lower levels of carbonyl and aromatic C, when compared with organic matter-rich soils (OG and ORG). Increasing incubation temperature led to a higher rate of mineralizable C in all soils. A sequence of soil fragility was suggested - LTC1 and LTC2 > OG > ORG - which showed a correlation with the Q10 coefficient and the ratio of labile and recalcitrant C fractions of soil organic matter (R2 = 0.83).

Sign in / Sign up

Export Citation Format

Share Document