Effects of pH Conditions and Application Rates of Commercial Humic Substances on Cu and Zn Mobility in Anthropogenic Mine Soils

We studied the effects of commercial humic substances derived from leonardite at different rates (0, 0.25, 2, 10 g kg−1) and pH (4.5, 6.0, 8.0) on Cu and Zn mobility, to evaluate their use for remediation of metal contaminated mine soils and to optimize their application conditions. We conducted a single-step extraction experiment and analyzed extracts for metal concentrations, soluble organic carbon and their E4/E6 ratio (ratio of absorption at 465 to 665 nm). Metal speciation in a soil solution was simulated by the non-ideal competitive adsorption-Donnan (NICA-Donnan) model. Increasing the amount of humic substances and the pH caused higher release rates of soluble organic carbon with a lower humic/fulvic acids ratio. This led to a higher mobility of metals (up to 110 times Cu concentration in control and 12 times for Zn) due to the formation of soluble metal-humic complexes. Speciation modeling predicted that increasing rates of humic substances would result in a higher proportion of Cu and Zn associated with fulvic acids, more mobile than the humic acids fraction. Application of commercial leonardite humic substances at 2–10 g kg−1 and with pH levels similar to or below natural soil could be useful for assisted-phytoextraction of contaminated anthropogenic soils. High rates of humic substances in more alkaline conditions could entail a considerable risk of metal leaching to groundwater, toxicity and transfer to the trophic chain.

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New possibility for characterization of dissociation behaviour of supramolecular electrolytes: results obtained for the International Humic Substances Society standard and reference samples by coulometry

Chemical and Biological Technologies in Agriculture ◽

10.1186/s40538-021-00229-4 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Martina Klučáková

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Humic Substances ◽

Functional Groups ◽

Dissociation Constants ◽

Fulvic Acids ◽

Molecular Organization ◽

Humic And Fulvic Acids ◽

Acid Base ◽

Reference Samples

Abstract Background Humic substances can be considered as polyelectrolytes with supramolecular character and complicated behaviour in water environment. The fractions of humic substances dissolved in water are the most active ones and determinative for their functioning in nature, where the proton-binding and dissociation ability play a crucial role. The dissociation behaviour of humic and fulvic acids can be affected by different circumstances including their concentration which is directly connected with the molecular organization of humic particles in solution and the accessibility of their ionizable functional groups. This study is focused just on these active fractions and their dissociation behaviour in the dependence on their content in studied system. Results Standards and reference samples of International Humic Substances Society were used. Flow-through coulometry was used to determine the total content of acidic functional groups in fulvic solutions and humic leachates. The amount of dissociated acidic groups was determined on the basis of potentiometry. Several differences between the behaviour of humic and fulvic acids were found. While whole samples of fulvic acids including the weakest functional groups were analysed, only the active dissolved humic fractions containing stronger acidic functional groups were characterized. The fractions containing higher amounts of the weakest functional groups remained insoluble. The dissociation degree of fulvic acids decreased with their increasing content, but a maximum on its concentration dependence obtained for humic acids was observed. Conclusions Two different values of dissociation constants were determined for each sample. The first was determined on the basis of the extrapolation of infinite dilution, second was determined as their average value in the region of high concentrations in which it was constant. Obtained values characterize the functioning of dissolved humic substances from point of view of their dissociation ability. The results obtained by this approach can help to predict the acid–base behaviour of dissolved organic carbon in soil and generally in nature. The acid–base behaviour of dissolved organic carbon depends on its ratio to water. It behaves differently in soil which is dry and in soil which is wet or saturated by water.

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Soluble organic carbon and pH of organic amendments affect metal mobility and chemical speciation in mine soils

Chemosphere ◽

10.1016/j.chemosphere.2013.11.055 ◽

2014 ◽

Vol 103 ◽

pp. 164-171 ◽

Cited By ~ 52

Author(s):

Javier Pérez-Esteban ◽

Consuelo Escolástico ◽

Alberto Masaguer ◽

Carmen Vargas ◽

Ana Moliner

Keyword(s):

Organic Carbon ◽

Chemical Speciation ◽

Organic Amendments ◽

Metal Mobility ◽

Mine Soils ◽

Soluble Organic Carbon

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Partitioning of water soluble organic carbon in three sediment size fractions: Effect of the humic substances

Journal of Environmental Sciences ◽

10.1016/s1001-0742(09)60020-6 ◽

2009 ◽

Vol 21 (1) ◽

pp. 113-119 ◽

Cited By ~ 3

Author(s):

Liying SUN ◽

Weiling SUN ◽

Jinren NI

Keyword(s):

Organic Carbon ◽

Humic Substances ◽

Water Soluble ◽

Size Fractions ◽

Sediment Size ◽

Water Soluble Organic Carbon ◽

Soluble Organic Carbon

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Nuclear Magnetic Resonance Characterization of Water Soluble Organic Carbon of Atmospheric Aerosol Types

Natural Product Communications ◽

10.1177/1934578x19849972 ◽

2019 ◽

Vol 14 (5) ◽

pp. 1934578X1984997 ◽

Cited By ~ 3

Author(s):

Marie-Cecile G. Chalbot ◽

Ilias G. Kavouras

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Organic Carbon ◽

Atmospheric Aerosol ◽

Road Dust ◽

Water Soluble ◽

Natural Soil ◽

Water Soluble Organic Carbon ◽

Soluble Organic Carbon ◽

Aerosol Sources

The water soluble organic carbon of the prevalent atmospheric aerosol sources (traffic exhausts, paved road dust, agricultural soil, native soil, wood combustion, epicuticular waxes from pine and broad-leaved trees, and pollen) has been characterized using 1H (1-dimensional), 1H-1H-correlation spectroscopy and 1H-13C-heteronuclear single quantum correlation 2-dimensional (2D) nuclear magnetic resonance (NMR) spectroscopy. Traffic exhaust particles were mainly constituted of primary alcohols, carbohydrates, functionalized olefins, C3 and C4 oxy- and hydroxyl-carboxylic acids, and short-chain alkanes. Road dust was a mixture of soil particles and traffic components. Agricultural, natural, road dust, and traffic particles contained broad signals that were attributed to poly-carboxylic compounds typically found in humic compounds and humic-like substances. Traces of traffic particles (ie, peaks in the 7.3-7.5 ppm [phthalic acid derivatives] and signals found in the 0.5-3 ppm originating from functionalized carboxylic acids) were also found in natural soil dust. Long-chain (>C3) fatty acids and amino acids were found in road dust, natural soil, pine trees waxes, pollen, and woodburning. The aromatic region mainly constituted of lignin derivatives and cellulose/hemicellulose pyrolysis products (signals in 2D-NMR) in woodburning. Primary biogenic and woodburning particles were uniquely clustered as compared to traffic exhausts, road, agricultural, and natural dust based on the relative ratio of hydro-oxygenated functional groups (H-C-O and H-C-C=O) to the sum of aliphatics. Overall, source-specific NMR spectrometric fingerprints, functional composition profiles, and several organic compounds were identified allowing for the reconciliation of ambient organic aerosol sources including the degree of atmospheric aging.

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Quantitative elemental and structural analysis of dissolved organic carbon fractions from lakes near Sudbury, Ontario

Canadian Journal of Chemistry ◽

10.1139/v96-275 ◽

1996 ◽

Vol 74 (12) ◽

pp. 2460-2470 ◽

Cited By ~ 10

Author(s):

Roy Carl Boerschke ◽

Elizabeth Ann Gallie ◽

Nelson Belzile ◽

Richard Neville Gedye ◽

James Robert Morris

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Organic Acids ◽

Humic Substances ◽

Humic Acids ◽

Nmr Spectra ◽

Fulvic Acids ◽

Published Data ◽

Organic Carbon Fractions ◽

C Nmr

Dissolved organic carbon (DOC) was quantitatively isolated as five separate fractions from two Sudbury area lakes (Ontario, Canada) using the tandem XAD-8/XAD-4 resin technique. Fulvic acids made up ≈ 48% of the total, humic acids ≈ 8%, hydrophobic neutrals ≈ 8%, XAD-4 acids ≈ 11%, and XAD-4 acetonitrile extracts ≈ 13%. Hydrophobic:hydrophilic ratios were about 65:35. Solid-state CPMAS 13C NMR indicated a primarily aliphatic nature in all fractions. Percent aromaticity was in the order humic acids > fulvic acids > XAD-4 acetonitrile extracts ≈ XAD-4 acids ≈ hydrophobic neutrals. Titration analysis showed that the 13C NMR peaks of fulvic acids, humic acids, and XAD-4 acids from 160–190 ppm were primarily carboxyl in nature. The XAD-4 acids were the most acidic, suggesting that they may be important geochemical agents. 13C NMR indicated that polysaccharides formed < 20% of any fraction. The two neutral fractions (hydrophobic neutrals and XAD-4 acetonitrile extracts) had relatively high N contents, possibly due to the acetonitrile used to extract them. However, the 13C NMR spectra did not show significant quantities of acetonitrile. The elemental and structural composition covaries in the three acid fractions, such that if one acid is enriched or depleted, so are the others. This suggests that the humic and non-humic acids form a continuum in which all fractions are affected by the same formative processes. Compared to published data for other freshwater samples, the three acid fractions from the Sudbury area lakes have low or very low aromaticity. This may indicate that the acid and metal loadings in the Sudbury area have affected the structure of the organic acids, despite the circumneutral character of the study lakes. These are the first quantitative 13C NMR results published for the hydrophobic neutrals and XAD-4 acetonitrile extracts, so comparisons are not possible. Key words: aquatic DOC, organic acids, 13C NMR, humic substances, non-humic substances.

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Accumulation of humic substances in an Oxisol fertilized with pig slurry for 15 years

Revista Brasileira de Engenharia Agrícola e Ambiental ◽

10.1590/1807-1929/agriambi.v25n2p109-115 ◽

2021 ◽

Vol 25 (2) ◽

pp. 109-115

Author(s):

Wagner Sacomori ◽

Paulo C. Cassol ◽

Maria S. H. Mafra ◽

Luiza F. Erdemann ◽

Jaime A. de Almeida

Keyword(s):

Humic Acid ◽

Organic Carbon ◽

Fulvic Acid ◽

Humic Substances ◽

Soil Layer ◽

Mineral Fertilizer ◽

Soil Surface ◽

Fulvic Acids ◽

Pig Slurry ◽

Continuous Application

ABSTRACT The growth of swine production in Brazil has increased the amount of production and use of pig slurry (PS) as soil fertilizer. This product provides nutrients to plants, and a continuous application of this residue usually increases total soil organic carbon (SOC) content. The objective of this study was to determine the SOC content and its distribution into humic substance fractions (humic acids, fulvic acids, and humin) in an Oxisol annually fertilized with PS for 15 years. The experiment was implemented in 2001 with a maize and oat crop rotation under no-tillage system in Campos Novos, SC, Brazil. The treatments used were: PS at rates of 0 (Control), 25, 50, 100, and 200 m3 ha-1 year-1, mineral fertilizer, and PS combined with mineral fertilizer, applied on the soil surface once a year. The 0-2.5, 2.5-5, 5-10, 10-20, 20-40, and 40-60 cm soil layers were evaluated for SOC content in the fractions humic acid, fulvic acid, and humin, and E4/E6 ratio of humic substances. Increases in PS rates up to 100 m3 ha-1 increased the SOC content in the 5-10 cm soil layer; however, decreased the proportion of the soil fulvic acid and humic acid fractions, favoring the accumulation of organic carbon in the humin fraction. The E4/E6 ratio was higher when using the soil mineral fertilizer than that found in treatments with PS.

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

Agronomy ◽

10.3390/agronomy11061067 ◽

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.

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Organic Materials and Their Chemically Extracted Humic and Fulvic Acids as Potential Soil Amendments for Faba Bean Cultivation in Soils with Varying CaCO3 Contents

Horticulturae ◽

10.3390/horticulturae7080205 ◽

2021 ◽

Vol 7 (8) ◽

pp. 205

Author(s):

Ihab M. Farid ◽

Mohamed A. El-Ghozoli ◽

Mohamed H. H. Abbas ◽

Dalia S. El-Atrony ◽

Hassan H. Abbas ◽

...

Keyword(s):

Humic Substances ◽

Faba Bean ◽

Plant Biomass ◽

Nitrogenase Activity ◽

Organic Amendments ◽

Fulvic Acids ◽

Mineral N ◽

Randomized Design ◽

Long Time ◽

Factor C

Organic amendments are important sources of nutrients that release upon organic matter degradation, yet the stability of these organics in arid and semi-arid regions is relatively low. In contrast, humic substances (HS) are resistant to biodegradation and can keep nutrients in the soil available for the plant over a long time. Combinations between humic substances (HS) and mineral-N fertilizers are assumed to retain higher available nutrients in soils than those recorded for the sole application of either mineral or organic applications. We anticipate, however, that humic substances might not be as efficient as the organics from which they were extracted in increasing NP uptake by plants. To test these assumptions, faba bean was planted in a pot experiment under greenhouse conditions following a complete randomized design while considering three factors: two soils (calcareous and non-calcareous, Factor A), two organics (biogas and compost, Factor B) and combinations of the organics and their extracts (HA or FA) together with complementary doses of mineral-N ((NH4)2SO4) to attain a total rate of 50 kg N ha−1 (the recommended dose for faba bean plants) (Factor C). Results indicated that nitrogenase activity increased significantly due to the application of the used organics. In this respect, compost manure caused higher nitrogenase activity than biogas manure did. Humic substances raised NP-availability and the uptake by plants significantly; however, the values of increase were lower than those that occurred due to the compost or biogas manure. Moreover, the sole application of the used organics recorded the highest increases in plant biomass. Significant correlations were also detected between NP-availability, uptake and plant biomass. This means that HS could probably retain nutrients in available forms for long time periods, yet nutrients released continuously but slowly upon decomposition of organics seemed more important for plant nutrition.

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