Influence Of Humic Substances Research Articles

The influence of humic substances on the weathering of PGE in chromitite of the Bushveld Complex: An experimental simulation of the weathering environment

Abstract Organic acids, including humic acid, play a significant role in the weathering of minerals containing metals such as Pt and Pd. They are also among the reactants which are under consideration for new hydrometallurgical methods of liberating unconventional PGE ores (such as the oxidised ores of the Great Dyke, Zimbabwe, and at locations in the Bushveld Complex of South Africa where PGE-bearing layers have been exposed to weathering). In order to better understand the processes operating during weathering of PGE-bearing chromitite seams of the Bushveld Complex, chromite concentrate originating from a South African chromium mine was subjected to reaction with different concentrations of synthetic humic acid. The results confirm the greater mobility of palladium in the environment compared to platinum. Crushed chromite concentrate showed greater mobility of Cr, but not of Pd or Pt, compared to uncrushed concentrate. Increasing the concentration of humic acid increased the amount of Pd and Pt in solution. These experiments give insight into the processes that govern the weathering of chromitite in the Bushveld Complex. The main Pd– and Pt-bearing minerals are not enclosed within chromite but occur at grain boundaries. Thus, they can be liberated by disaggregation of chromite and infiltration of water along chromite grain boundaries. Once in solution, Pd is more mobile than Pt and is dispersed further. Organic acids play an important role during the weathering process as they are capable of enhancing the mobility of the PGE, particularly Pd.

The influence of humic substances on environmental behavior of antibiotic resistance genes: A mini-review

The global antibiotic resistance pollution caused by antibiotic resistance genes (ARGs) has led to serious harm to the ecological environment and human beings. As a type of organic matter that commonly exists in the environment, humic substances (HS) may affect the fate of contaminants. Based on the high possibility of ARGs coexisting with HS in the environment, it is necessary to understand the influence of HS on environmental behavior of ARGs. This article reviews the impact of HS on environmental behavior of ARGs, and finds that the topic has received increasing attention by scientometric analysis using CiteSpace software. The environmental behavior of ARGs is not only affected by HS and its by-products, but also frequently implicated through antibiotics, heavy metals and particles in various environments, such as wastewater, activated sludge and soil. The main mechanisms by which HS affects the ARGs evolution include electrostatic interactions, hydrophobic interactions, hydrogen bonding, non-specific van der Waals interactions, and microbial community alterations. Finally, future research directions are proposed to help refine the theoretical basis for the interaction between HS and ARGs, and can contribute to the prevention and control of ARGs pollution in practical applications.

Influence of humic acid on microbial induced carbonate precipitation for organic soil improvement.

Microbial induced carbonate precipitation (MICP) is one of the most commonly researched topics on biocementation, which achieves cementation of soil particles by carbonate from urea hydrolysis catalyzed by microbial urease. Although most MICP studies are limited to stabilizing sandy soils, more researchers are now turning their interest to other weak soils, particularly organic soils. To stabilize organic soils, the influence of humic substances should be investigated since it has been reported to inhibit urease activity and disrupt the formation of calcium carbonate. This study investigates the effect of humic acid (HA), one fraction of humic substances, on MICP. For this purpose, the effects of HA content on CaCO3 precipitation using three strains and on CaCO3 morphology were examined. The results showed that native species in organic soils were less adversely affected by HA addition than the exogenous one. Another interesting finding is that bacteria seem to have strategies to cope with harsh conditions with HA. Observation of CaCO3 morphology revealed that the crystallization process was hindered by HA to some extent, producing lots of fine amorphous precipitates and large aggregated CaCO3. Overall, this study could provide an insightful understanding of possible obstacles when using MICP to stabilize organic soils.

Modeling kinetics of Cu(II) release during Fe oxide transformation under the influence of humic substances

The dynamic behavior of Cu(II) in soil is usually affected by Fe oxides and humic substances, both of which are capable of Cu(II) binding. However, Fe oxides may undergo transformation processes and the presence of humic substances may complicate the Fe oxide transformation and Cu(II) binding. There is still a lack of quantitative understanding on how varying Fe oxide compositions and humic substances affect Cu(II) kinetic behavior. In this study, we developed a unified quantitative model for Cu(II) release from Fe oxides or Fe oxide-humic substance composites during the Fe oxide transformation based on the experimental data from our previous studies. The kinetic data were collected in a stirred-flow reactor system, in which Cu(II) release kinetics was studied during the Fe oxide transformation processes. Our model successfully reproduced the temporal changes of effluent Cu(II) concentrations with only one fitting parameter while other parameters were derived from the thermodynamic constraints or from the literatures. The modeling results indicated that Cu(II) release rates decreased with Fe oxide aging processes, while the presence of humic substances increased Cu(II) mobility. Our model was able to quantitatively assess the roles of different adsorbents in controlling the Cu(II) release rates, which highlighted the importance of accounting for the variations of Fe oxide transformation and the impact of humic substances in kinetic modeling. Our model has provided a quantitative tool for quantifying the kinetic behavior of heavy metals in multi-adsorbent systems, which is helpful for predicting the geochemical cycling of heavy metals in the environment.

Influence of humic substances on the landfill leachate biodegradability with a focus on temporal seasonality.

The high resilience to biological treatments from the landfill leachate is generally associated with the presence of humic substances (HS). The brown color characteristic of this effluent is also related to these substances. Landfill leachate with low biodegradability can make biological treatments unfeasible, which can drive up the cost for the treatment of large leachate volumes. In this context, this research aimed to characterize the leachate in different seasonal periods, and verify the influence of HS species on the biodegradability of the effluent to assist in the selection of adequate treatment techniques. The HS quantification was performed using the modified Lowry method and speciation through fractionation according to the molar masses of the HS species. The tropical regions can be the precursor for the rapid stabilization of biodegradable organic matter. The warmer climate contributed to a reduced BOD/COD ratio (0.03) and the predominance of compounds of lower mass (e.g.: fulvic acids). The tests showed an HS concentration of 26.9% of the total COD in the raw leachate in the rainy season, which increased to 37.3% in the dry season. Approximately 70% of HS species refer to fulvic acids, a fraction identified as having the highest biologic treatment resilience.

Cadmium and arsenic availability in soil under submerged incubation: The influence of humic substances on iron speciation

Humic substances (HSs), as electron shuttles, are associated with iron oxide transformation, yet the manner by which HSs affect Cd/As availabilities during this process under anaerobic conditions remains unclear. Two HSs (humic sodium, HA-Na, and biochemical fulvic acid, BFA) were applied at 0, 1, 2, and 4 gCkg−1 in a submerged incubation experiment. The dissolved, extractable and fractions of Cd/As and different iron oxides in soils were monitored. The addition of both HA-Na and BFA decreased the CaCl2-extractable Cd by 12.66–93.13%, and increased the KH2PO4-extractable As by 18.81–71.38% on the 60th day of incubation. The soil Eh and crystalline iron oxides (Fed) decreased, while amorphous iron oxides (Feo) and dissolved As increased after addition of both HSs. However, the two HSs had opposite effects on soil pH and dissolved Cd at the end of the incubation. HA-Na immobilized 19.47–85.99% more available Cd than did BFA over the incubation, although the extent of immobilization was similar with the maximum application rate on the 60th day. BFA mobilized 5.22–26.12% more available As than did HA-Na. XPS data showed that FeOOH decreased while the FeO component increased over the incubation. Correlation analysis and SEM showed that the reduction in the soil Eh and Fed and relative increase in Feo increased the available Cd, while decreased the available As. Consequently, the addition of HA-Na and BFA, particularly combined with flooding irrigation management, could effectively reduce the available Cd in Cd-contaminated soil. However, this method should be used with caution in As-contaminated soil.

The Effects of Humic Substances and Humic Substance-Based Silver Nanocomposites on the Viability of Rhizospheric Microorganisms

The influence of humic substances (HSs) of coals (HS-cl), shale (HS-sl), and mud (HS-md) isolated in Mongolia and silver nanocomposites (NCs) synthesized on their basis on the viability of Rhodococcus erythropolis (gram positive bacteria) and Pseudomonas oryzihabitans (gram negative bacteria) is investigated using methods for measuring the optical density of a bacterial suspension, diffusion into agar, as well as studying the intensity of biofilm formation. It is shown that the effects of HSs and NCs on bacteria in dynamics are different in R. erythropolis and P. oryzihabitans. HS-sl stimulated the growth of R. erythropolis on the first day of observation, and in P. oryzihabitans this effect was noted later, at 2 days of the experiment. Despite the absence of bacteriostatic effects for HSs, a decrease in biofilm formation of bacteria under their influence has been revealed. HS-cl and HS-md reduced the biofilm formation of R. erythropolis, and HS-sl reduced P. oryzihabitans. The addition of HSs to HCs retains the bactericidal effect of NC HS-cl/Ag and NC HS-md/Ag with respect to R. erythropolis. A decrease in biofilm formation of gram-negative bacteria P. oryzihabitans occurred under the influence of NC HS-md/Ag. NC HS-cl/Ag, in contrast, enhanced the reproduction of P. oryzihabitans throughout the observation period. Thus, the reaction of microorganisms to the effects of HSs in the composition of NCs depends on the morphology of the bacteria themselves, as well as on the chemical structure and functional composition of the active substances. The obtained data and previously published results on the positive effect of silver NCs and HSs on plants open the prospects for further investigation of the effects of using NCs of HSs when introduced into the soil in combination with rhizospheric bacteria to increase the resistance of cultivated plants to stress factors.

Metal Speciation in Water of the Flooded Mine “Arsenic” (Karelia, Russia): Equilibrium-Kinetic Modeling with a Focus on the Influence of Humic Substances

Equilibrium-kinetic modeling allows investigating metal behavior in the water–rock-organic matter system with time to evaluate anthropogenic effects on the environment. In the article, the interactions of stagnant mine drainage water of the flooded mine “Arsenic” with ore and gangue minerals were simulated using different organic matter incorporation approaches. If the model is closed to humic substances (no additional organic matter input), most fulvic acids are bound in the Fe fulvate complex. While under the removal of Fe fulvate from the model, the Cu fulvate becomes prevalent, the contribution of the fulvate complexes with Zn, Mg, and Ca also increases. This scenario simulates the organo-mineral complexes behavior well and allows identifying the sequence of metal binding to organic ligands as follows Fe > Cu > Zn > Mg > Ca. The second scenario imitates the constant input of organic matter to the model (open system regarding humic substances). The dissolved metal concentrations in the model solution are extremely high in comparison to the mine drainage water. This scenario demonstrates that excessive input of organic matter leads to the accumulation of the metals in a dissolved form and blocks the secondary mineral formation despite the faster dissolution of the primary minerals under a more acidic pH than in the first scenario. However, despite the differences between the model solution and the mine drainage water, this scenario is useful to address specific issues associated with changes in natural and anthropogenic conditions. Both scenarios show the importance of organic matter incorporation to the equilibrium-kinetic models.

Metal Distribution in the Environmental Compartments of Manguaba Lagoon (Alagoas State, Brazil)

The metal concentrations in water, sediments and mollusks (Tagelus plebeius) of the Manguaba Lagoon and the influence of humic substances from water and sediments in the distribution of these metals were investigated in this work. The mean metal concentrations in water were: Mg (89.0 ± 0.11), Ca (32.0 ± 0.10), Fe (0.97 ± 0.02), Mn (0.52 ± 0.01), Zn (0.33 ± 0.10) and Pb (0.22 ± 0.02) mg L-1. The Pb concentrations were above the Brazilian legislation limit. All sediment data were below maximum limit established by the National Council for the Environment (CONAMA, Brazil) of the Ministry of the Environment, and the concentration ranges for metals were: Fe (1199-60000), Mg (339-8870), Ca (461-3838), Cr (< LOQ-39.5) and Pb (< LOQ-12.5) mg kg-1 (LOQ: limit of quantification). None of the principal contaminants (Cr, Pb and Cd) was determined in Tagelus plebeius, being a positive fact once the population nearby Manguaba Lagoon consumes large amounts of this mollusk. According to the results, the influence of humic substances in the contaminant retention is evident as they become unavailable for absorption by mollusks of Manguaba Lagoon.

WITHDRAWN: Challenges from pretreatment to sludge anaerobic digestion: A review on the influence of humic substances

This article has been withdrawn at the request of the authors. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal .

Influence of Humic Substances on Cucumber Seeds Storability and Root Rot Diseases Incidence under Salinity Conditions

Seed germination is a complex process, which is regulated by many factors including storage. The present study aims at assessing the validity of stored cucumber seeds under stressed-soil. In-vitro experiment was conducted to investigate the influence of soaking of stored cucumber (Cucumis sativus L.) seeds produced during three consequent years (2015, 2016 & 2017) in five concentrations of humic substances (HS'c) solution (0.3, 0.6, 0.9, 1.2 & 1.5%) for five different intervals (30, 90, 150, 210 & 270 min), on germination percentage (G%), germination velocity (GV) and vigor index (VI). Another In vitro experiment was conducted to assess the direct effect of HS'c on two nutritional media for Rhizoctonia solani and Fusarium solani mycelial growth, sclerotial productivity & viability, conidia viability. Greenhouse experiment was conducted to assess the effect of soaking cucumber seeds in HS'c and spraying with salicylic acid (SA) (100 and 200mg L-1) twice on growth parameters of cucumber seedlings, and controlling the root rot disease caused by R. solani and F. solani under saline conditions (2.36, 4, 5 & 6 dS m-1). The results indicate that T5 (0.3% for 210 min.) for 2015 and 2017 and T4 (0.3% for 150 min.) recorded the highest values for all studied parameters. No morphological changes were observed for the highest pathogenic two fungal isolate's mycelial growth on both fungal strains. R. solani was affected less than F. solani for the presence of different HS'c into nutrient media. 1.5% HS concentration had a reduction effect on the radical growth of fungal isolates, R. solani sclerotial production (30%) and viability (53%) and F. solani conidial viability (58%). Root rot disease was affected differently by seedling treatments of HS'c and/or SA under the four salinity conditions. The combined treatment; soaking seeds in 0.3% HS (for different period/year) and spraying seedlings with 200 SA had significantly reduced the disease incidence (DI) and disease index of both R. solani and F. solani specially in the lowest and highest salinity conditions.

Influence of humic substances on the transport of indium and gallium in porous media

Indium and gallium are used widely in modern industry, mostly for the production of semiconductors. They are considered as Technology-Critical Elements and have therefore received growing attention in the past few years. We investigated the influence of different types of humic substances on the transport of indium and gallium in laboratory-scale, saturated column experiments, to gain understanding of their mobility in natural environments. We evaluated the effect of different humic substances on the transport of indium and gallium in quartz sand: a commercial humic acid (Aldrich Humic Acid, AHA), a fulvic acid (Suwannee River Fulvic Acid, SRFA) and an aquatic natural organic matter (Suwannee River Natural Organic Matter, SRNOM). The impact of the flow rate and the influence of different concentrations of organic matter were also investigated. Indium was shown to be more mobile than gallium in the presence of humic substances. The mobility of indium in sand was highest for SRNOM, followed by SRFA and then AHA, while for gallium the order was SRFA > SRNOM > AHA. These results can be significant in understanding the mobility of indium and gallium in soils with various compositions of organic matter.

Вплив гумінових речовин на фізіологічний остеогенез та кровотворну систему кроленят на тлі застосування PLA імплантатів

PLA-based implants are characterized by high biocompatibility with body tissues, and are also distinguished by their biodegradable and osseointegrative properties. The regulation of bone tissue growth and development is inextricably linked with the blood system, which is a source of plastic substances and hormones of calcium homeostasis. When PLA implants were inserted into the parietal bone of rabbits, changes occurred in their bodies that were typical for the period after orthopedic and traumatological operations. Metabolism dysregulation of macro- and microelements and disturbances of erythropoiesis, which can occur in the postoperative period, have a negative effect on the bone tissue growth in the young rabbits’ body. It has been proven that humic substances were able to influence the activity of osteoblasts and regulate mineral metabolism. For the experiment, 32 rabbits were divided into four groups, 8 rabbits in each group; sixteen rabbits underwent surgery using PLA implants, which were placed bilaterally in the parietal bone. Eight of the 16 operated rabbits were given Humilid together with water, the rest of them received pure water. Eight of 16 rabbits, intact before surgery, received Humilid together with water, the non-surgical control group did not receive Humilid. The influence of humic substances on physiological osteogenesis and hematological parameters during the use of PLA implants was determined. On the 14th day of the experiment, the rabbits of the surgical group receiving Humilid did not show a decrease in erythrocytes, hemoglobin, and an increase in leukocytes, in contrast to the rabbits of the surgical control group. An increase in the number of osteons and osteoblasts layers was recorded in the femur of the young rabbits that were receiving Humilid, and in the sternum – the number of osteons and layers of osteoblasts. There was also an increase in the number of erythrocytes and hemoglobin in the non-surgical group rabbits that were receiving Humilid to compare the rabbits of the non-surgical control group. ln rabbits that received Humilid, there was an intensification of bone tissue growth against the background of physiological and reparative osteogenesis.

Influence of humic substances on the toxic effects of cadmium and SDBS to the green alga Scenedesmus obliquus

The joint toxicity of chemicals mixture in the aquatic environment was still not well clear. To clarify the joint toxicity of the mixtures of metals and organic pollutants, as well as the influence of dissolved organic matter (DOM) in field water-body on their toxic effects, we conducted the toxicity tests with cadmium (Cd) and sodium dodecyl benzene sulfonate (SDBS) on Scenedesmus obliquus (S. obliquus) with or without the presence of fulvic acid (FA), a typical of DOM. Our results showed Cd was more toxic to S. obliquus than SDBS, and the effects of fulvic acid on SDBS were greater than Cd. The joint toxicity of Cd and SDBS expressed a synergistic effect on S. obliquus, which was observed to be increased with the presence of FA. Our results gave an example for the joint toxicity investigations of organics and metals, aiding to understanding the toxicity of pollutant mixtures in field water bodies containing DOM.

The influence of humic substances on uranium biomineralization induced by Bacillus sp. dwc-2

In this paper, the influence of humic acid (HA) and fulvic acid (FA) on biomineralization behaviour was evaluated. The results showed HA and FA did not obviously inhabit or promote the precipitation of U-phosphate minerals. The data from molecular dynamic simulation indicated that the free energy for the dissociation of uranyl the PO43− -uranyl was 202.49 kJ/mol, which was much larger than that form HA-uranyl (88.3 kJ/mol). These simulated results revealed the less competitiveness of HA and FA with PO43− for uranyl and explained why HA and FA had less impacted on the formation of U-phosphate minerals. However, the influence of HA/FA on the morphology was obvious, the microstructure of the bio-minerals changed from small particles to lamellar stacking structure with the addition of HA or FA. The findings of this study are helpful for us to gain a better understanding natural U-phosphate biomineralization behaviour.

Influence of humic substances on iron distribution in the East China Sea

The influence of humic substances (specifically humic and fulvic acids, referred to as HS-HA and HS-FA) as well as other factors, such as major nutrient concentrations of total dissolved nitrogen (TDN), total dissolved phosphate (TDP) and hydrologic factors, on the distribution of total dissolved iron (DFe) and the chemical speciation of DFe was studied in the East China Sea (ECS) during a summer cruise in 2013. As the wide rage fraction of nature organic matter, the HS-HA, HS-FA in ESC contains most part of the organic ligand (Lt) of DFe. The concentrations of HS-HA, DFe and Lt in coastal water masses were higher than those in the water masses affected by the Kuroshio Current. The highest concentrations of HS-HA and DFe were observed in surface water at stations MT1 and MC4, with the value of 336.5 μg SRHA/L and 20.3 nmol/L, respectively, whereas, the lowest concentrations of HS-HA and DFe were observed in surface waters with the value of 149.6 μg SRHA/L and 0.4 nmol/L, respectively. HS-HA concentrations were more conservative than that of DFe. The DFe which were combined by unit weight HS-HA (mg−1, IB) in the surface and bottom waters quickly decreased with increasing salinities from the Yangtze River estuary to the southeast of the ECS. Average IB values in bottom waters were higher than those in surface waters. This study indicated that Yangtze River dilution water and cold water from the Yellow Sea were the main source of HS-HA and DFe in ECS.

Influence of humic substances and iron and aluminum ions on the sorption of acetamiprid to an arable soil

Humic substances (HS) in soil and sediments, and surface water influence the behavior of organic xenobiotics in the environment. However, our knowledge of the effects of specific HS fractions, i.e., humic acids (HAs), fulvic acids (FAs), and humin (HM), on the sorption of organic xenobiotics is limited. The neonicotinoid insecticide acetamiprid is thought to contribute to the collapse of honeybee colonies. To understand the role that soil organic matter plays in the fate of acetamiprid, interactions between acetamiprid and the above HS fractions were examined. Batch experiments were conducted using various combinations of a field soil sample and the above 3 HS fractions prepared from the same soil, and differences in isotherm values for acetamiprid sorption were investigated based on the structural differences among the HS fractions. The sorption of acetamiprid to soil minerals associated with HM (MHM) (Freundlich isotherm constant, Kf: 6.100) was reduced when HAs or FAs were added (Kf: 4.179 and 4.756, respectively). This can be attributed to hydrophobic interactions between HM and HAs or FAs in which their dissociated carboxyl and phenolic groups become oriented to face the soil solution. The amount of acetamiprid that was adsorbed to (MHM+HA) or (MHM+FA) increased when aluminum ions were added (Kf: 6.933 and 10.48, respectively), or iron ions were added (Kf: 7.303 and 11.29, respectively). Since acetamiprid has no affinity for inorganic components in soil, the formation of HS–metal complexes by cation bridging may have oriented the hydrophobic moieties in the HAs or FAs to face the soil solution and may also have resulted in the formation of dense structures, resulting in an increase in the amount of acetamiprid that becomes adsorbed to these structures. These results highlight the importance of interactions among soil components in the pedospheric diffusion of acetamiprid.

The Influence of Humic Substances on the Sorption of Three Organic Contaminants with Different Structure and Polarity to Clay Minerals

The sorption of three organic contaminants with different structure and polarity including non-polar phenanthrene (PHEN), 1,2,4,5-tetrachlorobenzene (TeCB), and polar 1,2-dichlorobenzene (DCB) onto original kaolinite, smectite, vermiculite, and fulvic acid (FA)/humic acid (HA)–clay complexes were investigated, and possible sorption mechanisms were inferred from sorption isotherms and characteristics of humic substances (HS) and HS–mineral complexes. Results showed smectite and vermiculite had stronger sorption ability than kaolinite, and the adsorbed amount of DCB was much higher than that of PHEN and TeCB on each clay. Due to FA/HA-facilitated hydrophobic interaction, FA/HA–clay complexes except FA–vermiculite complex showed a stronger affinity for PHEN and TeCB than the original clays, particularly for HA–clay complexes. The non-linearity parameter values of n for all the Freundlich sorption isotherms of DCB were greater than 1, indicating that clays possessed some unique sites with strong affinity and capacity to sorb DCB from aqueous solutions. FA/HA did not significantly affect the sorption of polar DCB on clays, implying sorption of DCB on clays was probably due to polar interactions between the polar group of DCB and clays. Cation-π bonding between PHEN and iron cation was directly evidenced by X-ray photoelectron spectroscopy, and FA impeded the sorption of PHEN on vermiculite by occupation of iron cation sites. This study will benefit understanding behaviors of contaminants in the soil environments.

Interaction of radionuclides with natural and manmade materials using XAFS technique

The X-ray absorption fine structure (XAFS) technology has exhibited a very unique application in the study of sorption mechanism, chemical species and microstructures of radionuclides at the natural solid-water interfaces. In this review, the interaction mechanism of radionuclides with clay minerals and nanomaterials under different environmental conditions are summarized from the XAFS spectroscopy analysis. The coordination number and the bond distances of radionuclides, the oxidation-reduction reactions, the influence of humic substances and microorganisms on the species and structures of radionuclides at molecule level are reviewed and compared. This review is helpful to understand the interactions of radionuclides with oxides, natural clay minerals and nanomaterials, which is also crucial to evaluate the physicochemical behaviors of radionuclides in the natural environment.

酸化マグネシウムによるヒ素( V ) 汚染土壌の不溶化にフミン物質が与える影響およびそのメカニズム

酸化マグネシウムによるヒ素( V ) 汚染土壌の不溶化にフミン物質が与える影響およびそのメカニズム