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1.
In the presence of H2O2 as donor, horseradish peroxidase was used to catalyze the polymerization of seven monomeric phenols. Yields of humic acid (HA) polymers from meta phenols—resorcinol and phloroglucinol—were insignificant. Of the five ortho and para phenols—phenol, catechol, hydroquinone, pyrogallol and 1,2,4-trihydroxybenzene—all except hydroquinone inhibited the enzyme at high concentration. The kinetics of polymerization of the ortho and para compounds were complex and dependent on the concentration of both electron acceptor and donor.The percentage yield of HA before dialysis was far greater from pyrogallol than from catechol or hydroquinone. After dialysis, the yield of the catechol HA was higher than those of the hydroquinone and pyrogallol HAs. A higher molecular weight for the catechol HA over those of the hydroquinone and pyrogallol HAs was also indicated by the lowest E4/E6 ratio and highest free radical content.All of the synthetic HAs were relatively rich in free radicals, suggesting that their synthesis occurred via free radicals, i.r. and 13C NMR spectra showed that the HAs were molecularly complex polymers or mixtures of complex aromatic structures rich in phenolic OH groups and to a lesser extent in CO2H groups. The only HA which showed fine structure in the i.r. spectrum was the pyrogallol HA; the presence of aryl ethers was indicated. 13C NMR spectra showed that all synthetic HAs were highly aromatic, that aromatic rings of the initial phenols had been built into the HAs, but that molecular environments around phenolic OH groups had changed during the formation of the HAs. 相似文献
2.
Alejandro Cánepa Silvana B. Basack Norma B. Casabé Noemí R. Verrengia Guerrero 《Journal of Soils and Sediments》2013,13(4):775-782
Purpose
The relative sensitivity of two freshwater invertebrate organisms to the organophosphorus insecticide fenitrothion was assessed by measuring cholinesterase (ChE) activity, a well-known biomarker of both exposure and effect to organophosphorus pesticides. The influence of different concentrations of humic acids (HAs) and particulate matter on fenitrothion bioavailability was assessed in the more sensitive species.Materials and methods
The selected invertebrates were the dwelling feeding oligochaete Lumbriculus variegatus and the pulmonate gastropod Biomphalaria glabrata. Acute 48-h bioassays were performed exposing organisms to different fenitrothion concentrations. The concentrations that induced 50 % inhibition of enzyme activity (EC50) were calculated. Fenitrothion bioavailability was investigated using different concentrations of commercial HA or particulate matter. Sand and a diverse selection of chromatographic resins that have been proposed as analogues of natural sediments were selected. For these experiments, animals were exposed to a fenitrothion value similar to the EC50.Results and discussion
The 48-h EC50 values were 12?±?2 and 23?±?3 μg?l?1 for L. variegatus and B. glabrata, respectively. Depending on HA concentration and the characteristics of particles, ChE activity was similar or higher than the value recorded for animals exposed only to the pesticide in aqueous solution.Conclusion
The results indicated that L. variegatus was the more sensitive species of the two. In this species, fenitrothion bioavailability did not increase due to the presence of either different HA concentrations or particulate matter. The experimental approach may constitute a useful tool to predict the influence of dissolved organic matter and sediment particles on fenitrothion bioavailability and toxicity to non-target aquatic invertebrates. 相似文献3.
Chendong Shuang Mengqiao Wang Penghui Li Aimin Li Qing Zhou Fei Pan Weiwei Zhou 《Journal of Soils and Sediments》2014,14(2):312-319
Purpose
Anion exchange resin has been shown to be efficient for adsorption of humic acid (HA). However, the mechanism of the effect(s) of the molecular weight (MW) of HA on the adsorption by anion exchange resin needs to be further explored. The objective of this work was to investigated the effect(s) of HA MW on their adsorption and desorption behavior by interacting with anion exchange resin.Materials and methods
HA fractions with different MW were obtained by ultrafiltration and characterized. For adsorption kinetic study, the magnetic polyacrylic anion exchange resin (NDMP) was shaken with each HA fraction. The amounts of HA in the solutions at different sampling times were obtained by measurement of the total organic carbon. For isotherm study, batch experiments were performed to obtain the isotherms of each HA fractions. The effects of pH value and the regeneration efficiency for HA fractions with different MW were all investigated.Results and discussion
The characterization reveals that aromaticity of HA increases as the MW rises, while the negative charge follows the order: HA3 (2,500–1,000 Da)?>?HA4 (>10,000 Da)?>?HA2 (1,000–2,500 Da)?>?HA1 (<1,000 Da). The adsorption amount of HA increases as the negative surface charge rises. Thus, HA3 has the largest adsorption amount by NDMP resin among HA fractions, while the adsorption amount of HA1 is the smallest. HA2 adsorption could be modeled by Freundlich equation, suggesting the interaction between HA2 and NDMP is a heterogeneous process. However, the adsorption isotherms of HA3 and HA4 were both better described by Langmuir equation than Freundlich equation. In addition, the resin fouling follows the order: HA2?>?HA1?>?HA4?>?HA3.Conclusions
The aromaticity of HA freactions increases as MW rises. HA fractions with 1,000?–?2,500 Da have the largest surface negative charge, while the fractions with MW lower than 1,000 Da are almost electroneutral. The adsorptions of HA fractions onto NDMP suggest there is little effect of size exclusion on adsorption, and the adsorption behavior mainly depends on the negative charge of HAs. 相似文献4.
《Communications in Soil Science and Plant Analysis》2012,43(19-20):2893-2904
Abstract An investigation was conducted on physico‐chemical properties of humic acids (HAs) in Venezuelan soils. The HAs were extracted by the NaOH method from a Banco‐Bajio‐Estero soil toposequence (local names for soils located at high, intermediate and low topographic levels), in the Venezuelan plains (Mantecal, Apure State). The extracted HAs were analyzed for elemental composition and characterized by fluorescence, Fourier transform infrared (FT‐IR) and electron spin resonance (ESR) spectroscopies. The results showed that free radical concentration of HAs increased from soils at the highest to soils at the lowest topographic position. High carbon (C), nitrogen (N), and carboxyl group contents, E4/E6 ratio, aliphatic character and concentration of free radicals, and low oxygen (O) and phenolic hydroxyl group contents and total acidity were typical of HA from soils at the lower relief position. The FT‐IR spectra indicated that the HA from the soil at the lowest topographic position tended to have a slightly higher content of carboxyl groups than the HAs from soils at higher topographic levels. The observed fluorescence was attributed to the presence of condensed aromatic moieties and/or conjugated unsaturated systems of various complexity in the HA macromolecules. 相似文献
5.
Jinyang Wang Zhaozhi Chen Yuchun Ma Liying Sun Zhengqin Xiong Qiwei Huang Qirong Sheng 《Journal of Soils and Sediments》2013,13(8):1408-1417
Purpose
The effects of commercial compost fertilizer application on trace gas emissions are not well understood due to a lack of field experiments. The objective of this study was to evaluate the emissions of methane (CH4) and nitrous oxide (N2O) along with grain yield from a rice paddy as affected by different organic–inorganic mixed fertilizer (OIMF) treatments.Materials and methods
A field experiment was initiated in 2006 with chemical compound fertilizer (CF) and three OIMF amendments including pig manure compost (PMC), Chinese medicine residue compost (CMC), and rapeseed cake compost (RCC), from a rice paddy in southeast China. The emissions of CH4 and N2O were simultaneously measured using the static opaque chamber method over the entire rice growing season in 2011. Soil biotic parameters were measured in soil collected after the rice was harvested in 2011.Results and discussion
Relative to the control, the OIMF treatments significantly increased CH4 emissions by 56–99 %, mainly due to exogenous organic substrate input, whereas no difference was observed in the CF treatment. The N2O emissions were stimulated substantially by an average of 40 % due to nitrogen fertilization compared with the control. Consecutive OIMF application tended to increase the grain yield, making it marginally higher than that of the CF treatment (7 %, P?=?0.06). Compared with the control, the CF treatment slightly decreased the global warming potential and greenhouse gas (GHG) intensity, while they were remarkably increased in the OIMF treatments. Over the 5-year period of 2006–2011, the annual soil carbon sequestration rate was estimated to be 1.19 t C ha?1 year?1 for the control and 1.73–1.98 t C ha?1 year?1 for the fertilized treatments.Conclusions
Our results suggest that despite the beneficial effects of increasing both grain yield and soil organic matter, OIMF application such as PMC, CMC, and RCC may be responsible for increased global warming due mainly to the stimulated CH4 emissions. This effect should be thus taken into account when balancing agricultural production and GHG mitigation. 相似文献6.
Saudi A. Rekaby Mahrous Y. M. Awad Sabry A. Hegab Mamdouh A. Eissa 《Journal of plant nutrition》2020,43(12):1840-1851
AbstractEnrichment of soils with organic amendments could increase the content of available nutrients, improve soil chemical characteristics and increase plant growth. In the current pots experiment, the influences of biochar (BC), humic acid (HA), and compost (CO) on barely growth were investigated under saline conditions. Barely plants grown on a clay loam soil and irrigated with saline water concentration of (EC?=?13.8 dS m?1) were amended with BC, HA and CO at a rate of 1 or 3% of soil weight. The results showed that BC, HA and CO treatments had significant effects on the soil salinity, pH, organic matter (SOM), and plant nutrients. The results showed that the high rate application of BC, HA and CO increased the SOM by 14, 75 and 58% respectively, above the control. Consequently, the total chlorophyll as affected by the treatments can be arranged in descending order: BC3 > CO1 > CO3 > HA3 > HA1 > BC1 > C. The high rates of BC, HA and CO increased the dry biomass by 28.0, 21.6 and 39.7% respectively, above the control %, respectively, above the control. The investigated organic amendments increased the nutrients availability and uptake and enhanced the synthesis of chlorophyll in the plant tissues and this may be the reason of increasing the ability of barley to tolerate salinity. 相似文献
7.
Shenia Oliveira Souza Marina de Magalhães Silva Josué Carinhanha Caldas Santos Luciana Camargo de Oliveira Janaina Braga do Carmo Wander Gustavo Botero 《Journal of Soils and Sediments》2016,16(6):1764-1775
Purpose
Due to the modernization of the agro-industrial sector, compounds with different toxicity and effects on human health and animal have been used and consequently affecting the environment. Among them, tetracycline (TC) stands out as one of the antibiotics most commonly used worldwide. This study evaluated the TC interaction with different fractions of peat in natura and humic substances, humic acid, fulvic acid, and humin.Materials and methods
The different fractions of the organic matter were characterized by organic matter content, elemental analysis, spectroscopic analysis (E4/E6), and nuclear magnetic resonance of carbon 13 (NMR 13C), and the interaction between TC and different fractions of organic matter was made by fluorescence spectrometry. We used the tangential ultra-filtration system for determining the complexation capability of humic substances (HSs), fulvic acids (FA), humic acids (HA), and humin (HUM) from peat with TC. Finally, we evaluated sorption kinetic experiments between TC and peat in natura.Results and discussion
The peat samples, humic substances, FAs, HAs, and HUM were characterized by organic matter (OM), atomic ratio (H/C and C/O) calculated from elemental analysis data, functional groups quantified by NMR 13C data, and E4/E6 ratio, and the results show significant differences in the structural characteristics of the fractions of OM influenced by the type of microorganisms and environmental factors associated with this decomposition. Data analysis revealed the strongest interaction between HUM and TC (59.19 mg g?1), followed by interaction between HS and TC (43.36 mg g?1 HS). In the sorption studies, these conditions showed the best model to describe the system under consideration using the Freundlich model.Conclusions
The results showed that the different fractions of the OM extracted from peat show different contributions that affect the bioavailability of contaminants to the environment.8.
Environmental impact of two organic amendments on sorption and mobility of propachlor in soils 总被引：1，自引：1，他引：0
Jiajun Zhang Lijiao Yang Lina Wei Xiao Du Lingling Zhou Lei Jiang Qing Ding Hong Yang 《Journal of Soils and Sediments》2012,12(9):1380-1388
Purpose
The purposes of this study were to understand the sorption?Cdesorption characteristics of propachlor in three types of soils with added solid organic matters and the effect of solid organic matters on propachlor mobilization in soil microstructures.Materials and methods
Three soil types, Eutric gleysols (EG), Hap udic cambisols (HUC), and Haplic alisol (HA), along with the lakebed sludge (SL) and pig manure compost (PMC), were used in the study. The sorption and desorption experiments were carried out using the standard batch equilibration method. Soil column leaching was performed with soil samples packed into PVC columns. Soil thin-layer chromatography was performed using soils and water mixture spread on a 0.5?C0.7-mm thick layer over 20?×?10-cm glass plates.Results and discussion
Propachlor was shown to be more mobile in EG and HUC than in HA. Application of PMC and SL to soils affected the propachlor mobilization in the soils. Using batch experiment, soil column, and soil thin-layer chromatography, we showed that addition of SL and PMC increased the sorption and decreased desorption of propachlor in the soils. Addition of PMC and SL reduced the total concentration of propachlor in the soil leachate and migration of propachlor in the soil profiles. Physicochemical properties of the three soils were analyzed and showed that the content of organic carbon (in percentage) was higher in Haplic alisol than in Eutric gleysols and Hap udic cambisols.Conclusion
The soil organic matter played critical roles in modifying the absorption and mobility of organic chemicals (e.g., herbicide and contaminants) in soil ecosystem. 相似文献9.
Juan Carlos Rodríguez-Murillo Gonzalo Almendros Heike Knicker 《Journal of Soils and Sediments》2017,17(8):2104-2115
Purpose
The present study focuses on a compositional characterization of the humic acid (HA) fraction of several wetland soils using solid-state 13C NMR spectroscopy. The data were analysed using the molecular mixing model (MMM), based on an empirical approach by Nelson and Baldock. The compositional data from HAs obtained with this model were used to obtain a wider assessment of the process of humification from comparison of total soil wetland organic matter composition and HA composition.Materials and methods
Twenty samples of humic acids (HAs) isolated from a Mediterranean semiarid wetland (‘Tablas de Daimiel’, central Spain) were studied using elemental analysis and cross polarization magic angle spinning (CPMAS)13C nuclear magnetic resonance (NMR) spectroscopy. The NMR data were analysed with the molecular mixing model (MMM) considering up to six generic components (carbohydrate, protein, lignin, lipid, char and ‘carbonyl’). HAs are considered a conceptual mixture of these model components, and the MMM determines the proportions of the characteristic biomolecules contributing to HA composition.Results and discussion
The composition of the HAs under study depends on local factors such as site vegetation and occurrence of fire. Correlations between the proportions of the six generic components and further comparison with those determined for the unfractionated OM (whole sample, WS), gave information on HA origin and humification mechanisms. In particular, the proportions of char and carbohydrate (R 2 0.637) and contents of lignin and protein (R 2 0.471) in the HAs were negatively correlated (P < 0.05). Significant correlations (R 2 0.439) also existed for char contents in whole sample (WS) compared to HA, and for carbohydrates in WS compared to HA (R 2 0.558). Char proportion grew in HA with respect to the WS, and carbohydrates dropped to a half on average in HA compared to WS.Conclusions
Two different humification mechanisms could be identified for no-fire and fire areas. In the former, HA-char was preserved selectively from char in the sample, whereas in the latter, char was newly formed by fire effect.10.
Beibei Han Kyoko Kitamura Mitsuru Hirota Haihua Shen Yanhong Tang Takeshi Suzuki 《Soil Science and Plant Nutrition》2019,65(1):11-19
The characteristics of humus composition are important for understanding the mechanism of carbon storage in the Qinghai–Tibet Plateau. The aim of this study was to characterize the quality of soil organic matter (SOM) in this region. Soil samples from four soil profiles in fenced study sites in the alpine grassland were collected at altitudes of 4200, 4000, 3800, and 3400 m, along the southwest facing slope in the Qilian Mountains. The humus composition and humification degree of the humic acid (HA) were determined by two methods: (1) extraction with 0.5% sodium hydroxide (NaOH) followed by 0.1 M sodium pyrophosphate (Na4P2O7) (OH-PP method); and (2) treating once with 0.1 M hydrochloric acid (HCl) followed by extracting with 0.5% NaOH (Cl-OH method). Physico-chemical analysis revealed higher exchangeable cation content and higher base saturation ratios could be related to slightly acidic to neutral soils, which could be regarded as calcium (Ca)-rich soils. The amounts of combined-form HAs obtained by HCl pretreatment (HACl – HAOH; ?HACl) were remarkably higher than those extracted with Na4P2O7 (HAPP), indicating that the combined form of HAs is mainly Ca. In addition, the proportion of HAPP in the total HAs extracted with both NaOH and Na4P2O7 (HAOH + HAPP) obtained in the OH-PP method increased with soil depth and decreasing elevation, indicating that HAs associated with aluminum (Al) and iron (Fe) were distinguished in the subsoils of lower elevation. Therefore, the formation of the organo-mineral complex may contribute to stabilizing SOM in the Qinghai–Tibet Plateau. Moreover, Type A-HA with the highest degree of humification was obtained from the deeper horizons with the Cl-OH method and almost all horizons by extraction with Na4P2O7 in the OH-PP method. Further studies using various spectroscopic analyses are necessary to elucidate the chemical properties of SOM in this region. 相似文献
11.
Purpose
Metal distribution patterns among geochemical fractions are informative for metal phytoavailability. Compost added to polluted soils may adsorb metals on the less phytoavailable fractions. A bioassay experiment was conducted to establish possible correlations between metal concentrations in different soil fractions and metal contents in edible plant parts and to investigate the influence of different compost loads on heavy metal availability to plants.Materials and methods
Chinese cabbage plants were grown in pots with sandy and clayey soils and soils mixed with different doses of biosolid compost spiked with soluble heavy metal salts (Cd, Cu, and Pb). The metals’ distribution pattern in the soil and mixed samples was determined by sequential extraction procedure (modified BCR protocol). The studied fractions, from most to least bioavailable, were water-extractable (WE), exchangeable-adsorbed (EXC), associated with carbonates and acetic acid-soluble forms (CARB), occluded by reducible (hydro)oxides of Fe and Mn (RO), and associated with organic matter (OM) and a residual fraction (RES). Metal concentrations in soil extracts and in the digested plant tissue were measured by ICP-AES.Results and discussion
The highest compost doses (72 and 115 Mg ha?1) enhanced cabbage yield significantly. No excessive phytoaccumulation of metals was observed in plants grown in the clayey soil or its mixtures with compost. The compost dose of 72 Mg ha?1 was optimal in decreasing Cu accumulation by plants grown in sandy soil, and 28.8 Mg ha?1 was found to be effective in reducing Cd and Pb uptake. Metals were accumulated in plants primarily from the WE, EXC, and CARB fractions, whereas other fractions decreased phytoaccumulation. Compost addition suppressed heavy metal mobility, but different fractions were active in pollutant sorption, depending on soil type and metal.Conclusions
Compost addition increased metal proportions in the RO and OM fractions, reducing metal phytoavailability. This is especially important for sandy soils with low adsorption ability and higher vulnerability to metal pollution than clayey soils. A compost dose of 20% v/v (or 28.8 Mg ha?1) effectively reduced plant accumulation of Cd and Pb. We propose using the first three steps of the modified BCR protocol as a three-step sequential-extraction procedure for the most phytoavailable fractions of heavy metal: WE, EXC, and CARB. 相似文献12.
Ines Ahumada Karen Sepúlveda Priscilla Fernández Loreto Ascar Cristina Pedraza Pablo Richter Sally Brown 《Journal of Soils and Sediments》2014,14(5):886-896
Purpose
This study assessed the effect of biosolid application on the bioavailable fraction of some trace elements (Cu, Cr, Ni, and Zn) using a bioassay with sunflower (Helianthus annuus) and a chemical assay, diffusion gradient in thin films (DGT).Materials and methods
Five surface soil samples (0–20 cm) were collected from an agricultural zone in Central Chile where biosolids are likely to be applied. Municipal biosolids were mixed with the soil at concentrations of 0, 30, 90, and 200 Mg ha?1. The experiment to determine the bioavailability of metals in the soil using the bioassay was performed using sunflower. The DGT technique and Community Bureau of Reference (BCR) sequential extraction were used to determine the bioavailable fractions of the metals.Results and discussion
The application of biosolids increased the phytoavailability of Zn, Ni, and Cr in most of the soils, as indicated by the increasing concentrations in sunflower plants as the biosolid application rate increased. In two of the soils, Codigua and Pelvín, this increase peaked at an application rate of 90 Mg ha?1. Decreases in the bioavailable fractions of Zn, Ni, and Cr were observed with higher biosolid application rates. The bioavailability of metals was estimated through multiple linear regression models between the metals in the sunflower plants and the different chemical fractions of metals in the soils treated with different biosolid rates, which displayed a positive contribution of the labile (water soluble, carbonate, and exchangeable), oxide, and organic metal forms in the soil, particularly with respect to Ni and Zn at application rates of 30 and 90 Mg ha?1. The bioavailable fraction of metals was determined in soils using the DGT technique. The effective concentration (C E) results were compared with those in sunflower plants. The DGT technique could effectively predict the bioavailable fractions of Cr, Ni, and Zn in the Taqueral soil but only that of Zn in the Polpaico soil.Conclusions
The application of biosolids significantly increased the labile fraction of most of the metals in the studied soils, particularly at the highest biosolid application rate. C E increased as the concentration of biosolids increased for most of the metals. The effectiveness of the DGT technique for predicting the bioavailability of metals was dependent on the soil type and the metal. However, the C E for soil Cu was not related to plant Cu for all soils studied. 相似文献13.
Gabriela Barančíková Maria Jarzykiewicz Erika Gömöryová Erika Tobiašová Tadeáš Litavec 《Journal of Soils and Sediments》2018,18(8):2738-2747
Purpose
Windthrows and fires are major natural disturbances in forest ecosystems, which can affect organic matter in the surface and the mineral layer of forest soil. The main aim of this study was to evaluate the changes occurring in the structure and properties of humic acid (HA) in the lands where windthrows and wildfires occurred.Materials and methods
In November 2004, the forest in the area of 12,000 ha in the Tatra National Park, Slovakia, was seriously damaged by northern wind gusts exceeding 200 km/h. In July 2005, a wildfire broke out in a 220 ha of wind-damaged area. The HAs have been isolated from four research plots: (a) the area where the fallen trees were removed (EXT); (b) an area after windstorm covered by wood from struck trees (NEX), left for spontaneous succession; (c) an area after extracted timber, damaged by the surface wildfire (FIR); and (d) a reference intact spruce forest area (REF). Changes in the chemical structure of the HAs isolated from the research plots were determined on the basis of elemental analysis and UV-Vis, EPR, IR, and 13C NMR spectroscopy.Results and discussion
All used analytical methods showed a decrease in the humification degree of the humic acids extracted from the soils where the spruce forest has been affected by a wildfire and a windthrow. In the case of the control sample HA (REF), the calculated atomic H/C and O/C ratios and the degree of aromaticity (α) calculated from the 13C NMR spectra were higher, indicating higher aromaticity of HA from the REF area. The more complex and developed structure of REF HA was confirmed by the higher value of E1%6 and the lower E4/E6 ratio obtained using UV-Vis spectroscopy. Also, the higher g-parameters determined from the EPR spectra of the stable radicals present in HA confirmed the lower aromaticity on the plots that have been subjected to the calamities. The 13C NMR spectra and the elemental analysis show that the structure of the HA extracted from the NEX plot is the closest to the REF.Conclusions
The results of the systematic research showed significant changes in the structure of HA taken from spruce forest soils that were subjected to windstorms and fires. An enrichment of the HAs in aliphatic carbon and so a lower humification degree of the organic matter in the areas calamity-affected were observed. The results clearly indicate that the HAs extracted from the disturbed plots of the spruce forest are not as stable as those extracted taken from the control plot.14.
Purpose
Despite experiments with humic substances and positively charged proteins, the colloidal behavior of HS-protein mixture in the system of two immiscible liquids has been neglected. In this context, the main objective of this study was to reveal the interference of HS and globular proteins on its partition in an aqueous/organic liquid system and the adsorption at liquid/liquid interface as a model of natural organic matter interaction with proteins in nature at hydrophobic/hydrophilic surfaces.Materials and methods
Coal humic acids (HA) and two globular proteins lysozyme and albumin were under the test. Aqueous phase was prepared in phosphate-buffered saline (pH 7.2?±?0.1, 0.16 M); p-xylene was chosen as an organic phase. Experiments were performed for fixed concentration of protein (0.1 g L?1 for lysozyme and 0.06 g L?1 for albumin) and varied HA concentration from 0.2 to 50 mg L?1. Radiotracer method including tritium thermal activation and scintillation phase method, dynamic light scattering, and optical microscopy were used to control mixed adsorption layer at the aqueous/p-xylene interface and composition of each contact phase.Results and discussion
The results suggest that if both HA and protein are negatively charged (HA-albumin mixture), the mechanism of interaction between them in the bulk of water and at liquid/liquid interface is controlled by HA concentration. At low HA concentrations, free protein prevents HA adsorption at liquid/liquid interface and its transition to the organic phase via coulomb repulsion. At high HA concentration, the formation of hydrophilic complexes occurs via both electrostatic attraction between positively charged amino acid residues and the hydrophobic interaction. In HA-lysozyme mixture, the interaction between protein and HA is preferably provided by electrostatic attraction that provides higher hydrophobicity of HA-lysozyme complex compared with free HA. An increase in HA concentration results in partial recharge of the conjugate that leads to lysozyme amount reduction at the interface. We also measured the composition of spontaneously formed precipitate of HA-lysozyme conjugate and followed its self-organization.Conclusions
This work demonstrates colloidal chemical behavior of net positively and negatively charged model protein by coal humic acids under environmentally relevant solution conditions in the system of two immiscible liquids that were used as a model of natural membrane. For the first time, quantities of both protein and HA in mixed adsorption layer at the liquid/liquid interface in the cases of positively and negatively charged protein have been determined. 相似文献15.
Chemical and spectroscopic characteristics of humic acids in marshes from the Iberian Peninsula 总被引：2，自引：2，他引：0
Fernando Perobelli Ferreira Pablo Vidal-Torrado Xose L. Otero Peter Buurman Ladislau Martin-Neto Rafael Boluda Felipe Macias 《Journal of Soils and Sediments》2013,13(2):253-264
Purpose
To characterise soil humic acids (HAs) extracted from Spanish marshes formed under different vegetation types (Spartina maritima (GSp), Juncus maritimus (GJc), Phragmites australis (GPh), and Scirpus maritimus (VSc)), soil depths (0–20, 20–40 and 40–60 cm), physiographic position (low and high marshes), wetland types (salt marshes and lagoons) and environmental conditions (Atlantic and Mediterranean coast).Material and methods
Soil samples were collected in five Spanish marshes, three on the Galicia province and two on the Valencia province. Humic acids were extracted and their elemental composition, semiquinone-type free radical (SFR) content, FTIR and CPMAS 13C NMR spectra determined. Total carbon (TC), total nitrogen (TN), total sulphur (TS), CaCO3 content, and field pH and Eh (mV) in the marsh soils sampled were also measured.Results and discussion
The field pH and Eh values were typical of coastal areas submitted to periodic inundations and the highest TC, TN and TS contents were found in the soil of lagoon marshes as an effect of physiographic position and wetland type. The HAs, in general, were highly aliphatic and exhibited a low SFR content, which suggests a low humification degree of the SOM formed in the studied areas. This is a result of the anaerobic decomposition to which SOM is submitted and the high input of plant-derived organic matter (OM) by vegetation. However, among the studied sites low salt marsh and subsurface layer of the high salt marsh showed higher SFR content, simpler FTIR spectra, higher lignin degradation and lower O-alkyl C/alkyl C ratio than the lagoon marshes, thus suggesting the presence of a more humificated SOM in these sites.Conclusions
From the different factors analysed, only physiographic position (low versus high salt marshes) and wetland type (marshes versus lagoons) caused variations in the HAs characteristics, because as the studied soils are under anaerobic conditions, they control the exportation of plant-derived OM and the allochthonous OM contribution in the studied areas. 相似文献16.
Purpose
Interestingly, soil is the component of the natural environment in which most hydrophobic organic pollution including polycyclic aromatic hydrocarbons (PAHs) gets accumulated. The aim of the present paper was to determine the effect of soil pollution with PAHs on the elemental composition, spectral properties, and hydrophobic and hydrophilic properties of humic acids. The research was performed on different types of soil samples that were artificially polluted with selected PAHs (anthracene, pyrene, fluorene and chrysene).Materials and methods
The soil samples were polluted with selected PAHs in an amount corresponding to 10 mg PAHs kg?1. The PAHs-polluted soil samples were incubated for 180 and 360 days at a temperature of 20–25 °C and fixed moisture (50 % of field water capacity). Humic acids (HAs) were extracted from the soil samples prior to the incubation (additionally, soils not polluted with PAHs) and after 180 and 360 days of incubation. For isolated HAs, the following analyses were performed: elemental composition, UV–Vis and IR spectra, susceptibility to oxidation, and hydrophilic (HIL) and hydrophobic (HOB) properties were determined using high-performance liquid chromatography.Results and discussion
The research demonstrated that introducing anthracene, fluorene, pyrene and chrysene to soil samples resulted in a change in some of the quality parameters of humic acids. However, the intensity and the direction of those changes were determined by soil properties. The changes of the parameters, once PAHs were introduced, that did not depend on the soil properties were ΔA 665u and ΔA 465u (susceptibility to oxidation at wavelengths of 465 and 665 nm) as well as HIL/ΣHOB. The same tendency in changes in the structure of humic acids, once PAHs were introduced, was also observed based on the Fourier transform infrared spectra pattern.Conclusions
A single pollution of soils with PAHs that leads to changes in the quality parameters of humic acids shows that, as for the soils permanently exposed to pollution with those compounds, significant changes can occur in the properties of humic acids. As a result, it can lead to a change in the functions played by humic acids in the environment. 相似文献17.
Elsayed A. Elkhatib Ahmed M. Mahdy Mohamed M. ElManeah 《Journal of Soils and Sediments》2013,13(1):94-105
Purpose
Recent research has focused on using water treatment residuals (WTRs) as cost-effective materials to remove potential environmental contaminants. To better understand and predict how WTRs affect the mobility and retention of nickel (Ni) in soils with time, it is crucial that the kinetics and thermodynamics of these reactions be understood. Such information is lacking in the literature and would aid in evaluating the suitability of WTR as a soil amendment for adsorbing Ni contaminant. Accordingly, we focused on investigating the retention of Ni in differing soils and the subsequent influence of WTR application on Ni retention.Materials and methods
To examine the effects of WTR application on the characteristics of Ni retention, equilibrium, and kinetics, sorption batch experiments were performed on three soils having different properties. The sorption data were applied to the first-order kinetic model, and the Arrhenius equation was used to determine the thermodynamic parameters.Results and discussion
The quantity of Ni sorbed by the soils followed the trend Typic Torrifluvent > Typic Calciorthids > Typic Torripsamment. Soil sorption isotherms shift toward a higher sorption of Ni indicating addition of more sorption sites as a result of WTRs’ application. Data generated at different temperatures for soils and WTR-amended soils fitted well to Freundlich isotherm and first-order kinetic models. The energy of activation (E a) and enthalpy (ΔH #), entropy (ΔS #), and free energy of activation (ΔG #) related to Ni sorption were calculated using the Arrhenius equation. The activation energy (E a) values (51.65–130.0 kJ mol?1) and the positive ΔH # values characterize Ni sorption process onto the sorbents studied as chemisorption with an endothermic nature. The large negative ΔS # values (?262 to ?290 J?mol?1) and the large positive ΔG # values (88.11–89.14 kJ mol?1) indicate the involvement of an associative mechanism in the Ni sorption process.Conclusions
WTR addition has led to an overall increase in Ni sorption by the amended soils. Such increase in Ni sorption provides evidence that WTR has the potential for land application as a Ni sorbent in soil remediation techniques. The sorption capacity of the soils and WTR-amended soils enhanced with an increase in temperature. Therefore, to truly understand the potential fate and mobility of Ni in the natural environment, temperature, in particular, should be considered. 相似文献18.
19.
Iris Hindersmann Jörg Hippler Alfred V. Hirner Tim Mansfeldt 《Journal of Soils and Sediments》2014,14(9):1549-1558
Purpose
Middle-European floodplain soils are often contaminated with mercury (Hg) and periodically flooded. In this study, the influence of a flooding event and subsequent dewatering on the volatilization of elemental Hg and methylated species was investigated in a laboratory experiment.Material and methods
Undisturbed soil cores were taken from a topsoil (12.1?±?0.75 mg kg?1 Hg) at the Elbe River in Lower Saxony, Germany. Soil columns were incubated at 20 °C with varying soil moisture (water-saturated for 2 weeks, 95 and 90 % water content for 1 week each), and the redox potential (EH) was recorded. The gaseous Hg that accumulated in the headspace of the flux chamber of the columns was pumped over cooled traps filled with adsorber material and analyzed by gas chromatography/inductively coupled plasma mass spectrometry for the various Hg species.Results and discussion
The watering of the soil resulted in a rapid decrease in the EH and the achievement of strongly reducing conditions (EH??1 Hg at the beginning to 5.78 μg L?1 Hg at the end of the experiment. Species analyses revealed that exclusively elemental Hg volatilized. The volatilization rate was between 1.73 and 824 ng m?2 h?1 Hg, which is consistent with other studies at the Elbe River.Conclusions
Even when flooded for a longer period of time, floodplain soils should show neither emission of methylated Hg nor exceptionally high volatilization of elemental Hg. 相似文献20.