Influence of fulvic acid on bacteriophage adsorption and complexation in soil.

The effect of fulvic acid, the major fraction of natural soluble organic matter, on the adsorption of MS2 bacteriophage to soil was investigated in controlled laboratory experiments. Batch experiments together with scanning electron microscopy-energy-dispersive X-ray analysis showed that fulvic acid complexed phage, which prevented its adsorption to soil. Phage strongly adsorbed to soil in the absence of fulvic acid. Phage which was complexed with fulvic acid was not irreversibly inactivated and could become viable under proper conditions, illustrating the importance of assay and elution procedures in the recovery of virus from aqueous solutions.     

Comparative effects of soil organic matter fractions on phosphatase activities in wheat roots

Summary Soil organic matter was obtained from two agricultural soils using alkali extraction followed by acidification to produce humic and fulvic acids which were further fractionated by adsorption and gel chromatography.All the products inhibited the activity of phosphatase prepared from wheat roots, but to different extents. Humic acids produced a greater inhibition of enzyme activity than either the fulvic acids or water extracts of soil. Aspergillin, fromAspergillus niger, had a similar C, H and N content to humic acid and produced a similar inhibition of phosphatase activity.The inhibitions produced by corresponding fractions derived from the two soils were slightly different, but the trends between similar fractions from different soils were comparable. The lower mol. wt. components of humic acid inhibited phosphatase activity to a greater extent than higher mot. wt. fractions. Although fulvic acid comprised only low mol. wt. components it was less effective in inhibiting enzyme activity than those components of comparable mol. wt. present in the corresponding humic acid. Synthetic polymaleic acid, produced an inhibition of phosphatase activity similar to that caused by fulvic acid.     

冻融环境下亚高山森林凋落叶添加对土壤腐殖质动态的影响

亚高山森林土壤形成过程中,胡敏酸、富里酸等腐殖物质的累积是维持土壤肥力及物质循环的重要途径,它受到土壤基质质量、凋落叶和环境因素的调控.本研究以川西亚高山典型的针叶林、针阔混交林和阔叶林土壤为对象,采用室内培养控制冻融环境和凋落叶添加的方法,研究冻融环境下凋落叶添加对土壤腐殖物质累积的影响.结果表明:冻融循环环境下针叶林土壤腐殖质含量升高,而针阔混交林和阔叶林土壤腐殖质含量降低,且凋落叶对土壤腐殖质含量无显著影响.培养前期冻融环境下3种林型土壤胡敏酸净累积,净累积量大小为针阔混交林>针叶林>阔叶林,富里酸含量下降,下降程度为阔叶林>针阔混交林>针叶林,且凋落叶对土壤胡敏酸和富里酸含量无显著影响.随培养时间的延长,3种林型土壤胡敏酸及富里酸含量均下降.这表明,凋落叶对土壤腐殖质含量的影响与土壤基质质量存在密切关系,且受到冬季土壤冻融时间长短的影响.     

Intestinal absorption of copper from drinking water containing fulvic acids and an infant formula mixture studied in a suckling rat model

The purpose of this study was to investigate if the intestinal absorption of copper in drinking water is altered in the presence of complexing agents from a fulvic acid mixture and an infant formula powder. Ten to twelve day old rat pups were given a single oral dose of radio-labeled Cu in deionized water (0.93 mg Cu/l), in water containing fulvic acids (10 mg/l), in infant formula mixed with deionized water, or in infant formula mixed with water containing fulvic acids. Six hours after dosage, radioactive Cu was analyzed in the mucosa of the small intestine, the liver and the remaining carcass (excluding the liver and gastrointestinal tract) by gamma counting. Dialysis and centrifugation experiments showed that Cu was complexed by components in the fulvic acid and formula mixtures, although the presence of fulvic acids in the water did not alter the Cu fractionation in the formula. The fractional Cu uptake (% of dose) from the intestinal lumen to the mucosa was not markedly changed by the presence of the chelating agents. However, the retention of Cu in the intestinal mucosa was increased by both fulvic acids and formula. Concomitantly, the absorption rate of Cd to the circulatory system was decreased. No interactive effect between fulvic acids and formula was found on the Cu absorption. These findings indicate that the water quality may be an important determinant of the rate of intestinal Cu absorption from drinking water. Moreover, in the future risk assessment of copper in drinking water, the possibility of alterations in absorption of drinking-water Cu has to be considered when the drinking water is used for cooking.     

川西亚高山森林凋落物去除对土壤腐殖质动态的影响

森林凋落物作为森林土壤腐殖质的主要来源, 在土壤腐殖质的形成中发挥着重要作用, 但不同森林类型凋落物因其含量、组成等的不同, 对土壤腐殖质的影响也不同。该研究以川西亚高山针叶林、阔叶林和针阔混交林3种不同森林类型为对象, 采用凋落物原位控制实验, 对比研究不同关键期凋落物去除对土壤可提取腐殖质、胡敏酸和富里酸含量及胡敏酸/富里酸、胡敏酸/可提取腐殖质的影响。主要结果: (1)土壤可提取腐殖质、胡敏酸和富里酸含量在不同森林类型中差异显著。土壤可提取腐殖质含量总体表现为针叶林>针阔混交林>阔叶林, 胡敏酸含量总体表现为针阔混交林>针叶林>阔叶林, 而富里酸含量则表现为针叶林>阔叶林>针阔混交林, 其中3种林型中土壤腐殖质的主要成分为富里酸, 总体均表现为富里酸型。不同采样时期也显著影响了土壤可提取腐殖质、胡敏酸和富里酸含量, 总体均表现为先升高后下降的趋势。除个别采样时期外, 凋落物去除总体降低了土壤可提取腐殖质、胡敏酸和富里酸的含量。(2)胡敏酸/富里酸和胡敏酸/可提取腐殖质的结果显示3种林型土壤总体腐殖化程度均较低, 整体表现为针阔混交林>阔叶林>针叶林, 凋落物去除在一定程度上有利于提高阔叶林与针阔混交林的腐殖质品质。(3)相关分析表明不同凋落物处理间土壤可提取腐殖质与土壤有机碳含量、全氮含量和土壤含水量呈显著正相关关系, 与温度呈显著负相关关系。综上所述, 短期的凋落物去除会降低土壤腐殖物质的含量, 但不同林型间由于凋落物类型差异会导致土壤腐殖质的不同变化, 说明土壤腐殖质的动态变化受凋落物类型以及环境因素的综合调控。因此, 关于凋落物变化对土壤腐殖质的影响还需进一步的长期研究。     

Effect of gypsum,pressmud, fulvic acid and zinc sources on yield and zinc uptake by rice crop in a saline-sodic soil

Summary The application of fulvic acid to a saline-sodic soil augmented the solubility of zinc by thousands fold. Zinc fulvate when applied at levels equivalent to that of zinc sulphate was more effective in enhancing diffusion of zinc in the soil. Application of gypsum, zinc sulphate and fulvic acid significantly increased dry matter yield and uptake of zinc by rice crop in a saline-sodic soil. Application of gypsum with pressmud or with fulvic acid and zinc sulphate resulted in significantly higher yield and zinc uptake than in other treatments.     

Influence of fulvic acid on transport of iron in soils and uptake by paddy seedlings

The influence of fulvic acid (FA) on the porous system self diffusion coefficient (Dp) of Fe in Calciorthent soils of Bihar, India, was determined with the half cell technique. Significantly higher values of Dp were observed when Fe was applied as Fe–FA to the soil compared to FeCl₃. The capacity factor of Fe decreased considerably due to its complexation by fulvic acid, resulting in an increase in the Dp of Fe. The organic carbon content of the soils correlated positively with Dp of Fe while it showed a negative relationship with active CaCO₃ and the clay content of soils. A soil culture system simulating acquisition of Fe by rice was developed to investigate transport of Fe from the soil solution to the surface of the plant roots through diffusion and mass flow. Mass flow contributed only 5–9% of the total Fe uptake by rice, with the remainder being ascribed to diffusion and root interception. A significant relationship ( r =0.96^**) between Dp- and Fe-uptake by rice was observed. The uptake of Fe by the crop and the percentage of tissue iron content derived from fertilizer were higher in the case of Fe–FA in comparison with FeCl₃, indicating the superiority of organically complexed Fe fertilizers over inorganic salts.     

Effects of humic materials on virus recovery from water

Humic and fulvic acids were tested for their ability to interfere with virus recovery by microporous filters. Two electropositively charged types of filter (Seitz S and Zeta Plus 60S) were used to concentrate poliovirus in the presence of humic materials. Humic acid inhibited virus adsorption, but even at the highest humic acid concentrations tested (200 mg/liter), 30 to 40% of the virus was recovered by the filters. Fulvic acid, tested with Zeta Plus filters, did not affect virus recovery. For comparison, two electronegatively charged filter types were tested (Cox and Balston). These two types of filter were more sensitive to interference at lower concentrations of humic acid than the more positively charged filters. With Balston filters, at humic acid concentrations above 10 mg/liter, most of the virus was recovered in the filtrate. Fulvic acid, tested with Balston filters, did not interfere with virus recovery. With the electropositively charged filters, the humic materials adsorbed efficiently, even at high input concentrations. Interference with virus adsorption occurred at humic acid concentrations which were below the level of saturation of the filters. In addition, in high-volume experiments, humic acid led to premature blockage of the filters. The efficiency of virus recovery by a second concentration step, organic flocculation of the filter eluate, was tested. For all the filter types tested, this procedure was not affected by the presence of humic or fulvic acid in the input water.     

Effects of Fulvic Acid on TNT Adsorption in Soil

In order to study the effect of fulvic acids (FA) on the migration of TNT in soil, batch experiments in which 2%, 5%, and 10% (w/w) of FA were added to soils were conducted. Adsorption kinetics and adsorption-desorption isotherms of TNT in soils were investigated, with results of the kinetics tests showing that the adsorption process could be divided into a fast and a slow stage and that FA could extend the adsorption time. Kinetic data were fit to pseudo first-order, pseudo second-order, Elovich, and intra-particle diffusion kinetic models. The fitting results showed that a pseudo second-order kinetic model best described the adsorption process, while Elovich and intra-particle diffusion kinetic models could accurately predict the adsorption at higher FA content. The adsorption-desorption isotherms were predicted using Linear, Freundlich, and Langmuir isotherm models. Results showed that the Freundlich model best described the adsorption-desorption process, and that FA increased adsorption capacity and enhanced the adsorption affinity. The hysteresis index suggested that FA could reduce the desorption of TNT in soil.     

Effects of humic materials on virus recovery from water.

Humic and fulvic acids were tested for their ability to interfere with virus recovery by microporous filters. Two electropositively charged types of filter (Seitz S and Zeta Plus 60S) were used to concentrate poliovirus in the presence of humic materials. Humic acid inhibited virus adsorption, but even at the highest humic acid concentrations tested (200 mg/liter), 30 to 40% of the virus was recovered by the filters. Fulvic acid, tested with Zeta Plus filters, did not affect virus recovery. For comparison, two electronegatively charged filter types were tested (Cox and Balston). These two types of filter were more sensitive to interference at lower concentrations of humic acid than the more positively charged filters. With Balston filters, at humic acid concentrations above 10 mg/liter, most of the virus was recovered in the filtrate. Fulvic acid, tested with Balston filters, did not interfere with virus recovery. With the electropositively charged filters, the humic materials adsorbed efficiently, even at high input concentrations. Interference with virus adsorption occurred at humic acid concentrations which were below the level of saturation of the filters. In addition, in high-volume experiments, humic acid led to premature blockage of the filters. The efficiency of virus recovery by a second concentration step, organic flocculation of the filter eluate, was tested. For all the filter types tested, this procedure was not affected by the presence of humic or fulvic acid in the input water.     

Distribution of heavy metals in a sewage oxidation pond and their adsorption in residual solid (sewage sludge ash)

Abstract

Electrometric studies were carried out on the interaction of heavy metal ions such as manganese, chromium, nickel, copper, zinc, cadmium and lead with the extracted organic matter, humic and fulvic acid from the sludge in a sewage oxidation pond. The distribution of heavy metals was between 60 and 97%, which is associated with the solid waste (sludge) of the oxidation pond. The adsorption/removal efficiency of metal ions onto the sludge ash was more than 90% and 97%, respectively, in the pure system. To obtain the ash, the sludge was burnt at 500°C, treated with nitric acid (1+1) to leach out all the metals and then filtered; the residue left on the filter paper was the pure ash. Both this and that coated with organic matter were studied. The adsorption isotherm for metals, humic/fulvic acids and metal-humic/fulvic acid complexes in the metal-free sludge ash and in the organic matter in the pure system were studied using the Freundlich relationship. Good agreement was found suggesting that sediment and humic/fulvic acids have an important role in the mobility, dispersion and sedimentation of metal ions in an aquatic environment. More of these heavy metals are removed in the pure system than in the natural system. This may be due to the lesser availability of humic and fulvic acids in the lagoons during the short detention time of sewage in suspension in the oxidation pond, whereas the sludge which has settled to the bottom of the pond for several years contains rich decomposed organic matter in the form of humic and fulvic acids containing heavy metals. Such pure systems could be useful for the effective removal of heavy metals.     

Effects of humic and fulvic acids on poliovirus concentration from water by microporous filtration

Because naturally occurring organic matter is thought to interfere with virus adsorption to microporous filters, humic and fulvic acids isolated from a highly colored, soft surface water were used as model organics in studies on poliovirus adsorption to and recovery from electropositive Virosorb 1MDS and electronegative Filterite filters. Solutions of activated carbon-treated tap water containing 3, 10, and 30-mg/liter concentrations of humic or fulvic acid were seeded with known amounts of poliovirus and processed with Virosorb 1MDS filters at pH 7.5 or Filterite filters at pH 3.5 (with and without 5 mM MgCl2). Organic acids caused appreciable reductions in virus adsorption and recovery efficiencies with both types of filter. Fulvic acid caused greater reductions in poliovirus recovery with Virosorb 1MDS filters than with Filterite filters. Fulvic acid interference with poliovirus recovery by Filterite filters was overcome by the presence of 5 mM MgCl2. Although humic acid reduced poliovirus recoveries by both types of filter, its greatest effect was on virus elution and recovery from Filterite filters. Single-particle analyses demonstrated MgCl2 enhancement of poliovirus association with both organic acids at pH 3.5. The mechanisms by which each organic acid reduced virus adsorption and recovery appeared to be different for each type of filter.     

Chromatographic techniques for the separation of Al and associated organic ligands present in soil solution

Organic acids including humic, fulvic, aliphatic and aromatic acids comprise part of the dissolved organic carbon (DOC) present in soil solution. They act as ligands for trace metals and are effective detoxifiers of monomeric aluminium (Al). Solid phase extraction (SPE) techniques permit fractionation of the DOC into organic classes but yield no information on the pre-existing Al/organic acid complexes. Aliphatic and aromatic acids may be separated and determined by High Performance Liquid Chromatography (HPLC); however, the conditions used dissociate the organic acid Al complexes. Humic and fulvic acids are of a variable and ill-defined nature and only limited information exists regarding their binding of Al. This paper reports on fractionation studies of soil solutions, using both SPE and molecular weight cut-off filters, to characterise the DOC components and on the subsequent development of a size exclusion chromatography (SEC) system for the separation of organically complexed Al into different species using a low ionic strength mobile phase at pH 4.2. Model complexes of Al and Cu citrate were used to evaluate chromatographic performance of a Fractogel TSK HW-40(S) column (1×30 cm). For soil solution samples, the column eluate, after passing through a UV detector, was directly coupled to an Inductively Coupled Plasma Atomic Emission Spectrometer (ICPAES) for on-line multi-element detection to characterise DOC and trace metal distribution.Fractionation studies revealed that polysaccharides constituted the major proportion of the DOC which passed the 10000 dalton molecular weight cut-off filter. Analysis of soil solutions from an organically amended soil by the SEC-ICPAES system showed that Al, Fe and Mn eluted as multiple peaks prior to the bed volume, indicating their presence as complexes with organic ligands.     

Adsorption isotherms of lanthanum to soil constituents and effects of pH,EDTA and fulvic acid on adsorption of lanthanum onto goethite and humic acid

Abstract

La³⁺ adsorption isotherms to five soil constituents (quartz, feldspar, kaolinite, goethite and humic acid) are studied. EDTA, fulvic acid and pH effects are also investigated on the adsorption of lanthanum by goethite and humic acid because of their relative importance in affecting metal environmental behavior. Adsorption isotherms of La³⁺ to five constituents show differences in adsorption capacity and in shape in the studied range of La³⁺. These constituents can be classified according to their adsorption capacity: humic acid > goethite ≈ kaolinite > feldspar ≈ quartz. pH increase could promote humic acid and goethite adsorption of La³⁺ while EDTA could reduce the adsorption by these two adsorbents. Fulvic acid can reduce humic acid adsorption but has less effect on adsorption by goethite.     

Effects of humic and fulvic acids on poliovirus concentration from water by microporous filtration.

Because naturally occurring organic matter is thought to interfere with virus adsorption to microporous filters, humic and fulvic acids isolated from a highly colored, soft surface water were used as model organics in studies on poliovirus adsorption to and recovery from electropositive Virosorb 1MDS and electronegative Filterite filters. Solutions of activated carbon-treated tap water containing 3, 10, and 30-mg/liter concentrations of humic or fulvic acid were seeded with known amounts of poliovirus and processed with Virosorb 1MDS filters at pH 7.5 or Filterite filters at pH 3.5 (with and without 5 mM MgCl2). Organic acids caused appreciable reductions in virus adsorption and recovery efficiencies with both types of filter. Fulvic acid caused greater reductions in poliovirus recovery with Virosorb 1MDS filters than with Filterite filters. Fulvic acid interference with poliovirus recovery by Filterite filters was overcome by the presence of 5 mM MgCl2. Although humic acid reduced poliovirus recoveries by both types of filter, its greatest effect was on virus elution and recovery from Filterite filters. Single-particle analyses demonstrated MgCl2 enhancement of poliovirus association with both organic acids at pH 3.5. The mechanisms by which each organic acid reduced virus adsorption and recovery appeared to be different for each type of filter.     

Long-term fertilization affects the abundance of saprotrophic microfungi degrading resistant forms of soil organic matter

The effect of mineral and organic fertilization on the occurrence of soil microorganisms was determined in a field experiment. The colony-forming unit counts of saprotrophic microfungi, when estimated on a silicate gel medium containing fulvic acid as a sole carbon source, increased significantly with increasing doses of mineral and organic fertilization. Partial correlation analysis indicated that, unlike bacteria and actinomycetes, microfungi utilizing fulvic acid were significantly associated with soil organic carbon. No significant effects on bacteria and microfungi counted on common microbiological media were observed but counts of actinomycetes increased in a manured soil extensively fertilized by a mineral fertilizer. Fulvic acid utilizing microfungi, which are associated with areas rich in organics, play possibly the main role in mineralization of resistant forms of soil organic matter.     

Fluorescence and FT-IR spectroscopic studies of Suwannee River fulvic acid complexation with aluminum, terbium and calcium.

In this study fluorescence emission and IR spectroscopy have been used to investigate the interaction of the class A (oxygen seeking "hard acid") metal Al(3+), with Suwannee River fulvic acid. Addition of Al(3+) ion results in a significant enhancement in fulvic acid fluorescence emission (at lambda(em)=424 nm) and significant red shift of the excitation wavelength (from lambda(ex)=324 nm to lambda(ex)=344 nm) at low pH values (pH approximately 4.0-5.0). At pH 4.0 (0.1 M ionic strength), where the predominant aluminum ion species is the "free" (aquo) ion, the fulvic acid fluorescence reaches 142% of the value in the absence of added metal ion. Analysis of the pH 4.0 and pH 5.0 fluorescence enhancement data with the nonlinear (single site) model of Ryan and Weber indicated binding constants in the range of 4.67.10(4)-2.87.10(6) M(-1) and concentrations of ligand sites in the range of 18.6.10(-6)-24.0.10(-6) M, both consistent with previous studies performed on both aquatic and soil fulvic acids. Companion fluorescence experiments performed on two other class A metal ions, Ca(2+) and Tb(3+), indicated no significant enhancement or quenching with Ca(2+) and only slight quenching with Tb(3+). Comparison of FT-IR spectra collected on fulvic acid alone and fulvic acid in the presence of the three class A metals (Al(3+), Ca(2+) and Tb(3+)) provides strong evidence for the involvement of carboxyl carbonyl functions in the binding of all three metal ions, which is not unexpected. The spectra also reveal, however, a very pronounced difference in the 4000-2000 cm(-1) IR spectral region between the Al(3+) spectrum and the Ca(2+) and Tb(3+) spectra. The -OH stretch spectral region in the Al(3+) spectrum has a major component shifted to higher energy (compared to fulvic acid alone or to fulvic acid in the presence of Ca(2+) or Tb(3+)). Even more striking is the emergence of a pronounced IR band at 2407 cm(-1), which is present only in the Al(3+) spectrum. The results of fluorescence and IR experiments with the model compounds salicylic acid and phthalic acid further confirm that both salicylic acid-like sites and phthalic acid-like sites are likely complexation sites for Al(3+) in fulvic acid and are major contributors to the observed spectroscopic changes associated with Al(3+) ion complexation. From a comparison of both the fluorescence and IR spectral results for all three class A metals, differing most strongly in the value of their ionic index, it seems clear that major sources of the deviation in spectral properties between Al(3+) and Ca(2+)/Tb(3+) is the unusually high value of its charge density and relatively low propensity for involvement in covalent bonding interactions (very high ionic index and relatively low covalent index in the Nieboer and Richardson classification of environmental metals), as well as affinity for certain functional groups.     

Roles of Soil Organic Matter and Humic Substance Structure in Cu and Pb Adsorption in Histosols

ABSTRACT

Histosols have a high organic matter content and therefore a high variability of structures and chemical functional groups with adsorptive capacity. This study aimed to select the most appropriate models to describe the sorption phenomena of Cu and Pb in Histosols, identify the types of bonds between these metals and soil samples, and assess the influence of soil attributes and soil humic substance structures on these bonds. The Freundlich and Langmuir models were selected based on the values of the corrected Akaike information criterion and variation of Akaike information criterion as the best models for describing Cu and Pb sorption in Histosols. The values of the adsorption coefficients provided by the models indicated that Pb has higher affinity with the studied soil relative to Cu. However, Cu adsorption to soil occurs specifically and Pb is adsorbed nonspecifically. In general, the contents of N and fulvic acids were the factors that most influenced Pb sorption. Pb has a higher association with more aliphatic fulvic character structures, while Cu has a higher association with soil humic character structures. Therefore, compared to Cu, Pb in the studied Histosol has greater bioavailability potential and, consequently, greater risks of contamination and entering the food chain.     

东北大骨节病病区主要土壤腐殖酸硒与大骨节病关系的研究

本文研究东北大骨节病病区土壤中硒的形态和含量与大骨节病的关系。研究结果表明,病区土壤中硒以有机结合态硒为主,又以富里酸态硒占主要比重。根据20个土壤样点的对比研究,显示土壤富里酸中硒含量与病情呈显著负相关。     

Aluminium-organic acid interactions in acid soils

A study was undertaken to quantify the rates of aluminum release in an acid soil (pH 4.40) which was known to produce differential growth responses to Al in Al-resistant and sensitive wheat cultivars which are characterized by differences in root organic acid exudation. Soil columns were leached with artificial soil solutions containing no Al in the presence or absence of citrate for periods of up to 12 days. The Al release rates could be resolved into two dissolution phases: A fast release phase for Al was attributed to the cation exchangeable pool while a second slower phase was attributable to the dissolution of readily weatherable minerals. Citrate increased the dissolution rates two fold in comparison to experiments performed without citrate. It was concluded that for rhizosphere considerations, the total releasable Al pool was finite in size and constituted approximately 2% of the soil's total Al reserves. This pool was not increased markedly in the presence of citrate. It was concluded that citrate not only complexed Al in solution but also complexed Al directly from the mineral phase. From experimental Al release rates, it was deduced that only the soil solution and exchangeable Al pools were responsible for Al rhizotoxicity and that organic acids exuded from the root probably provide an efficient mechanism for excluding Al from the root. Empirical equations were also constructed to describe Al dissolution from the two release pools for use in soil Al flux models.