Concentrations of monosaccharides in humic substances in the early stages of humification.

Deteriorated liquid packaging board (LPB) and biowaste compost are matrices, mainly consisting of cellulose, in the early stages of humification. Degradative studies on these matrices allow an examination of the role of carbohydrates in the synthesis of humic substances. Samples of different age were collected and divided by extraction into hot water extract (HWE), bitumen, humic acid (HA), fulvic acid (FA) and humin or residual fibre fractions. The following monosaccharides were identified in these fractions: L-arabinose, D-ribose, D-xylose, L-fucose, D-mannose, D-fructose, D-galactose, D-glucose, L-rhamnose and xylitol. The main component in all fractions was glucose. The concentrations of monosaccharides in humic acids (HAs) of LPB ranged from 67 to 503 mg/g of organic matter, and the concentrations in HAs of compost from 52 to 101 mg/g. As a general trend, the concentrations of monosaccharides decreased during LPB degradation and composting in all fractions. At the same time the relative amounts of D-xylose, D-mannose and D-galactose increased in HAs of compost samples.     

Comparison of structural features of water-soluble organic matter from atmospheric aerosols with those of aquatic humic substances

Elemental analysis, Fourier transform infrared coupled to attenuated total reflectance (FTIR-ATR) and solid-state cross polarization with magic angle spinning-¹³C-nuclear magnetic resonance (CPMAS ¹³C NMR) spectroscopies were used to compare the chemical features of water-soluble organic compounds (WSOC) from atmospheric aerosols with those of aquatic humic and fulvic acids. The influence of different meteorological conditions on the structural composition of aerosol WSOC was also evaluated. Prior to the structural characterisation, the WSOC samples were separated into hydrophobic acids and hydrophilic acids fractions by using a XAD-8/XAD-4 isolation procedure. Results showed that WSOC hydrophobic acids are mostly aliphatic (40–62% of total NMR peak area), followed by oxygenated alkyls (15–21%) and carboxylic acid (5.4–13.4%) functional groups. Moreover, the aromatic content of aerosol WSOC samples collected between autumn and winter seasons is higher (∼18–19%) than that of samples collected during warmer periods (∼6–10%). The presence of aromatic signals typical of lignin-derived structures in samples collected during low-temperature conditions highlights the major contribution of wood burning processes in domestic fireplaces into the bulk chemical properties of WSOC from aerosols. According to our investigations, aerosol WSOC hydrophobic acids and aquatic fulvic and humic acids hold similar carbon functional groups; however, they differ in terms of the relative carbon distribution. Elemental analysis indicates that H and N contents of WSOC hydrophobic acids samples surpass those of aquatic fulvic and humic acids. In general, the obtained results suggest that WSOC hydrophobic acids have a higher aliphatic character and a lower degree of oxidation than those of standard fulvic and humic acids. The study here reported suggests that aquatic fulvic and humic acids may not be good models for WSOC from airborne particulate matter.     

Characterization of the humic material formed by composting of domestic and industrial biowastes Part 1. HPLC of the cupric oxide oxidation products from humic acids

The changes induced by humification of anaerobically digested sewage sludge, source separated biowaste, and pulp mill biosludge were determined by extracting the fractions of bitumen and humic and fulvic acids from the samples of fresh and humified composts. In all cases, a distinct decrease in the amount of bitumen could be detected during humification. The amount of humic acids increased in sewage sludge and biowaste samples, but decreased in pulp mill biosludge sample during humification. The humic acids were degraded by CuO oxidation and the phenolic degradation products were analysed by reversed-phase high-performance liquid chromatography. The yield of these aromatic degradation products was in the range 0.9–2.0 % for each sample. The main phenolic degradation products were 4-hydroxybenzoic acid, vanillic acid, 4-hydroxybenzaldehyde, vanillin, syringaldehyde, and acetovanillone. Two lignin dimers, dehydrodivanillin and dehydrodiacetovanillone, were also identified.     

凹凸棒土对腐殖酸的低温吸附性能研究

首次研究凹凸棒土对饮用水中腐殖酸的低温吸附性能,考察5℃条件下,吸附时间与腐殖酸初始浓度、吸附剂投加量、pH对凹凸棒土吸附腐殖酸的影响,确定吸附剂的吸附等温线、吸附动力学和热力学等相关理论参数,研究凹凸棒土对腐殖酸的吸附性能与机理。结果表明,江苏盱眙凹凸棒土在温度5℃、pH=4、水中腐殖酸初始浓度为5 mg/L,投加量为15 g/L的条件下,吸附180 min后对腐殖酸的去除率可达97.26%。凹凸棒土对腐殖酸的吸附符合二级吸附动力学方程与Freundlich吸附等温式,吸附过程由孔隙内扩散过程控制,吸附为自发的吸热过程,包括物理吸附与化学吸附。根据Fre-undlich吸附等温式拟合计算,5℃、pH=7时理论最大吸附量为9 mg/g,说明凹凸棒土对于低温饮用水中腐殖酸具有良好的吸附效果。     

Influence of dissolved humic substances on the leaching of MCPA in a soil column experiment

The influence of dissolved humic substances on the transport of (4-chloro-2-methylphenoxy) acetic acid (MCPA) in a sandy soil with a low organic carbon content was studied in a column experiment. Soil columns were eluted with aqueous solutions containing different fractions of humic substances. More than 70% of the applied compound was found in the leachate in all sandy soil experiments, but distinct differences were obtained depending on the composition of the eluent. The addition of both humic and fulvic acids to the eluent affected the leaching behaviour of MCPA. While the presence of humic acids increased and accelerated the movement of MCPA in the investigated sandy soil, fulvic acids caused the opposite effect: increased retention was observed relative to the control. We concluded that a possible carrier transport or retention strongly depends on the composition of the dissolved organic matter. Thus, changes in the composition of dissolved organic matter may affect MCPA movement into deeper soil layers.     

Kinetics and mechanisms of interaction of simazine with humic acids

Abstract

The adsorption of simazine on two fractions of hu‐mic acids of different molecular size was investigated at a pH range of 2.5 to 6.2. The amounts of the herbicide adsorbed decreased with increasing pH for both of the two humic acids fractions used and no adsorption was observed at pH 5.5. The adsorption capacity of fraction I (M_v >100,000) exceeded that of fraction IV (M_v < 4,000) over the entire pH region used. No appreciable changes in the adsorbed amounts were observed after 24 hours.

Continuous flow dialysis techniques were used to determine the extent of binding between simazine and dissolved humic acids. It was observed that 50% and 60% of simazine added were thus removed from the dialysis bags containing humic acids fractions I and IV,respectively. Higher amounts of simazine were adsorbed by the high molecular weight humic fraction. The adsorption processes involve ionic bonds between simazine and humic acids. In addition it is likely that hydrogen bonds and physical forces are also involved in the adsorption of simazine by humic acids.     

Effects of humic substances on the decomposition of 2,4-dichlorophenol by ozone after extraction from water into acetic acid through activated carbon

The objectives of this study are to clarify the behavior of humic substances throughout the processes of 2,4-dichlorophenol (2,4-DCP) adsorption on granular activated carbon (GAC) from water and extraction into acetic acid, and the influence of the extracted humic substances on the decomposition of 2,4-DCP by ozone in the acetic acid. The adsorption capacity of GAC for 2,4-DCP was not influenced by the humic substances preloaded to have equilibrium concentration of 24.9mg Cl(-1) (14.5mg Cg(-1)). The adsorption capacity of GAC for 2,4-DCP decreased to one tenth of new GAC after the first adsorption-extraction step because of only 16% desorption in the first step. However, 2,4-DCP adsorbed on GAC was completely extracted after the second step suggesting that GAC can be used as adsorbent to transfer 2,4-DCP from water to acetic acid. The concentration ratio of 2,4-DCP from water into acetic acid was around 2x10(5), whereas the concentration ratio of humic substances was about 3.5, indicating that 2,4-DCP was selectively adsorbed and extracted by this system. The first order degradation rate constant for 2,4-DCP by ozone in acetic acid increased with the addition of humic substances. The rate constant with 16mg Cl(-1) of humic substances was 2.6 times as high as that without humic substances. Humic substances behaved as a promoter for the degradation of 2,4-DCP by ozone.     

Removal of humic substances from water by means of calcium-ion-enriched natural zeolites.

The ability of the natural zeolited Neapolitan Yellow Tuff (NYT) enriched with calcium ions to remove humic acids from water was evaluated by batch adsorption equilibrium tests and dynamic experiments carried out by percolating humic acid solutions through a small NYT column (breakthrough curves). Under the experimental condition explored, the sorption capacity increases with the ionic strength and has the highest value at pH 7.4. The partition coefficient for a low concentration of humic acid ([humic acid] --> 0), at pH 7.4 in 0.01 M sodium chloride, was approximately 1000 L/kg, versus the value of approximately 100 L/kg in the absence of the alkaline metal salt. Therefore, after humic acids have been adsorbed in a column filled with the calcium-ion-enriched tuff, a reduction of the salt concentration in the ongoing solution enhances the release of the adsorbed material. These findings show that NYT can be used for the removal of humic acids from water.     

Hydrogen peroxide-assisted UV photodegradation of Lindane

Aqueous solutions of gamma-hexachlorocyclohexane (Lindane) were photolyzed (lambda=254 nm) under a variety of solution conditions. The initial concentrations of hydrogen peroxide (H(2)O(2)) and Lindane varied from 0 to 20 mM and 0.21 to 0.22 microM, respectively, the pH ranged from 3 to 11, and several concentration ratios of Suwannee River humic acid and fulvic acid were dissolved in the irradiated solutions. Lindane rapidly reacted, and the maximum reaction rate constant (9.7 x 10(-3) s(-1)) was observed at pH 7 and initial [H(2)O(2)]=1 mM. Thus, 90% of the Lindane is destroyed in approximately 4 min under these conditions. In addition, within 15 min, all chlorine atoms were converted to chloride ion, indicating that chlorinated organic by-products do not accumulate. The reactor was characterized by measuring the photon flux (7.04 x 10(-6) E s(-1)) and the cumulative production of *OH during irradiation. The cumulative *OH production during irradiation was fastest at an initial [H(2)O(2)]=5 mM (k=0.77 micro M s(-1)).     

The effect of humic acids on the water solubility and water-organic carbon partitioning of fluorene and its NSO-heteroanalogues: carbazole, dibenzofuran, and dibenzothiophene

The solubilizing effect of humic acids on fluorene and its NSO analogues carbazole, dibenzofuran and dibenzothiophene has been studied. The interaction between these substances and humic acids was found to depend significantly on the actual humic acid concentration. A pronounced decrease in the interaction constant, as well as in the water-organic matter partitioning coefficient was observed with increasing humic acid concentration. The effects are discussed in terms of concentration dependent macromolecular structural changes in the humic acids. A linear free energy relation for the interaction is suggested.     

Effect of humification processes on polyaromatic hydrocarbons concentration during wastewater treatment.

The aim of the present work was to compare the concentration changes of polyaromatic hydrocarbons (PAH) and the course of humification processes during wastewater treatment. Studies of samples from a biological-mechanical wastewater treatment plant in Sosnowiec-Zagórze (Poland) were carried out. Determination of PAH was performed both for wastewater sludge and sludge water. Observations of the course of humification processes for humic acid fractions isolated from sludges were conducted. Analysis of PAH extracted from wastewaters and from sludge was performed by means of high-performance liquid chromatography. Investigations of humification processes were conducted by electron paramagnetic resonance and nuclear magnetic resonance methods. The elementary composition changes in the structure of the extracted humic acids were determined. It was found that polyaromatic hydrocarbons appear during the processes of humification. Their content in water decreased only after the process of sludge aeration; however, sludge water leaving the settlers was PAH-enriched.     

The formation and control of disinfection by-products using chlorine dioxide

In this study, chlorine dioxide (ClO2) was used as an alternative disinfectant with vanillic acid, p-hydroxybenzoic acid, and humic acid as the organic precursors in a natural aquatic environment. The primary disinfection by-products (DBPs) formed were trihalomethanes (THMs) and haloacetic acids (HAAs). Under neutral conditions (pH = 7) for vanillic acid, more total haloacetic acids (THAAs) than total trihalomethanes (TTHMs) were found, with a substantial increase during the later stages of the reaction. In the case of p-hydroxybenzoic acid, the amount of THAAs produced was minimal. Raising the concentration of ClO2 was not favorable for the control of THAAs in low concentrations of vanillic acid. ClO2 could reduce the total amount of TTHMs and THAAs for higher concentration of vanillic acid. It was found that the humic acid treatment dosage was not significant. Under alkaline conditions (pH = 9), the control of TTHMs and THAAs for the treatment of vanillic acid was better and more economical, however, an appreciable amount of inorganic by-products were observed. Under the same alkaline condition, the control of THAA for the treatment of p-hydroxybenzoic acid was not beneficial and for the treatment of humic acid was not significant.     

Fractionation and spectroscopic properties of fulvic acid and its extract

Novel results were obtained when a fulvic acid was isolated from Acros humic acid and fractionated by traditional preparative thin-layer chromatography. Eight colorful bands were directly viewed and analyzed showing very different fluorescence and absorption properties. The fluorescence quantum yield of the bands ranged from 2% to 9.4%, significantly higher than that of natural humic substances. An aqueous fulvic acid solution was also extracted with methylene chloride (CH(2)Cl(2)) by continuous liquid-liquid extraction. The CH(2)Cl(2) extract was further fractionated by thin-layer chromatography. Eleven highly fluorescent colorful bands and six weakly fluorescent bands were observed and examined. UV-vis absorption and fluorescence (including 3D matrix) spectra and fluorescence quantum yields revealed that each band still represented a mixture of compounds. Moreover, substantial differences in optical properties were observed among bands. A single band possessed the highest fluorescence quantum yield (6%) and highest specific fluorescence (fluorescence/mass), and accounted for 21% of the total fluorescence of the extract. The mass of individual bands varied from 1.6% to 14.1% of the total materials recovered. Components of all fractions were grouped into 11 fluorophore families according to their maxima on 3D matrix fluorescence spectra. No component is dominant in the whole fulvic acid or extracted portion in terms of optical properties. Over 40 natural products are proposed for model chromophores.     

Fractionation of fulvic acids: characteristics and complexation with copper

Two fulvic acid samples isolated from Suwannee river (International Humic Substance Society) and Feeitsuey reservoir were subjected to gel filtration chromatography (GFC) for molecular size fractionation. The GFC-eluted samples were separated into three groups corresponding to the molecular weight ranges: < 220, 220-1000, and 1000-4000. Fluorescence quenching techniques were employed for determining the conditional stability coefficient and kinetic parameters of copper complexation with the three fractions of fulvic acids. Experimental conditions were pH 6, 5 x 10(-5)m total copper and 5 mg C litre(-1) of fulvic acids. The conditional stability coefficients of the fulvic acid fractions were in the order of 0.9-3.3 x 10(5)m(-1), and the forward and reverse rate constants were in the order of 6.9-12.4 x 10(3)m(-1) s(-1) and 3.5-8.0 x 10(-2) s(-1). Information could be useful in modelling copper transport in the hydrosphere.     

Removal of organic polyelectrolytes and their metal complexes by adsorption onto xonotlite

Natural organic polyelectrolytes (humic and fulvic acids) and their metal complexes were removed by adsorption onto xonotlite. The removal percentages of humic and fulvic acids by xonotlite were approximately 80% and 30%, respectively. Humic acid removal from solution by adsorption onto xonotlite took place more readily than fulvic acid removal. The molecular weight distributions of the humic substances remaining in solution after adsorption with the xonotlite were measured with size exclusion chromatography. A comparison of molecular weight distributions demonstrated conclusively that large molecular weight components were adsorbed preferentially, indicating that adsorption efficiency depends on the number of functional groups of humic substances. Furthermore, the surface topography of the adsorbent was observed before and after adsorption by scanning electron microscopy. The calculated heat of adsorption was of 330 kJ mol(-1) which was evaluated from the Clapeyron-Clausius equation. Therefore, the adsorption type can be considered chemical. Since xonotlite can be easily synthesized and obtained at low cost, the adsorption method of humic and fulvic acids is superior to their precipitation.     

Evaluation of the leachability of polychlorinated dibenzo-p-dioxins and dibenzofurans in raw and solidified air pollution control residues from municipal waste incinerators

Leachability of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from raw and solidified air pollution control (APC) residues with selected solvents, including acetic acid, simulated acid rain, humic acid, linear alkylbenzene sulfonate (LAS) and n-hexane was investigated. High-chlorinated PCDD/F congeners were observed in all leachates of raw APC residue samples, with the largest total leaching concentration (61.60 ngm(-3); 0.30 ngI-TEQm(-3)) from treatment with humic acid. Low-chlorinated congeners were mainly leached with LAS and n-hexane. Solidification and stabilization (S/S) processes with cement and sulfur-containing chelating agent decreased the leachability of PCDD/Fs by up to 98% with humic acid and LAS as solvents. However, S/S processes enhanced the leachability of both high- and low-chlorinated PCDD/F congeners with n-hexane as the solvent, which largely increased the toxic equivalent quantity of leachates. These results suggest that conventional S/S processes may effectively restrain the release of PCDD/Fs when APC residues are leached with rain water or natural organic compounds (e.g., humic acid), but may have a deteriorated effect when APC residues are leached with nonpolar organic solvents (e.g., n-hexane) coexisting in the landfill sites.     

Copper binding by peat fulvic and humic acids extracted from two horizons of an ombrotrophic peat bog

We studied the binding of Cu(II) to humic acids and fulvic acids extracted from two horizons of an ombrotrophic peat bog by metal titration experiments at pH 4.5, 5.0, 5.5, and 6.0 and 0.1 M KNO3 ionic strength. Free metal ion concentrations in solution were measured using an ion selective electrode. The amounts of base required to maintain constant pH conditions were recorded and used to calculate H+/Cu2+ exchange ratios. The amount of Cu(II) bound to the humic fractions was greater than the amount bound to the fulvic fractions and only at the highest concentrations of metal ion the amount of Cu(II) sorbed by both fractions became equal. The proton to metal ion exchange ratios are similar for all humic substances, with values ranging from 1.0 to 2.0, and decreasing with increased pH. The amount of Cu(II) bound is practically independent of the horizon from which the sample was extracted. The results indicate that the humic substances show similar cation binding behaviour, despite the differences in chemical composition. The copper binding data are quantitatively described with the NICA-Donnan model, which allows to characterize only the carboxylic type binding sites. The values of the binding constants are higher for the humic acids than for the fulvic acids.     

Photochemical behavior of parathion in the presence of humic acids from different origins

This paper reports the effect of ultraviolet radiation on the degradation of pesticide ethyl parathion in the presence of humic acids. Ethyl parathion was completely degraded in 300 min using an artificial lamp of 7.41 x 10(-10) einstein/s. Humic acid from peat did not influence the photochemical rate (k = 8.92 x 10(-3) min). However, in the presence of aquatic humic acid, the photochemical rate was higher (11.5 x 10(-3) min). The analytical determinations show the presence of p-nitrophenol and aminophenol in the reaction medium during the photochemical experiments. The kinetic of degradation in all experiments obeyed a first-order reaction pattern.     

Identification of single cultured micro-organisms based on their whole-community fatty acid profiles, using an extended extraction procedure.

Fatty acid profiles obtained from single cultured organisms have been used to estimate which taxonomic groups are actually represented. The lipid extraction was modified to liberate fatty acids with ester-linkages, as well as those with non-ester-linkages and classify them in different chemically relevant groups. The discriminatory power of fatty acids, in different chemically relevant fractions and subfractions varied considerably. Saturated fatty acids were least able to predict actual group membership (ca. 75%), while nonester-linked hydroxy fatty acids, which largely go undetected by the simple extraction procedure, gave the highest predictability values (ca. 94%). The discriminatory power of the method used was enhanced by increasing the number of well-defined fatty acid methyl esters. The estimation capacity of the results was improved, when the fatty acids, which were presumed to be common and widespread, were excluded from the whole-community fatty acid profiles prior to multivariate analysis.     

Photoinductive efficiency of soil extracted humic and fulvic acids

Humic and fulvic acids extracted from soils of different genesis were investigated for their ability to photoinduce the transformation of fenuron (2 x 10(-4) mol(-1)) at 365 nm. The ratio of the initial rate of fenuron consumption over the rate of light absorption by humic substances was found to be higher for fulvic acids (range 2.0 x 10(-3) to 9.0 x 10(-5)) than for humic acids (range 1.7 x 10(-4) to - 3.6 x 10(-5)). Within the FAs population, this ratio decreased as the specific absorption coefficient at 365 nm increased. It seems therefore that most of 365-nm absorbing components have no photoinductive activity and even reduce that of photoinductive chromophores.