This review starts with the description of the quantitative significance of dissolved organic material in general and dissolved humic substances (HS) in particular in various ecosystems. Despite their high quantities,...This review starts with the description of the quantitative significance of dissolved organic material in general and dissolved humic substances (HS) in particular in various ecosystems. Despite their high quantities, the knowledge about the role of HS is still very low and full of old, but still recycled paradigms. HS are thought to be inert or at least refractory and too large to be taken up by aquatic organisms. Instead, I present evidence that dissolved HS that mainly derives from the terrestrial environment, are taken up and directly and/or indirectly interfere with freshwater organisms and, thus, structure biocenoses. Relatively well known is in the meantime the fuelling function of allochthonous HS, which, upon irradiation, release fatty acids, which serve as substrates for microbial growth. This is an indirect effect of HS. Microbes, in turn, are food for mixotrophic algae and (heterotrophic) zooplankton. Thus, non-eutrophicated freshwaters are net-heterotrophic, meaning that respiration exceeds primary production. Furthermore, model calculations exemplify that only a very small portion of the terrestrial production is sufficient to cause net-heterotrophy in these freshwater bodies. But, recent papers show also that due to different stoichiometries the maximal plankton biomass production with algae or mixotrophs is higher than with bacteria. Very recently, several direct effects of HS have been elucidated. Among them are:induction of chaperons (stress shock proteins), induction and modulation of biotransformation enzymes, modulation (mainly inhibition) of photosynthetic oxygen release of aquatic plants, production of an internal oxidative stress, modulation of the offspring numbers in the nematode Caenorhabditis elegans[WTBZ], feminization of fish and amphibs, interference within the thyroid system, and action as chemical attractant to C. elegans. We are still in the phase of identifying the various physiological, biochemical, and molecular-biological effects. Hence, the ecological and ecophysiological significance of these HS-mediated effects still remain somewhat obscure. Nevertheless, HS appear generally to have an impact on the individual as well as on the community and even ecosystem level comparable to that of, for instance, nutrients.展开更多
For phosphorus （P） recovery from wastewater, the effect of humic substances （HS） on the precipitation of calcium phosphate was studied. Batch experiments of calcium phosphate precipitation were undertaken with syn...For phosphorus （P） recovery from wastewater, the effect of humic substances （HS） on the precipitation of calcium phosphate was studied. Batch experiments of calcium phosphate precipitation were undertaken with synthetic water that contained 20 mg/L phosphate （as P） and 20 mg/L HS （as dissolved organic carbon, DOC） at a constant pH value in the range of 8.0-10.0. The concentration variations of phosphate, calcium （Ca） and HS were measured in the precipitation process; the crystalline state and compositions of the precipitates were analysed by powder X-ray diffraction （XRD） and chemical methods, respectively. It showed that at solution pH 8.0, the precipitation rate and removal efficiency of phosphate were greatly reduced by HS, but at solution pH ≥9.0, the effect of HS was very small. The Ca consumption for the precipitation of phosphate increased when HS was added; HS was also removed from solution with the precipitation of calcium phosphate. At solution pH 8.0 and HS concentrations ≤3.5 mg/L, and at pH ≥ 9.0 and HS concentrations ≤ 10 mg/L, the final precipitates were proved to be hydroxyapatite （HAP） by XRD. The increases of solution pH value and initial Ca/P ratio helped reduce the influence of HS on the precipitation of phosphate.展开更多
The present work extended the knowledge on the binding and complexation of humic substances(humic acid or fulvic acid) and hematite by Fourier transform infrared spectroscopy(FTIR). The FTIR data gained gave the consi...The present work extended the knowledge on the binding and complexation of humic substances(humic acid or fulvic acid) and hematite by Fourier transform infrared spectroscopy(FTIR). The FTIR data gained gave the consist evidences by two different sampling preparation methods that the interaction mechanism between humic substances and hematite was mainly conform to the ligand exchange involving carboxylic functional groups of humic substances and the surfaces sites of hematite. The present method, although associated with some uncertainties, provided an opportunity to increase the knowledge in this field.展开更多
The sorption and desorption behaviors of two perfluoroalkane sulfonates（PFSAs）, including perfluorohexane sulfonate（PFHx S） and perfluorooctane sulfonate（PFOS） on two humic acids（HAs） and humin（HM）, which we...The sorption and desorption behaviors of two perfluoroalkane sulfonates（PFSAs）, including perfluorohexane sulfonate（PFHx S） and perfluorooctane sulfonate（PFOS） on two humic acids（HAs） and humin（HM）, which were extracted from a peat soil, were investigated. The sorption kinetics and isotherms showed that the sorption of PFOS on the humic substances（HSs） was much higher than PFHx S. For the same PFSA compound, the sorption on HSs followed the order of HM 〉 HA2 〉 HA1. These suggest that hydrophobic interaction plays a key role in the sorption of PFSAs on HSs. The sorption capacities of PFSAs on HSs were significantly related to their aliphaticity, but negatively correlated to aromatic carbons,indicating the importance of aliphatic groups in the sorption of PFSAs. Compared to PFOS,PFHx S displayed distinct desorption hysteresis, probably due to irreversible pore deformation after sorption of PFHx S. The sorption of the two PFSAs on HSs decreased with an increase in p H in the solution. This is ascribed to the electrostatic interaction and hydrogen bonding at lower p H. Hydrophobic interaction might also be stronger at lower p H due to the aggregation of HSs.展开更多
Based on the characteristics of the lignite sample, effects of assistant anthraquinone （AQ） on extraction yield of humic substances （HS） and the action mechanisms of AQ in alkaline condition were studied by Fouvie...Based on the characteristics of the lignite sample, effects of assistant anthraquinone （AQ） on extraction yield of humic substances （HS） and the action mechanisms of AQ in alkaline condition were studied by Fouvier transform infrared （FT-IR） spectroscopy. The results indicate that assistant AQ can not only increase the extraction yield of HS but also reduce the alkali dosage （NaOH） as well as the extraction temperature and extraction time. Under the optimal conditions of alkali dosage of 9%, AQ dosage of 0.75%, extraction temperature of 80 ℃, extraction time of 30 min, stirring speed of 600 r/min and solid-to-liquid ratio of 1：3, the extraction yield of HS reaches 80.08%, which is increased by more than 20% compared with the conventional extraction. FT-IR spectra show that AQ is able to prevent dissolved HS from being destroyed into undissolved substance by alkali and 1-IS obtained in the presence of AQ possesses more groups of COOR and --COOH than that obtained without AQ.展开更多
The compost-derived humic substances(HS)can function as electron mediators for promoting hematite bioreduction because of its redox capacity.Humification process can affect redox capacities of compost-derived HS by ch...The compost-derived humic substances(HS)can function as electron mediators for promoting hematite bioreduction because of its redox capacity.Humification process can affect redox capacities of compost-derived HS by changing its intrinsic structure.However,the redox properties of compost-derived HS link-ing with hematite bioreduction during composting still remain unclear.Herein,we investigated the redox capacities of compost-derived HS,and assessed the responses of the redox capacities to the hematite bioreduction.The result showed that compost-derived HS(i.e.,humic acids(HA)and fulvic acids(FA))were able to accept electrons from Shewanella oneidensis MR-1,and the electron accepting capacity was increased during composting.Furthermore,it could be functioned as electron mediators for promoting the hematite bioreduction,achieving 1.19-2.15 times compared with the control experience.Not only the aromatic structures(quinone)but also the non-quinone structures such as nitrogen-and sulfur-containing functional moieties were served as the redox-active functional groups of compost-derived HS.Our work proved that the aromatic functional groups and the heteroatom structures(especially N)were important to the hematite bioreduction.This study highlights the redox-active properties of compost-derived HS and its impact on the microbial reduction of iron mineral.Redox capacity of compost-derived HS might mitigate the environmental risk of contaminants when the composting production was added into the contaminated soils as low-cost repair materials.展开更多
Cake layer formation is inevitable over time for ultrafiltration(UF)membrane-based drinking water treatment.Although the cake layer is always considered to cause membrane fouling,it can also act as a"dynamic prot...Cake layer formation is inevitable over time for ultrafiltration(UF)membrane-based drinking water treatment.Although the cake layer is always considered to cause membrane fouling,it can also act as a"dynamic protection layer",as it further adsorbs pollutants and dramatically reduces their chance of getting to the membrane surface.Here,the UF membrane fouling performance was investigated with pre-deposited loose flocs in the presence of humic acid(HA).The results showed that the floc dynamic protection layer played an important role in removing HA.The higher the solution pH,the more negative the floc charge,resulting in lower HA removal efficiency due to the electrostatic repulsion and large pore size of the floc layer.With decreasing solution pH,a positively charged floc dynamic protection layer was formed,and more HA molecules were adsorbed.The potential reasons were ascribed to the smaller floc size,greater positive charge,and higher roughness of the floc layer.However,similar membrane fouling performance was also observed for the negative and positive floc dynamic protection layers due to their strong looseness characteristics.In addition,the molecular weight(MW)distribution of HA also played an important role in UF membrane fouling behavior.For the small MW HA molecules,the chance of forming a loose cake layer was high with a negatively charged floc dynamic protection layer,while for the large MW HA molecules it was high with a positively charged floc dynamic protection layer.As a result,slight UF membrane fouling was induced.展开更多
Nitrogen forms of humic substances from a subalpine meadow soil, a latentic red soil and a weathered coal and the effect of acid hydrolysis on N structures of soil humic substances were studied by using 15N cross-pola...Nitrogen forms of humic substances from a subalpine meadow soil, a latentic red soil and a weathered coal and the effect of acid hydrolysis on N structures of soil humic substances were studied by using 15N cross-polarization magic angle spinning nuclear magnetic resonance (CPMAS NMR) spectroscopy. Of the detectable 15N-signal intensity in the spectra of soil humic substances 71%-79% may be attributed to amide groups, 10%-18% to aromatic/aliphatic amines and 6%~11% to indole- and pyrrole-like N. Whereas in the spectrum of the fulvic acid from weathered coal 46%, at least, of the total 15N-signal intensity might be assigned to pyrrole-like N, 14% to aromatic/aliphatic ammes, and the remaining intensities could not be assigned with certainty. Data on nonhydrolyzable residue of protein-sugar mixture and a 15N-labelled soil fulvic acid confirm the formation of nonhydrolyzable heterocyclic N during acid hydrolysis. Project (No. 39790100) supported by the National Natural Science Foundation of China.展开更多
Water soluble organic carbon(WSOC)in sediments plays an important role in transference and transformation of aquatic pollutants.This article investigated the inherent mechanisms of how sediemnt grain size affect the p...Water soluble organic carbon(WSOC)in sediments plays an important role in transference and transformation of aquatic pollutants.This article investigated the inherent mechanisms of how sediemnt grain size affect the partitioning coeffcient(k)of WSOC.Influences of NaOH extracted humic substances were particularly focused on.Sediments were sampled from two cross-sections of the middle Yellow River and sieved into three size fractions(〈63μm,63-100μm,and 100-300μm).The total concentration of WSOC in sediments(Cwsoc)and k were estimated using multiple water-sediment ratio experiments.Results showed that Cwsoc ranged from 0.012 to 0.022 mg/g,while k ranged from 0.8 to 3.9 L/kg.Correlations between the spectrum characteristics of NaOH extracted humic substances and k were analyzed.Strong positive correlations are determined between k and the aromaticity indicators of NaOH extracted humic substances in different sediment size fractions.Comparing with finer fractions(〈63μm),k is higher in larger size fractions(63-100μm and 100-300μm)related to higher aromaticity degree of NaOH extracted humic substances mostly.While negative relationship between k and the area ratio of fourier transform infrared spectroscopy(FT-IR)at 3400 and 1430 cm^-1 implied that the lowest k was related to the highest concentration of acidic humic groups in particles〈63μm.WSOC in finer fractions(〈63μm)is likely to enter into pore water,which may further accelerate the transportation of aquatic contaminants from sediment to water.展开更多
17α-Ethynylestradiol（EE2） in natural waters may cause adverse effects on organisms due to its high estrogenic potency. Laboratory studies were performed to study the effects of a local humic acid（LHA）, fulvic aci...17α-Ethynylestradiol（EE2） in natural waters may cause adverse effects on organisms due to its high estrogenic potency. Laboratory studies were performed to study the effects of a local humic acid（LHA）, fulvic acid（LFA） and Aldrich humic acid（AHA） on the photochemical behavior and estrogenic potency of EE2. Here photolytic experiments demonstrated that pure aqueous EE2 could undergo direct and self-sensitized photodegradation at a global rate of 0.0068 hr^-1.Photodegradation rate of EE2 in 5.0 mg/L dissolved humic substances（DHS） was determined to be 0.0274, 0.0296 and 0.0254 hr^-1 for LHA, LFA and AHA, respectively. Reactive oxygen species（ROS） and triplet dissolved humic substances（^3DHS＊） scavenging experiments indicated that the promotion effect of DHS on EE2 photodegradation was mainly aroused by the reactions of HOU（35%–50%）,~1O2（〈10%） andDHS＊（22%–34%）. However, the photodegradation of EE2 could also be inhibited when DHS exceeded the threshold of 10 mg/L. Three hydroxylation products of EE2 were identified using GC–MS and their formation pathways were also proposed. In vitro estrogenicity tests showed that EE2 was transformed into chemicals without estrogenic potency. These findings could extend our knowledge on the photochemical behaviors of steroid estrogens in sunlit natural waters.展开更多
Fungal pellets of Aspergillus niger 405,Aspergillus ustus 326,and Stachybotrys sp.1103 were used for the removal of humic substances from aqueous solutions.Batchwise biosorption,carried out at pH 6 and 25°C,was m...Fungal pellets of Aspergillus niger 405,Aspergillus ustus 326,and Stachybotrys sp.1103 were used for the removal of humic substances from aqueous solutions.Batchwise biosorption,carried out at pH 6 and 25°C,was monitored spectrophotometrically and the process described with Freundlich’s model.Calculated sorption coeffcients Kf and n showed that A.niger exhibited the highest effciency.A good match between the model and experimental data and a high correlation coeffcient(R2)pointed out to judicious choice of ...展开更多
Potentiometric experiments were carried out on the proton binding equilibria of FA extracted from a weathered coal and HA and Fa extracted from a dark loessial soil.The affinity spectrum model was employed to treat th...Potentiometric experiments were carried out on the proton binding equilibria of FA extracted from a weathered coal and HA and Fa extracted from a dark loessial soil.The affinity spectrum model was employed to treat the experimental data.The affinity spectrum model technique could“magnify” the heterogeneity of the proton binding equilibria.so it was useful for comparing and studying the characteristics of humic substances with similar properties.According to the affinity spectra,we also found that the direction of the titration could affect the properties of the equilibria of FA from the weathered coal,and the acidic functional groups contained in FA from the weathered coal were larger in quantity than those contained in HA and FA from the dark loessial soil.展开更多
The influence of humic substances (HS) formulations derived from sedimentary and compost sources was studied on plant growth at cell level and chlorophyll retention during accelerated senescence of leaf tissue. The di...The influence of humic substances (HS) formulations derived from sedimentary and compost sources was studied on plant growth at cell level and chlorophyll retention during accelerated senescence of leaf tissue. The direct effect of HS formulations was studied on cell expansion using cucumber and radish cotyledon expansion test. The cucumber hypocotyl elongation test was used to study the effect on cell elongation. Chlorophyll pigment retention in excised leaf tissue incubated in dark with high temperature was assessed to study the effect on leaf senescence. Explant tissues were incubated directly in the solutions of the formulations at the concentration recommended for foliar application to the crop plants. HS formulations showed significant variations in their direct bio-stimulatory effects. Formulations derived from compost sources were found superior in terms of inducing a direct stimulatory effect on cell expansion and cell elongation and in maintaining chlorophyll pigment retention during accelerated senescence. HS from sedimentary sources stimulated cell expansion and delayed chlorophyll degradation to a lesser extent compared to HS from compost. However, HS formulations derived from sedimentary sources used in this study were not effective in inducing cell elongation in the cucumber hypocotyl elongation test. The direct bio-stimulatory effect of HS formulations differed significantly between the formulations that were evaluated.展开更多
Perfluorooctane sulfonate(PFOS)is a persistent organic pollutant(POP)and emergent contaminant that are widespread in the environment.Understanding the mechanisms controlling the distribution of PFOS and its isomers be...Perfluorooctane sulfonate(PFOS)is a persistent organic pollutant(POP)and emergent contaminant that are widespread in the environment.Understanding the mechanisms controlling the distribution of PFOS and its isomers between hydrargillite and the water phase is important in order to study their redistribution and mobility in the environment.This study investigated the effects of pH,humic acid,fulvic acid and Na_(2)SO_(4) on sorption of PFOS isomers to hydrargillite.A mixture of PFOS isomers was spiked into water and hydrargillite was added to the system and shaken for one day;the system was tested with different aqueous composition.Concentrations of PFOS isomers in the aqueous phase were quantified using an ultra-performance liquid chromatograph coupled to a triple quadrupole mass spectrometer.Our results showed that the distribution coefficients of PFOS isomers were found to be 0.76,0.71,0.93 and 0.90 at pH 6.5,for 3-/4-/5-PFOS,6-/2-PFOS,L-PFOS and total PFOS respectively.The distribution coefficients increased at lower pH and decreased at alkaline conditions.The presence of humic substances(HS)increased the sorption slightly at the environmental pH of 6.5,although a competition effect was observed during acidic conditions.A tendency of PFOS distribution to hydrargillite in the presence of Na_(2)SO_(4) was like its behavior in the presence of HS although the mechanisms behind the sorption were interpreted differently.This study revealed that L-PFOS was readily sorbed when no other chemicals were added or in 20 mg/L FA or 100 mg/L Na_(2)SO_(4).We suggest that an increase in PFOS sorption in the presence of HS may be due to hydrophobic mechanisms while Na_(2)SO_(4) contributed to increased sorption through ionic strength effects.展开更多
X-ray photoelectron spectroscopy (XPS) was applied to examine the N structures of soil humic substances and some of their analogues. It was found that for soil humic substances XPS method gave similar results as those...X-ray photoelectron spectroscopy (XPS) was applied to examine the N structures of soil humic substances and some of their analogues. It was found that for soil humic substances XPS method gave similar results as those obtained by 15N CPMAS NMR (cross-polarization magic-angle spinning nuclear magnetic resonance) method. 70%～86% of total N in soil humic substances was in the form of amide, and 6%～13% was presented as amines, with the remaining part as heterocyclic N. There was no difference in the distribution of the forms of N between the humic substances from soils formed over hundreds or thousands of years and the newly formed ones. For fulvic acid from weathered coal and benzoqu inone- (N H-4 )-2 S O-4 polymer the XPS results deviated significantly from the 15N CPMAS NMR data.展开更多
The structure characteristics and adhesive property of humic substance(HS) extracted with different methods were mainly studied by terms of elementary analysis,visible spectrum,FT-IR spectroscopy,viscosity,adsorption ...The structure characteristics and adhesive property of humic substance(HS) extracted with different methods were mainly studied by terms of elementary analysis,visible spectrum,FT-IR spectroscopy,viscosity,adsorption and pelletizing experiments.The results show that HSs extracted with new method(HS-a) own higher degree of aromatization and polymerization,larger relative molecular mass and more polar functional groups than HS extracted with usual method(HS-b).The viscosity of HS-b is about 30-40 mPa·s lower than that of HS-a.The maximum adsorption amounts of HS-a and HS-b onto iron concentrates are 9.11 mg/g and 8.08 mg/g,respectively.Meanwhile,HS-a has a better performance than HS-b in the practical application for pelletizing of iron concentrates.The difference in agglomeration behaviors with iron concentrates lies in the differences of the structure characteristics of HSs.With higher content of polar functional groups,larger relative molecular mass and viscosity of HSs,the agglomeration behavior is improved.展开更多
Concentrations of dissolved humic substances in the rivers of eastern China were found to be 0.9- 14.4 mg/L with a median value of 4.6.The contents of dissolved humic substances in river water generally decrease from ...Concentrations of dissolved humic substances in the rivers of eastern China were found to be 0.9- 14.4 mg/L with a median value of 4.6.The contents of dissolved humic substances in river water generally decrease from north to south,a trend similar to that of aquatic sediments and soils.Results of multiple regression analysis and path analysis showed that the dissolved stream humic substances are of a combined autochthonous and allochthonous origin.展开更多
Surface-enhanced Raman Spectroscopy(SERS)has been used to characterize hurnic substances.By using HNO_3 -roughened silver foils as the enhancing surface,both fluorescence quenching and strong SERS signals have been ob...Surface-enhanced Raman Spectroscopy(SERS)has been used to characterize hurnic substances.By using HNO_3 -roughened silver foils as the enhancing surface,both fluorescence quenching and strong SERS signals have been observed at the same time.The results obtained herein show that SERS is a particularly sensitive and highly selective technique for the characterization of humic substances in the environment. Humic substances axe receiving ever-inereasing attention because of their importance in the environment. Very recently,we have reported the first successful application of Raman spectroscopy for characterizing humic substances.In this present paper,the application of surface-enhanced Raman spectroscopy(SERS)for humic substances has further been investigated.To our knowledge,no such studies have previously been reported.The results obtained herein dearly demonstrate that SERS has a great deal of promise as an analytical method for“In Situ”characterizing humic substances in the environment.展开更多
This work evaluated the complexation capacity, exchange constants and availability of micronutrients for plants and humic substances extracted from peat samples. Samples of humic substances extracted from two tropical...This work evaluated the complexation capacity, exchange constants and availability of micronutrients for plants and humic substances extracted from peat samples. Samples of humic substances extracted from two tropical peats （HS-P1 and HS-P2） were enriched with the micronutrients Cu（II）, Co（II）, Fe（II）, Mn（II）, Ni（II） and Zn（II） and the parameters for formation of the complexes （HS-N） were evaluated at different pH. The Scatchard model was used to calculate the maximum complexation capacity and the nutrient availability was studied using exchange capacity experiments based on ultrafiltration procedure. The optimum pH for complexation was 4.5 and the order of affinity was： Fe（II） 〉 Cu（II） 〉 Co（II） 〉 Mn（II） = Ni（II） 〉 Zn（II）. The maximum complexation capacity reached 56.8 mg·g-1 Fe of HS-P1 （the highest） and 1.7 mg.g1 Zn of HS-P2 （the slightest）. The exchange experiments showed that HS-P-Fe complexes were formed preferentially. The least stable complex was formed with Zn, which was therefore, more easily available. The results contribute to understand the behavior and availability of some nutrients in soils.展开更多
Quality of soil humic substances and compost quality was assessed using different techniques of fluorescence spectroscopy. Emission, excitation, synchronous and emission-excitation matrix help us to characterize diffe...Quality of soil humic substances and compost quality was assessed using different techniques of fluorescence spectroscopy. Emission, excitation, synchronous and emission-excitation matrix help us to characterize different fluorophores in humic substances molecule. Content of stabile carbon forms in soil was assessed by humic substances fractionation. Content of labile water extractable carbon and nitrogen was determined by analyzer Shimadzu TOC-VCSH with chemo-luminescent detection in infrared spectral region. Results showed that compost amendment caused changes in both stabile （recalcitrant） and labile carbon content. Humic substances isolated from compost consist mainly of simple structural components of wide molecular heterogeneity and low molecular weight. Humification degree and content of conjugated fluorophores in compost was lower compared with stabile soil humic substances. The last contained more conjugated aromatic π-electron systems with electron-withdrawing functional groups, which are responsible for the fluorescence shift to lower energy levels or longer wavelengths.展开更多
文摘This review starts with the description of the quantitative significance of dissolved organic material in general and dissolved humic substances (HS) in particular in various ecosystems. Despite their high quantities, the knowledge about the role of HS is still very low and full of old, but still recycled paradigms. HS are thought to be inert or at least refractory and too large to be taken up by aquatic organisms. Instead, I present evidence that dissolved HS that mainly derives from the terrestrial environment, are taken up and directly and/or indirectly interfere with freshwater organisms and, thus, structure biocenoses. Relatively well known is in the meantime the fuelling function of allochthonous HS, which, upon irradiation, release fatty acids, which serve as substrates for microbial growth. This is an indirect effect of HS. Microbes, in turn, are food for mixotrophic algae and (heterotrophic) zooplankton. Thus, non-eutrophicated freshwaters are net-heterotrophic, meaning that respiration exceeds primary production. Furthermore, model calculations exemplify that only a very small portion of the terrestrial production is sufficient to cause net-heterotrophy in these freshwater bodies. But, recent papers show also that due to different stoichiometries the maximal plankton biomass production with algae or mixotrophs is higher than with bacteria. Very recently, several direct effects of HS have been elucidated. Among them are:induction of chaperons (stress shock proteins), induction and modulation of biotransformation enzymes, modulation (mainly inhibition) of photosynthetic oxygen release of aquatic plants, production of an internal oxidative stress, modulation of the offspring numbers in the nematode Caenorhabditis elegans[WTBZ], feminization of fish and amphibs, interference within the thyroid system, and action as chemical attractant to C. elegans. We are still in the phase of identifying the various physiological, biochemical, and molecular-biological effects. Hence, the ecological and ecophysiological significance of these HS-mediated effects still remain somewhat obscure. Nevertheless, HS appear generally to have an impact on the individual as well as on the community and even ecosystem level comparable to that of, for instance, nutrients.
基金The German Research Foundation (DFG-Graduiertenkolleg 366) Grant Program for the High-Level Returned Scholars fromAbroad, Ministry of Personnel of China (No. 2004-2005)
文摘For phosphorus （P） recovery from wastewater, the effect of humic substances （HS） on the precipitation of calcium phosphate was studied. Batch experiments of calcium phosphate precipitation were undertaken with synthetic water that contained 20 mg/L phosphate （as P） and 20 mg/L HS （as dissolved organic carbon, DOC） at a constant pH value in the range of 8.0-10.0. The concentration variations of phosphate, calcium （Ca） and HS were measured in the precipitation process; the crystalline state and compositions of the precipitates were analysed by powder X-ray diffraction （XRD） and chemical methods, respectively. It showed that at solution pH 8.0, the precipitation rate and removal efficiency of phosphate were greatly reduced by HS, but at solution pH ≥9.0, the effect of HS was very small. The Ca consumption for the precipitation of phosphate increased when HS was added; HS was also removed from solution with the precipitation of calcium phosphate. At solution pH 8.0 and HS concentrations ≤3.5 mg/L, and at pH ≥ 9.0 and HS concentrations ≤ 10 mg/L, the final precipitates were proved to be hydroxyapatite （HAP） by XRD. The increases of solution pH value and initial Ca/P ratio helped reduce the influence of HS on the precipitation of phosphate.
文摘The present work extended the knowledge on the binding and complexation of humic substances(humic acid or fulvic acid) and hematite by Fourier transform infrared spectroscopy(FTIR). The FTIR data gained gave the consist evidences by two different sampling preparation methods that the interaction mechanism between humic substances and hematite was mainly conform to the ligand exchange involving carboxylic functional groups of humic substances and the surfaces sites of hematite. The present method, although associated with some uncertainties, provided an opportunity to increase the knowledge in this field.
基金support of Chinese Natural Science Foundation(No.21277077,21325730)Ministry of Education(No.20130031130005)+1 种基金Ministry of Science and Technology(No.2012ZX07529-003)Ministry of Education Innovation Team(IRT 13024)
文摘The sorption and desorption behaviors of two perfluoroalkane sulfonates（PFSAs）, including perfluorohexane sulfonate（PFHx S） and perfluorooctane sulfonate（PFOS） on two humic acids（HAs） and humin（HM）, which were extracted from a peat soil, were investigated. The sorption kinetics and isotherms showed that the sorption of PFOS on the humic substances（HSs） was much higher than PFHx S. For the same PFSA compound, the sorption on HSs followed the order of HM 〉 HA2 〉 HA1. These suggest that hydrophobic interaction plays a key role in the sorption of PFSAs on HSs. The sorption capacities of PFSAs on HSs were significantly related to their aliphaticity, but negatively correlated to aromatic carbons,indicating the importance of aliphatic groups in the sorption of PFSAs. Compared to PFOS,PFHx S displayed distinct desorption hysteresis, probably due to irreversible pore deformation after sorption of PFHx S. The sorption of the two PFSAs on HSs decreased with an increase in p H in the solution. This is ascribed to the electrostatic interaction and hydrogen bonding at lower p H. Hydrophobic interaction might also be stronger at lower p H due to the aggregation of HSs.
基金Project(50725416) supported by the National Science Fund for Distinguished Young Scholars in ChinaProject(50804059) supported by the National Natural Science Foundation of China+1 种基金Project(2008BAB32B06) supported by the Key Program in National Science and Technology Pillar Program during the 11th Five-year Plan Period of ChinaProject(200805331080) supported by Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘Based on the characteristics of the lignite sample, effects of assistant anthraquinone （AQ） on extraction yield of humic substances （HS） and the action mechanisms of AQ in alkaline condition were studied by Fouvier transform infrared （FT-IR） spectroscopy. The results indicate that assistant AQ can not only increase the extraction yield of HS but also reduce the alkali dosage （NaOH） as well as the extraction temperature and extraction time. Under the optimal conditions of alkali dosage of 9%, AQ dosage of 0.75%, extraction temperature of 80 ℃, extraction time of 30 min, stirring speed of 600 r/min and solid-to-liquid ratio of 1：3, the extraction yield of HS reaches 80.08%, which is increased by more than 20% compared with the conventional extraction. FT-IR spectra show that AQ is able to prevent dissolved HS from being destroyed into undissolved substance by alkali and 1-IS obtained in the presence of AQ possesses more groups of COOR and --COOH than that obtained without AQ.
基金supported by Central Research Institutes of Basic Research and Public Service Special Operations of Chinese Research Academy of Environmental Sciences(No.2019YSKY-023).
文摘The compost-derived humic substances(HS)can function as electron mediators for promoting hematite bioreduction because of its redox capacity.Humification process can affect redox capacities of compost-derived HS by changing its intrinsic structure.However,the redox properties of compost-derived HS link-ing with hematite bioreduction during composting still remain unclear.Herein,we investigated the redox capacities of compost-derived HS,and assessed the responses of the redox capacities to the hematite bioreduction.The result showed that compost-derived HS(i.e.,humic acids(HA)and fulvic acids(FA))were able to accept electrons from Shewanella oneidensis MR-1,and the electron accepting capacity was increased during composting.Furthermore,it could be functioned as electron mediators for promoting the hematite bioreduction,achieving 1.19-2.15 times compared with the control experience.Not only the aromatic structures(quinone)but also the non-quinone structures such as nitrogen-and sulfur-containing functional moieties were served as the redox-active functional groups of compost-derived HS.Our work proved that the aromatic functional groups and the heteroatom structures(especially N)were important to the hematite bioreduction.This study highlights the redox-active properties of compost-derived HS and its impact on the microbial reduction of iron mineral.Redox capacity of compost-derived HS might mitigate the environmental risk of contaminants when the composting production was added into the contaminated soils as low-cost repair materials.
基金supported by the National Natural Science Foundation for Young Scientists of China(No.51608514)the Funds for International Cooperation and Exchange of the National Natural Science Foundation of China(No.51820105011)+1 种基金the National Key R&D Program of China(No.2016YFC0400802)the Program of the Youth Innovation Promotion Association of Chinese Academy of Sciences
文摘Cake layer formation is inevitable over time for ultrafiltration(UF)membrane-based drinking water treatment.Although the cake layer is always considered to cause membrane fouling,it can also act as a"dynamic protection layer",as it further adsorbs pollutants and dramatically reduces their chance of getting to the membrane surface.Here,the UF membrane fouling performance was investigated with pre-deposited loose flocs in the presence of humic acid(HA).The results showed that the floc dynamic protection layer played an important role in removing HA.The higher the solution pH,the more negative the floc charge,resulting in lower HA removal efficiency due to the electrostatic repulsion and large pore size of the floc layer.With decreasing solution pH,a positively charged floc dynamic protection layer was formed,and more HA molecules were adsorbed.The potential reasons were ascribed to the smaller floc size,greater positive charge,and higher roughness of the floc layer.However,similar membrane fouling performance was also observed for the negative and positive floc dynamic protection layers due to their strong looseness characteristics.In addition,the molecular weight(MW)distribution of HA also played an important role in UF membrane fouling behavior.For the small MW HA molecules,the chance of forming a loose cake layer was high with a negatively charged floc dynamic protection layer,while for the large MW HA molecules it was high with a positively charged floc dynamic protection layer.As a result,slight UF membrane fouling was induced.
基金supported by the National Natural science Foundation of China.(No.39790100)
文摘Nitrogen forms of humic substances from a subalpine meadow soil, a latentic red soil and a weathered coal and the effect of acid hydrolysis on N structures of soil humic substances were studied by using 15N cross-polarization magic angle spinning nuclear magnetic resonance (CPMAS NMR) spectroscopy. Of the detectable 15N-signal intensity in the spectra of soil humic substances 71%-79% may be attributed to amide groups, 10%-18% to aromatic/aliphatic amines and 6%~11% to indole- and pyrrole-like N. Whereas in the spectrum of the fulvic acid from weathered coal 46%, at least, of the total 15N-signal intensity might be assigned to pyrrole-like N, 14% to aromatic/aliphatic ammes, and the remaining intensities could not be assigned with certainty. Data on nonhydrolyzable residue of protein-sugar mixture and a 15N-labelled soil fulvic acid confirm the formation of nonhydrolyzable heterocyclic N during acid hydrolysis. Project (No. 39790100) supported by the National Natural Science Foundation of China.
基金supported by the Major State Basic Research Program of China(No.2007CB407202)the National Natural Science Foundation of China(No.40501063).
文摘Water soluble organic carbon(WSOC)in sediments plays an important role in transference and transformation of aquatic pollutants.This article investigated the inherent mechanisms of how sediemnt grain size affect the partitioning coeffcient(k)of WSOC.Influences of NaOH extracted humic substances were particularly focused on.Sediments were sampled from two cross-sections of the middle Yellow River and sieved into three size fractions(〈63μm,63-100μm,and 100-300μm).The total concentration of WSOC in sediments(Cwsoc)and k were estimated using multiple water-sediment ratio experiments.Results showed that Cwsoc ranged from 0.012 to 0.022 mg/g,while k ranged from 0.8 to 3.9 L/kg.Correlations between the spectrum characteristics of NaOH extracted humic substances and k were analyzed.Strong positive correlations are determined between k and the aromaticity indicators of NaOH extracted humic substances in different sediment size fractions.Comparing with finer fractions(〈63μm),k is higher in larger size fractions(63-100μm and 100-300μm)related to higher aromaticity degree of NaOH extracted humic substances mostly.While negative relationship between k and the area ratio of fourier transform infrared spectroscopy(FT-IR)at 3400 and 1430 cm^-1 implied that the lowest k was related to the highest concentration of acidic humic groups in particles〈63μm.WSOC in finer fractions(〈63μm)is likely to enter into pore water,which may further accelerate the transportation of aquatic contaminants from sediment to water.
基金sponsored by the National Natural Science Foundation of China(No.41401558)the Application Fundamental Key Basic Research Foundation of Yunnan Province,China(No.2013FA011)+1 种基金the Education Department Science Research Foundation of Yunnan Province,China(No.2014J022)the China Postdoctoral Science Foundation(No.2014T70887)
文摘17α-Ethynylestradiol（EE2） in natural waters may cause adverse effects on organisms due to its high estrogenic potency. Laboratory studies were performed to study the effects of a local humic acid（LHA）, fulvic acid（LFA） and Aldrich humic acid（AHA） on the photochemical behavior and estrogenic potency of EE2. Here photolytic experiments demonstrated that pure aqueous EE2 could undergo direct and self-sensitized photodegradation at a global rate of 0.0068 hr^-1.Photodegradation rate of EE2 in 5.0 mg/L dissolved humic substances（DHS） was determined to be 0.0274, 0.0296 and 0.0254 hr^-1 for LHA, LFA and AHA, respectively. Reactive oxygen species（ROS） and triplet dissolved humic substances（^3DHS＊） scavenging experiments indicated that the promotion effect of DHS on EE2 photodegradation was mainly aroused by the reactions of HOU（35%–50%）,~1O2（〈10%） andDHS＊（22%–34%）. However, the photodegradation of EE2 could also be inhibited when DHS exceeded the threshold of 10 mg/L. Three hydroxylation products of EE2 were identified using GC–MS and their formation pathways were also proposed. In vitro estrogenicity tests showed that EE2 was transformed into chemicals without estrogenic potency. These findings could extend our knowledge on the photochemical behaviors of steroid estrogens in sunlit natural waters.
文摘Fungal pellets of Aspergillus niger 405,Aspergillus ustus 326,and Stachybotrys sp.1103 were used for the removal of humic substances from aqueous solutions.Batchwise biosorption,carried out at pH 6 and 25°C,was monitored spectrophotometrically and the process described with Freundlich’s model.Calculated sorption coeffcients Kf and n showed that A.niger exhibited the highest effciency.A good match between the model and experimental data and a high correlation coeffcient(R2)pointed out to judicious choice of ...
文摘Potentiometric experiments were carried out on the proton binding equilibria of FA extracted from a weathered coal and HA and Fa extracted from a dark loessial soil.The affinity spectrum model was employed to treat the experimental data.The affinity spectrum model technique could“magnify” the heterogeneity of the proton binding equilibria.so it was useful for comparing and studying the characteristics of humic substances with similar properties.According to the affinity spectra,we also found that the direction of the titration could affect the properties of the equilibria of FA from the weathered coal,and the acidic functional groups contained in FA from the weathered coal were larger in quantity than those contained in HA and FA from the dark loessial soil.
文摘The influence of humic substances (HS) formulations derived from sedimentary and compost sources was studied on plant growth at cell level and chlorophyll retention during accelerated senescence of leaf tissue. The direct effect of HS formulations was studied on cell expansion using cucumber and radish cotyledon expansion test. The cucumber hypocotyl elongation test was used to study the effect on cell elongation. Chlorophyll pigment retention in excised leaf tissue incubated in dark with high temperature was assessed to study the effect on leaf senescence. Explant tissues were incubated directly in the solutions of the formulations at the concentration recommended for foliar application to the crop plants. HS formulations showed significant variations in their direct bio-stimulatory effects. Formulations derived from compost sources were found superior in terms of inducing a direct stimulatory effect on cell expansion and cell elongation and in maintaining chlorophyll pigment retention during accelerated senescence. HS from sedimentary sources stimulated cell expansion and delayed chlorophyll degradation to a lesser extent compared to HS from compost. However, HS formulations derived from sedimentary sources used in this study were not effective in inducing cell elongation in the cucumber hypocotyl elongation test. The direct bio-stimulatory effect of HS formulations differed significantly between the formulations that were evaluated.
基金the Knowledge Foundation(KKS)for funding the project within the Enforce Research Project(No.20160019)。
文摘Perfluorooctane sulfonate(PFOS)is a persistent organic pollutant(POP)and emergent contaminant that are widespread in the environment.Understanding the mechanisms controlling the distribution of PFOS and its isomers between hydrargillite and the water phase is important in order to study their redistribution and mobility in the environment.This study investigated the effects of pH,humic acid,fulvic acid and Na_(2)SO_(4) on sorption of PFOS isomers to hydrargillite.A mixture of PFOS isomers was spiked into water and hydrargillite was added to the system and shaken for one day;the system was tested with different aqueous composition.Concentrations of PFOS isomers in the aqueous phase were quantified using an ultra-performance liquid chromatograph coupled to a triple quadrupole mass spectrometer.Our results showed that the distribution coefficients of PFOS isomers were found to be 0.76,0.71,0.93 and 0.90 at pH 6.5,for 3-/4-/5-PFOS,6-/2-PFOS,L-PFOS and total PFOS respectively.The distribution coefficients increased at lower pH and decreased at alkaline conditions.The presence of humic substances(HS)increased the sorption slightly at the environmental pH of 6.5,although a competition effect was observed during acidic conditions.A tendency of PFOS distribution to hydrargillite in the presence of Na_(2)SO_(4) was like its behavior in the presence of HS although the mechanisms behind the sorption were interpreted differently.This study revealed that L-PFOS was readily sorbed when no other chemicals were added or in 20 mg/L FA or 100 mg/L Na_(2)SO_(4).We suggest that an increase in PFOS sorption in the presence of HS may be due to hydrophobic mechanisms while Na_(2)SO_(4) contributed to increased sorption through ionic strength effects.
基金Project (No. 39790100) supported by the National Natural Science Foundation of China.
文摘X-ray photoelectron spectroscopy (XPS) was applied to examine the N structures of soil humic substances and some of their analogues. It was found that for soil humic substances XPS method gave similar results as those obtained by 15N CPMAS NMR (cross-polarization magic-angle spinning nuclear magnetic resonance) method. 70%～86% of total N in soil humic substances was in the form of amide, and 6%～13% was presented as amines, with the remaining part as heterocyclic N. There was no difference in the distribution of the forms of N between the humic substances from soils formed over hundreds or thousands of years and the newly formed ones. For fulvic acid from weathered coal and benzoqu inone- (N H-4 )-2 S O-4 polymer the XPS results deviated significantly from the 15N CPMAS NMR data.
基金Project(50725416) supported by the National Science Fund for Distinguished Young Scholars of ChinaProject(50804059) supported by the National Natural Science Foundation of China+1 种基金Project(200805331080) supported by Specialized Research Fund for the Doctoral Program of Higher Education of ChinaProject supported by the Graduate Degree Thesis Innovation Foundation of Central South University,China
文摘The structure characteristics and adhesive property of humic substance(HS) extracted with different methods were mainly studied by terms of elementary analysis,visible spectrum,FT-IR spectroscopy,viscosity,adsorption and pelletizing experiments.The results show that HSs extracted with new method(HS-a) own higher degree of aromatization and polymerization,larger relative molecular mass and more polar functional groups than HS extracted with usual method(HS-b).The viscosity of HS-b is about 30-40 mPa·s lower than that of HS-a.The maximum adsorption amounts of HS-a and HS-b onto iron concentrates are 9.11 mg/g and 8.08 mg/g,respectively.Meanwhile,HS-a has a better performance than HS-b in the practical application for pelletizing of iron concentrates.The difference in agglomeration behaviors with iron concentrates lies in the differences of the structure characteristics of HSs.With higher content of polar functional groups,larger relative molecular mass and viscosity of HSs,the agglomeration behavior is improved.
基金Under auspices of National Science Foundation of China
文摘Concentrations of dissolved humic substances in the rivers of eastern China were found to be 0.9- 14.4 mg/L with a median value of 4.6.The contents of dissolved humic substances in river water generally decrease from north to south,a trend similar to that of aquatic sediments and soils.Results of multiple regression analysis and path analysis showed that the dissolved stream humic substances are of a combined autochthonous and allochthonous origin.
文摘Surface-enhanced Raman Spectroscopy(SERS)has been used to characterize hurnic substances.By using HNO_3 -roughened silver foils as the enhancing surface,both fluorescence quenching and strong SERS signals have been observed at the same time.The results obtained herein show that SERS is a particularly sensitive and highly selective technique for the characterization of humic substances in the environment. Humic substances axe receiving ever-inereasing attention because of their importance in the environment. Very recently,we have reported the first successful application of Raman spectroscopy for characterizing humic substances.In this present paper,the application of surface-enhanced Raman spectroscopy(SERS)for humic substances has further been investigated.To our knowledge,no such studies have previously been reported.The results obtained herein dearly demonstrate that SERS has a great deal of promise as an analytical method for“In Situ”characterizing humic substances in the environment.
文摘This work evaluated the complexation capacity, exchange constants and availability of micronutrients for plants and humic substances extracted from peat samples. Samples of humic substances extracted from two tropical peats （HS-P1 and HS-P2） were enriched with the micronutrients Cu（II）, Co（II）, Fe（II）, Mn（II）, Ni（II） and Zn（II） and the parameters for formation of the complexes （HS-N） were evaluated at different pH. The Scatchard model was used to calculate the maximum complexation capacity and the nutrient availability was studied using exchange capacity experiments based on ultrafiltration procedure. The optimum pH for complexation was 4.5 and the order of affinity was： Fe（II） 〉 Cu（II） 〉 Co（II） 〉 Mn（II） = Ni（II） 〉 Zn（II）. The maximum complexation capacity reached 56.8 mg·g-1 Fe of HS-P1 （the highest） and 1.7 mg.g1 Zn of HS-P2 （the slightest）. The exchange experiments showed that HS-P-Fe complexes were formed preferentially. The least stable complex was formed with Zn, which was therefore, more easily available. The results contribute to understand the behavior and availability of some nutrients in soils.
文摘Quality of soil humic substances and compost quality was assessed using different techniques of fluorescence spectroscopy. Emission, excitation, synchronous and emission-excitation matrix help us to characterize different fluorophores in humic substances molecule. Content of stabile carbon forms in soil was assessed by humic substances fractionation. Content of labile water extractable carbon and nitrogen was determined by analyzer Shimadzu TOC-VCSH with chemo-luminescent detection in infrared spectral region. Results showed that compost amendment caused changes in both stabile （recalcitrant） and labile carbon content. Humic substances isolated from compost consist mainly of simple structural components of wide molecular heterogeneity and low molecular weight. Humification degree and content of conjugated fluorophores in compost was lower compared with stabile soil humic substances. The last contained more conjugated aromatic π-electron systems with electron-withdrawing functional groups, which are responsible for the fluorescence shift to lower energy levels or longer wavelengths.
