Morphology and growth rate of carbon dioxide hydrate on the interface between liquid carbon dioxide and humic acid solutions were studied in this work.It was found that after the growth of the hydrate film at the inte...Morphology and growth rate of carbon dioxide hydrate on the interface between liquid carbon dioxide and humic acid solutions were studied in this work.It was found that after the growth of the hydrate film at the interface,further growth of hydrate due to the suction of water in the capillary system formed between the wall of the cuvette and the end boundary of the hydrate layer occurs.Most probably,substantial effects on the formation of this capillary system may be caused by variations in reactor wall properties,for example,hydrophobic-hydrophilic balance,roughness,etc.We found,that the rate of CO_(2) hydrate film growth on the surface of the humic acid aqueous solution is 4-fold to lower in comparison with the growth rate on the surface of pure water.We suppose that this is caused by the adsorption of humic acid associates on the surface of hydrate particles and,as a consequence,by the deceleration of the diffusion of dissolved carbon dioxide to the growing hydrate particle.展开更多
The main goal of the article is the creation and study of thermosensitive and wound-healing gelatin-alginate bio-polymer hydrogels modified with humic acids.Their rheological properties,swelling and contraction behavi...The main goal of the article is the creation and study of thermosensitive and wound-healing gelatin-alginate bio-polymer hydrogels modified with humic acids.Their rheological properties,swelling and contraction behavior were experimentally investigated,elucidated using Fourier transform infrared spectroscopy and used to achieve the physiological melting point,which is necessary for successful drug delivery.It has been shown that in the gelatin-alginate-humic acid biopolymer hydrogels systems,it is possible to obtain a gel-sol transition temperature close to the physiological temperature of 37℃,which is important for drug delivery in the treatment of wounds.By changing the type and concentration of humic acids in the gelatin-alginate hydrogel,it turned out to be achiev-able to regulate the softening time of the gel on the human body in the range from 6 to 20 min,which provides the possibility of controlled prolonged delivery of drugs.Based on the study of the influence of calcium ions on the properties of humic acids and ion exchange,as well as the interaction of humic acids,sodium alginate and gelatin with the formation of tighter gel networks,approaches to regulate the rate of softening of hydrogels at physiological temperature and their swelling,which simulates the absorption of exudate,were proposed and implemented.In addition,low shrinkage of the hydrogel surface due to cross-linking of gelatin-alginate networks when modified with humic acids was experimentally confirmed,which is important for avoiding problems of wound contracture and contour deformations when using dressings for wound healing.Thus,the developed opti-mized innovative biopolymer hydrogels synergistically combine the outstanding properties of natural molecular polymers and humic acids and are promising for the creation of effective medicines for wound healing.展开更多
Humic acids can promote the germination of many vegetable seeds,but the key active components remain unclear.This study utilized nutrient content,cross polarization magic angle spin ^(13)C solid magnetic resonance(CPM...Humic acids can promote the germination of many vegetable seeds,but the key active components remain unclear.This study utilized nutrient content,cross polarization magic angle spin ^(13)C solid magnetic resonance(CPMAS-^(13)C-NMR)and ultra-high performance liquid chromatography-mass spectrometry(UHPLC-MS)to characterize the chemical components of humic acids.Tomato seed germination index(GI)was determined with the goal of screening the key active components of humic acids.Humic acids had a significantly higher nutrient content,except for the total nitrogen(TN)and the total phosphorus(TP)contents.Humic acids had a higher content of O-CH_(3)/NCH,aromatic C-O and carbonyl C compared to weathered coal,with significantly lower anomeric C,aromatic C and O-alkyl C/alkyl C.There were 611 different compounds identified among the test materials using UHPLC-MS.Humic acids also had a significantly higher GI(158.0%and 153.1%)than weathered coal(85.5%).The organic matter(OM),TP and available potassium(AK)contents in humic acids were significantly positively correlated with GI,and available phosphorus(AP)was significantly negatively correlated.Among the carbon components,O-CH3/NCH,aromatic C-O and O-alkyl C/alkyl C were significantly positively correlated with GI,while anomeric C was significantly negatively correlated.Furthermore,among the top 10 positive and five negative correlation compounds,lipids and lipid-like molecules[armexifolin,boviquinone 4,3-methyladipic acid,lxocarpalactone A,monic acid,DG(20:1(11Z)/18:4(6Z,9Z,12Z,15Z)/0:0),and brassinolide]and organic acids and derivatives(N-acetylglutamic acid,8-hydroxy-5,6-octadienoic acid,acetyl-L-tyrosine,and hydroxyprolyl-methionine)in humic acids might be crucial active components for improving tomato seed germination.The results provided direct evidence for the identification of bioactive molecules of humic acids,and a scientific basis for the precise utilization of bioactive molecular components of humic acids in sustainable agricultural development.展开更多
The humic acids (HAs) isolated from the sediments of the various rivers,lakes,and reservoirs in China were studied using elemental analyzer,fourier transform infrared (FT-IR),and CP/MAS 13C nuclear magnetic resonance ...The humic acids (HAs) isolated from the sediments of the various rivers,lakes,and reservoirs in China were studied using elemental analyzer,fourier transform infrared (FT-IR),and CP/MAS 13C nuclear magnetic resonance (NMR) spectroscopy.The results showed that the HAs were characterized by some common chemical and physicochemical properties,but they also pose some differences in the C-containing functional groups.The C/N,C/H,O/C,and O/H ratios differ widely for the various HAs,showing that the elemental comp...展开更多
The adsorption capacities of new humic acids isolated from Yakouren forest （YHA） and Sahara （Tamenrasset： THA） soils （Algeria） and commercial humic acid （PFHA） on polyaniline emeraldine base （PEB） were stud...The adsorption capacities of new humic acids isolated from Yakouren forest （YHA） and Sahara （Tamenrasset： THA） soils （Algeria） and commercial humic acid （PFHA） on polyaniline emeraldine base （PEB） were studied at pH 6.6. Also the adsorption of heavy metals such as Cd 2＋ , Zn 2＋ and Ni 2＋ on humic acid-polyaniline systems （HA-PEB） was investigated at the same conditions. HA-PEB compounds were characterized by scanning electron microscopy （SEM）, infrared spectrometry and cavity microelectrode. In addition, batch adsorption and cavity microelectrode were used in the adsorption study of Cd 2＋ , Zn 2＋ and Ni 2＋ on HA-PEB. To develop biocaptors of polluting metals using a cavity microelectrode modified by HA-PEB systems, the adsorption kinetic and adsorption capacity were investigated. The SEM analysis showed that the presence of humic acid affected the PEB surface and caused the formation of a granular morphology. The maximum adsorption capacities （q max ） of PFHA, THA and YHA determined by adsorption isotherms were 91.31, 132.1 and 151.0 mg/g, respectively. Batch adsorption results showed that q max of Cd 2＋ , Zn 2＋ and Ni 2＋ on HA-PEB followed the order： THA-PEB YHA-PEB PFHA-PEB. The voltammograms obtained with HA-PEB modified cavity microelectrode showed the appearance of new redox couples reflecting the adsorption of HA on PEB. Metal-humic acid-polyaniline voltammograms were characterized by appearance of oxidation-reduction couples or reduction wave corresponding to metal. Finally, the result may be exploited to develop a biocaptor based on the cavity microelectrode amended by THA-PEB and YHA-PEB.展开更多
AIMTo test the effects of humic acids on innate microbial communities of the colon.METHODSWe followed the effects of oral supplementation with humic acids (Activomin<sup>®</sup>) on concentrati...AIMTo test the effects of humic acids on innate microbial communities of the colon.METHODSWe followed the effects of oral supplementation with humic acids (Activomin<sup>®</sup>) on concentrations and composition of colonic microbiome in 14 healthy volunteers for 45 d. 3 × 800 mg Activomin<sup>®</sup> were taken orally for 10 d followed by 3 × 400 mg for 35 d. Colonic microbiota were investigated using multicolor fluorescence in situ hybridization (FISH) of Carnoy fixated and paraffin embedded stool cylinders. Two stool samples were collected a week prior to therapy and one stool sample on days 10, 31 and 45. Forty-one FISH probes representing different bacterial groups were used.RESULTSThe sum concentration of colonic microbiota increased from 20% at day 10 to 30% by day 31 and remained stable until day 45 (32%) of humic acid supplementation (P < 0.001). The increase in the concentrations in each person was due to growth of preexisting groups. The individual microbial profile of the patients remained unchanged. Similarly, the bacterial diversity remained stable. Concentrations of 24 of the 35 substantial groups increased from 20% to 96%. Two bacterial groups detected with Bac303 (Bacteroides) and Myc657 (mycolic acid-containing Actinomycetes) FISH probes decreased (P > 0.05). The others remained unaffected. Bacterial groups with initially marginal concentrations (< 0.1 × 10<sup>9</sup>/mL) demonstrated no response to humic acids. The concentrations of pioneer groups of Bifidobacteriaceae, Enterobacteriaceae and Clostridium difficile increased but the observed differences were statistically not significant.CONCLUSIONHumic acids have a profound effect on healthy colonic microbiome and may be potentially interesting substances for the development of drugs that control the innate colonic microbiome.展开更多
Composting can enhance the nutrie nt ele ments cycling and reduce carbon dioxide production.However,little information is available regarding the application of compost for the remediation of the contaminated soil.In ...Composting can enhance the nutrie nt ele ments cycling and reduce carbon dioxide production.However,little information is available regarding the application of compost for the remediation of the contaminated soil.In this study,we assess the response of the redox capacities(electron accepting capacities(EAC)and electron donating capacities(EDC))of compost-derived humic acids(HAs)to the bioreduction of hexavalent chromium(Cr(Ⅵ)),especially in presence of hematite.The result showed that the compost-derived HAs played an important role in the bioreduction of Cr(Ⅵ)in presence and absence of hematite under the anoxic,neutral(pH 7)and motionless conditions.Based on the pseudo-first order kinetic model,the rate constants of Cr(Ⅵ)reduction increased by 1.36-2.0 times when compost-derived HAs was added.The redox capacity originating from the polysaccharide structure of compost-derived HAs made them effective in the direct Cr(Ⅵ)reduction(without MR-1)at pH 7.Meanwhile,the reduction rates were inversely proportional to the composting treatment time.When iron mineral(Fe_(2)O_(3))and compost-derived HAs were both present,the rate constants of Cr(Ⅵ)reduction increased by 2.35-5.09,which were higher than the rate of Cr(Ⅵ)reduction in HA-only systems,indicating that the hematite played a crucial role in the bioreduction process of Cr(Ⅵ).EAC and quinonoid structures played a major role in enhancing the bioreduction of Cr(Ⅵ)when iron mineral and compost-derived HAs coexisted in the system.The results can extend the application fields of compost and will provide a new insight for the remediation of Cr(Ⅵ)-contaminated soil.展开更多
Humic acids, especially FA in fractions, contain more oxygen functional groups. In this experiment, on the basis of confirming the action of humic acids on KBD, what was studied is the biological effects of one of mai...Humic acids, especially FA in fractions, contain more oxygen functional groups. In this experiment, on the basis of confirming the action of humic acids on KBD, what was studied is the biological effects of one of main oxygen functional groups, hydroxy group (-OH). The results indicate that inducing pathologic process of KBD, obviously decrease the GSH-Px activity and induce peroxidation membrane injury of tissue. The SOD activity increase in the tissues caused by oxygen functional groups showed that enhancing of free radical reaction should not be neglected.展开更多
[Objective] This study was conducted to obtain the optimal process for the preparation of biological humic acids （BHAs） from fermented furfural residue by al- kali-dissolution and acidification. [Method] BHAs were e...[Objective] This study was conducted to obtain the optimal process for the preparation of biological humic acids （BHAs） from fermented furfural residue by al- kali-dissolution and acidification. [Method] BHAs were extracted from fermented furfural residue by the alkali-dissolution and acidification method, to investigate the effects of solid-liquid ratio （mass ratio of fermented furfural residue to water）, alkali concentration, extraction temperature and extraction time on the extraction rate of BHAs by an orthogonal experiment, and then a solid BHA product was obtained by acidification of its extract followed by solid-liquid separation and oven-drying. [Result] The results showed that the optimal extracting conditions were as follows： solid-liquid ratio of 1：8, alkali concentration of 8% KOH, with extracting temperature at 70℃ and extracting time of 2.5 h in the alkali-dissolution step, and in the acidification step, the pH of the BHA mixture was 2.5. Under the optimal conditions, the content of solid BHAs was 76%, and the extraction rate of BHAs was 49%. [Conclusion] This study provides a theoretical basis for the separation and purification of BHAs from fermented furfural residue by the alkali dissolution and acidification method.展开更多
The research was done at Havana Biofabric, Mayabeque Province. The vitro plants of banana （Musa sp） used came from the clone Enano Guantanamero （viand type）. They come from multiplication phase in a Murashige and ...The research was done at Havana Biofabric, Mayabeque Province. The vitro plants of banana （Musa sp） used came from the clone Enano Guantanamero （viand type）. They come from multiplication phase in a Murashige and MS （Skoog medium）. The objective of this work was to study the potentialities of HA （humic acids） for stimulation of rooting and cell division process, searching for completely synthetic hormone substitution due to its high cost. The multiplication medium contained thiamine （2 mg·L^-1）, myo-inositol （100 mg·L^-1）, sugar （30mg·L^-1）. By the use of HA, five treatments were used with total substitution of auxin and cytokinin （TI： HA （10 mg.Ll）; （T2： HA （20 mg·L^-1）; （T3： HA （30mg·L^-1）; （T4： HA （40 mg·L^-1）; （T5： HA （50 mg·L^-1） and the control with 6BAP （benzil amino purine） （4 mg·L^-1） ＋ IBA （indol butyric acid） （0.65 mg·L^-1）, pH of the medium was adjust just before agar were add. The results showed that in the explants under HA treatments, elongation and cell multiplication were favored confirmed by explants great high, root number and length due to dry mass. The total protein content, reduced carbohydrate and peroxidases enzymatic activity were determine. The use of Vermicompost HA in the in vitro micropropagation of banana allow the elimination of rooting phase saving materials and be able to pass explants directly to Acclimatization phase.展开更多
[ Objective l The study aimed to discuss the optimal conditions of extracting humic acids from brown coal using hydrogen peroxide （H202）. [ Method] Fulvic acid （FA） was prepared through oxidizing the brown coal fr...[ Objective l The study aimed to discuss the optimal conditions of extracting humic acids from brown coal using hydrogen peroxide （H202）. [ Method] Fulvic acid （FA） was prepared through oxidizing the brown coal from Qujing City, Yunnan Province using H202, and humic acids were extracted from the original brown coal and its residues respectively, then the dominate constituents of humic acids were obtained by using pH grading method, finally their chemical composition of humid acids was characterized by Fourier transform infrared spectrometry and func- tional group content analysis. [Result] The mass ratio of the brown coal and oxidant affected the yield of FA most obviously, followed by oxidization temperature and duration, while oxidant concentration had no obvious effect. The optimum conditions were determined as follows： coal-oxidant ratio was 1 ： 0.60, oxidization temperature was 45 ℃, oxidization duration was 210 min, and the concentration of hydrogen peroxide was 20%. Under the conditions, the yield of FA was up to 20.40%. Analysis of component properties indicated that the content of carboxyl and total acidic groups in FA improved obviously under the optimum conditions, and the content of active functional groups in OHA was higher than that of HA, while the domi- nate constituents of OHA needed higher pH during precipitation compared with those of HA. [ Conclusion] The research could provide a new method to prepare good humic acids using brown coal,展开更多
Twenty-three progressive extractions were performed to study individual humic acids (HAs) and humin fractions from a typical black soil (Mollisol) in Heilongjiang Province, China using elemental analysis and spectrosc...Twenty-three progressive extractions were performed to study individual humic acids (HAs) and humin fractions from a typical black soil (Mollisol) in Heilongjiang Province, China using elemental analysis and spectroscopic techniques. After 23 HA extractions the residue was separated into high and low organic carbon humin fractions. HA yield was the highest for the first extraction and then gradually decreased with further extractions. Organic carbon (OC) of the humin fractions accounted for 58% of total OC …展开更多
Molecular weight（Mw） is a fundamental property of humic acids（HAs）, which considerably affect the mobility and speciation of heavy metals in the environment. In this study, soil humic acid（HA） extracted from Jin...Molecular weight（Mw） is a fundamental property of humic acids（HAs）, which considerably affect the mobility and speciation of heavy metals in the environment. In this study, soil humic acid（HA） extracted from Jinyun Mountain, Chongqing was ultra-filtered into four fractions according to the molecular weight, and their properties were characterized.Complexation of cadmium was investigated by titration experiments. For the first time,Langmuir and non-ideal competitive adsorption-Donna（NICA-Donnan） models combined with fluorescence excitation-emission matrix（EEM） quenching were employed to elucidate the binding characteristics of individual Mw fractions of HA. The results showed that the concentration of acidic functional groups decreased with increasing Mw, especially the phenolic groups. The humification degree and aliphaticity increased with increasing Mw as indicated by elemental composition analysis and FT-IR spectra. The binding capacity of Cd2＋ to Mw fractions of HA followed the order UF1（〈 5 kDa） 〉 UF2（5–10 kDa） 〉 UF4（〉 30 kDa） 〉 UF3（10–30 kDa）. Moreover, the distribution of cadmium speciation indicated that the phenolic groups were responsible for the variations in binding of Cd2＋ among different Mw fractions. The results of fluorescence quenching illustrated that the binding capacity of Cd2＋ to Mw fractions was controlled by the content of functional groups, while the binding affinity was largely influenced by structural factors. The results provide a better understanding of the roles that different HA Mw fractions play in heavy metal binding,which has important implications in the control of heavy metal migration and bio-toxicity.展开更多
Two humic acids （HAs） were isolated from contaminated river sediments present under comparative conditions in the Pearl River Basin, China. YFHA （the HA extracted at an open pyrite mining area in Yunfu） exhibited ...Two humic acids （HAs） were isolated from contaminated river sediments present under comparative conditions in the Pearl River Basin, China. YFHA （the HA extracted at an open pyrite mining area in Yunfu） exhibited a lower absorption intensity for certain bands in the Fourier transform infrared spectra, a lower E 4 /E 6 value （the UV absorbances at 465 nm （E 4 ） and 665 nm （E 6 ））, a lower apparent molecular weight, a lower polarity and a lower oxygen functionality in comparison with GZHA （the HA isolated at an urban living area in Guangzhou）. All these differences indicated a higher degree of humification of YFHA than GZHA. Overall, the enrichment patterns of permanent heavy metals in the studied HAs were similar to those in corresponding sediments. In particular, YFHA exhibited high enrichment of trace element Tl, a characteristic concomitant from the mining of the pyrite minerals. The adsorption isotherms of two HAs for goethite and pyrolusite, two representative geological materials, conformed to the Langmuir equation. Based on the qualitative relationships between the Langmuir constants of the adsorption isotherms and the chemical characteristics of HAs, the main mechanism of HA adsorption on these materials was suggested to be hydrophobic interaction. This study highlighted the promising use of HA as a peculiar bio-indicator of uncommon trace metal contaminations. The HA adsorption mechanism on representative geological materials further provided a theoretical basis for the study on the unusual metal behavior in complex environmental settings.展开更多
The adsorption of Cu（Ⅱ） from aqueous solution onto humic acid （HA） which was isolated from cattle manure （CHA）, peat （PHA）, and leaf litter （LHA） as a function of contact time, pH, ion strength, and initial...The adsorption of Cu（Ⅱ） from aqueous solution onto humic acid （HA） which was isolated from cattle manure （CHA）, peat （PHA）, and leaf litter （LHA） as a function of contact time, pH, ion strength, and initial concentration was studied using the batch method. X-ray absorption spectroscopy （XAS） was used to examine the coordination environment of the Cu（ll） adsorbed by HA at a molecular level. Moreover, the chemical compositions of the isolated HA were characterized by elemental analysis and solid-state 13C nuclear magnetic resonance spectroscopy （NMR）. The kinetic data showed that the adsorption equilibrium can be achieved within 8 h. The adsorption kinetics followed the pseudo-second-order equation. The adsorption isotherms could be well fitted by the Langmuir model, and the maximum adsorption capacities of Cu（ll） on CHA, PHA, and LHA were 229.4,210.4, and 197.7 mg g-1, respectively. The adsorption of Cu（Ⅱ） on HA increased with the increase in pH from 2 to 7, and maintained a high level at pH〉7. The adsorption of Cu（Ⅱ） was also strongly influenced by the low ionic strength of 0.01 to 0.2 mol L-1 NaNO3, but was weakly influenced by high ionic strength of 0.4 to 1 mol L-1 NaNO3. The Cu（Ⅱ） adsorption on HA may be mainly attributed to ion exchange and surface complexation. XAS results revealed that the binding site and oxidation state of Cu adsorbed on HA surface did not change at the initial Cu（Ⅱ） concentrations of 15 to 40 mg L 1. For all the Cu（Ⅱ） adsorption samples, each Cu atom was surrounded by 40/N atoms at a bond distance of 1.95 A in the first coordination shell. The presence of the higher Cu coordination shells proved that Cu（Ⅱ） was adsorbed via an inner-sphere covalent bond onto the HA surface. Among the three HA samples, the adsorption capacity and affinity of CHA for Cu（Ⅱ） was the greatest, followed by that of PHA and LHA. All the three HA samples exhibited similar types of elemental and functional groups, but different contents of elemental and functional groups. CHA contained larger proportions of methoxyl C, phenolic C and carbonyl C, and smaller proportions of alkyl C and carbohydrate C than PHA and LHA. The structural differences of the three HA samples are responsible for their distinct adsorption capacity and affinity toward Cu（Ⅱ）. These results are important to achieve better understanding of the behavior of Cu（Ⅱ） in soil and water bodies in the presence of organic materials.展开更多
The sorption behavior was determined for a model polycyclic aromatic hydrocarbon(PAH), i.e., phenanthrene(PHN), from water to three humic acids(HAs) and three sediments in different reacting time. The chemical composi...The sorption behavior was determined for a model polycyclic aromatic hydrocarbon(PAH), i.e., phenanthrene(PHN), from water to three humic acids(HAs) and three sediments in different reacting time. The chemical compositions of HA samples were measured using cross polarization magic angle spinning carbon 13(CPMAS 13 C NMR along with elemental analysis. The dissolved humic substances dissociating from solid HAs and sediments were characterized by 1 H NMR. The experiments indicated that the sorption modes and mechanisms of natural sorbents for PHN varied significantly between short(<7 d) and long contact time and the reaction time should be taken into consideration in studying the overall sorption process. The sorption capacity( K ′ f) and exponent( n ) might be relative to the properties of dissolved humic materials in initial stage but the solid aromatic organic matter after long time reaction. According to the experiments performed in this investigation and the previous researches, a conceptive sorption model was established.展开更多
The effect of a terrestrial humic acid （HA） and Suwannee River HA on the cytotoxicity of engineered zinc oxide nanoparticles （ZnONPs） and titanium dioxide nanoparticles （TiO2NPs） to natural aquatic bacterial ass...The effect of a terrestrial humic acid （HA） and Suwannee River HA on the cytotoxicity of engineered zinc oxide nanoparticles （ZnONPs） and titanium dioxide nanoparticles （TiO2NPs） to natural aquatic bacterial assemblages was measured with spread plate counting. The effect of HA （10 and 40 ppm） on the cytotoxicity of ZnONPs and TiO2NPs was tested factorially in the presence and absence of natural sunlight （light irradiation （LI））. The experiment was of full factorial, completely randomized design and the results were analyzed using the General Linear Model in SAS analytical software. The method of least squares means was used to separate the means or combinations of means. We determined the mechanism of toxicity via measurements of oxidative stress and metal ions. The toxicity of ZnONPs and TiO2NPs to natural aquatic bacterial assemblages appears to be concentration dependent. Moreover, the cytotoxicity of ZnONPs and TiO2NPs appeared to be affected by HA concentration, the presence of sunlight irradiation, and the dynamic multiple interactions among these factors. With respect to light versus darkness in the control group, the data indicate that bacterial viability was inhibited more in the light exposure than in the darkness exposure. The same was true in the HA treatment groups. With respect to terrestrial versus Suwanee River HA for a given nanoparticle, in light versus darkness, bacterial viability was more inhibited in the light treatment groups containing the terrestrial HA than in those containing Suwanee River HA. Differences in the extent of reactive oxygen species formation, adsorption/binding of ZnONPs/TiO2NPs by HA, and the levels of free metal ions were speculated to account for the observed cytotoxicity. TEM images indicate the attachment and binding of the tested nanoparticles to natural bacterial assemblages. Besides the individual parameter, significant effects on bacterial viability count were also observed in the following combined treatments： HA-ZnONPs, HA-LI, ZnONPs-LI, and HA-ZnONPs-LI. The main effects of all independent variables, plus interaction effects in all cases were significant with TiO2NPs.展开更多
The effect of application of pig manure (PM) on the structural characteristics of humic acids (HAs) of brown soil was studied in field and incubation experiments. The results showed that the number-average molecular w...The effect of application of pig manure (PM) on the structural characteristics of humic acids (HAs) of brown soil was studied in field and incubation experiments. The results showed that the number-average molecular weights (Mn), the ratios of C/ H, C/ N and O/C, the contents of carboxyl and phenolic hydroxyl groups, the content ofaromatic C, the values of E2, E4and λ Exmax of HAs all decreased; whereas, the contents of alkyl C and O-alkyl C, the ratio of carboxyl to phenolic hydroxyl groups, the degree of oxidation stability, the absorption intensity at 285 mμ (UV), and 2920cm-1 of HAs increased after the application of PM. The above results indicated that the molecular structure of HAs tended to be more aliphatic and simpler after the application of PM.展开更多
The adsorption and desorption characteristics of Al^3＋ to/from humic acids at different pH, ionic strength, and temperature were studied by the C-25 glucosan-gel chromatography method. The results showed that the max...The adsorption and desorption characteristics of Al^3＋ to/from humic acids at different pH, ionic strength, and temperature were studied by the C-25 glucosan-gel chromatography method. The results showed that the maximum adsorption amount （Qmax） and adsorption constant （k） increased, whereas, the absolute value of standard thermodynamic molar free energy change （ΔGm^0） decreased with the increase of pH at constant ionic strength and temperature. With ionic strength increasing from 0 to 0.15 mol/L, Qmax, and k increased and the absolute value of ΔGm^0 decreased at constant pH and temperature. High temperature was unfavorable for the adsorption reaction, as indicated by the dramatic decrease of Qmax and the absolute value of ΔGm^0 with an increase in temperature. The standard thermodynamic molar free energy change （ΔGm^0） and the standard thermodynamic enthalpy change （ΔHm^0） of the adsorption reaction were both negative, suggesting that adsorption reaction was spontaneous and exothermic. The desorption rate of HA-Al^3＋ complex accelerated with the decrease of pH, and a significant linear relationship could be obtained between pH and the desorption rates of Al^3＋ from humic acids. These results demonstrated that the Al^3＋ adsorption reaction was a ＂biphase＂ reaction, and adsorption occurred at both the interior and exterior adsorption sites of humic acids.展开更多
Bulblet development is a problem in global lily bulb production and carbohydrate metabolism is a crucial factor. Micropropagation acts as an efficient substitute for faster propagation and can provide a controllable c...Bulblet development is a problem in global lily bulb production and carbohydrate metabolism is a crucial factor. Micropropagation acts as an efficient substitute for faster propagation and can provide a controllable condition to explore bulb growth. The present study was conducted to investigate the effects of humic acid （HA） on bulblet swelling and the carbohydrate metabolic pathway in Li/ium Oriental Hybrids ＇Sorbonne＇ under in vitro conditions. HA greatly promoted bulblet growth at 0.2, 2.0, and 20.0 mg/L, and pronounced increases in bulblet sucrose, total soluble sugar, and starch content were observed for higher HA concentrations （_〉2.0 mg/L） within 45 d after transplanting （DAT）. The activities of three major starch synthetic enzymes （including adenosine 5＇-diphosphate glucose pyro- phosphorylase, granule-bound starch synthase, and soluble starch synthase） were enhanced dramatically after HA application especially low concentration HA （LHA）, indicating a quick response of starch metabolism. However, higher doses of HA also caused excessive aboveground biomass accumulation and inhibited root growth. Accordingly, an earlier carbon starvation emerged by observing evident starch degradation. Relative bulblet weight gradually decreased with increased HA doses and thereby broke the balance between the source and sink. A low HA concentration at 0.2 mg/L performed best in both root and bulblet growth. The number of roots and root length peaked at 14.5 and 5.75 cm respectively. The fresh bulblet weight and diameter reached 468 mg （2.9 times that under the control treatment） and 11.68 mm, respectively. Further, sucrose/starch utilization and conversion were accelerated and carbon famine was delayed as a result with an average relative bulblet weight of 80.09%. To our knowledge, this is the first HA application and mechanism research into starch metabolism in both in vitro and in vivo condition in bulbous crops.展开更多
基金supported by the Russian Science Foundation(23-29-00830).
文摘Morphology and growth rate of carbon dioxide hydrate on the interface between liquid carbon dioxide and humic acid solutions were studied in this work.It was found that after the growth of the hydrate film at the interface,further growth of hydrate due to the suction of water in the capillary system formed between the wall of the cuvette and the end boundary of the hydrate layer occurs.Most probably,substantial effects on the formation of this capillary system may be caused by variations in reactor wall properties,for example,hydrophobic-hydrophilic balance,roughness,etc.We found,that the rate of CO_(2) hydrate film growth on the surface of the humic acid aqueous solution is 4-fold to lower in comparison with the growth rate on the surface of pure water.We suppose that this is caused by the adsorption of humic acid associates on the surface of hydrate particles and,as a consequence,by the deceleration of the diffusion of dissolved carbon dioxide to the growing hydrate particle.
文摘The main goal of the article is the creation and study of thermosensitive and wound-healing gelatin-alginate bio-polymer hydrogels modified with humic acids.Their rheological properties,swelling and contraction behavior were experimentally investigated,elucidated using Fourier transform infrared spectroscopy and used to achieve the physiological melting point,which is necessary for successful drug delivery.It has been shown that in the gelatin-alginate-humic acid biopolymer hydrogels systems,it is possible to obtain a gel-sol transition temperature close to the physiological temperature of 37℃,which is important for drug delivery in the treatment of wounds.By changing the type and concentration of humic acids in the gelatin-alginate hydrogel,it turned out to be achiev-able to regulate the softening time of the gel on the human body in the range from 6 to 20 min,which provides the possibility of controlled prolonged delivery of drugs.Based on the study of the influence of calcium ions on the properties of humic acids and ion exchange,as well as the interaction of humic acids,sodium alginate and gelatin with the formation of tighter gel networks,approaches to regulate the rate of softening of hydrogels at physiological temperature and their swelling,which simulates the absorption of exudate,were proposed and implemented.In addition,low shrinkage of the hydrogel surface due to cross-linking of gelatin-alginate networks when modified with humic acids was experimentally confirmed,which is important for avoiding problems of wound contracture and contour deformations when using dressings for wound healing.Thus,the developed opti-mized innovative biopolymer hydrogels synergistically combine the outstanding properties of natural molecular polymers and humic acids and are promising for the creation of effective medicines for wound healing.
基金Supported by the National Natural Science Foundation of China(42207371)the Technological Project of Jiangsu Vocational College of Agriculture and Forestry(2021kj17)+1 种基金Yafu Technology Innovation and Service Major Project of Jiangsu Vocational College of Agriculture and Forestry(2024kj01)Key Research Projects of Jiangsu Vocational College of Agriculture and Forestry(2023kj14)。
文摘Humic acids can promote the germination of many vegetable seeds,but the key active components remain unclear.This study utilized nutrient content,cross polarization magic angle spin ^(13)C solid magnetic resonance(CPMAS-^(13)C-NMR)and ultra-high performance liquid chromatography-mass spectrometry(UHPLC-MS)to characterize the chemical components of humic acids.Tomato seed germination index(GI)was determined with the goal of screening the key active components of humic acids.Humic acids had a significantly higher nutrient content,except for the total nitrogen(TN)and the total phosphorus(TP)contents.Humic acids had a higher content of O-CH_(3)/NCH,aromatic C-O and carbonyl C compared to weathered coal,with significantly lower anomeric C,aromatic C and O-alkyl C/alkyl C.There were 611 different compounds identified among the test materials using UHPLC-MS.Humic acids also had a significantly higher GI(158.0%and 153.1%)than weathered coal(85.5%).The organic matter(OM),TP and available potassium(AK)contents in humic acids were significantly positively correlated with GI,and available phosphorus(AP)was significantly negatively correlated.Among the carbon components,O-CH3/NCH,aromatic C-O and O-alkyl C/alkyl C were significantly positively correlated with GI,while anomeric C was significantly negatively correlated.Furthermore,among the top 10 positive and five negative correlation compounds,lipids and lipid-like molecules[armexifolin,boviquinone 4,3-methyladipic acid,lxocarpalactone A,monic acid,DG(20:1(11Z)/18:4(6Z,9Z,12Z,15Z)/0:0),and brassinolide]and organic acids and derivatives(N-acetylglutamic acid,8-hydroxy-5,6-octadienoic acid,acetyl-L-tyrosine,and hydroxyprolyl-methionine)in humic acids might be crucial active components for improving tomato seed germination.The results provided direct evidence for the identification of bioactive molecules of humic acids,and a scientific basis for the precise utilization of bioactive molecular components of humic acids in sustainable agricultural development.
基金the National Basic Research Program (973) of China (No.2004CB418502,2003CB415002)the National Natural Science Foundation of China (No.29977002).
文摘The humic acids (HAs) isolated from the sediments of the various rivers,lakes,and reservoirs in China were studied using elemental analyzer,fourier transform infrared (FT-IR),and CP/MAS 13C nuclear magnetic resonance (NMR) spectroscopy.The results showed that the HAs were characterized by some common chemical and physicochemical properties,but they also pose some differences in the C-containing functional groups.The C/N,C/H,O/C,and O/H ratios differ widely for the various HAs,showing that the elemental comp...
文摘The adsorption capacities of new humic acids isolated from Yakouren forest （YHA） and Sahara （Tamenrasset： THA） soils （Algeria） and commercial humic acid （PFHA） on polyaniline emeraldine base （PEB） were studied at pH 6.6. Also the adsorption of heavy metals such as Cd 2＋ , Zn 2＋ and Ni 2＋ on humic acid-polyaniline systems （HA-PEB） was investigated at the same conditions. HA-PEB compounds were characterized by scanning electron microscopy （SEM）, infrared spectrometry and cavity microelectrode. In addition, batch adsorption and cavity microelectrode were used in the adsorption study of Cd 2＋ , Zn 2＋ and Ni 2＋ on HA-PEB. To develop biocaptors of polluting metals using a cavity microelectrode modified by HA-PEB systems, the adsorption kinetic and adsorption capacity were investigated. The SEM analysis showed that the presence of humic acid affected the PEB surface and caused the formation of a granular morphology. The maximum adsorption capacities （q max ） of PFHA, THA and YHA determined by adsorption isotherms were 91.31, 132.1 and 151.0 mg/g, respectively. Batch adsorption results showed that q max of Cd 2＋ , Zn 2＋ and Ni 2＋ on HA-PEB followed the order： THA-PEB YHA-PEB PFHA-PEB. The voltammograms obtained with HA-PEB modified cavity microelectrode showed the appearance of new redox couples reflecting the adsorption of HA on PEB. Metal-humic acid-polyaniline voltammograms were characterized by appearance of oxidation-reduction couples or reduction wave corresponding to metal. Finally, the result may be exploited to develop a biocaptor based on the cavity microelectrode amended by THA-PEB and YHA-PEB.
文摘AIMTo test the effects of humic acids on innate microbial communities of the colon.METHODSWe followed the effects of oral supplementation with humic acids (Activomin<sup>®</sup>) on concentrations and composition of colonic microbiome in 14 healthy volunteers for 45 d. 3 × 800 mg Activomin<sup>®</sup> were taken orally for 10 d followed by 3 × 400 mg for 35 d. Colonic microbiota were investigated using multicolor fluorescence in situ hybridization (FISH) of Carnoy fixated and paraffin embedded stool cylinders. Two stool samples were collected a week prior to therapy and one stool sample on days 10, 31 and 45. Forty-one FISH probes representing different bacterial groups were used.RESULTSThe sum concentration of colonic microbiota increased from 20% at day 10 to 30% by day 31 and remained stable until day 45 (32%) of humic acid supplementation (P < 0.001). The increase in the concentrations in each person was due to growth of preexisting groups. The individual microbial profile of the patients remained unchanged. Similarly, the bacterial diversity remained stable. Concentrations of 24 of the 35 substantial groups increased from 20% to 96%. Two bacterial groups detected with Bac303 (Bacteroides) and Myc657 (mycolic acid-containing Actinomycetes) FISH probes decreased (P > 0.05). The others remained unaffected. Bacterial groups with initially marginal concentrations (< 0.1 × 10<sup>9</sup>/mL) demonstrated no response to humic acids. The concentrations of pioneer groups of Bifidobacteriaceae, Enterobacteriaceae and Clostridium difficile increased but the observed differences were statistically not significant.CONCLUSIONHumic acids have a profound effect on healthy colonic microbiome and may be potentially interesting substances for the development of drugs that control the innate colonic microbiome.
基金the National Key Research and Development Program of China(No.2018YFC1800703)the National Water Pollution Control and Management Technology Major Project of China(No.2018ZX07110006)。
文摘Composting can enhance the nutrie nt ele ments cycling and reduce carbon dioxide production.However,little information is available regarding the application of compost for the remediation of the contaminated soil.In this study,we assess the response of the redox capacities(electron accepting capacities(EAC)and electron donating capacities(EDC))of compost-derived humic acids(HAs)to the bioreduction of hexavalent chromium(Cr(Ⅵ)),especially in presence of hematite.The result showed that the compost-derived HAs played an important role in the bioreduction of Cr(Ⅵ)in presence and absence of hematite under the anoxic,neutral(pH 7)and motionless conditions.Based on the pseudo-first order kinetic model,the rate constants of Cr(Ⅵ)reduction increased by 1.36-2.0 times when compost-derived HAs was added.The redox capacity originating from the polysaccharide structure of compost-derived HAs made them effective in the direct Cr(Ⅵ)reduction(without MR-1)at pH 7.Meanwhile,the reduction rates were inversely proportional to the composting treatment time.When iron mineral(Fe_(2)O_(3))and compost-derived HAs were both present,the rate constants of Cr(Ⅵ)reduction increased by 2.35-5.09,which were higher than the rate of Cr(Ⅵ)reduction in HA-only systems,indicating that the hematite played a crucial role in the bioreduction process of Cr(Ⅵ).EAC and quinonoid structures played a major role in enhancing the bioreduction of Cr(Ⅵ)when iron mineral and compost-derived HAs coexisted in the system.The results can extend the application fields of compost and will provide a new insight for the remediation of Cr(Ⅵ)-contaminated soil.
文摘Humic acids, especially FA in fractions, contain more oxygen functional groups. In this experiment, on the basis of confirming the action of humic acids on KBD, what was studied is the biological effects of one of main oxygen functional groups, hydroxy group (-OH). The results indicate that inducing pathologic process of KBD, obviously decrease the GSH-Px activity and induce peroxidation membrane injury of tissue. The SOD activity increase in the tissues caused by oxygen functional groups showed that enhancing of free radical reaction should not be neglected.
文摘[Objective] This study was conducted to obtain the optimal process for the preparation of biological humic acids （BHAs） from fermented furfural residue by al- kali-dissolution and acidification. [Method] BHAs were extracted from fermented furfural residue by the alkali-dissolution and acidification method, to investigate the effects of solid-liquid ratio （mass ratio of fermented furfural residue to water）, alkali concentration, extraction temperature and extraction time on the extraction rate of BHAs by an orthogonal experiment, and then a solid BHA product was obtained by acidification of its extract followed by solid-liquid separation and oven-drying. [Result] The results showed that the optimal extracting conditions were as follows： solid-liquid ratio of 1：8, alkali concentration of 8% KOH, with extracting temperature at 70℃ and extracting time of 2.5 h in the alkali-dissolution step, and in the acidification step, the pH of the BHA mixture was 2.5. Under the optimal conditions, the content of solid BHAs was 76%, and the extraction rate of BHAs was 49%. [Conclusion] This study provides a theoretical basis for the separation and purification of BHAs from fermented furfural residue by the alkali dissolution and acidification method.
文摘The research was done at Havana Biofabric, Mayabeque Province. The vitro plants of banana （Musa sp） used came from the clone Enano Guantanamero （viand type）. They come from multiplication phase in a Murashige and MS （Skoog medium）. The objective of this work was to study the potentialities of HA （humic acids） for stimulation of rooting and cell division process, searching for completely synthetic hormone substitution due to its high cost. The multiplication medium contained thiamine （2 mg·L^-1）, myo-inositol （100 mg·L^-1）, sugar （30mg·L^-1）. By the use of HA, five treatments were used with total substitution of auxin and cytokinin （TI： HA （10 mg.Ll）; （T2： HA （20 mg·L^-1）; （T3： HA （30mg·L^-1）; （T4： HA （40 mg·L^-1）; （T5： HA （50 mg·L^-1） and the control with 6BAP （benzil amino purine） （4 mg·L^-1） ＋ IBA （indol butyric acid） （0.65 mg·L^-1）, pH of the medium was adjust just before agar were add. The results showed that in the explants under HA treatments, elongation and cell multiplication were favored confirmed by explants great high, root number and length due to dry mass. The total protein content, reduced carbohydrate and peroxidases enzymatic activity were determine. The use of Vermicompost HA in the in vitro micropropagation of banana allow the elimination of rooting phase saving materials and be able to pass explants directly to Acclimatization phase.
基金Supported by Scientific Research Foundation of Educational Commission of Yunnan Province,China (08C0186)
文摘[ Objective l The study aimed to discuss the optimal conditions of extracting humic acids from brown coal using hydrogen peroxide （H202）. [ Method] Fulvic acid （FA） was prepared through oxidizing the brown coal from Qujing City, Yunnan Province using H202, and humic acids were extracted from the original brown coal and its residues respectively, then the dominate constituents of humic acids were obtained by using pH grading method, finally their chemical composition of humid acids was characterized by Fourier transform infrared spectrometry and func- tional group content analysis. [Result] The mass ratio of the brown coal and oxidant affected the yield of FA most obviously, followed by oxidization temperature and duration, while oxidant concentration had no obvious effect. The optimum conditions were determined as follows： coal-oxidant ratio was 1 ： 0.60, oxidization temperature was 45 ℃, oxidization duration was 210 min, and the concentration of hydrogen peroxide was 20%. Under the conditions, the yield of FA was up to 20.40%. Analysis of component properties indicated that the content of carboxyl and total acidic groups in FA improved obviously under the optimum conditions, and the content of active functional groups in OHA was higher than that of HA, while the domi- nate constituents of OHA needed higher pH during precipitation compared with those of HA. [ Conclusion] The research could provide a new method to prepare good humic acids using brown coal,
文摘Twenty-three progressive extractions were performed to study individual humic acids (HAs) and humin fractions from a typical black soil (Mollisol) in Heilongjiang Province, China using elemental analysis and spectroscopic techniques. After 23 HA extractions the residue was separated into high and low organic carbon humin fractions. HA yield was the highest for the first extraction and then gradually decreased with further extractions. Organic carbon (OC) of the humin fractions accounted for 58% of total OC …
基金supported by the National Natural Science Foundation of China(Nos.41771347 and 4177010514)
文摘Molecular weight（Mw） is a fundamental property of humic acids（HAs）, which considerably affect the mobility and speciation of heavy metals in the environment. In this study, soil humic acid（HA） extracted from Jinyun Mountain, Chongqing was ultra-filtered into four fractions according to the molecular weight, and their properties were characterized.Complexation of cadmium was investigated by titration experiments. For the first time,Langmuir and non-ideal competitive adsorption-Donna（NICA-Donnan） models combined with fluorescence excitation-emission matrix（EEM） quenching were employed to elucidate the binding characteristics of individual Mw fractions of HA. The results showed that the concentration of acidic functional groups decreased with increasing Mw, especially the phenolic groups. The humification degree and aliphaticity increased with increasing Mw as indicated by elemental composition analysis and FT-IR spectra. The binding capacity of Cd2＋ to Mw fractions of HA followed the order UF1（〈 5 kDa） 〉 UF2（5–10 kDa） 〉 UF4（〉 30 kDa） 〉 UF3（10–30 kDa）. Moreover, the distribution of cadmium speciation indicated that the phenolic groups were responsible for the variations in binding of Cd2＋ among different Mw fractions. The results of fluorescence quenching illustrated that the binding capacity of Cd2＋ to Mw fractions was controlled by the content of functional groups, while the binding affinity was largely influenced by structural factors. The results provide a better understanding of the roles that different HA Mw fractions play in heavy metal binding,which has important implications in the control of heavy metal migration and bio-toxicity.
基金supported by the United Foundation of National Natural Science Foundation of China and Guang-dong Provincial Government(No.U0633001)the National Natural Science Foundation of China(No.40930743)
文摘Two humic acids （HAs） were isolated from contaminated river sediments present under comparative conditions in the Pearl River Basin, China. YFHA （the HA extracted at an open pyrite mining area in Yunfu） exhibited a lower absorption intensity for certain bands in the Fourier transform infrared spectra, a lower E 4 /E 6 value （the UV absorbances at 465 nm （E 4 ） and 665 nm （E 6 ））, a lower apparent molecular weight, a lower polarity and a lower oxygen functionality in comparison with GZHA （the HA isolated at an urban living area in Guangzhou）. All these differences indicated a higher degree of humification of YFHA than GZHA. Overall, the enrichment patterns of permanent heavy metals in the studied HAs were similar to those in corresponding sediments. In particular, YFHA exhibited high enrichment of trace element Tl, a characteristic concomitant from the mining of the pyrite minerals. The adsorption isotherms of two HAs for goethite and pyrolusite, two representative geological materials, conformed to the Langmuir equation. Based on the qualitative relationships between the Langmuir constants of the adsorption isotherms and the chemical characteristics of HAs, the main mechanism of HA adsorption on these materials was suggested to be hydrophobic interaction. This study highlighted the promising use of HA as a peculiar bio-indicator of uncommon trace metal contaminations. The HA adsorption mechanism on representative geological materials further provided a theoretical basis for the study on the unusual metal behavior in complex environmental settings.
基金supported by the Key Technologies R&D Program of China (2013BAD07B02 and 2013BAC09B01)the Special Fund for Agro-Scientific Research in the Public Interest of China (201103003)+1 种基金the Postdoctoral Project of Jilin Province, China (01912)the Doctoral Initiative Foundation of Jilin Agricultural University, China (201216)
文摘The adsorption of Cu（Ⅱ） from aqueous solution onto humic acid （HA） which was isolated from cattle manure （CHA）, peat （PHA）, and leaf litter （LHA） as a function of contact time, pH, ion strength, and initial concentration was studied using the batch method. X-ray absorption spectroscopy （XAS） was used to examine the coordination environment of the Cu（ll） adsorbed by HA at a molecular level. Moreover, the chemical compositions of the isolated HA were characterized by elemental analysis and solid-state 13C nuclear magnetic resonance spectroscopy （NMR）. The kinetic data showed that the adsorption equilibrium can be achieved within 8 h. The adsorption kinetics followed the pseudo-second-order equation. The adsorption isotherms could be well fitted by the Langmuir model, and the maximum adsorption capacities of Cu（ll） on CHA, PHA, and LHA were 229.4,210.4, and 197.7 mg g-1, respectively. The adsorption of Cu（Ⅱ） on HA increased with the increase in pH from 2 to 7, and maintained a high level at pH〉7. The adsorption of Cu（Ⅱ） was also strongly influenced by the low ionic strength of 0.01 to 0.2 mol L-1 NaNO3, but was weakly influenced by high ionic strength of 0.4 to 1 mol L-1 NaNO3. The Cu（Ⅱ） adsorption on HA may be mainly attributed to ion exchange and surface complexation. XAS results revealed that the binding site and oxidation state of Cu adsorbed on HA surface did not change at the initial Cu（Ⅱ） concentrations of 15 to 40 mg L 1. For all the Cu（Ⅱ） adsorption samples, each Cu atom was surrounded by 40/N atoms at a bond distance of 1.95 A in the first coordination shell. The presence of the higher Cu coordination shells proved that Cu（Ⅱ） was adsorbed via an inner-sphere covalent bond onto the HA surface. Among the three HA samples, the adsorption capacity and affinity of CHA for Cu（Ⅱ） was the greatest, followed by that of PHA and LHA. All the three HA samples exhibited similar types of elemental and functional groups, but different contents of elemental and functional groups. CHA contained larger proportions of methoxyl C, phenolic C and carbonyl C, and smaller proportions of alkyl C and carbohydrate C than PHA and LHA. The structural differences of the three HA samples are responsible for their distinct adsorption capacity and affinity toward Cu（Ⅱ）. These results are important to achieve better understanding of the behavior of Cu（Ⅱ） in soil and water bodies in the presence of organic materials.
文摘The sorption behavior was determined for a model polycyclic aromatic hydrocarbon(PAH), i.e., phenanthrene(PHN), from water to three humic acids(HAs) and three sediments in different reacting time. The chemical compositions of HA samples were measured using cross polarization magic angle spinning carbon 13(CPMAS 13 C NMR along with elemental analysis. The dissolved humic substances dissociating from solid HAs and sediments were characterized by 1 H NMR. The experiments indicated that the sorption modes and mechanisms of natural sorbents for PHN varied significantly between short(<7 d) and long contact time and the reaction time should be taken into consideration in studying the overall sorption process. The sorption capacity( K ′ f) and exponent( n ) might be relative to the properties of dissolved humic materials in initial stage but the solid aromatic organic matter after long time reaction. According to the experiments performed in this investigation and the previous researches, a conceptive sorption model was established.
基金supported by NSF-SBIR grant # IIP-0823040NSF-CREST Program with grant # HRD-0833178Strengthening the Environmental Science Ph.D Program in instruction, grant # P031B090210-11
文摘The effect of a terrestrial humic acid （HA） and Suwannee River HA on the cytotoxicity of engineered zinc oxide nanoparticles （ZnONPs） and titanium dioxide nanoparticles （TiO2NPs） to natural aquatic bacterial assemblages was measured with spread plate counting. The effect of HA （10 and 40 ppm） on the cytotoxicity of ZnONPs and TiO2NPs was tested factorially in the presence and absence of natural sunlight （light irradiation （LI））. The experiment was of full factorial, completely randomized design and the results were analyzed using the General Linear Model in SAS analytical software. The method of least squares means was used to separate the means or combinations of means. We determined the mechanism of toxicity via measurements of oxidative stress and metal ions. The toxicity of ZnONPs and TiO2NPs to natural aquatic bacterial assemblages appears to be concentration dependent. Moreover, the cytotoxicity of ZnONPs and TiO2NPs appeared to be affected by HA concentration, the presence of sunlight irradiation, and the dynamic multiple interactions among these factors. With respect to light versus darkness in the control group, the data indicate that bacterial viability was inhibited more in the light exposure than in the darkness exposure. The same was true in the HA treatment groups. With respect to terrestrial versus Suwanee River HA for a given nanoparticle, in light versus darkness, bacterial viability was more inhibited in the light treatment groups containing the terrestrial HA than in those containing Suwanee River HA. Differences in the extent of reactive oxygen species formation, adsorption/binding of ZnONPs/TiO2NPs by HA, and the levels of free metal ions were speculated to account for the observed cytotoxicity. TEM images indicate the attachment and binding of the tested nanoparticles to natural bacterial assemblages. Besides the individual parameter, significant effects on bacterial viability count were also observed in the following combined treatments： HA-ZnONPs, HA-LI, ZnONPs-LI, and HA-ZnONPs-LI. The main effects of all independent variables, plus interaction effects in all cases were significant with TiO2NPs.
文摘The effect of application of pig manure (PM) on the structural characteristics of humic acids (HAs) of brown soil was studied in field and incubation experiments. The results showed that the number-average molecular weights (Mn), the ratios of C/ H, C/ N and O/C, the contents of carboxyl and phenolic hydroxyl groups, the content ofaromatic C, the values of E2, E4and λ Exmax of HAs all decreased; whereas, the contents of alkyl C and O-alkyl C, the ratio of carboxyl to phenolic hydroxyl groups, the degree of oxidation stability, the absorption intensity at 285 mμ (UV), and 2920cm-1 of HAs increased after the application of PM. The above results indicated that the molecular structure of HAs tended to be more aliphatic and simpler after the application of PM.
文摘The adsorption and desorption characteristics of Al^3＋ to/from humic acids at different pH, ionic strength, and temperature were studied by the C-25 glucosan-gel chromatography method. The results showed that the maximum adsorption amount （Qmax） and adsorption constant （k） increased, whereas, the absolute value of standard thermodynamic molar free energy change （ΔGm^0） decreased with the increase of pH at constant ionic strength and temperature. With ionic strength increasing from 0 to 0.15 mol/L, Qmax, and k increased and the absolute value of ΔGm^0 decreased at constant pH and temperature. High temperature was unfavorable for the adsorption reaction, as indicated by the dramatic decrease of Qmax and the absolute value of ΔGm^0 with an increase in temperature. The standard thermodynamic molar free energy change （ΔGm^0） and the standard thermodynamic enthalpy change （ΔHm^0） of the adsorption reaction were both negative, suggesting that adsorption reaction was spontaneous and exothermic. The desorption rate of HA-Al^3＋ complex accelerated with the decrease of pH, and a significant linear relationship could be obtained between pH and the desorption rates of Al^3＋ from humic acids. These results demonstrated that the Al^3＋ adsorption reaction was a ＂biphase＂ reaction, and adsorption occurred at both the interior and exterior adsorption sites of humic acids.
基金Project supported by the National High-Tech R&D Program(863) of China(No.2011AA100208)the Zhejiang Provincial Natural Science Foundation of China(No.LY12C15003)
文摘Bulblet development is a problem in global lily bulb production and carbohydrate metabolism is a crucial factor. Micropropagation acts as an efficient substitute for faster propagation and can provide a controllable condition to explore bulb growth. The present study was conducted to investigate the effects of humic acid （HA） on bulblet swelling and the carbohydrate metabolic pathway in Li/ium Oriental Hybrids ＇Sorbonne＇ under in vitro conditions. HA greatly promoted bulblet growth at 0.2, 2.0, and 20.0 mg/L, and pronounced increases in bulblet sucrose, total soluble sugar, and starch content were observed for higher HA concentrations （_〉2.0 mg/L） within 45 d after transplanting （DAT）. The activities of three major starch synthetic enzymes （including adenosine 5＇-diphosphate glucose pyro- phosphorylase, granule-bound starch synthase, and soluble starch synthase） were enhanced dramatically after HA application especially low concentration HA （LHA）, indicating a quick response of starch metabolism. However, higher doses of HA also caused excessive aboveground biomass accumulation and inhibited root growth. Accordingly, an earlier carbon starvation emerged by observing evident starch degradation. Relative bulblet weight gradually decreased with increased HA doses and thereby broke the balance between the source and sink. A low HA concentration at 0.2 mg/L performed best in both root and bulblet growth. The number of roots and root length peaked at 14.5 and 5.75 cm respectively. The fresh bulblet weight and diameter reached 468 mg （2.9 times that under the control treatment） and 11.68 mm, respectively. Further, sucrose/starch utilization and conversion were accelerated and carbon famine was delayed as a result with an average relative bulblet weight of 80.09%. To our knowledge, this is the first HA application and mechanism research into starch metabolism in both in vitro and in vivo condition in bulbous crops.
