Effect of humic acids on numbers and activities of micro-organisms within physiological groups

The incorporation of humic acid fractions in media designed for the enumeration of soil micro-organisms belonging to specific physiological groups was found to result for some groups in appreciably higher counts. It is suggested that by influencing the enzyme systems of certain micro-organisms, humic compounds may affect the range of substrates which they can utilize. The effect could have implications on the activity of organisms in environments in which humic substances are normally present, such as soils and natural waters.     

内蒙古西胡里吐盆地有机质特征及其与铀矿化的关系

在砂岩型铀矿床中 ,有机质与铀矿化之间有着较为密切的关系。西胡里吐盆地的有机质主要是以松柏类和蕨类等高等植物残体为母质的腐殖型有机质。通过镜质体反射率、有机质碎屑的颜色、粘土矿物X 衍射和古地温恢复等分析测试发现 ,有机质的成熟度较低 ,处于未成熟—低成熟早期阶段。有机质的类型和成熟度决定了其在热演化中产生了大量腐殖酸并保存在地层中。褐煤、腐殖酸、残余植物碎屑和地沥青等是现存有机质的主要类型。除大量产出的煤层外 ,有机质主要呈碎屑状和细分散状分布于地层之中。 70 %的岩石中有机质的丰度在 0 1 %～ 3 % ,对铀矿化的形成较为有利。铀与有机质的紧密共生以及二者之间的正相关性 ,表明了有机质在西胡里吐盆地铀矿化形成中所起的重要作用。有机质中的腐殖酸与铀矿化的关系最为密切 ,有机粘土复合体、蚀变岩屑、植物碎屑和地沥青等吸附剂对铀的吸附均与腐殖酸有关。腐殖酸吸附铀后可以将铀还原 ,还可以与铀酰离子等进行络 (鳌 )合形成铀酰腐殖酸盐 ,并最终引起铀的沉淀富集。     

CPMAS 13C NMR spectra of estuarine sedimentary humic acids

CPMAS ¹³C NMR spectra of two estuarine sedimentary humic acids were recorded on a Bruker WP-SY 200 spectrometer. Both samples were found to contain similar aromatic and aliphatic carbon fractions. The sedimentary humic acids have unusually high methoxyl contents and more than one type of methoxyl is indicated. The high methoxyl content may be related to relatively low values for estuarine sedimentary humic acid-metal complexes. Carbohydrate contents of the humic acid samples were also found to be low.     

Direct observation of Cm(III)-fulvate species on fulvic acid-montmorillonite hybrid by laser-induced fluorescence spectroscopy

Particulate matter plays an important role in the removal of metal ions from water in natural aquifers. Some of the most important of these materials consist of associations of inorganic particles (clay minerals, oxides) with humic substances, associations that can form readily in such an environment due to the strong affinity between inorganic particles and humic substances. These associations are referred to in this paper as organic-inorganic hybrids. However, it is not clear whether the sorbed species of metal ions in such organic-inorganic hybrids are organic or inorganic species because of the complexity of such hybrids and the lack of appropriate methods for characterizing the trace metal ions incorporated in them. In this study, laser-induced fluorescence spectroscopy (LIF) was used successfully to characterize the Cm(III) species on an FA(fulvic acid)-montmorillonite hybrid, an example of such organic-inorganic hybrids. The LIF clearly showed that Cm(III) can be sorbed as Cm(III)-fulvate complex in the FA-montmorillonite hybrid. These results were consistent with those of experiments of solid-water partitioning of Cm(III) (or Eu(III) used as an analogue) and speciation calculations based on the stability constants of Cm(III)-fulvate complexes determined in this study. The results of LIF and the partitioning experiments showed that the solid-water distribution of humic substances governed that of Cm(III) under our experimental conditions. The Cm(III) preference for forming Cm(III)-fulvate complexes was also evident under a condition that would be found in a natural aquifer with a fairly low concentration of organic matter in freshwater (dissolved organic carbon: 2 mg/dm³), as determined by our speciation calculations. These findings on the importance of humic substances in the migration of Cm(III) indicate that the clarification of the environmental behavior of humic substances is necessary to understand fully the behavior of Cm(III), or actinide(III) and lanthanide(III) ions, in natural aquifers.     

Chemistry of metal–humic complexes contained in Megalopolis lignite and potential application in modern organomineral fertilization

Lignite samples from two deposits located in the Megalopolis Basin, Southern Greece, were evaluated for their potential applicability as raw materials for the production of organomineral fertilizers. Fundamental chemical analyses were carried out to demonstrate high humic substances and metal contents. To determine their relative distribution in the Megalopolis lignite extract, eight elements, namely Na, K, Cd, Mn, Mg, Pb, Zn, and Cu, were studied both in H₂O and in Na₄P₂O₇/NaOH solutions. The behavior of these metals showed significant variations; Zn, Pb, Cd, and Cu associate mostly to the humic substances and proved scarce in the water extract. Contrarily, K and Mg gave a significantly low total yield in the Na₄P₂O₇/NaOH solution, while Mn was classified among the least extracted elements. Further enrichment of Megalopolis humic substances in these metals was achieved; Pb and Mg proved the most and least retained metal, respectively. Decomplexation titration curves of humic matter saturated with these metal ions demonstrated that novel organomineral fertilizing materials may develop based on optimized metal ion and humate contents, which can retain metals in a soluble form within a wide pH range. Formation of complexes between humic substances and Zn, Cd, and Mg was clearly indicated.     

Characterisation of brown coal humic acids and modified humic acids using pyrolysis gcms and other techniques

It has been proposed that Victorian brown coal can be considered as a two-component structure — a lignocellulosic “host”, containing various amounts of weakly bound or entrapped “guest” material together with very small amounts of inorganic and/or mineral matter. The latter predominantly consists of wax esters and/or terpenoid material. In this paper we describe attempts to gain structural information regarding the more complex, “host” component of the coal. Our initial model compound has been humic acid that can be readily obtained from the coal by alkaline extraction. It has been found that “pure” humic acid, free from material associated with the “guest” components of the coal, can be obtained by a highly selective, low-yielding alkaline extraction. This humic acid has been studied by nmr spectroscopy and pyrolysis gas chromatography-mass spectroscopy (py-gc/ms). The products arising from py-gc/ms have been compared with those obtained from similar pyrolysis of whole coals. Alkylation of humic acids using alkyl halides in the presence of base has been successfully carried out and reactivity of the resulting materials compared with those of the parent coal and humic acid.     

Thermal characterization of natural and synthetic humic substances

Thermogravimetric technique was used for the characterization of natural (humic) and synthetic (melanoidins) substances. The influence of pH on the thermal stability of humic substances was studied. A similarity in thermal behaviour of natural humic substances and of melanoidins (prepared from an excess of sugar) and the unique thermal properties of melanoidins (prepared from basic amino acids) was observed. Thermal behavior of natural and synthetic substances was compared with model compounds of sugar, peptide and kerogen types.     

Oxygen-containing functional groups in land-derived humic acids—I. Evaluation by derivatization methods

Determinations of reactive oxygen-containing functional groups were performed by usual chemical derivatization methods of four humic acids isolated from soils and deltaic sediments. Statistical tests and calculations based on elemental analysis demonstrated the validity and limits of these techniques and allowed us to identify from 60 to 71% of the total humic oxygen. Oxygen budgets of humic acids are discussed.     

The coagulation,solubility and adsorption properties of Fe,Mn, Cu,Ni, Cd,Co and humic acids in a river water

River water (Water of Luce, Scotland) is used in laboratory experiments designed to investigate physical and chemical properties of Fe. Mn, Cu, Ni, Co, Cd and humic acids in riverine and estuarine systems. Using NaCl, MgCl₂ and CaCl₂ as coagulating agents, coagulation of dissolved (0.4 μm filtered) Fe, Cu, Ni, Cd and humic acids increases in a similar matter with increasing salt molarily: Ca²⁺ is the most dominant coagulating agent. Removal by coagulation with Ca²⁺ at seawater concentrations ranges from large (Fe-80%. HA-60%, Cu-40%) to small (Ni, Cd-15%) to essentially nothing (Cd, Mn-3%). Destabilization of colloids is the indicated mechanism. Solubility-pH measurements show that between a pH of 3 and 9, Fe, Cu, Ni, Mn, Co and Cd are being held in the dissolved phase by naturally occurring organic substances. Between pH of 2.2 and 1.2 a large proportion of dissolved Fe, Cu. Ni and Cd (72, 35,44 and 36% respectively) is precipitated along with the humic acids; in contrast, Mn and Co show little precipitation (3%). Adsorption-pH experiments, using unfiltered river water spiked with Cu, indicate that adsorption of Cu onto suspended particles is inhibited to a large extent by the formation of dissolved Cu-organic complexes.The experimental results demonstrate that solubilities and adsorption properties of certain trace metals in freshwaters can be opposite to those observed with artificial solutions or predicted with chemical models. Interaction with organic substances is a critical factor.     

Geochemistry of porewater and sulfate-reducing bacteria in sediment cores from the Chianan Plain, Taiwan

High concentrations of arsenic and humic substances in groundwater from the southwestern coastal plain of Taiwan were well known for their probable relationships with black-foot disease. In order to realize the relationships between the concentrations of humic substances and arsenic in this area, 24 well water samples were analyzed. After filtered through 0.45 μm glass fiber membrane in the field, samples were kept in the dark at 4℃ and then separated into six fractions with varying range of molecular weight （〈0.5, 0.5-1, 1-5, 5-10, 10-50 and 〉50 k Da） by ultrafiltration apparatus （Molecular/Por Stirred Cell system） in the lab. Concentrations of humic substances were measured by fluorescence spectrometer （HITACHI F-2000, ex=370, em=445） and arsenic by FIAS-AA （Perkin Elmer AAnalyst 100, FIAS-400）. On average, only 6.2% of the total arsenic in water existed in the fraction of 〉0.5 k Da. and the others were complexed with humic substances （including humic acid and fulvic acid）. The results demonstrated a distinct positive correlation between the concentrations of humic substances and arsenic.     

土壤腐殖质提取和分组综述

土壤腐殖质的定量提取、分离与纯化是深入研究土壤腐殖质的重要前提。本文详细综述了国内外腐殖质提取和分组的实验手段和研究进展;以国际腐殖质协会提供的标准方法为参考,对比论述了提取剂种类,提取次数、提取剂用量等的选择;对比讨论了两种主要的土壤腐殖质的分组方法。超滤分离和体积排阻色谱是腐殖质物理化学表征研究中的两种新兴技术,笔者认为组合使用两种实验手段对土壤腐殖质进行细致的分离与分组研究有助于深化理解土壤腐殖质的化学性质和分子结构。     

高岭石和硅／铝-氧化物对腐殖酸的吸附实验研究

矿物结合的腐殖质可改变矿物的表面性质,矿物对腐殖酸的吸附强度与矿物的吸附位性质、密度、荷电性及比表面积有关.若按比表面积计算,矿物对腐殖酸的吸附强度顺序为氢氧化铝>高岭石>石英;按单位质量计算,吸附强度顺序为高岭石>氢氧化铝>石英.研究表明,矿物表面活性受水溶液pH值的调控,且当pH值在4～7时,上述3种矿物对腐殖酸的吸附机理为石英主要表现为氢键作用;氢氧化铝主要表现为配体交换表面配位作用;高岭石表现为多种形式并存,包括氢键、配体交换表面配位和疏水性作用以及金属离子桥键作用.     

Pyrolysis-GC-MS and NMR studies of dissolved seawater humic substances and isolates of a marine diatom

¹³C- and ¹H-NMR spectra were obtained for humic substances isolated from a coastal marine environment and also for the intracellular and extracellular extracts of a marine diatom. Phaeodactylum tricornutum Bohlin. Highly branched alkyl chains constitute a large proportion of the structure of the marine humic material, whereas aromatic components are less important. Carbohydrate-type materials, possibly uronic acids, are also present in appreciable amounts. Furans (derived from carbohydrates). pyrroles and nitriles (derived from proteins, nucleic acids and/or tetrapyrroles) and phenols and methylphenols (non-lignin derived) are pyrolysis products derived from pyrolysis-gas chromatography-mass spectrometry of the extracts. The results indicate the similarities in chemical structure of P. tricornutum exudate and dissolved marine humic material.     

粘土矿物对胡敏酸的吸附行为研究

以蒙脱石和高岭土为吸附剂,分别与胡敏酸反应,研究胡敏酸在蒙脱石和高岭石上的吸附行为,并运用红外光谱、热重和Zeta电位等分析方法,表征分析了吸附前后的粘土矿物.实验结果表明,吸附过程受胡敏酸的初始浓度和pH值等因素影响;胡敏酸对粘土矿物的吸附等温线符合Freundlich等温方程;表征分析表明两种粘土矿物与胡敏酸复合体的红外光谱出现了C-H振动吸收峰;粘土矿物与胡敏酸结合后Zeta电位下降.实验的结果将有助于进一步探明环境中粘土矿物对胡敏酸的吸附机理.     

The formation, and clay mineral and CaCO3 association reactions of melanoidins

Melanoidin syntheses, which are carried out by preparing aqueous solutions of glucose and glycine, and glucose and alanine are examined with respect to variation of concentration of reactants, hydrogen ion concentration, molecular weights, functional groups and elemental compositions with increasing heating time at constant temperature (90°C). The experiments reveal that “melanoidins” consist of a mixture of fulvic acid-, humic acid- and kerogen-like polymers, with the initial formation of fulvic acid-, followed by humic acid- and kerogen-like polymers, but showing a period of coexistence of humic acid- and kerogen-like polymers. The kerogen-like polymers have elemental compositions similar to type II or II/III kerogens. The rate of melanoidin formation is much higher in the presence of montmorillonite. The CaCO₃ association reactions of the same experiments, however, show extremely low rates of melanoidin formation. Laboratory simulations seem to be consistent with the observation that carbonate sediments usually contain small amounts of kerogens compared with clayey sediments, both Recent and ancient.     

Effects of heat treatment on fluorescence properties of humic substances from sandy soil in arid land and their Hg(II) binding behaviors

The topsoil temperature in arid areas of Xinjiang, China can be up to about 80°C in summer. This may significantly affect the chemical properties of soil humic substances. However, the effects of high temperature on characteristics of soil humic substances and their complexation with toxic metals are still poorly known. In the present study, binding of Hg(II) to unheated soil humic substances and heated soil humic substances from sandy soils was comparatively investigated using three-dimensional excitation?Cemission matrix (EEM) fluorescence spectroscopy. Two fluorescent peaks (peak I at Ex/Em?=?365?C370/470?C474?nm; peak II at Ex/Em?=?270?C275/468?C472?nm) identified as humic-like fluorescence were observed in the EEM spectra of humic substances. Both peaks were clearly quenched by Hg(II), indicating the strong interaction of humic-like substances with Hg(II), and showed blue shifts after heat treatment. Heat treatment caused an increase of the fraction of accessible fluorophore (f _a), binding sites number (n) and effective quenching constants (logK _a), indicating that more binding sites in humic substances could bind Hg(II) and form more stable humic substances?CHg(II) complexes after heat treatment. However, a decrease of binding constants (logK _b) suggested that heat treatment would reduce the binding capacity of each binding site of humic substances to Hg(II). This study implies the transport of Hg(II) may be affected by high temperature in the arid zone due to the modification of the physicochemical properties of humic substances in soil.     

土壤和水体环境中矿物-腐殖质交互作用的研究进展

矿物-腐殖质间的交互作用是土壤和水体沉积物及悬浮颗粒物中环境物质的重要界面过程。不管是氮、磷植物性营养元素还是有毒的重金属、有机物，它们在表生环境中的迁移转化与归趋受到矿物、腐殖质及其复合体的表面活性和迁移性的调控。矿物-腐殖质体系的界面作用研究是前沿性的研究领域，主要目的是揭示矿物-腐殖质复合体的结构特性(例如颗粒物的圈层结构与表面微形貌)及其与颗粒物表面活性的关系，进而揭示土壤和水体环境中矿物-腐殖质间的交互作用规律。本文对该领域的研究现状进行评述，并提出未来可能的发展趋势。     

Organic carbon and cation associations in humic material from pond water and sediment

Organic matter was isolated from the water columns and sediments of two pond systems in the south-eastern United States. Water column material was ultrafiltered to provide three fractions, i.e. <0.45 μm, but > 50,000 daltons; <50,000 daltons, but > 5000 daltons; and <5000 daltons. Sedimentary organic matter was separated into humic acid and fulvic acid fractions based on solubility criteria and the humic acid fraction was ultrafiltered to provide the same fractions as the water column isolates. All fractions were analysed for organic carbon, Al, Ca, Cu, Fe, Mg and Mn. Infra-red spectra were also measured for the sedimentary organic fractions. Organic matter isolated from the water column of the two ponds had similar organic carbon and elemental distributions, as did the organic matter isolated from the two sediments. However, significant differences in the organic carbon and elemental distributions were observed for water column and sedimentary organic matter isolated from the same pond. These studies have relevance to diagenetic alterations of organic matter and geochemical cycles of elements within lakes.     

紫外/氯工艺对水中微囊藻毒素的去除

水体富营养化导致藻类的爆发进而引起藻毒素的释放。微囊藻毒素(MCLR)是最为常见的藻毒素,具有很强的毒性,对人类健康具有潜在危害。本文采用紫外/氯组合工艺,研究其对水中微囊藻毒素的控制效果。结果表明：紫外/氯共同作用下能够产生·Cl、·OH等活性自由基,具有协同降解MCLR的作用,30 min即可实现MCLR的完全去除,其降解效率随着氯投加质量浓度的增加而升高。在酸性及中性条件下,pH的变化对紫外/氯降解MCLR没有影响;在碱性条件下,MCLR的降解效率随pH的升高显著降低,pH升高至9时,30 min MCLR的降解效率仅为41.3%。此外,不同的水样来源和水质特点对紫外/氯联合降解MCLR的效率具有显著影响,纯水、西湖水及水厂滤后水的30 min去除率分别为99.5%,40.2%及63.3%。MCLR 的降解效率随腐殖酸质量浓度增大而降低,在60 min作用时间内,不含腐殖酸水样的MCLR去除率高达99.5%,当腐殖酸质量浓度增加到10 mg/L时,MCLR去除率仅为45.3%。     

Speciation Study of Cr in a Geochemical Reference Material Sediment Series Using Sequential Extraction and XANES Spectroscopy

Speciation of Cr in geochemical reference materials was characterised by sequential extraction and X‐ray absorption near‐edge structure (XANES) spectroscopy to identify Cr(III) resulting from the reduction of pollutant Cr(VI). Sequential extraction suggested that the amount of Cr associated with an acetic acid soluble fraction was low; Cr associated with a reducible phase and an oxidisable phase was extracted at 5–10% of the total Cr concentration, and the residual phase was found to be the dominant Cr‐containing fraction. Cr speciation in soil artificially doped with Cr(VI) and sediment samples collected from highly populated and industrialised areas was different from that in naturally occurring materials. Substantial Cr was extracted as a reducible phase (15–30%) and an oxidisable phase (30–60%) for these samples. Through subsequent XANES spectroscopy analysis, the reducible phase was explained by Cr bound to Fe hydroxide, while the oxidisable phase was a mixture of Cr bound to humic substances and Cr hydroxides. That is, Cr(VI) present as a contaminant in sediments and soils was reduced to Cr(III), which then bound to Fe hydroxide and humic substances, precipitating as a hydroxide. Thus, a combination of sequential extraction and XANES spectroscopy allows for effective identification and quantification of the chemical forms of Cr in sediments and soils.