共查询到20条相似文献，搜索用时 15 毫秒
1.
土壤有机无机复合体的研究进展 总被引：19，自引：0，他引：19
对土壤有机无机复合体结构模型、有机无机复合体与团聚体的关系、有机无机复合体的肥力特征等方面的最新研究成果进行了综合评述。现代测试技术和计算机技术的应用为土壤有机无机复合体的研究提供了新的研究途径,发展形成了腐殖质胶体、有机无机复合体及有机质-异源生物物质复合体的结构模型,在纳米化学水平和三维分子结构模型上重新认识和阐明土壤有机无机复合体的结构和功能;有机无机复合体是土壤改良剂、营养源和重金属或有机有毒污染物过滤器;应在土壤科学、环境科学和生态学中,重视有机物质与矿物质相互作用和结构模型研究,加强土壤有机无机复合体环境化学行为和颗粒迁移动力学的研究。 相似文献
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Cherkasova Elena V. Konyshev Artem A. Soldatova Evgeniya A. Sidkina Evgeniya S. Mironenko Mikhail V. 《Aquatic Geochemistry》2021,27(2):141-158
Equilibrium-kinetic modeling allows investigating metal behavior in the water–rock-organic matter system with time to evaluate anthropogenic effects on the environment. In the article, the interactions of stagnant mine drainage water of the flooded mine “Arsenic” with ore and gangue minerals were simulated using different organic matter incorporation approaches. If the model is closed to humic substances (no additional organic matter input), most fulvic acids are bound in the Fe fulvate complex. While under the removal of Fe fulvate from the model, the Cu fulvate becomes prevalent, the contribution of the fulvate complexes with Zn, Mg, and Ca also increases. This scenario simulates the organo-mineral complexes behavior well and allows identifying the sequence of metal binding to organic ligands as follows Fe?>?Cu?>?Zn?>?Mg?>?Ca. The second scenario imitates the constant input of organic matter to the model (open system regarding humic substances). The dissolved metal concentrations in the model solution are extremely high in comparison to the mine drainage water. This scenario demonstrates that excessive input of organic matter leads to the accumulation of the metals in a dissolved form and blocks the secondary mineral formation despite the faster dissolution of the primary minerals under a more acidic pH than in the first scenario. However, despite the differences between the model solution and the mine drainage water, this scenario is useful to address specific issues associated with changes in natural and anthropogenic conditions. Both scenarios show the importance of organic matter incorporation to the equilibrium-kinetic models.
相似文献3.
红壤中矿物表面对腐殖质吸附萘的影响 总被引：5，自引：1，他引：5
矿物表面可改变土壤腐殖质对疏水性有机污染物的结合能力。采用红壤和高岭石分别与胡敏酸结合制备得到的两种复合体对萘的吸附等温线非线性显著,其n=0.76或0.74,并且有机碳归一化吸附分配系数的实验值Koacds是采用Kow计算得出的理论值Koc的5倍以上,表明红壤、高岭石均对腐殖质吸附萘有强化作用,且红壤较之高岭石对腐殖质吸附萘的影响稍强些。主要原因是,红壤中除了高岭石外,还有与腐殖质结合力很强的铁氧化物,而且很可能是吸附态腐殖质组成结构形态发生了有利于对萘吸附的改变。 相似文献
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Cross-linking of humic substances with organic bridging groups is thought to contribute to the humification of soil organic matter. Model cross-linked humic substances were prepared by cross-linking Amherst soil humic acid by a diepoxide and a polycarboxylic acid, applying procedures established for cross-linking of polymers and textile fabrics. Products of the cross-linking reactions were analyzed by FTIR and 13C CPMAS NMR. Physicochemical properties of the products were determined by solubility experiments and thermal analysis. The incorporation of the cross-linker into the matrix of the humic acid by covalent linkages was confirmed by both the disappearance of bands of the reactive functional groups of the cross-linker in the FTIR spectrum and the increase of signals related to the incorporation of the cross-linker into the matrix of the humic acid in the FTIR and 13C CPMAS NMR spectra. The formation of covalent ester and ether linkages by the cross-linking reaction was indicated. Water solubilities at pH 6.2 of the cross-linked samples as determined by UV/Vis spectrometry were reduced compared to controls. Fewer water molecule bridges were formed in the cross-linked samples, which was attributed to a lower number of available functional groups and increased distances between humic acid strands caused by the cross-linking molecules. Reduced reactivities of humic acid strands in the cross-linked samples further indicated successful cross-linking. The reactions investigated in this study can be regarded as models for reactions occurring in natural soils to test the significance of cross-linking reactions in the humification process of soil organic matter and the physico-chemical properties and ecological function of organic matter in geosolids. 相似文献
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本文以华南早第三纪含煤碎屑岩型铀矿床为例,研究了矿床表生带天然水中铀和有机质的关系。 А.И盖尔曼诺夫等人在研究干旱气候条件下层间氧化带型铀矿床时,曾提出在该矿床的舌状强氧化前锋,水强烈富集铀,以含铀有机化合物的形式出现,有机质中含铀48-86%,甚至达100%。而在还原带中,水中的铀以无机化合物形式为主,含铀68-81%。但该研究只限于水中有机质富集铀的数量,并未说明铀与有机质呈什么形式结合。另一些研究者又只考虑到有机质与UO22+结合的问题。众所周知,地下水是一个具有复杂组分的天然体系,UⅥ在该体系中可以有各种各样存在形式的机率:如UO2OH+、UO2(Co3)2(H2O)22-、UO2(C03)34-、UO2SO4、UO2(SO4)22-、UO2(S04)34-以及UO2Cl+等。因此，在研究天然水体系中溶解腐殖酸结合铀时，必须要考虑它结合的是什么形式的铀，才能合理地评价天然水中溶解有机质对铀的迁移富集作用。 相似文献
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东胜煤系砂岩型高岭土的富集机理 总被引：6，自引：0，他引：6
通过对东胜含煤地层成煤期沉积环境、古介质等的分析,并用有机吸附实验对高岭石与有机质的吸附关系进行了实验,探讨了东胜砂岩型高岭土的富集机理。结果表明,高岭石在河流环境中的富集成矿与水介质中大量有机质的存在有关,植物分解产生的腐殖质具有很强的吸附性,在pH值>5.5和适量的多价阳离子存在的条件下,介质水中的腐殖质可通过多价阳离子与高岭石和石英相互牢固吸附,形成高岭石-有机质-石英复合体,从而使高岭石能够与石英一起搬运、沉积;某些具有一定疏水性的有机质与矿物的吸附,改变了矿物颗粒表面的亲水性,促进了高岭石的沉积富集。 相似文献
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James A. Davis 《Geochimica et cosmochimica acta》1982,46(11):2381-2393
Natural organic matter is readily adsorbed by alumina and kaolinite in the pH range of natural waters. Adsorption occurs by complex formation between surface hydroxyls and the acidic functional groups of the organic matter. Oxides with relatively acidic surface hydroxyls, e.g. silica, do not react strongly with the organic matter. Under conditions typical for natural waters, almost complete surface coverage by adsorbed organic matter may be expected for alumina, hydrous iron oxides and the edge sites of aluminosilicates. Potentiometric titration and electrophoresis indicate that most of the acidic functional groups of the adsorbed organic matter are neutralized by protons from solution. The organic coating is expected to have a great influence on subsequent adsorption of inorganic cations and anions. 相似文献
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A review with 227 references of the title subject is presented. It is divided into two main sections, viz., nature and properties of humic matter, and water—metal—sediment interactions.The first section deals with the essential properties of organic matter which occurs naturally in drainage sediments and waters. Discussion of the basic molecular structure of humic and fulvic acids is followed by some details of the chemical nature of functional groups within these structures which are important in metal-ion adsorption and complexing reactions which these materials can undergo. Information is also presented for colloidal and polyelectrolyte properties, complexation properties, and finally a summary discussion of metal-ion—humic-acid, metal-ion—fulvic-acid stability constants for both single ligand and mixed ligand systems completes the section.The second section comprises discussions of some specific aspects of interactions between metals, sediments and waters, including metal and organic speciation studies; sorption interactions between organic matter, clays and humic acids; chemical reaction between humic acids, heavy-metal minerals, clays and other silicate minerals; metal-ion adsorption—desorption studies, oxidation—reduction reactions between metal ions and humic acids; effects of sulphide ion on some of the above interactions and finally a summary of some relevant field geochemical dispersion studies.This second section describes both laboratory and field studies for each aspect. 相似文献
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The role of organic ligands in metal complexing in natural waters has received little attention because of uncertainties regarding both the abundance and nature of dissolved organic carbon compounds. Recent data show that the bulk of dissolved organic matter in natural waters consists of highly oxidized and chemically and biologically stable polymeric compounds closely resembling soil humic substances. Average molar concentrations of these aquatic humics in major U.S. rivers range from 5 × 10?6to 3 × 10?5 moles 1?1. Fractional elution of soil organic matter by meteoric waters may be considered to be the main process contributing to the presence of humic matter in rivers. The aquatic humic polymers participate in complex formation through ionizable functional groups with a range of differential acidities. The stabilities of metal-humic complexes in natural waters are higher than those of the corresponding inorganic metal complexes. Quantitative evaluation of the metal-organic interactions can be approached by applying variable equilibrium functions which take into account the differential physico-chemical characteristics of the active complexing sites on the polymer molecule. Assuming an average humic concentration of 10 mg 1?1, complexation of trace metals can be significant even in the presence of excess concentrations of major cations. 相似文献
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The sequential extraction procedure was proposed and used to study of mercury speciation in real samples of soil. Samples
of soil profiles together with bedrock and coal were taken from sampling spots in the vicinity of surficial coal beds in an
area with natural coal outcrops. The proposed sequential extraction procedure involves the following fractionation: organic
mercury compounds, extractable mercury in an acidic medium, mercury bound to humic substances, elemental Hg and mercury bound
to complexes, HgS and residual mercury. The significant distribution of mercury between the two portions—mercury bound to
humic substance and HgS was determined in the majority of samples. The mercury bound to humic substances created a significant
contribution, especially to the top layer of soil. On the other hand, HgS was the dominant form in the samples from lower
layers of the soil profile. The mercury content in the samples did not show a distinct mobility. The influence of soil parameters
on the mercury distribution in the studied samples was investigated and discussed. 相似文献
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吉林西部土壤铁形态分布及其与土壤性质的关系研究 总被引：1，自引：0，他引：1
对吉林西部三个主要农牧区(洮南市、通榆县和乾安县)50个表层土样进行测试,探究其土壤铁形态分布及其与土壤性质的关系。研究结果表明,其土壤铁形态的含量分布为:残渣态铁(A)铁锰结合态铁(B)腐植酸结合态铁(C)碳酸盐态铁(D)强有机结合态铁(E)水溶态铁(F)离子交换态铁(G),主要以A形式存在,且全铁平均含量均低于中国铁元素背景值。A与阳离子交换量(CEC)呈极显著正相关,B与p H值呈极显著正相关,C、E与有机质呈极显著正相关。A与土壤矿质元素的关系最为密切,C、D、G次之。各形态铁之间,B、C、D两两呈极显著正相关,其他形态铁彼此间关系不大。 相似文献
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内蒙古西胡里吐盆地有机质特征及其与铀矿化的关系 总被引：7，自引：2，他引：7
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。 相似文献
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陆架边缘海是“河口—陆架”体系重要的碳汇,黏土矿物作为主要载体将有机质与金属元素吸附于表面或层间,通常表现为粒度、有机质和金属元素含量之间高度正相关。本文通过分析南黄海中部沉积物粒度、总有机碳、主微量元素,探讨三者之间分布特征和相互关系,进一步开展金属元素、有机质与黏土矿物吸附模拟实验,结果表明,酸性条件（pH=4）下适量的金属离子（Zn2+、Ni2+、Pb2+）明显促进伊利石对腐殖酸（有机质主要组成部分）吸附,腐殖酸吸附量达到20.06 mg/g,其中金属离子加入使腐殖酸吸附量提高6.25%;同时碱性条件（pH=8）下金属离子也能够促进伊利石对腐殖酸吸附,腐殖酸吸附量达到15.7 mg/g,金属离子加入使腐殖酸吸附量提高38.9%。金属离子的阳离子键桥作用促进伊利石吸附腐殖酸,且酸性环境下腐殖酸的吸附量高于碱性环境。证实了陆架边缘海背下金属元素的参与对黏土矿物吸附腐殖酸具有明显促进作用,有利于在全球碳循环过程形成边缘海“碳库”,同时海洋酸化可能造成海洋溶解有机质降低和重金属离子浓度升高,对陆架边缘海海洋生态系统平衡构成威胁。 相似文献
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砂岩铀矿成矿过程中有机质作用的实验研究--以吐鲁番-哈密盆地十红滩铀矿床为例 总被引：7，自引：2，他引：5
本文利用采自吐鲁番-哈密盆地西南部的样品,有针对性地做了一系列有机质抽提及分离实验,即①利用氯仿抽提岩石中有机质实验;②利用CS2-NmP(二硫化碳-N-甲基-2吡咯烷酮)抽提岩石中有机质实验;③腐殖质提取及分离实验。以上有机质抽提物及分离物分别做铀含量测试。通过实验发现,按以上实验顺序．岩石有机质提取物或分离物中铀含量依次有不同程度的提高,其中以腐殖质中分离出的黄腐酸(Fulvic acids)中铀含量最高,说明在吐哈盆地西南部砂岩铀矿的形成过程中有机质(主要是腐殖质和沥青质)的吸附作用起到部分作用．起最主要作用的是黄腐酸,而且与铀酰离子是以络合(或螯合)形式进行迁移。通过实验和分析,作者认为腐殖质(Humic substances)的络合作用和吸附作用在铀的迁移过程中是紧密相联的,而不是互相孤立的两种作用。在铀的迁移和沉淀富集过程中,黄腐酸(Fulvic acids)和腐殖酸(Humic acids)分别起到不同作用。 相似文献
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O. Yu. Drozdova N. A. Anokhina V. V. Demin S. A. Lapitskiy 《Moscow University Geology Bulletin》2018,73(5):467-471
The photodegradation of organo-mineral complexes in natural conditions was studied using samples of soil and swamp waters to study the effect of sunlight on the composition and properties of organic matter and metal forms dissolved in natural waters. The total contents of certain aliphatic and aromatic carboxylic acids increased in the samples after irradiation. Photodegradation of organic matter of the natural waters with the high Fe content is accompanied by the formation of colloidal particles (Fe hydroxides). The number of negatively-charged complexes of Ni, Cu, Zn, and Cd increased under insolation in swamp waters and decreased in soil waters. 相似文献
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淤泥富含大量有机质,受微生物作用,有机质会逐步分解出腐殖酸;同时,腐殖酸又会影响有机质降解,进而影响淤泥固化效果。为此,通过维持恒定的碱性缓冲溶液环境（pH=9.0）,将淤泥浸泡其中,观测其有机质含量的变化过程。结果表明,碱性缓冲溶液既能加快有机质分解,也能消耗腐殖酸,使溶液保持为碱性状态;当有机质分解完成,腐殖酸也释放结束,降解过程大约持续28 d。通过掺入水泥和石灰固化淤泥,发现含有机质的固化淤泥,其强度随养护时间会先增长后衰减,但预降解有机质的固化淤泥强度不会衰减。由此说明,通过碱性缓冲溶液预降解淤泥有机质,可以提升固化土耐久性。 相似文献
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Enhanced microbial reduction of Cr(VI) and U(VI) by different natural organic matter fractions 总被引：1，自引：0，他引：1
Although direct microbial reduction of Cr(VI) and U(VI) is known, few studies have examined the kinetics and the underlying mechanisms of the reduction of these contaminants by different natural organic matter (NOM) fractions in the presence or absence of microorganisms. In this study, NOM was found to chemically reduce Cr(VI) at pH 3, but the reduction rates were negligible at pH ∼7. The abiotic reduction of U(VI) by NOM was not observed, possibly because of the presence of small amounts of nitrate in the reactant solution. However, all NOM fractions, particularly the soil humic acid (HA), enhanced the bioreduction of Cr(VI) or U(VI) in the presence of Shewanella putrefaciens CN32. The reduction rates varied greatly among NOM fractions with different chemical and structural properties: the polyphenolic-rich NOM-PP fraction appeared to be the most reactive in abiotically reducing Cr(VI) at a low pH, but soil HA was more effective in mediating the microbial reduction of Cr(VI) and U(VI) under anaerobic, circumneutral pH conditions. These observations are attributed to an increased solubility and conformational changes of the soil HA with pH and, more importantly, its relatively high contents of polycondensed and conjugated aromatic organic moieties. An important implication of this study is that, depending on chemical and structural properties, different NOM components may play different roles in enhancing the bioreduction of Cr(VI) and U(VI) by microorganisms. Polycondensed aromatic humic materials may be particularly useful in mediating the bioreduction and rapid immobilization of these contaminant metals in soil. 相似文献