共查询到19条相似文献，搜索用时 203 毫秒
1.
淡水文石珍珠可溶性有机质对CaCO3结晶的影响 总被引：1，自引：0，他引：1
以浙江诸暨淡水文石珍珠为实验原料,提取文石珍珠中的两种基质蛋白--酸可溶蛋白(ASM)和水可溶有蛋白(WSM),并分别将其制备成一系列不同浓度的基质蛋白溶液.利用上述两种不同浓度的可溶性有机基质溶液采用扩散法开展了碳酸钙的体外模拟矿化实验,探讨两种可溶性有机质的浓度在控制CaCO3结晶方面的作用.通过扫描电子显微镜及显微共聚焦拉曼光谱等方法对体外模拟矿化结果进行了观察和分析.结果表明,酸可溶蛋白对碳酸钙晶体的形貌和尺寸具有明显的调控作用,而对晶型无影响,不同浓度的酸可溶蛋白对碳酸钙晶体形貌影响差别不大,对尺寸的影响略有不同;水可溶蛋白对碳酸钙晶体的晶型、形貌及尺寸均有显著影响.不同浓度的水可溶蛋白对碳酸钙晶体的形貌和尺寸影响较大,对晶型有一定的调控作用. 相似文献
2.
在利用气体扩散法制取碳酸钙的过程中,样品的叠加摆放会导致不同层位的沉淀过程不同步进而增大实验误差。文章研究了样品在干燥器中摆放高度对实验结果的影响,并改进了收集沉淀物的方法。结果显示,随着摆放高度的增加,溶液pH值、电导率和沉淀物重量均呈规律性下降。培养皿之间的相互遮挡也会在一定程度上影响碳酸钙的矿化进程。少量沉淀物残留于培养皿上和/或溶液中是造成沉淀物收集不完全（或重量数据不准确）的主要原因。文章的实验结果对于利用气体扩散法研究碳酸钙仿生合成具有一定的借鉴意义。 相似文献
3.
非晶碳酸钙(amorphous calcium carbonate,ACC)是碳酸钙矿物体系中极不稳定的矿物相。但由海鞘类动物的研究表明,ACC可作为碳酸钙晶体矿物的前驱体在生物体内稳定存在,并且这些生物成因的ACC常常是由膜包裹着的。文中选用生物膜的主要成分卵磷脂(PC)为主要矿化调节剂,通过调控与碳酸钙矿化过程密切相关的无机离子Mg2+的浓度,模拟生物膜表面碳酸钙矿化作用过程。在空气/水界面处的膜脂调控下合成出可在溶液中稳定存在数天的非晶碳酸钙。该结果有力地证明了在生物矿化过程中,除了受生物体中可溶性有机大分子调控外,生物膜可能对ACC的形成和稳定也有显著的调控作用。 相似文献
4.
采用SEM、XRD、FT-IR等手段对氨基酸、多糖以及有机酸混合体系中形成的碳酸钙晶体进行了表征,进而比较了多组分有机质作用下碳酸钙的矿化现象。结果表明,氨基酸-单糖体系(A-M)促进了碳酸钙的沉积,其钙化速率相较于对照组提高了36%;有机酸则抑制了碳酸钙的沉积,单糖-有机酸体系(M-O)、氨基酸-有机酸体系(A-O)和氨基酸-有机酸-单糖体系(A-O-M)的钙化速率分别下降了33%、29%、17%。其次,A-M体系合成的晶体以方解石为主,包含少量的球霰石,M-O、A-O和A-O-M体系则在柠檬酸的调控下合成了方解石。最后,A-M体系合成了块状晶体(粒径为10μm)及中空的环状晶体(粒径为5μm),而A-O和M-O体系合成了棒状晶体(长轴径5～15μm,短轴径3～5μm)。A-O-M体系存在含量最高的有机质,导致成核速率高于生长速率,因此合成的晶体呈粒状(粒径1～3μm)且发育不完整。研究揭示了多组分共存体系中的生物矿化现象,阐明了柠檬酸在多组分体系中对晶体成核及生长的主导调控作用,对研究黄龙高寒环境下的生物矿化机制具有重要意义。 相似文献
5.
电气石是一种天然的硅酸盐矿物,具有自发极化效应,晶体表面存在静电场,在水处理领域具有广阔的应用前景。本研究利用碳酸钙沉积法考察电气石颗粒的阻垢性能,对投加不同粒径电气石颗粒后产生的碳酸钙钙垢的结构和微观形貌进行分析,探讨电气石颗粒对碳酸钙水溶液结晶性能的影响。实验结果表明,电气石颗粒具有一定的表面阻垢效果,能够降低碳酸钙在水溶液中的溶解度,促使溶液中碳酸钙形成并黏附在电气石颗粒表面,从而抑制碳酸钙钙垢黏附在换热固体表面,且电气石颗粒粒径越小,抑制效果越明显。XRD和SEM分析表明,电气石颗粒能够影响碳酸钙晶体的成核过程,改变碳酸钙的晶体形貌,形成附着性较差的文石型碳酸钙,达到阻垢效果。 相似文献
6.
生物矿化作用是指生物在生命活动中形成无机矿物的过程,它与传统地质意义上的矿化作用明显不同的是生物体内的有机质对矿物的晶型和晶向有严格的控制作用[1].碳酸钙是自然界分布最广泛的一类生物矿物.在生物体系中,碳酸钙常见的多型体有:方解石,文石,球文石,非晶质碳酸钙,水合碳酸钙等. 相似文献
7.
黄龙景区高寒冷水型钙华沉积地貌环境中生存着大量的嗜冷微生物。为了探究这些微生物在低温及高浓度Ca~(2+)和HCO_3~-水环境中的代谢产物对钙华沉积的影响,本实验选取黄龙嗜冷细菌的两种特征代谢产物L-苯丙氨酸和L-半胱氨酸,通过模拟低温、含较高浓度的Ca~(2+)和HCO_3~-的实验环境,并利用X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FT-IR)、扫描电子显微镜(SEM)等分析方法,来探讨氨基酸对矿化体系中碳酸钙沉积速率及其晶型和形貌的影响。实验结果表明:在特定模拟环境条件下,(1)L-苯丙氨酸和L-半胱氨酸均能促进碳酸钙的沉积。L-苯丙氨酸对晶型影响不大,产物均为方解石型碳酸钙,但是L-苯丙氨酸能抑制方解石晶面棱边的生长,使得晶体出现多面不规则的立方体形态;(2)L-半胱氨酸除诱导并促进方解石型碳酸钙的合成外还可以诱导文石型碳酸钙的合成。该结果可为黄龙地区钙华的生物成因研究提供一定的基础数据。 相似文献
8.
脲酶诱导碳酸钙沉淀（EICP）是岩土工程古迹和土遗址加固领域具有广阔发展前景的前沿技术。然而,关于脲酶矿化作用机制的研究鲜有报道。以试管试验模拟脲酶矿化过程,研究不同底物浓度、不同镁离子浓度、不同铵根离子浓度对脲酶矿化过程中电导率、酸碱度、碳酸钙沉淀量及沉淀率变化的影响规律,从而揭示脲酶矿化强化及劣化机制,并对个别机制作用下的砖瓦试件进行吸水率、透气率及风蚀试验。结果表明：随着底物浓度的升高,电导率逐渐升高但曲线演变趋势基本不变,pH值变化不显著,沉淀量先升高再降低,沉淀率逐渐降低,其中脲素水解速率和脲酶活性是碳酸根的转化及提高沉淀量和沉淀率的关键;随着氯化镁浓度的升高,沉淀量先增加后降低,沉淀效率逐渐升高,除了生成碳酸钙外,还生成碳酸镁,镁离子在提高脲酶活性从而形成最优矿化效果上具有积极作用;随着氯化铵浓度的增加,电导率逐渐升高,p H值逐渐降低,铵根是导致脲酶活性、沉淀量及沉淀效率劣化的主要原因。吸水率、透气率及抗风蚀性能试验结果突出脲酶诱导碳酸钙沉淀技术用于古迹建筑保护的可行性,为将来实际应用和技术拓展提供数据和理论支持。 相似文献
9.
生物成因矿物的形成过程通常是通过先沉积非晶前驱体,进而转变形成某一种结晶相的途径来实现的。对生物成因
碳酸钙而言,普遍认为其非晶的前驱体相是在生物有机大分子和无机离子共同作用下形成的。在阴离子柠檬酸根存在的情
况下,仿生合成了非晶碳酸钙（Amorphous calcium carbonate,ACC）,运用场发射扫描电子显微镜（FESEM）、X-射线衍射（XRD）、
傅里叶红外光谱（FTIR）和热重-差热分析（TG-DTA）等实验手段进行了分析并观测了非晶碳酸钙后续转变。结果显示,
多羧基的阴离子能够诱导形成非晶碳酸钙,并且这些非晶碳酸钙具有与生物成因非晶碳酸钙类似的组成。这可能指示与生
物矿化相关的生物大分子,特别是一些富含极性羧基大分子能够诱导碳酸钙矿物非晶态前驱体相的形成,同时也能暂时稳
定这些非晶前驱体相。 相似文献
10.
江西冷水斑岩型银铅锌矿床矿化特征 总被引：1，自引：0，他引：1
本文阐述冷水斑岩型银铅锌矿床的不同矿化过程和矿化分带的原因。对不同矿化过程中的主要硫化物及矿物组合进行标型特征和成因方面的研究,并以物理化学原理为基础,进行推导和计算,得出成矿的物理化学条件和成矿溶液的演化规律. 相似文献
11.
Interaction of organic compounds with calcium carbonate—III. Amino acid composition of sorbed layers
Nitrogenous organic compounds in sorbed surface layers and in calcified organic matter associated with calcium carbonate sediment particles consist of 40–50% amino acids, 2% amino sugars and 25% ammonia. In grain size classes > 20 μm these compounds are mainly contained in the calcified protein of carbonate secreting organisms but with smaller grain sizes—and consequently increased specific surface area—they are contained in sorbed layers at the mineral surface. The composition of the sorbed layer is characterized by a predominance of neutral amino acids, a relative enrichment of basic and weakly polar amino acids, and a deficiency of acidic amino acids in comparison with the proteinaceous matter of calcifying organisms. The respective abundances for sorbed and calcified matter are: 505 and 380 Res./ of neutral amino acids, 262 and 450 Res./1000 of acidic amino acids, 92 and 51 Res./l000 of basic amino acids, and 141 and 129 Res./1000 of weakly polar amino acids.The composition of the sorbed layer appears to be the result of sorption of proteinaceous matter from solution since it reflects the free and peptide-bound amino acid composition of seawater. The characteristic amino acid assemblage could also be the result of preferential decomposition of protein and subsequent enrichment of neutral and basic amino acids; however, sorption from solution appears more likely since the total amount of amino acids sorbed to calcium carbonate (0.58 mg m ?2) corresponds closely to the amount of protein known to cover one m2 of aqueous substrate in monolayer arrangement. Sorption from solution is further supported by the low arginine/ornithine ratios in both the sorbed layer and the natural dissolved organic matter. This process might lead to a characteristic amino acid spectrum in fine grained calcareous sediments that reflects the composition of the dissolved organic matter in seawater rather than that of the carbonate secreting proteinaceous matter. 相似文献
12.
13.
A. Rivadeneyra Torres M. V. Martinez-Toledo A. Gonzalez-Martinez J. Gonzalez-Lopez D. Martín-Ramos M. A. Rivadeneyra 《International Journal of Environmental Science and Technology》2013,10(1):141-150
This research studied the precipitation of calcium carbonate by populations of bacteria from domestic wastewater cultivated in both natural and artificial solid culture media. The only carbonate-forming bacteria detected appeared in an artificial medium added with calcium acetate. Precipitation occurred three days after inoculation, and the percentage was slightly higher than 65 %. Our results showed that nine major carbonate-forming colony types were the dominant heterotrophic platable bacteria growing aerobically in artificial media added with calcium acetate. According to their taxonomic affiliations (based on partial sequencing of the 16S-rRNA), the nine strains belonged to the following nine genera of Gram-negative and Gram-positive bacteria: Caulobacter, Blastomonas, Roseobacter, Staphylococcus, Bacillus, Gemmatimonas, Saccharopolyspora, Microthrix, and Sphingomonas. All of these strains formed calcium carbonate, precipitated as calcite and vaterite in different proportions and shapes (spheres, hemispheres, dumbbells, and pseudopolyhedral forms). The results of this study suggest that in real domestic wastewater, the precipitation of carbonates through bacterial action could not take place in situ because the concentrations of calcium did not create the optimal circumstances for biomineralization. However, in the artificial media, it was possible to induce this process by adding calcium ions. 相似文献
14.
许多生物矿化作用过程都与其不寻常的膜的组成和结构密切相关。作为双亲分子的磷脂,是生物膜的重要组成成分之一。运用以粉末X-射线衍射、扫描电子显微镜和动态光散射技术等实验手段,研究了卵磷脂(PC)和双甘氨肽参与下的碳酸钙矿化过程。结果表明,PC在溶液中形成的脂质体结构,导致了方解石(calcite)表面多孔结构的形成,且其含量的改变,可有效地调控方解石表面孔隙的孔径大小,并在一定程度上促进球霰石(vaterite)的生长和稳定;而PC在溶液表面形成的膜脂层,则通过静电力与双甘氨肽相互作用,有效调控膜脂层下矿物的形成。 相似文献
15.
活性炭固定微生物固化贵阳红黏土力学特性 总被引：2，自引：0，他引：2
微生物能够固化土体,但是在固化强度上还有待提高。为了增强微生物固化土体的力学特性,文章提出固定化微生物技术与微生物诱导碳酸钙沉淀技术（MICP）相结合的方法,即将掺量为0、4%、7%、10%、15%的活性炭与重塑红黏土均匀混合后,再通过MICP固化土体后进行常规三轴压缩试验,同时进行相同条件下在菌液瓶中有无胶结液与活性炭的生成碳酸钙的对比试验、有无活性炭重塑红黏土的常规三轴压缩对比试验。通过扫描电镜分析,得到试样的力学特性、活性炭在MICP过程中的作用、微观结构等试验结果。试验结果表明:在微生物固化土体过程中,活性炭作为固定微生物的载体,在MICP过程中对微生物起到“增效”的作用,在微生物诱导碳酸钙沉淀过程中提高了碳酸钙产量;同时,活性炭的有无及含量多少对微生物固化土体有重要影响,结合水膜厚度改变、碳酸钙填充孔隙及胶结作用使得红黏土抗剪强度有效C值大幅增加,有效φ值减小,剪应力峰值增加;加入活性炭使生物矿化环境得到优化,并在碳酸钙结晶时对晶体结构、形态产生了一定的控制作用,生成了以活性炭为“核心”具有一定结构的块体,而使土体的力学特性增强。该研究成果对微生物岩土技术以及工程应用具有重要价值。 相似文献
16.
Mollusc and brachiopod skeletal hard parts: Intricate archives of their marine environment 
下载免费PDF全文
下载免费PDF全文 The biogenic carbonate hard parts of fossil bivalves, cephalopods and brachiopods are among the most widely exploited marine archives of Phanerozoic environmental and climate dynamics research. The advent of novel analytical tools has led many workers to explore non‐traditional geochemical and petrographic proxies, and work performed in neighbouring disciplines sheds light on the complex biomineralization strategies applied by these organisms. These considerations form a strong motivation to review the potential and problems related to the compilation and interpretation of proxy data from bivalve, cephalopod and brachiopod hard parts from the viewpoint of the sedimentologist and palaeoceanographer. Specific focus is on the complex biomineralization pathways of a given dissolved ion or food particle from its aquatic environment via the digestion and biomineralization apparatus in molluscs and brachiopods and its incorporation into a biomineral. Given that molluscs and brachiopods do not secrete their hard parts from seawater but rather from their mantle and periostracum, this paper evaluates differences and similarities of seawater versus that of body fluids. Cephalopods, bivalves and brachiopods exert a strong biological control on biomineralization that, to some degree, may buffer their shell geochemistry against secular changes in seawater chemistry. Disordered (amorphous) calcium carbonate precursor phases, later transformed to crystalline biominerals, may be significant in carbonate archive research due to expected geochemical offset relative to the direct precipitation of stable phases. A reasonable level of understanding of the related mechanisms is thus crucial for those who use these skeletal hard parts as archives of the palaeo‐environment. The impact of what is commonly referred to as ‘biological factors’ on the geochemistry of mollusc and brachiopod hard parts is explored for conventional isotope systems such as carbon, oxygen, strontium and traditionally used element to calcium ratios. In particular, the often used δ13Ccarb or the Mg/Ca and Sr/Ca elemental proxies are fraught with problems. An interesting new research field represents the analysis, calibration and application of non‐traditional proxies to mollusc and brachiopod hard parts. Examples include the carbonate clumped isotope (Δ47) approach and the analysis of the isotopes of Ca, Mg, N, Li, S or element to Ca ratios such as Li/Ca or B/Ca and rare earth elements. Based on considerations discussed here, a series of “do's and don'ts” in mollusc and brachiopod archive research are proposed and suggestions for future work are presented. In essence, the suggestions proposed here include experimental work (also field experiments) making use of recent archive organisms or, where possible, a reasonable recent analogue in the case of extinct groups. Moreover, the detailed understanding of the architecture of mollusc and brachiopod hard parts and their ultra‐structures must guide sampling strategies for geochemical analyses. Where feasible, a detailed understanding of the diagenetic pathways and the application of multi‐proxy and multi‐archive approaches should form the foundation of fossil carbonate archive research. The uncritical compilation of large data sets from various carbonate‐shelled organisms collected at different locations is not encouraged. 相似文献
17.
This study demonstrates that intracrystalline organic matter in coral skeletons is well preserved over century timescales. The extent of preservation of organic matter in coral skeletons was investigated by measuring total organic carbon (TOC), total hydrolyzable amino acid (THAA), chloropigment, and lipid concentrations in 0-300 year old annual growth bands from Montastraea annularis (Florida Keys) and Porites lutea (Red Sea). Organic matter intrinsic to the calcium carbonate mineral (intracrystalline) was analyzed separately from total skeletal organic matter. The Red Sea coral had less TOC (0.02-0.04 wt%) than the Florida Keys coral (0.04-0.11 wt%), but a higher percent of intracrystalline organic matter in all annual bands measured. Carbon in the form of THAA, most likely from mineral-precipitating proteins, contributed 30-45% of the TOC in both corals. Carbon in lipids represented about 3% of the TOC in the coral skeletons. Chlorophyll-a and b were present in annual bands where endolithic algae were present, but these compounds were minor contributors to TOC. The distribution of specific organic compounds showed that organic matter was well preserved throughout the time period sampled in both the total and intracrystalline pools. Variations in THAA were not correlated with TOC over time, suggesting that organic matter that is involved in biomineralization, like amino acids, may be deposited in response to different environmental factors than are other components of skeletal organic matter. Differences in the quantity and composition of organic matter between the two corals investigated here were assessed using principal components analysis and suggest that location, species and skeletal structure may all influence organic matter content and possibly the degree of physical protection of organic matter by the coral skeleton. Further, our study suggests that intracrystalline organic matter may be better protected from diagenesis than non-intracrystalline organic matter and may therefore be a more reliable source of organic matter for paleoceanographic studies than total skeletal organic matter. 相似文献
18.
显生宙非骨屑碳酸盐矿物经历了文石海和方解石海的交替,主要造礁生物和沉积物生产者的骨骼矿物与非骨屑碳酸盐矿物具有同步变化的趋势。这种长期的变化趋势可以用海水化学Mg/Ca摩尔比的变化来解释。流体包裹体、同位素和微量元素等证据也证实了海水化学在地质历史中经历过剧烈的变化。虽然生物诱导矿化和生物控制矿化的相对重要性一直存在争议,但古生物地层记录和人工海水养殖实验结果都表明,海水化学演化对生物矿化有重要的影响,体现在造礁生物群落的兴衰、生物起源时对骨骼矿物类型的选择以及微生物碳酸盐岩在地质历史中的分布等。这些为研究前寒武纪海水化学演化、古气候和古环境的重建、同位素地层对比以及碳酸盐的沉积和成岩等问题提供了新的思路。 相似文献
19.
Amino acids comprise from 15 to 36% by weight of humic substances from carbonate and non-carbonate sediments. Humic and fulvic acids extracted from carbonate sediments are characterized by an amino acid composition consisting primarily of the acidic amino acids, aspartic and glutamic acid. Humic substances from non-carbonate sediments have a distinctly different amino acid composition consisting primarily of glycine and alanine. Amino acid analyses of various molecular weight fractions of fulvic acids extracted from carbonates show that lower molecular weight fractions have appreciably higher relative abundances of the acidic amino acids compared to higher molecular weight fractions. Based on typical values for carboxyl group content in humic substances, acidic amino acids may be a significant contributor of these functional groups. Carbonate surfaces appear to selectively adsorb aspartic acid-enriched organic matter while non-carbonates do not have this property. 相似文献