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1.
研究了溶液ＰＨ值、离子强度、氨基酸和微量金属元素对珠江口悬浮物电泳淌度的影响，结果表明：随着溶液ＰＨ值的升高，电泳淌度（负值）的绝对值开始逐渐增大，至ＰＨ值为８左右开始下降；随着离子强度的增大，电泳淌度的绝对值也相应增大，至１０＾－２时趋向平稳；氨基酸对电泳淌度无影响；而微量金属元素对电泳淌度的影响取决于该元素的含量。 相似文献
2.
天然水体中悬浮颗粒物电泳性质的研究——Ⅰ.离子强度及pH对悬浮颗粒物电泳淌度的影响 总被引：2，自引：0，他引：2
本文采用天然悬浮物力最常见的粘土(包括高岭石、伊利石、蒙脱石)和水合氧化物(包括α-FeOOH、γ-AlOOH)为模拟颗粒物,系统地研究了介质的离子强度,得到了比较完整的关系曲线.实验结果表明,不管颗粒物带何种电荷,当介质的离子强度介于10-4-4×10-2mol/l之间时,随着离子强度的增大,悬浮颗粒物电泳淌度的绝对值也随着增大,这基本上可用Zukoski等的Stern层动力学模型来解释.当介质离子强度大于4×102mol/l时,电泳淌度的绝对值反之随着离子强度的增大而减少,这可用双电层厚度变薄来解释.在电泳淌度与介质pH关系研究中,测得一种新型的M-pH曲线,这可解释对界面羟基的两性变化和离子强度效应“反常”之故. 相似文献
3.
天然水体中悬浮颗粒物电泳性质的研究 Ⅲ.金属离子及金属离子-有机物对悬浮颗粒物电泳淌度的影响 总被引：1，自引：0，他引：1
本文研究了金属离子对悬浮颗粒物电泳淌度的影响,实验结果表明,海水中的常量碱土金属离子Ca~(2+)和Mg~(2+)使高岭石及伊利石的电泳淌度的绝对值明显变小,很可能是粘土类悬浮物电泳淌度的控制因素.金属离子Cu~(2+)和Cd~(2+)对γ-AlOOH的电泳淌度影响很小,而对高岭石的电泳淌度影响较大,但考虑到海水中重金属离子的浓度远比本实验中浓度小得多,因此可以认为天然水体中重金属离子对悬浮颗粒物的电泳淌度的影响可以忽略,当有机物与金属离子共存时,有机物与自由金属离子络合,从而减小了自由金属离子浓度,因而减小了金属离子对悬浮颗粒物电泳淌度的影响. 相似文献
4.
本文用微电泳的方法研究了针铁矿及δ—MnO2悬浮粒子的电泳行为。支持电解质的离子强度影响淌度的大小，但不改变等电点(IEP)。重金属离子在悬浮粒子上的吸附，使pH高于IEP时的表面电荷由负变正，而在pH低于IEP影响不大。小分子量的有机物如氨基酸对悬浮粒子的淌度影响不大，而大分子量的有机物如腐殖酸使IEP左移。天然海水，河水等对悬浮粒子表面电荷的影响是其中的有机物使IEP左移的结果，故天然水体中悬浮粒子无例外地均荷负电。 相似文献
5.
本文用微电泳的方法研究了针铁矿及δ-MnO_2悬浮粒子的电泳行为。支持电解质的离子强度影响淌度的大小,但不改变等电点(IEP)。重金属离子在悬浮粒子上的吸附,使pH高于IEP时的表面电荷由负变正,而在pH低于IEP时影响不大。 小分子量的有机物如氨基酸对悬浮粒子的淌度影响不大,而大分子量的有机物如腐殖酸使IEP左移。天然海水,河水等对悬浮粒子表面电荷的影响是其中的有机物使IEP左移的结果,故天然水体中悬浮粒子无例外地均荷负电。 相似文献
6.
实验结果表明,氧化物表面物种决定了氧化物体系电泳淌度。由于δ-MnO_2表面交换位置以R-O~θ为主,针铁矿在低pH时以R—OH为主,故铜(Ⅱ)使δ-MnO_2电泳淌度增大,而使针铁矿电泳淌度变得更负。由于组氨酸-针铁矿之间的阳离子交换,组氨酸使针铁矿或铜(Ⅱ)-针铁矿电泳淌度变得更负。而在δ-MnO_2表面组氨酸可脱羧成为组胺,组胺-δ-MnO_2之间的阳离子交换使δ-MnO_2或铜(Ⅱ)-δ-MnO_2电泳淌度增大。但甘氨酸脱羧产物甲胺对铜(Ⅱ)-δ-MnO_2电泳淌度无影响。电泳实验进一步证明δ-MnO_2能将氨基酸氧化为胺,而针铁矿则不能。 相似文献
7.
钝顶螺旋藻藻胆蛋白的提取及其特征初报 总被引：3，自引：0，他引：3
作者采用细胞破碎，等电点沉淀的方法，提取、分离螺旋藻的藻胆蛋白，并在藻胆蛋白中检测到１７种氨基酸。文中还研究了在５００－７００ｎｍ波长范围内不同外界因子对藻胆蛋白理化特性的影响，结果表明：（１）不同的ｐＨ值，藻胆蛋白液颜色及吸收光谱的形状和强度不同。当ｐＨ为４和５．５时，藻胆蛋白液呈绿蓝色，吸收峰在６２５ｎｍ处，而ｐＨ为７，吸收峰移至６００ｎｍ。（２）藻胆蛋白热稳定性差，吸收光谱强度随着温度升高而 相似文献
8.
天然水体中悬浮颗粒物电泳性质的研究——Ⅱ.海洋有机物对悬浮颗粒物电泳淌度的影响 总被引：1，自引：0，他引：1
本文对天然水体中悬浮颗粒物的带电机理,特别是海洋有机物对颗粒物电泳淌度的影响进行了系统地研究.实验结果表明,海洋有机物(主要是富里酸FA)吸附到悬浮颗粒物上后,使得原来带有不同电荷的颗粒物均带负电荷;海洋有机物(FA)与Ca~(2+)、Mg~(2+)等金属离子共同作用的结果,使得原来电泳淌度差别很大的各种悬浮颗粒物变得相互很接近.实验结果还表明,海水中的氨基酸由于其浓度小,以及其本身的性质所限,因而对悬浮颗粒物的电泳淌度基本没有影响;起决定影响性作用的有机物是海水腐植质(FA). 相似文献
9.
干旱区粉尘对古里雅冰帽中化学记录的影响 总被引：8，自引：0，他引：8
从雪冰样品中的阳离子（Ｃａ２＋、Ｎａ＋、Ｍｇ２＋和Ｋ＋）、阴离子（Ｃｌ－、ＳＯ４２－和ＮＯ３－）、ｐＨ值、电导率等几个方面分析了干旱区粉尘对古里雅冰帽中化学记录的影响特点。研究表明,干旱区粉尘对该冰帽的影响使得离子的浓度高于极地冰川中相应离子的浓度,离子之间的浓度大小顺序明显地不同于极地冰川。钻取样品中离子存在明显的空间变化趋势,反映了近源粉尘对冰帽中化学记录的影响;最新一次降水中离子没有明显的空间变化趋势,反映了远源粉尘对冰帽整体的均匀影响。８５％的样品的ｐＨ值大于７,部分样品的ｐＨ值大于９,归因于来自干旱区的尘埃中的易溶性弱酸盐的水解作用,电导率的主要贡献者是粉尘中的易溶盐 相似文献
10.
海水中铜离子对氨基酸—粘土体系液—固界面作用的影响 总被引：2，自引：0，他引：2
用Ｅ（％）－ｐＨ曲线法实验研究了海水中三元表面络合物的形成和构型。通过海水中金属铜离子对氨基酸—粘土界面作用的Ｅ（％）－ｐＨ曲线影响的研究,发现曲线具有“单向上移”的规律,表明甘氨酸、天冬氨酸—铜离子—高岭土三元体系在实验条件下主要形成（Ⅰ）型三元表面络合物即≡Ｓ—Ｏ—Ｍ—Ｌ。该系列论文另一部分已研究氨基酸对金属离子—粘土体系的影响,证明可形成（Ⅱ）型三元表面络合物即≡Ｓ—Ｏ—Ｌ—Ｍ。据此可以推测（Ⅰ）型和（Ⅱ）型在某一条件下可以转变构型,其中间构型可能即是Ｌｅｃｋｉｅ等提出的环形三元表面络合物。 相似文献
11.
The reduction of heavy metals (cadmium, lead and zinc) in the presence of long-chain fatty acids (lauric, oleic and linoleic) in 0.55 mol dm?3 NaCl and 0.03 mol dm?3 NaHCO3 at pH 8.7 has been studied by differential pulse polarography. The increase of the peak height of investigated metals by up to tenfold the value obtained in electrolyte without fatty acid is due to adsorption of metal ions at the electrode surface. The accumulation of metal increases with the increase of adsorption time (at potentials more positive than the reduction potential of the particular metal) and with increase of salinity. The heavy-metal adsorption depends on the concentrations of both metal ions and fatty acids. The interaction of heavy metals with the unsaturated fatty acids in the bulk and/or in the adsorbed layer at different natural interfaces could be of considerable importance in an understanding of the fate and distribution of heavy metals in the natural aquatic environment. 相似文献
12.
Settling characteristics of soils carry great importance for geotechnical engineers since sediments properties are formed during the settling of soil particles in an aqueous environment. In this study, settling characteristics of kaolinite are investigated. Different ionic strengths of NaCl, CaCl2 and AlCl3 were considered as a function of pH in aqueous environment of varying solid concentrations. Factors affecting the settling characteristics and fabric of kaolinitic sediments have been identified. The results of the study reveal that kaolinite settles in either flocculated or dispersed forms depending on pH and ion concentration. Flocculated settling occurs in acidic pH due to formation of flocs in edge-to-face structure with increasing positive charges at the particle edges. Dispersed settling occurs in alkaline pHs when ionic strength is low. When ionic strength is increased in alkaline pHs, kaolinite particles settle in flocculated form. Furthermore, the results show that pH has a significant role on the final sediment thickness or void ratio of kaolinite. Densely packed structures in alkaline and loosely packed structures in acidic aqueous environments are formed depending on pH level. Results also show that as the solid concentration increases, the settling rate decreases due to buoyancy effect. Finally, the zeta potential of kaolinite is correlated with the final sediment thickness or void ratio of kaolinite as a function of pH. This correlation proves that there is a good agreement between zeta potential and the final sediment thickness or void ratio, especially when the soil is settled in a dispersed form. 相似文献
13.
为研究带鱼(Trichiuruslepturus)蛋白复合酶解液中抗菌肽(ABP)的抑菌性及表征活性,本文以舟山小带鱼为研究对象,制备蛋白抗菌肽。研究得到抗菌肽分子量在区间(3000Da, 3000—800Da,800Da)内均有分布,在3000—800Da区间内含量达到49.61%,酶解程度最深,氨基酸总量为881.83mg/g,必需氨基酸与氨基酸总量比为44.75%,必需氨基酸与非必需氨基酸比为81.33%,营养价值高。六类提升抗菌效力的氨基酸占氨基酸总量42.71%,抗菌效力较高,具有广谱抗菌活性,为阳离子型抗菌肽,对G–具有较强的抑菌效能。抗菌效力与稀释128倍(10.15U/mL)土霉素抗菌效力相当,与稀释4倍的硫酸链霉素(325U/mL)抗菌效力相当。对抗菌肽的表征活性进行研究表明:该抗菌肽在pH 2—12下溶解度良好,均大于88%,有强适应性;乳化性随pH增大而增强, pH 4时乳化性最低,为53.68%,在pH 12时达到最高值78.34%;乳化稳定性在pH 6时达到最高,为85.83%, pH环境过酸或者过碱的情况下乳化稳定性均较低;发泡性随pH上升呈现增长趋势,在pH 12时达到最大值57.33%, pH 4时抗菌肽泡沫稳定性最低,为22.86%, pH升高,泡沫稳定性也随之增强,在pH 12时达到最大值59.58%。该研究结果对探究带鱼抗菌肽的各项性质提供了理论依据,对带鱼抗菌肽的应用研究具有一定的理论指导意义。 相似文献
14.
《Marine Georesources & Geotechnology》2006,24(3):203-218
Settling characteristics of soils carry great importance for geotechnical engineers since sediments properties are formed during the settling of soil particles in an aqueous environment. In this study, settling characteristics of kaolinite are investigated. Different ionic strengths of NaCl, CaCl2 and AlCl3 were considered as a function of pH in aqueous environment of varying solid concentrations. Factors affecting the settling characteristics and fabric of kaolinitic sediments have been identified. The results of the study reveal that kaolinite settles in either flocculated or dispersed forms depending on pH and ion concentration. Flocculated settling occurs in acidic pH due to formation of flocs in edge-to-face structure with increasing positive charges at the particle edges. Dispersed settling occurs in alkaline pHs when ionic strength is low. When ionic strength is increased in alkaline pHs, kaolinite particles settle in flocculated form. Furthermore, the results show that pH has a significant role on the final sediment thickness or void ratio of kaolinite. Densely packed structures in alkaline and loosely packed structures in acidic aqueous environments are formed depending on pH level. Results also show that as the solid concentration increases, the settling rate decreases due to buoyancy effect. Finally, the zeta potential of kaolinite is correlated with the final sediment thickness or void ratio of kaolinite as a function of pH. This correlation proves that there is a good agreement between zeta potential and the final sediment thickness or void ratio, especially when the soil is settled in a dispersed form. 相似文献
15.
In seawater and lake water the complexation of several heavy metals, present in the dissolved state at relevant trace levels, with humic substances isolated from two marine and an estuarine sediment has been studied by differential pulse anodic stripping voltammetry (DPASV) at a hanging mercury drop electrode (HMDE). Taking Zn(II) as an example, the aim of this study was to gain direct information on the general level of importance of humic substances for the speciation of certain heavy metals in fresh and saline waters.In seawater humic acids originating from different sediments have very similar complexing properties for Zn(II), decreasing slightly in the order HAN > HAL > HAM. In lake water HAL is most efficient for complexing Zn(II), followed by HAN and HAM.In both types of natural waters, the sedimentary fulvic acid is less efficient in complexing Zn(II) than the respective humic acid from the same site. In general, the complexing efficiency decreases in the order EDTA > NTA > humic acids > fulvic acid.The problem of humic acid adsorption at the electrode, which somewhat limits the investigation of Pb(II) and Cd(II), and the impact of pH on the amount of complexed Zn(II) are also discussed.The findings provide further direct evidence for the conclusion previously drawn from existing complexation data that because of the rather low levels of dissolved humics in large parts of the oceans, the complexation efficiency of humics for Cd, Pb and Zn is too low to affect the speciation pattern of these three heavy metals. 相似文献
16.
Two humic acids, HAL and HAN, isolated from marine sediments (Adriatic and Norwegian Sea) and humic (HAM) and fulvic (FAM) acids isolated from an estuarine sediment (Mahakam, Borneo) were characterized.The following characteristics: carbon content, hydrophobicity, degree of condensation and the content of aliphatic groups, are most pronounced for HAN, less pronounced for HAL and the least pronounced for HAM. The abundance of trace metals in the humic acids decreases in the following order: Al > Cu > Zn > Pb > Cd.Fulvic acid (FAM) has a lower carbon and a higher oxygen content than humic acids. It is hydrophilic and hardly any aliphatic groups were recorded. At pH 7 the predominant fraction of FAM has the apparent molecular weight of 20 000 daltons while the humic acids are of higher molecular weight. 相似文献
17.
《Marine Chemistry》2002,78(1):29-45
The distribution of several trace metals has been studied in the surface waters of Galveston Bay, Texas, in order to assess the impact of complexation with organic and reduced sulfur species on the partitioning of trace metals between particulate and aqueous species. The distribution of trace metals in the filter-passing fraction (<0.45 μm) showed two apparent trends: (1) the carrier phase metals (i.e., Fe and Mn) were largely removed in the Anahuac Channel region, which was dominated by direct Trinity River inputs; (2) the other metals (Cd, Cu, Ni, Pb, and Zn) showed non-conservative mixing behaviour, with mid-salinity maxima, within the estuarine regions of Galveston Bay. The average percentage of metal in the filter-passing fraction, as compared to the total metal load, decreased in that region from 95% to 9% in the order Ni>Cu>Cd>Zn>Pb>Mn>Fe, while an increasing trend was found in the same sequence for the acid-leachable fractions. The average values of Kd1, the particle-water partition coefficient, expressed as the ratio of weak acid-leachable particulate fractions to the filter-passing fractions, increased in the order Ni<Cu<Cd<Zn<Mn<Pb<Fe. This sequence is consistent with the relative importance of particulate transport of these trace metals from estuaries to coastal oceans. The observed decrease of Kd1 of Cu with increasing concentrations of suspended particulate matter (SPM), also called the “particle concentration effect” (PCE), can be eliminated when the free ionic, rather than the total concentration of Cu in the filter-passing fraction is used for calculating this ratio. A particle concentration effect would be expected if the binding of these trace metals by particles is mediated by solution (i.e., filter-passing) phase ligands. Complexation of Cd, Cu, Ni, Pb, and Zn with reduced sulfur species could be one of the causes for the observed linear correlations between metals and reduced sulfur species in both the filter-passing and filter-retained fractions. Significant correlations between Cu in the weak acid-leachable fraction and chlorophyll a (Chl a) concentrations suggest biological mediation of Cu uptake into the particulate fraction. 相似文献
18.
Enzymatic mobilisation of trace metals from estuarine sediment 总被引：3，自引：1，他引：3
Proteinase K, a non-specific protease that is representative of enzymes encountered in the digestive environment of deposit-feeding organisms, has been employed to determine the nature and extent of enzymatic mobilisation of trace metals (Al, Fe, Mn, As, Cu, Pb and Zn) from contaminated estuarine sediment. The extent of metal release by the enzyme was critically dependent on whether and how the sample had been dried and, for all metals except Mn, mobilisation was greatest when the sample had not been dried. The fraction of metal available to the enzyme, fe, defined as the amount of metal released from undried sediment after 4 h incubation relative to the total metal concentration, was less than 1% in all cases. Significantly, however, there was a strong correlation between fe and published factors defining the enrichment of metals in the gut fluids of the deposit-feeding lugworm, Arenicola marina. This suggests that, at least qualitatively, the mechanics of metal mobilisation in situ are replicated by the commercial enzyme. Thermally denaturing the enzyme resulted in mobilisation that was greater than (As and Cu) or similar to (all other metals) release engendered by the active enzyme, suggesting that the principal mechanism of metal mobilisation is not related to proteolysis but more likely involves complexation or exchange with component amino acids of the enzyme. 相似文献
19.
Suspended sediments from large and middle size Chinese estuaries, including the Yalujiang, Shuangtaizihe, Luanhe, Jiaojiang and Zhujiang, were analysed to understand trace metal transport in the coastal zone. The determinations of 13 major and trace elements plus organic carbon were made of total concentrations and were fully validated by certified reference materials (CRMs). The combination of the data sets with other Chinese estuaries, such as Changjiang and Huanghe, provides an overview of particulate trace metal geochemistry in this region. Trace metal levels in Chinese rivers are relatively low compared with those draining industrialized regions of Europe and North America. In the estuaries, most particulate elements illustrate stable distribution in the mixing zone until a salinity of 30, especially when absolute concentrations are normalized to aluminium, although the total suspended matter (TSM) is quite different in time and space. Using Al as a reference, it was estimated that 25–40% for Cu, and 5–20% for Pb could remain in labile part in the Jiaojiang, Shuangtaizihe and Zhujiang, whereas different features of labile elements were found in the Changjiang and Luanhe. The mean enrichment factor (EFm) increases with higher sewage to river runoff ratio (S/R) over the drainage basin and EFm for suspended matter is higher than that for bottom sediments. Finally, inputs of particulate trace metals to the coast are estimated based on the riverine sediment load and chemical compositions. 相似文献
20.
Rain water-aerosol trace metal relationships at cap ferrat: A coastal site in the Western Mediterranean 总被引：1，自引：0，他引：1
The factors controlling the distributions of the trace metals Al, Co, Ni, Cu and Pb in a series of 25 individual rain water samples collected at Cap Ferrat, a site on the Western Mediterranean coast, are interpreted in relation to aerosols taken simultaneously at the same site. The trace metal chemistry and pH of the rain waters are constrained by the scavenged aerosols, which are composed of a mixture of urban-dominated (European) and crust-dominated (Saharan) components. Thus, the pH values of the rain waters, which range between 3.95 to 6.77, reflect the type of aerosol scavenged from the air; urban-dominated aerosol components giving rise to acidic rains, and crust-dominated aerosol resulting in neutral to basic rains. The average solubilities of the trace metals in the rain waters increase in the order Al (17%), Co (36%), Ni (53%), Pb (65%) and Cu (76%). The paniculate ↔ dissolved speciation of the non-crust-dominated metals Cu and Pb varies with pH, being more soluble at lower pH values, and exhibits the classical pH ‘adsorption edge’. However, the pH of rain can vary during an individual rain event in response to the sequential scavenging of crust-dominated and urban-dominated aerosol components. As a result, the solubility of non-crust-dominated trace metals, such as Pb, can also vary sequentially during an individual rain event; the maximum solubility being related to a ‘dip’ in pH associated with the scavenging of urban-rich aerosol components, followed by a return to the initial pH as the pH-influencing components are exhausted. Data from the present study therefore indicate that the pH-controlled trace metal solubility relationship reported for individual rain events can also occur sequentially in the same event. The particulate material in the rain waters does not contain the relatively high concentrations of Ni, Cu and Pb found in the parent aerosols, and its composition approaches that of crust-dominated aerosols transported to the Mediterranean. Data from the present study, together with those for other Western European coastal locations, indicate that there is a Pb-Cu fractionation between aerosols and rainwaters which results in a significantly greater fraction of the aerosol Pb, relative to Cu, escaping precipitation scavenging in the coastal zone and so becoming available for long-range atmospheric transport. 相似文献