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作者近十年来在研究痕量金属离子的水-汽界面转移时，发现宏观热力学无法解释转移机制，而微观量子化学及键参数与离子转移浓度之间，却存在函数关系——顾函数。即水蒸发时水汽带出的Zn2+等离子浓度C（μg／L），正相关于比电子亲和常数IZ／Z（eV）（与水合力相关），负相关于离子体积V（3）及配位数N（与水合数相关）。本研究运用顾函数方法进行水-汽离子通量（F）计算，结果表明，世界海洋的F=C×0．35（1012g/a），黄海的F=C×0．42（109g/a），揭示了自然规律。水汽化学离子浓度测定的可靠性，已由生物毒性实验证实。 相似文献
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于2006-05-07采用同站位多介质同时采样的方法获得了表层沉积物样20件,底层水20件,沉积物间隙水17件,生物样27件,系统分析了各介质中痕量金属浓度的分布特征、相关关系及生物体对痕量金属的富集状况.对于不同介质来说,表层沉积物中痕量金属浓度最高,生物体和间隙水次之,底层水最低;然而与各介质的国家标准相比较,沉积物中痕量金属浓度基本无超标,底层水中痕量金属Cu,Pb,Zn的平均浓度大大超过国家海水水质一级标准,生物体中痕量金属Zn和Cu在各类生物体内的平均浓度远远超过国家海洋生物质量一级标准,根据澳大利亚国家卫生和医学研究理事会制定的人体消费卫生标准,As和Cd的浓度则严重超过人体消费标准;各类生物对痕量金属的富集系数均大于20,最高可达10 000以上;相关分析表明,沉积物、底层水及间隙水之间均存在正相关关系(R＞0.6),生物体中多数痕量金属与其它介质中痕量金属的相关性不明显,仅元素Cu和Pb与沉积物中的Cu和Pb有相关性(R分别为0.547和-0.523,P值均小于0.05). 相似文献
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酸溶硫化物(AVS)对沉积物-孔隙水系统中二价有毒金属化学活动性的影响 总被引：11，自引：0，他引：11
本文的主要目的为,通过对具不同AVS含量的沉积物的金属加标实验和膜渗透平衡交换孔隙水采样技术,探讨孔隙水中二价有毒金属浓度对不同沉积物AVS含量的化学响应关系和沉积物-孔隙水系统中二价有毒金属在固、液两相间的地球化学分配机制,并以此揭示在AVS作用下,沉积物中二价微量金属的化学活动牲和生物可获得性.研究结果表明,用于加标实验的具不同硫化物含量的沉积物基质中,固相沉积物对镉、锌的吸收容量依AVS含量而异,如按摩尔浓度计,固相沉积物对铺或锌的吸收容量与AVS大致相等.当沉积物中与酸解硫化物同步被提取的金属铺或锌对AVS的摩尔比,[SEM]/[AVS]小于1时,孔隙水中辐或锌难于被检出;而[SEM]/[AVS]大于1时,沉积物中镉或锌开始表现出强烈的化学活动性,它们在孔隙水中的浓度开始跟随总量浓度变化而变化.[SEM]/[AVS]=1,似乎是判断缺氧海洋沉积物中二价有毒金属是否具有化学活动性的临界点.因此,AVS归一化沉积物中的二价有毒金属([SEM]/[AVS]摩尔比)被证明是一种方便直观地反映沉积物中二价有毒金属化学活动性的浓度表达方式,进而可被直接应用于金属沾污沉积物毒性或沉积物环境质量的评价. 相似文献
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于1978年采集了西藏高原26个盐湖、6条河流、10处泉水及3地盐湖区的大气降水的水样,以ZCP等离子光谱仪测定所采水样中Fe,Mn,Al,Cu,Pb,Zn,Ni,Cr等痕量金属含量,结果表明,1.盐湖水及河流、泉水和大气降水等水系中的痕量金属均高度富集,但以盐湖水的最大;盐湖水中各痕量金属富集程度不一,其顺序:Pb>Mn>Cr>Fe>Zn>Cu>Al>Ni。2.区域出露的岩性、气候、湖盆及水文等为盐湖水中富集痕量金属创造了有利条件。3.高痕量金属浓度的河流、泉水及大气降水是控制和影响盐湖水中痕量金属富集的主要的直接因素。4.盐湖水的矿化度、pH及水化学类型也影响着水中痕量金属的富集。 相似文献
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胶州湾水生系统中Pb、Zn 的分布特征及其在生物体中的浓缩 总被引：1，自引：1，他引：0
利用在胶州湾采集的47组同站位多介质样品,进行了痕量金属Pb、Zn及其它环境因子的化学成分测试,讨论了胶州湾水-沉积物-生物系统中Pb、Zn的生物地球化学总体特征及其在各介质平面上的分布,揭示了胶州湾水-沉积物-生物系统对陆源物质输入的响应.垂向上表层沉积物是Pb、Zn组分的富集带,该系统中的生物相对于其所处水环境具有显著的富集作用,生物体中Pb、Zn生物浓缩系数分别为36、935;横向上,Pb、Zn在底层水和沉积物介质中的分布主要受控于河口,即高值区分布于胶州湾的各个主要河口区,特别是在沉积物中金属组分浓度的高值区主要集中分布于胶州湾的东部.而孔隙水中Pb、Zn的高值主要分布于水交替较弱的海域,如红岛前缘.但生物体中的痕量金属组分化学场空间分布规律与上述各介质的化学场均不吻合,亦即是生物体中痕量金属组分的浓度与其所处环境中的同名金属组分浓度无关.作者认为,生物对痕量金属组分的富集并不简单地取决于它所处环境介质中同名金属组分的总量,而存在形态上的选择性.通过回归分析揭示了孔隙水对生物体中Pb、Zn的富集贡献较大. 相似文献
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黄、渤海是我国重要的海洋经济渔业开发区域,海水中痕量金属的含量及其存在形态会对海洋环境、海洋渔业产生重要影响。随着近年我国痕量金属采集与分析测试技术的发展,数据的准确性有了新的提升。2016-06—07采集黄、渤海40个站位的海水样品,测定其溶解态金属Cd的总浓度,并应用电化学方法(阳极溶出伏安法)分析Cd存在形态。结果表明,渤海海水中的总溶解态Cd浓度是南黄海海水中的2~3倍,这可能与渤海海水停留时间较长,水深较浅,周边较多河流输入有关。20%~92%以上的溶解态Cd是以有机络合物形态存在,以自由离子态存在的Cd浓度不超过100 pmol/L,低于Cd对浮游生物的毒性阈值。渤海比黄海的金属配体浓度高出2倍以上,高值出现在黄河口周围海域,表明黄河水携带较多有机配体输入。推测我国近海有机配体来源可能包括陆源输入、沉积物再悬浮的解析过程以及藻类分泌。研究还表明,黄、渤海海水中溶解态Cd的有机配体络合常数较其他海域的稍高,这与我国近海废、污水排放的有机络合配体类型有关。 相似文献
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合浦珠母贝基质蛋白KRMP-3对二价金属离子选择性的研究 总被引：1，自引：0，他引：1
用大肠杆菌表达含有GST标签的基质蛋白KRMP-3。利用圆二色谱(Circular Dichroism, CD)研究不同浓度钙离子和镁离子对基质蛋白 KRMP-3二级结构的影响。结果表明,钙离子对其二级结构的变化远大于镁离子;同时,采用荧光淬灭法研究 KRMP-3对钙,镁,锶,钡等二价金属离子的选择性,结果表明, KRMP-3对钙离子有特异性选择性,钙离子与KRMP-3的结合常数K约为103 L/mol,结合位点数 n 近似为1,表明 KRMP-3与钙离子的结合能力适中,推测基质蛋白 KRMP-3对合浦珠母贝( Pinctada fucata)棱柱层形成起到促进作用。 相似文献
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This study using tuna otoliths as working standards established a high lateral resolution and precision analysis to measure δ18Ootolith by secondary ion mass spectrometry. This analytical approach of the ion probe was applied to deep-sea fishes to reconstruct the likely depths inhabited by the fishes at different life history stages based on the measured δ18Ootolith values as a proxy of water temperature. Dramatic increases up to 5–6‰ in δ18Ootolith, representing a temperature decrease of approximately 20 °C, were detected in a blind cusk eel (Barathronus maculatus) otolith and in the otoliths of Synaphobranchus kaupii during leptocephalus metamorphosis to glass eel, inferred from the drop of otolith Sr/Ca ratios and increase of otolith growth increment width. δ18Ootolith profiles clearly divided the fish's life history into a planktonic stage in the mixed layer of the ocean and a benthic stage on the deep-sea ocean bottom. The habitat shift signal was recorded within a 150 µm width of otolith growth zone, which was too narrow to be clearly detected by mechanical drilling and conventional isotopic ratio mass spectrometry. However, variations down to −7‰ were found in δ18Ootolith profiles as the result of Cs2+ beam sputter in the core and larval portions of the otoliths. Carbon mapping by electron probe microanalyzer and staining by toluidine blue suggested abundant proteins existed in the areas with anomaly negative δ18Ootolith values, which cannot be interpreted as a habitat change but due to the isotopic fractionation by O emission from the proteins. These results implied that careful design and understanding of the chemical composition of the analytical areas or tracks on the heterogeneous otolith was essential for highly accurate and precise analysis. 相似文献
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1994年5月—1995年6月,利用黄河口悬浮颗粒物,在实验室内于不同温度、盐度、磷酸盐浓度、pH值及悬浮物粒度条件下进行了悬浮物对磷酸盐的吸附和解吸模拟实验,通过水体中几种磷—钙矿物的离子平衡计算,对黄河口磷酸盐的缓冲机制进行了探讨。结果表明,黄河口现场条件下水体中钙与磷之间存在某些离子平衡,黄河口水体中磷—钙矿物的离子积受温度、悬浮物种类及粒度影响较小,而与水体盐度、磷酸盐及钙含量有关,但不足以形成磷—钙矿物沉淀;磷—钙矿物的沉淀和溶解在黄河口磷酸盐浓度的控制机制上所起的作用较小,而悬浮颗粒物表面对磷酸盐的吸附和解吸起了较大的作用。 相似文献
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近几年,河蟹人工育苗已成为我省沿海种苗培育单位的重要产业 ,随着育苗规模的不断扩大及所带来的可观经济效益,各地又因地制宜发展起地下海水、浓缩海水的育苗生产,为搞清这几种育苗水体的水质特点 ,作者对这几种水体进行了分析检测,以服务于生产 ,为河蟹育苗的健康发展提供科学依据。１工作内容和方法１．１采样点自然海水采于营口市老边区三道沟和盘锦市二界沟;浓缩海水采于营口市青石岭育苗室及营口盐 种型苗水ｐ ＣＤ营盐含量Ｔａｂ .1 ｐＨ ,ＣＯＤａｎｄｎｕｔｒｉｔｉｏｎｓａｌｔｏｆｅｖｅｒｙｋｉｎｄｏｆｂｒｅｅｄｉｎｇｗａ… 相似文献
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Experiments with a set of electrolyte solutions have been carried out to investigate the effects of pore water composition changes on the stability conditions of methane hydrate in marine sediments. The results reveal that (1) SO42− and Cl− concentration changes can affect hydrate stability slightly, (2) the changes in both the type and the concentration of cations, which occur in normal diagenetic processes, do not exert a significant influence on the methane hydrate stability conditions, and (3) the shift of hydrate stability in pore water can be expressed as a function of the Cl− concentration only. Based on the results above, an empirical equation ΔT (K)=0.00206 Cl− (mmol/dm3) has been obtained for estimating the shift in the equilibrium temperature of methane hydrate in pore water at a given pressure. 相似文献
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Pasquale Crea Concetta De Stefano Demetrio Milea Silvio Sammartano 《Marine Chemistry》2008,112(3-4):142-148
The results of a potentiometric investigation (by ISE-H+, glass electrode) on the speciation of phytate ion (Phy12−) in an ionic medium simulating the major components (Na+, K+, Ca2+, Mg2+, Cl− and SO42−) of natural seawater, at different salinities and t = 25 °C, are reported. The work was particularly aimed at determining the possible formation of mixed Ca2+–Mg2+–phytate ion pairs, and to establish how including the formation of these mixed species would affect the speciation modeling in seawater media. After testing various speciation models, that considering the formation of the MgCaH3Phy5−, MgCaH4Phy4−, Mg2CaH3Phy3− and Mg2CaH4Phy2− species was accepted, and corresponding stability constants were determined at two salinities (S = 5, 10). A discussion is reported both on the choice of the experimental conditions and on the possibility to extend these results to those typical of real seawater. A detailed procedure is also described to demonstrate that the stability of these species is higher than that statistically predicted. As reported in literature, a parameter, namely log X, has been determined in order to quantify this extra stability for the formation of each mixed species at various salinities. For example, at S = 10, log X113 = 2.67 and log X114 = 1.37 for MgCaH3Phy5− and MgCaH4Phy4− (statistical value is log Xstat = 0.60), and log X213 = 6.11 and log X214 = 2.15 for Mg2CaH3Phy3− and Mg2CaH4Phy2− (log Xstat = 1.43), respectively. Results obtained also showed that the formation of these species may occur even in conditions of low salinity (i.e. low concentration of alkaline earth cations) and low pH (i.e., more protonated ligand). 相似文献
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Knowledge of the activity coefficients of solutes under temperature and pressure ranges of interest is generally required for calculations of the physicochemical properties of aqueous multicomponent electrolyte solutions such as seawater. Whilst these activity coefficients are well characterized for the predominant salts individually, fewer data are available for minor components under a sufficiently wide range of conditions and there are significant interactions between some of the chemical species involved which can substantially alter the required activity coefficients in mixtures.For these reasons, accurate thermodynamic predictions for seawater and other multi-electrolyte solutions in moderate or high concentration are more difficult than is often supposed. In particular, progress in this area has been slowed by uncertainty regarding the nature and extent of ion pairing in concentrated strong electrolyte solutions, a problem that has been debated for decades. Zdanovskii's rule, described originally almost a century ago but widely neglected, provides a fundamentally sound method for calculating the properties of mixed electrolyte solutions. Modelling developments are described, which accord with various types of experiment, from our laboratory and from the chemical literature. It has become clear that, when treated in an appropriate way based on solvent activity, linear mixing behaviour of strong electrolyte solutions can be considered the norm. This is an inevitable consequence, first recognized by Guggenheim, of the cancellation of ion pairing and other interactions as, conceptually, one ion replaces another. Stronger solute–solute interactions, described by equilibrium constants, can then easily be coupled in a thermodynamically consistent manner. 相似文献
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Meagan Eagle Gonneea Paul J. Morris Henrieta Dulaiova Matthew A. Charette 《Marine Chemistry》2008,109(3-4):250
Over the past decade, radium isotopes have been frequently applied as tracers of submarine groundwater discharge (SGD). The unique radium signature of SGD is acquired within the subterranean estuary, a mixing zone between fresh groundwater and seawater in coastal aquifers, yet little is known about what controls Ra cycling in this system. The focus of this study was to examine controls on sediment and groundwater radium activities within permeable aquifer sands (Waquoit Bay, MA, USA) through a combination of field and laboratory studies. In the field, a series of sediment cores and corresponding groundwater profiles were collected for analysis of the four radium isotopes, as well as dissolved and sediment associated manganese, iron, and barium. We found that in addition to greater desorption at increasing salinity, radium was also closely tied to manganese and iron redox cycling within these sediments. A series of laboratory adsorption/desorption experiments helped elucidate the importance of 1) contact time between sediment and water, 2) salinity of water in contact with sediment, 3) redox conditions of water in contact with sediment, and 4) the chemical characteristics of sediment on radium adsorption/desorption. We found that these reactions are rapid (on the order of hours), desorption increases with increasing salinity and decreasing pH, and the presence of Fe and Mn (hydr)oxides on the sediment inhibit the release of radium. These sediments have a large capacity to sorb radium from fresh water. Combined with these experimental results, we present evidence from time series groundwater sampling that within this subterranean estuary there are cyclic periods of Ra accumulation and release controlled by changing salinity and redox conditions. 相似文献
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Free floating subsea robots are often subjected to complex hydrodynamic loads due to waves/currents and wakes from nearby structures. This makes control extremely difficult. Good hydrodynamics data might counteract this. This paper presents hydrodynamics data for two configurations undergoing various combinations of steady translation and approximately steady rotation. The two configurations are: a spherical body with a single fixed link arm and a two link arm without a body. For both configurations neural networks were found to provide a reasonable fit to the data. We believe that such fits could be used to improve control. 相似文献
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We aim to relate the morphology of the pore network of finely porous claystones to their fluid transport properties. By using Focused Ion Beam in combination with Scanning Electron Microscopy (FIB/SEM), we image the pore network of COx claystone from 2D image stacks and as 3D reconstructed volumes. Our FIB/SEM samples are representative of the mesoscopic matrix clay. Porosity resolvable by this technique is in the range 1.7–5.9% with peak pore sizes of 50–90 nm. 3D pore network skeletonization provides connected pore volumes between end surfaces, tortuosity, density, and shortest pore paths with their pore size distribution. At higher resolution, 2D transmission electron microscopy (TEM) reveals large amounts of smaller pores (2–20 nm) between clay aggregates, associated to a local porosity of 14–25%, and peak sizes of 4–6 nm. Liquid permeability predictions with Katz–Thompson model, at the FIB/SEM volume scale and at the TEM surface scale, are in good agreement with macroscopic measurements (on the order of 10−20 m2), showing that both mesopore sizes (peaks at 50–90 nm and 4–6 nm), located within the clay matrix, contribute to liquid transport. 相似文献
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V. Balaram 《Marine Georesources & Geotechnology》1999,17(1):17-26
A polymetallic nodule reference sample (No. 2388)collected from the Indian Ocean, and seven other samples, two from the United States Geological Survey, USA (Nod-A-1 and Nod-P-1), three from Russia (OOPE 601, OOPE 602, and OOPE 603), and two from China (GSPN-2 and GSPN-3), collected from different loca tions, are available for calibration purposes and as control samples in the analytical programs for polymetallic nodules and associated sediments to ensure accurate measurements. They are not certified for precious metal concentrations, however, and the data available are very scanty. An attempt has been made to provide working values for platinum, palladium, gold, and silver and indicative values for osmium, iridium, and ruthenium in these eight ferromanganese nodule reference samples, using inductively coupled plasma mass spectrometry (ICP-MS). To assess the accuracy of the method, certified reference materials, WPR-1, WMS-1, WMG-1, and WGB-1 Canadian Certified Materials Project (CCRMP, Canada) were analyzed, and the data obtained were compared with the certified values. The estimate of analytical reproducibility was found to be better than 15 % RSD for most elements with comparable accuracy. The data presented for this set of manganese nodule reference samples may be useful in geochemical studies of manganese nodules and associated sediments. 相似文献