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1.
大庆齐家水源地Fe存在形式的研究 总被引：4，自引：1，他引：3
本文在大庆齐家水源地野外实测资料的基础上,运用热力学原理和ＰＨＲＥＥＱＣ程序,解释了室内测定易造成亚铁偏低的原因,讨论了ｐＨ和Ｅｈ值现场实测的必要性。在此基础上,指出大庆齐家水源地地下水所处环境应为弱酸性,弱还原环境,以Ｆｅ＾２＋存在为主。 相似文献
2.
含铁绿柱石的改色机制研究 总被引：7，自引：0，他引：7
含铁绿柱石经γ射线辐照或特定温度热处理,可因铁价态的改变引起颜色发生相应变化。处理前后的吸收光谱和顺磁共振谱研究表明,辐作用使隧道位的Ｆｅ＾２＋氧化Ｆｅ％３＋,八一位上的Ｆｅ＾３＋还原为Ｆｅ＾２＋,热处理使隧道位及八面体位Ｆｅ＾３＋均还原为Ｆｅ＾２＋。 相似文献
3.
亚铁离子（Ｆｅ２＋）是地表油气化探工作中重要的评价指标。铁元素的变价特征可导致铁离子的不同存在形式,直接利用Ｆｅ２＋值作为反映油气田上方还原柱性质的指标,存在一定的片面性。因此,提出用亚铁离子转化率Ｋ＝Ｆｅ２＋／Ｆｅ３＋＋Ｆｅ２＋的改进方法,并在实际勘查中验证,认为亚铁离子转化率可以为油气化探异常评价和靶区圈定提供更可靠的信息。 相似文献
4.
水文地球化学研究和模拟计算的结果表明，庆安铁力地区地下水起源于大气降水，地下水水文地质单元具有完整的补给、径流、排泄体系。地下水的水化学特征揭示了地下水经历了由氧化环境向还原环境的变迁过程。铀矿成矿直接指示铀、氧异常集中分布向阳山区段，饱和指数(SI)和临界值Eh等参数的计算显示了有利于铀成矿的条件和环境。 相似文献
5.
在对某石油污染场地地质、水文地质条件、污染源污染方式调查基础上,根据地下水样测试结果,分析了地下水石油烃污染分布特征、污染晕中指示生物降解作用的电子受体、代谢产物以及重要地球化学参数的变化规律,通过计算矿物饱和指数和采用含水层介质X射线矿物衍射方法研究了污染晕中矿物沉淀反应,计算了含水层的氧化容量。结果表明：由于SO42-背景浓度值较高,硫酸盐还原是污染场地地下水石油烃生物降解的优势反应;菱铁矿、黄铁矿和FeS的沉淀反应是HS-、Fe2＋浓度异常的原因;SO42-的氧化容量在含水层中的氧化容量（OXC）所占比例最大,可进一步推断硫酸盐还原反应是引起污染场地地下水石油烃生物降解的优势反应。 相似文献
6.
前寒武纪各种地质记录表明了太古代－元古代早期古全球天南环境具有显著的陆少洋多和大气富ＣＯ２，盆Ｏ２的特征。ＢＩＦｓ大气－海洋系统中Ｆｅ＾２＋的氧化是铁质发生沉淀的一个重要过程，在前寒武纪早期缺Ｏ２的环境，生物－无氧氧化和日光－紫外线为主的宇宙射线光致氧化作用产生的直接非生物－无氧氧化过程，在前寒武幻早期缺Ｏ２环境对Ｆｅ＾２＋的氧化可能起着重要和主导的作用。 相似文献
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古全球变化与非等时韵律沉积及前寒武纪条带状铁矿建造形成的终止 总被引：3，自引：0，他引：3
前寒武纪各种地质记录表明了太古代—元古代早期古全球环境具有显著的陆少洋多和大气富ＣＯ２、贫Ｏ２的特征。ＢＩＦｓ大气－海洋系统中Ｆｅ２＋的氧化是导致铁质发生沉淀的一个重要过程，在前寒武纪早期缺Ｏ２的环境，生物－无氧氧化和日光－紫外线为主的宇宙射线光致氧化作用产生的直接非生物－无氧氧化过程，在前寒武纪早期缺Ｏ２环境对Ｆｅ２＋的氧化可能起着重要的和主导的作用。ＢＩＦｓ条带状矿石的宏、微观ＳｉＯ２或Ｆｅ２Ｏ３／Ｆｅ３Ｏ４单层厚度非等厚性表征了硅、铁供给非等量性与交替淀积非等时性的韵律堆积。文章提出了一种与地球自转速率有关的日长年际变化（古ＥＬＮｉｎｏ事件）－硅铁临界饱和浓度模式，从统一的地球动力学条件和不同类型ＢＩＦｓ的成因联系解析了这种韵律堆积的机制。元古代早—中期大气－海洋系统发生了Ｏ２增多和ＣＯ２减少的古全球变化，导致了２．２～１．８Ｇａ之间大气圈平流层古臭氧层的形成。古臭氧层大幅度消减日光－紫外线对地球表面的强烈辐射，不仅使全球性由日光－紫外线光致氧化作用直接产生的Ｆｅ２＋非生物－缺氧氧化过程消失，而且也保证了生命演化的延续和生物进入多样性繁衍。与其伴随的全球性巨厚碳酸盐建造，导致了上壳岩下伏的地球早期富铁? 相似文献
9.
对用Fe^3＋／Fe^2＋探讨庐山地区第四纪古温度的讨论 总被引：10，自引：0，他引：10
本文认为用Ｆｅ＾３＋／Ｆｅ＾２＋值推算庐山地区第四纪古温度是可行的，但认为在推算方法上必须严谨合理，文中论证了用Ｆｅ２Ｏ３／ＦｅＯ值代替Ｆｅ＾３＋／Ｆｅ＾２＋值推算古温度，且用少量样品的实验分析结果来划分庐山地区第四纪冰期和间冰期地层是欠妥的，其计算结果误差达０．４１－４．３５。据笔者采用容量法对庐山大校场部面１０个样品Ｆｅ＾３＋和Ｆｅ＾２＋含量的测试，发现这些样品反映的第四纪古温度值未有低达０℃ 相似文献
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砂岩型铀矿床层间氧化带前锋区稀有元素富集机制 总被引：3，自引：0，他引：3
在深入研究砂岩型铀矿床层间氧化带各地球化学分带中铀及其伴生元素的分布规律时,发现一些单价态(不变价)元素也常常富集在层间氧化带前锋区,其典型代表是钪(Sc)、钇(Y)和稀土元素(REE)等。作者在综合分析前苏联众多砂岩型铀矿床各地球化学分带中各种元素大量测试数据的基础上,论述了层间氧化带前锋区Eh值和pH值的变化规律以及它们所导致的变价元素(U、Se、Mo和V)和不变价元素(Sc、Y和REE)的分布规律和富集机制。实际上,层间氧化带前锋区既是氧化-还原电位(Eh值)又是酸碱度(pH值)的急剧变化区,两者大致同步消长。层间氧化带前锋区有两类地球化学障:单纯的还原障和还原-碱性综合障。两种地球化学障的发育与强度取决于原始未氧化岩石中硫化物、有机质和碳酸盐的含量。 相似文献
12.
Groundwater in contact with ore deposits may acquire a chemical composition that could be used as a guide for exploration. Eight well-water samples are collected from a known uranium-mineralized area near Abu Zenima, west central Sinai to examine the applicability of using the hydrogeochemical technique in the search for uranium mineralization in similar arid areas. The analytical chemical data of the ground water is compared with ground radiometric measurements. The obtained results indicate that groundwater affected by uranium mineralization has a specific relativity of major anions expressed essentially as SO4>Cl>HCO3 and to a lesser extent as Cl>SO4>HCO3, associated as a rule with low magnesium content. This association constitutes a signature of uranium mineralization on the composition of groundwater in west central Sinai and could be used as an important exploration guide in the search for uranium deposits in similar areas. Anomalies in Ni, Fe, Zn and Cr and other pathfinder elements in groundwater can furnish geochemical guides to uranium ores. The immobile trace element anomalies, including Zn, Ni and Fe are strongly distributed near the orebody; whereas the relatively mobile trace elements, including Co, U, V and Cr, constitute the dispersion haloes away from the orebody. A new hydrogeochemical discrimination diagram is constructed to be used as a quick and cost effective exploration tool in the search for uranium occurrences in environmentally similar arid areas. Based on the obtained results, a new site for uranium occurrence, west of W. Baba, is delineated and recommended for future detailed geological and geochemical surveying. 相似文献
13.
《Chemical Geology》2006,225(1-2):156-171
Groundwater samples were collected along a groundwater flow path in the Carrizo Sand aquifer in south Texas, USA. Field measurements that included pH, specific conductivity, temperature, dissolved oxygen (DO), oxidation–reduction potentials (Eh in mV), alkalinity, iron speciation, and H2S concentrations were also conducted on site. The geochemistry (i.e., concentrations, shale-normalized patterns, and speciation) of dissolved rare element elements (REEs) in the Carrizo groundwaters are described as a function of distance along a flow path. Eh and other redox indicators (i.e., DO, Fe speciation, H2S, U, and Re) indicate that redox conditions change along the flow path in the Carrizo Sand aquifer. Within the region of the aquifer proximal to the recharge zone, groundwaters exhibit both highly oxidizing and localized mildly reducing conditions. However, from roughly 10 km to the discharge zone, groundwaters are reducing and exhibit a progressive decrease in redox conditions. Dissolved REE geochemical behavior exhibits regular variations along the groundwater flow path in the Carrizo Sand aquifer. The changes in REE concentrations, shale-normalized patterns, and speciation indicate that REEs are not conservative tracers. With flow down-gradient, redox conditions, pH and solution composite, and adsorption modify groundwater REE concentrations, fractionation patterns, and speciation. 相似文献
14.
Byoung-Young Choi Hyeon-Jung Kim Kangjoo Kim Seok-Hwi Kim Hwa-Jin Jeong Eungyu Park Seong-Taek Yun 《Environmental Geology》2008,54(2):335-345
Vertical variations of redox chemistry and groundwater quality were investigated in an alluvial aquifer beneath an agricultural
area, in which deep groundwaters are free of NO3, Fe, and Mn problems that are frequently encountered during the development of alluvial groundwaters. This study was performed
to identify and evaluate vertical chemical processes attenuating these chemical species in the study area. For this study,
the processes affecting groundwater chemistry were identified by factor analysis (FA) and the groundwater samples collected
from six multilevel samplers were hierarchically classified into three different redox zones by cluster analysis (CA) based
on the similarity of geochemical features. FA results indicated three major factors affecting the overall water chemistry:
agricultural activities (factor 1), redox reactions (factor 2), and remnant seawater (factor 3). The groundwater quality in
the study area was revealed to be controlled by a series of different redox reactions, resulting in different redox zones
as a function of depth. It was also revealed that the low Fe and Mn levels in the groundwater of the deeper part are associated
with sulfate reduction, which led to precipitation of Fe as iron sulfide and adsorption of Mn on it. 相似文献
15.
本文在调研我国西北内陆盆地中的红层与砂岩型铀矿关系的基础上,提出了一个以沉积相和红化成因为基础的红层分类:把内陆盆地中的红层分为陆解阶段形成的冲积平原红层和浅湖红层;成岩后生阶段形成的河流冲积红层、三角洲红层和沙漠红层;以及表生风化阶段形成的溅泼红(次生红层)等6类红层。并依据这6类红层的特征、产出构造环境,以及含矿主岩到各类红层的Eh、pH、Th/U、Fc~(3+)/Fc~(2+)、Sr/Ba等地化特征值的变化,确定了它们与砂岩型铀矿的关系,即陆解阶段岩石红化时为开放环境,活性铀易于流失,对成矿不利;而成岩后生阶段,岩石红化时的环境为封闭系统,对成矿有利,能形成铀矿床。 相似文献
16.
确定砂岩型铀矿体定位新方法--水岩体系Eh-pH法 总被引：1，自引：0，他引：1
水岩体系Eh-pH方法是根据水岩相互作用原理,来确定砂岩型铀矿体定位的一种新方法.研究结果表明:从氧化带到还原带,水岩体系Eh值明显下降,同一氧化还原环境水岩体系Eh平均值极为接近;不同氧化还原环境,其水岩体系pH值亦有所不同,氧化带和还原带处于弱碱性介质环境,过渡带(矿化地段)处于中性介质环境;水岩体系Eh和pH值可以作为划分含矿层氧化还原环境分带及圈定铀矿体位置的重要依据. 相似文献
17.
Seiichiro Ioka Toshiaki Sakai Toshifumi Igarashi Yoji Ishijima 《Environmental Earth Sciences》2011,64(1):143-149
The in situ redox potential (Eh) in anoxic groundwater with high methane and iron contents (approximately 12.3 and 28.4 mg/L,
respectively) was potentiometrically measured to identify the processes that control Eh. The measured Eh ranged from −213
to −187 mV; it had an inverse correlation with the concentration of methane and no correlation with that of iron. The saturation
indices indicate that goethite and amorphous FeS were nearly at solubility equilibrium. A comparison of the measured Eh with
those calculated for the particular redox pairs indicates that either Fe2+/FeOOH or CH4/CO2, but not sulfur redox pairs, controlled the measured Eh. The inverse relationship between measured Eh and methane concentration
suggests possible control of the redox conditions by the CH4/CO2 redox pair. Furthermore, the equilibrium solubility state of goethite, which has higher crystallinity and lower solubility
than Fe(OH)3 indicates that the iron reaction was electrochemically irreversible. This further supports the contribution of the CH4/CO2 pair to controlling the measured Eh of groundwater. 相似文献
18.
Groundwater samples were collected from 25 sampling sites of the Oropos–Kalamos basin aiming to describe the groundwater quality
in relation to geology, lithology and anthropogenic activities of the study area. Chromium speciation analysis, factor analysis,
GIS database and geochemical data proved successful tools for the identification of natural and anthropogenic factors controlling
the geochemical data variability and for the identification of the redox couple controlling Cr speciation. A Durov diagram
is used to classify groundwater quality into five types: Ca–HCO3, Mg–HCO3, Na–Cl, Mg–Cl and Ca–Cl. The groundwater quality of Oropos–Kalamos is influenced by various natural and anthropogenic factors.
Evaluation of water quality for drinking and irrigation purposes is discussed. 相似文献
19.
碳酸盐岩的Fe/Mn元素比值,作为一项新的地球化学指标,可以用于恢复海洋的氧化还原状态.在氧化条件下,Fe3+和Mn4+均不可溶,因此氧化海水中的溶解Fe和Mn的含量均很低.Fe3+和Mn4+在还原条件下可以被细菌还原为可溶的Fe2+和Mn2+,而氧化还原电位的计算表明,Mn4+的还原要早于Fe3+的还原,因此细菌的Mn还原过程发生在沉积物的更浅层.可溶的Fe2+和Mn2+向上扩散到海水中,替代碳酸盐岩晶格里的Ca2+,因此碳酸盐岩晶格中的Fe2+和Mn2+的含量受控于来自沉积物孔隙水的扩散,而后者又与水岩界面的氧化还原状态相关.因此可以预测,随着海水变得逐渐缺氧,碳酸盐岩中的Fe/Mn比值会逐渐增高.为了验证这一假说,我们分析了中元古代高于庄组白云岩的Fe/Mn比值.研究发现,几乎所有的样品的Fe/Mn比值介于20～30之间,显著高于泥盆纪末期深水碳酸盐岩和浅水台地碳酸盐岩的Fe/Mn比值.高于庄组碳酸盐岩高的Fe/Mn比值一方面可能指示了中元古代低的大气氧气浓度和海洋的广泛缺氧,也可能反映了白云岩形成于缺氧的沉积物空隙水里. 相似文献
20.
The remediation of ammonium-containing groundwater discharged from uranium mill tailing sites is a difficult problem facing the mining industry. The Monument Valley site is a former uranium mining site in the southwest US with both ammonium and nitrate contamination of groundwater. In this study, samples collected from 14 selected wells were analyzed for major cations and anions, trace elements, and isotopic composition of ammonium and nitrate. In addition, geochemical data from the U.S. Department of Energy (DOE) database were analyzed. Results showing oxic redox conditions and correspondence of isotopic compositions of ammonium and nitrate confirmed the natural attenuation of ammonium via nitrification. Moreover, it was observed that ammonium concentration within the plume area is closely related to concentrations of uranium and a series of other trace elements including chromium, selenium, vanadium, iron, and manganese. It is hypothesized that ammonium–nitrate transformation processes influence the disposition of the trace elements through mediation of redox potential, pH, and possibly aqueous complexation and solid-phase sorption. Despite the generally relatively low concentrations of trace elements present in groundwater, their transport and fate may be influenced by remediation of ammonium or nitrate at the site. 相似文献