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通过该区太古界一新生界氟的地层地球化学剖面及岩浆岩和土壤中氟的丰度的研究,论证了该区为一高氟的地球化学区。根据重矿物对比研究和地貌分析,阐明了泰沂隆起区太古界和元古界的高氟古老岩系为该区土壤沉积物源,黄河多次泛滥堆积（粘土矿物对氟的吸附）对土壤氟起了叠加富集的作用。研究揭示该区土壤水溶氟较高,经降水淋滤和浸取作用氟转入地下水,并在凹陷区或河间洼地中聚集,水体停泄、蒸发浓缩形成高氟地下水区。 相似文献
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南四湖流域许多地段浅层地下水中氟含量明显超出国家标准,最高含量达16．4mg／L,地方性氟中毒病分布范围广．为流域内主要的环境地质问题。从自然地理环境、地质环境、水文地质条件、水文地球化学环境等方面对地氟病成因进行了分析研究,认为湖东泰沂隆起区出露的岩浆岩和各类变质岩提供了丰富的氟源．岩石中的氟矿物通过表面扩散的反应动力学机制向地下水中传递,氟元素则通过对氟矿物的溶解和溶滤进入地下水中。南黄河冲洪积、湖积作用形成的粘土、亚粘土和粉细砂为主的含水层,氟的含量较高,其氟矿物以云母为主,粘性土巾有大量吸附性氟。地下水的垂向与侧向补给条件差,交替滞缓,氟存水中的集聚作用以蒸发浓缩为主,有利于氟元素富集。 相似文献
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海南岛农田土壤Se的地球化学特征 总被引：18，自引：0，他引：18
Se是人和动物必需的微量元素之一,具有广阔的开发应用前景,研究土壤中Se的地球化学分布规律和生物有效性控制因素意义重大。系统总结了海南岛27 426 km2范围内土壤Se的含量特征和影响因素。结果表明,研究区69.98%土地面积为足硒和富硒土壤,表层土壤Se含量在一定程度上继承了成土母岩(或深层土壤)Se含量,但不同成土母岩形成的表层土壤Se含量富集贫化趋势不同。进一步研究显示,土壤中Se含量与有机碳、Al2O3、TFe2O3、Mn和CIA等具有显著的正相关关系,说明土壤中粘土矿物、有机碳、铁锰氧化物及风化淋溶程度对Se的地球化学行为有重要影响,同时这些指标又是影响土壤Se生物有效性的重要参数。土壤有机碳、粘粒、CEC等含量或指标越高,Se的生物有效性越低。研究区土壤pH6.5时,土壤Se含量较低;土壤pH6.5时,土壤Se含量随pH下降而增加;当土壤pH为5.5～7.5时,土壤Se生物有效性相对较高。因此,开发富硒农产品不但要依据土壤总Se含量,还必须考虑土壤pH、TOC、CEC、粘粒等指标含量。 相似文献
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以代表性暗棕壤垂直剖面土壤地球化学数据为依据,研究了长白山区特定的森林景观条件下成土过程中元素的分异与富集特征。研究结果表明,在岩石风化过程中主要以CaO、Na2O、Sr淋溶为主,有机酸淋溶过程中SiO2、Al2O3、K2O部分被淋溶,部分游离铁下渗到土体中下部氧化成铁锰胶膜;微量元素在风化过程中被次生黏土矿物吸附,不同程度地富集,在腐殖质积累过程中Cd、Zn、Pb、Mo、Hg、Co、Mn、Cr等亲生物元素进一步富集于表层土壤,Ce、Ni、Sb、Ti、V、Y、Zr在表生环境中地球化学性质稳定,残留富集于土壤表层。母质层继承和保留了基岩元素地球化学分布的基本特征。 相似文献
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伊犁盆地512铀矿床粘土矿物特征与铀成矿作用 总被引：6，自引：0，他引：6
对５１２铀矿床粘土矿物质量分数,分布特征进行了较全面的分析,指出该矿床中粘土矿物以成岩国主,在后生成矿作用中又叠加了新的粘土蚀变产物,各亚带粘土矿物组成基本类似但又存在的一定差异,粘土总量和蒙皂石能较好地反映各亚带的成矿物理化学条件的改变;粘土矿物对Ｕ有明显的吸附富集作用,但又能抑制作用,即粘土质量分数过高或氧化带粘土变太强烈不利于铀在过渡带沉积富集成矿,此外,对粘土矿物成分对浸工艺开采过程中的不 相似文献
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本文首先分析了江西德兴铜矿区周围土壤的微量元素和矿物组成特征,结果显示该地区重金属元素富集,且表层土中重金属元素含量与粘土矿物相对含量变化具有较好的一致性。室内土柱淋滤实验结果表明,当总淋滤时间为451 h时,土壤对Pb2+的总吸附量为2 584.75 mg/kg,淋滤实验的前半期存在多种竞争吸附机制,后半期土壤对Pb2+的吸附基本达到动态平衡。淋滤后土壤矿物的相对质量分数发生了改变,粘土矿物有所减少。粘土矿物在不同土壤层对Pb2+的吸附能力也各异。 相似文献
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环境中氟的来源及健康风险评估研究进展 总被引：2，自引：0，他引：2
氟是存在于自然环境中的一种人体必需的微量元素,其在环境中的缺乏或过剩可能导致健康问题。本文综述了氟在自然界如大气、岩石、土壤、水体、植物中的来源,分析了其形态及含量受环境影响的因素如地形、雨水淋溶、土壤母质、土壤酸碱度、土壤有机质等。氟的来源广泛,目前全球超过2.6亿人受氟带来的环境问题影响,因此开展健康风险评估具有重要意义。氟的健康风险评估常用的风险评估模型有危害系数（Hazard Quotient）、危害指数（Hazard Index）,概率方法也常运用于风险分析中,目前还出现应用多途径暴露评估法对氟进行评估,不确定性和灵敏度的研究对于评估模型尤为关键。本文比较了传统模型的可行性和局限性,认为确定氟富集的途径,完善复合暴露评估的模式,考虑氟摄入的生物有效性,对于氟的健康风险评估十分必要;氟的健康风险评估下一步的研究还可以趋向于使用模型对氟的风险进行预测;对于氟的来源、赋存状态、迁移途径以及含量影响因素等仍然需要深入了解,全面评估其带来的健康风险。 相似文献
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为查明冀东北地区中低温对流型地热系统中氟的富集过程,通过对地热流体水化学特征和同位素数据的分析,研究地热流体中氟的分布特征、富集规律、水化学过程及影响因素。结果表明:研究区地热流体F^-含量为1.36~23.83 mg/L,呈现北高南低的趋势;在HCO3^-—Na^+和SO4^2-·HCO3^-—Na^+等Na型水中富集程度高于HCO3^-—Ca^2+和HCO3^-—Ca^2+·Mg^2+等Ca型水;碱性环境、温度和循环深度是影响氟离子富集的主要因素;水岩作用、含氟矿物溶解及阳离子交换作用,是控制高氟地热水水化学特征的主要地球化学过程。氟浓度异常可为寻找地热资源提供基础参考线索,为地热资源的科学合理利用提供科学依据。 相似文献
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锂铍金属是世界关键金属资源,矿床类型多样,成矿作用发生在大陆地壳。但大陆地壳中锂铍元素的迁移-循环规律及不同锂铍矿床间的成因联系尚不清楚。本文系统地总结与梳理了大陆地壳结构与物质循环特征和不同类型锂铍金属矿床间的成因联系,提出大陆地壳锂铍循环-成矿系统的概念与模型,并将大陆地壳锂铍的迁移与循环划分为四个过程:变质过程、深熔过程、花岗岩浆过程、花岗质岩浆岩风化、淋滤与蚀变的浅-表生过程。沉积岩中锂铍元素在变质过程中可富集到一些变质矿物中,一些富锂铍黏土矿物也在变质过程转变成新的富锂铍变质矿物(如绿泥石、云母与堇青石);地壳深熔过程使得锂铍元素从变质矿物中释放出来并聚集在花岗岩浆中,麻粒岩相深熔(如黑云母脱水熔融与堇青石分解熔融)可能是锂铍大规模成矿的主要熔融方式;绝大多数锂铍矿床与花岗岩浆及其岩浆岩有关,是花岗岩浆与花岗质岩浆岩在不同演化阶段与不同方式富集成矿的结果;浅-表生过程对锂铍花岗岩-伟晶岩和流纹岩与流纹质凝灰岩的物理化学改造,可形成盐湖卤水型锂矿床、黏土型锂矿床以及各种次生锂铍矿床。变质过程中锂铍的迁移与富集机制,大型-超大型花岗岩-伟晶岩型锂铍矿床形成条件与关键控制因素等问题,是亟待研究与思考的科学问题。 相似文献
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Chunying Chang Fangbai Li Chengshuai Liu Jianfeng Gao Hui Tong Manjia Chen 《中国地球化学学报》2016,35(4):329-339
Soil secondary minerals are important scavengers of rare earth elements (REEs) in soils and thus affect geochemical behavior and occurrence of REEs. The fractionation of REEs is a common geochemical phenomenon in soils but has received little attention, especially fractionation induced by secondary minerals. In this study, REEs (La to Lu and Y) associated with soil-abundant secondary minerals Fe-, Al-, and Mn-oxides in 196 soil samples were investigated to explore the fractionation and anomalies of REEs related to the minerals. The results show right-inclined chondrite-normalized REE patterns for La–Lu in soils subjected to total soil digestion and partial soil extraction. Light REEs (LREEs) enrichment features were negatively correlated with a Eu anomaly and positively correlated with a Ce anomaly. The fractionation between LREEs and heavy REEs (HREEs) was attributed to the high adsorption affinity of LREEs to secondary minerals and the preferred activation/leaching of HREEs. The substantial fractions of REEs in soils extracted by oxalate and Dithionite-Citrate-Bicarbonate buffer solutions were labile (10 %–30 %), which were similar to the mass fraction of Fe (10 %–20 %). Furthermore, Eu was found to be more mobile than the other REEs in the soils, whereas Ce was less mobile. These results add to our understanding of the distribution and geochemical behavior of REEs in soils, and also help to deduce the conditions of soil formation from REE fractionation. 相似文献
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REE Mineralization of Weathered Crust and Clay Sediment on Granitic Rocks in the Sanyo Belt,SW Japan and the Southern Jiangxi Province,China 总被引：1，自引：0，他引：1
Rare earth element (REE) geochemistry and mineralogy have been studied in the weathered crusts derived from the Early Yanshanian (Jurassic) biotite granites of Dabu and Dingnan, as well as in the Indosinian (Permian) muscovite–biotite granite of Aigao in southern Jiangxi province, China, and the weathered crusts and clay sediments on biotite granites in the Sanyo belt, SW Japan, that is, Okayama, Tanakami, and Naegi areas. In all of the weathered crusts, biotite and plagioclase commonly tend to decrease toward the upper part of the profile, whereas kaolinite and residual quartz and K‐feldspar increase. The weathered crusts of the Dingnan granites and some Naegi granites, which are characterized by the enrichment in light REE (LREE) in C horizons, have higher total REE (ΣREE) content than the parent REE‐enriched granites. Weathering of LREE‐bearing apatite and fluorocarbonates in the Dingnan granites and allanite and apatite in some Naegi granites may account for the leaching of LREE at the B horizons. The leached LREE must result in subsequent enrichment of LREE in the C horizons. The enrichment is probably associated with mainly adsorption onto kaolinite and partly formation of possible secondary LREE‐bearing minerals. In Japan it was found that REE mineralization occurs not in the weathered granitic crusts but in reworked clay sediments, especially kaolinite‐rich layers, derived mainly from the weathering materials of REE‐enriched granitic rocks. The clay sediments are more enriched in LREE, which likely adsorbed onto kaolinite. Concentration of heavy REE within almost all the weathered crusts and clay sediments, however, may reflect mainly residual REE‐bearing minerals such as zircon, which originated in the parent granitic rocks. The findings of the present study support the three processes for fractionation of the REE during weathering: (i) selective leaching of rocks containing both stable and unstable REE‐bearing minerals; (ii) adsorption onto clay minerals; and (iii) presence of possible secondary LREE‐bearing minerals. 相似文献
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地表油气化探的影响因素及消除方法 总被引：8，自引：4，他引：8
初步总结了油气化探中存在的4方面干扰因素:①地表特殊景观的干扰;②土壤性质引起的干扰,包括土壤粘土矿物、化学成分、土壤酸碱度;③地下非油气矿源的干扰,如断层、高碳质及煤层、岩体和地层等的干扰;④其它,如污染河流的影响。并指出形成干扰异常特征和消除方法。 相似文献
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《地学前缘(英文版)》2016,(5)
A paleosol horizon is described from the contact of the Sausar Group(w2400 Ma) and its basement(Tirodi Gneiss; 2500 Ma) in Central India. Physical evidence of pedogenesis is marked by the development of stress corrosion cracks, soil peds, corestone weathering and nodular rocks. XRD and SEM-EDX data indicate the presence of siderite, ankerite, uraninite, chlorite, alumino-silicate minerals, ilmenite,rutile and magnetite, in addition to quartz, feldspar and mica. The chemical index of alteration, the plagioclase index of alteration, and the chemical index of weathering show an increasing trend from parent rock to the paleosol and indicate a moderate trend of weathering. The A-CN-K plot indicates loss of feldspars, enrichment in Al2O3 and formation of illite. Different major element ratios indicate baseloss through hydrolysis, clay formation, leaching of some elements, and more precipitation with good surface drainage. The paleosol is depleted in HREE in comparison to the parent rock indicating high fluid-rock interaction during weathering. The paleosol samples show flat Ce and Eu anomalies, low SREE, and high(La/Yb)N, indicative of a reducing environment of formation. Reducing condition can also be inferred from the concentration of elements such as V, Co, Cu, Pb, and Zn in the paleosol profile. Although enriched in Fe and Mg, the overall geochemical patterns of the paleosol indicate oxygen deficient conditions in the atmosphere and development by weathering and leaching processes associated with high precipitation and good surface drainage at the time of development of this paleosol during the Archeane Paleoproterozoic transition. 相似文献
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加积型网纹红土网纹化机制及形成环境 总被引：1，自引：0，他引：1
选取九江地区JL剖面网纹层段典型样品,针对红基质与白网纹的物质组成及理化性质展开异同分析,在此基础上探讨网纹红土形成环境。初步得到以下结论:1)红基质与白网纹的粒度组成、元素组成、风化特征基本一致,但铁元素有显著差异,"网纹"并非原生构造,不是岩性差异及差异风化的产物,而是同源物质经历化学风化过程中元素分馏的结果。2)地球化学分析、磁学分析和粘粒级矿物组成分析一致表明,白网纹与红基质在铁含量、铁氧化物形态、铁矿物类型方面存在明显差异。白网纹与红基质相比,全铁含量(4.30%)低于红基质(8.63%);Fe^3+/Fe^2+比值(40.66)低于红基质(90.95);游离铁量及游离度(7.01 g/kg,32.96%)低于红基质(76.21 g/kg,77.52%);铁活化度和晶胶率(25.31%,37.77%)高于红基质(8.77%,9.69%);赤铁矿和针铁矿含量极少,这充分表明白网纹局部存在明显的铁淋失。3)白网纹局部脱色机制主要受控于赤铁矿及其转化,红基质主导矿物为赤铁矿,并含有一定的磁赤铁矿和针铁矿,而白网纹则不含磁赤铁矿,赤铁矿含量也极少。此外高岭石含量也是影响色浅的因素之一,白网纹蛭石、高岭石含量(20.24%和45.08%)均略高于红基质(11.45%和41.82%)。4)赤铁矿的富集、局部铁迁移的特点,整体上指示高温、中强程度化学风化和季节性多水的环境。这在一定程度上暗示网纹红土形成时期气候高温多雨,且季节性反差增强。 相似文献
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氟是煤中有害元素之一,燃煤型氟排放造成的污染已经对人类的健康安全构成威胁。研究煤中氟赋存状态及其沉积环境,对掌握高氟煤分布规律及控制燃煤造成的氟排放具有重要意义。通过对沁水煤田内6座煤矿15号煤样品的分析发现:煤中氟含量与灰分显著相关,与黄铁矿硫、有机硫无相关关系,表明煤中氟主要以无机物形式赋存,且与含硫矿物无关;与钾、镁、硅、铝等元素含量具有显著的相关关系,表明氟有可能的主要赋存形式为金云母、氟金云母等矿物,以及以吸附存在于高岭石、勃姆石、伊蒙混层等黏土矿物中;与钙、磷元素含量无显著相关性,表明氟不以氟磷灰石、含氟羟基磷灰石等矿物大量赋存。此外,通过对沁水煤田15号煤的沉积环境分析发现,弱还原环境、较低盐度、偏酸性、较强的水动力条件有利于该区域煤中氟的富集。 相似文献
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Source and distribution of metals in urban soil of Bombay,India, using multivariate statistical techniques 总被引：7，自引：0，他引：7
Simplification of a complex system of geochemical variables obtained from the soils of an industrialized area of Bombay is attempted by means of R-mode factor analysis. Prior to factor analysis, discriminant analysis was carried out taking rock and soil chemical data to establish the anthropogenic contribution of metals in soil. Trace elements (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) are expressed in terms of three rotated factors. The factors mostly indicate anthropogenic sources of metals such as atmospheric fallout, emission from different industrial chimneys, crushing operations in quarries, and sewage sludges. Major elements (Na, Mg, Al, Si, P, K, Ca, Ti, Mn, and Fe) are also expressed in terms of three rotated factors indicating natural processes such as chemical weathering, presence of clay minerals, and contribution from sewage sludges and municipal refuse. Summary statistics (mean, standard deviation, skewness, and kurtosis) for the particle size distribution were interpreted as moderate dominance of fine particles. Mineralogical studies revealed the presence of montmorillonite, kaolinite, and illite types of clay minerals. Thus the present study provides information about the metal content entering into the soil and their level, sources, and distribution in the area. 相似文献
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根据华南一个铅锌矿区和一个斑岩铜矿区的化探资料,结合国内外材料综述在表生带中岩石的化学成分、土壤溶液的酸碱度、氧化还原电位及土壤有机质含量等相互之间的关系以及其对化学元素的淋失和富集的影响,用以解释造成化探异常强或弱的原因,以对异常做出正确的评价。 相似文献
20.
Two weathering profiles developed over disseminated Cu mineralization hosted by granodiorites (porphyry type) and felsic volcanics respectively, in a savannah tropical environment (Burkina Faso) have been studied in detail. A mineralogical and geochemical study was carried out in order to determine the characteristics of both profiles and the behaviour of Cu in such deeply weathered environments. Our investigation was focused on the upper part of the weathering profile, respectively 4.0 and 10.5 m below the surface.The mineralogical study reveals that in the first case (profile A) the predominant clay minerals are smectites and kaolinite while in the second (profile B) a more kaolinitic composition is indicative of more severe leaching. In fact, field observations seem to demonstrate that the latter situation is more clearly related to an ancient lateritic-type weathering while the first one results from more recent processes.In both cases the Cu contents through the profiles are high (several thousands of ppm) and in good agreement with the grades obtained in depth, in the mineralized rock. Nevertheless, some leaching can be observed in the upper soil horizons, but the contents still remain highly anomalous, in the 1000 ppm range.It is shown that Cu is distributed in the main secondary minerals constituting the weathering products, whether they are silicates (smectites, phyllites, kaolinites) or oxides (goethite, hematite, Mn oxides).The main stable Cu-bearing mineral seems to be the kaolinite: indeed, smectites turn into kaolinite in the upper part of the profiles while goethite seems to be depleted in Cu under the same conditions.As concerns geochemical exploration, two observations can be noted. Firstly, Cu is very stable in such supergene environments, and secondly, the best size fraction in which to detect the Cu secondary dispersion haloes in soil or stream sediment samples is the <63 μ fraction, in terms of anomaly intensity or contrast. 相似文献