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1.
Soil samples collected from a depth of 8 cm near open wells were studied. Finer (minus 80-mesh) fractions of soil from the A-horizon contain more Mn and Fe compared to coarser fractions and these elements show higher concentrations in soils around wells with a deeper water-table. Greater weathering due to percolation of larger volumes of water through soil results in thorough decomposition of all the minerals, liberating the elements. During this process iron hydroxides with very little Mn form large fragile fragments. Higher Fe/Mn ratios in the minus 44 plus 60-mesh fractions of these soils are characteristic of deeper, high-yielding wells and have a positive correlation with depth of water table.  相似文献   

2.
The uptake of arsenic and other metals (iron, manganese, copper, zinc, lead, nickel and tungsten) by Pinus pinaster Aiton (the maritime pine tree) growing in soils and tailings around an abandoned mine (northern Portugal) was investigated. Aerial parts of Pinus pinaster trees were sampled from three substrate areas: a background area, in mine contaminated soils and in tailings. Vegetation material was separated into needles and stems and subdivided into tissues of different maturities (1-, 2-, 3- and 4-years-old). The sampling of the substrate in each area was also undertaken. In general, vegetation concentrations were strongly related to substrate concentrations. The results show that the contents of several elements depend as much on the plant organ as on the age of the tissue. For the researched elements, this species shows a great variability in behavior depending on the age of the organ. The data indicate that the older needles constitute the best samples for use in a conjunct biogeochemical analysis of these elements.  相似文献   

3.
Soil samples were collected over the North Silver Bell porphyry copper deposit near Tucson, Arizona. Volatile elements and compounds in gases derived from the soils and metallic elements in the soils were analyzed in order: (1) to see which volatile constituents of the soils might be indicative of the ore body or the alteration zones; and (2) to distinguish the ore and alteration zones by comparison of trace elements in the soil.Plots of analytical data on trace elements in soils indicated a typical distribution pattern for metals around a porphyry copper deposit, with copper, molybdenum, and arsenic concentrations higher over the ore body, and zinc, lead, and silver concentrations higher over the alteration zones.Higher than average concentrations of helium, carbon disulfide, and sulfur dioxide adsorbed on soils were found over the ore body, whereas higher concentrations of carbon dioxide and carbonyl sulfide were found over the alteration zones.  相似文献   

4.
土壤、农作物中及家畜体内的微量营养元素   总被引:2,自引:0,他引:2  
微量营养元素通常富集在表层土壤中,其含量随土层深度递减。尽管土壤中大多数微量元素的含量很高,但只有一小部分能被植物吸收。微量营养元素,也被称为痕迹元素,所需数量微小,但其缺乏会对农作物生产和动物健康造成严重影响。农作物对不同微量营养元素有着不同的反应。芸苔和豆类对Mo和B有较高的响应度,而玉米和其他谷类对Zn和Cu较为敏感。在温润和湿热地区,由于强降雨和强淋溶作用,微量营养元素缺乏较为普遍。土壤pH值是影响微量营养元素对植物有效性的重要因素之一。除Mo以外,微量营养元素的有效性随pH的增加而减小,Mo的有效性随pH的增加而增加。对于大多数植物来说,叶片中的微量营养元素含量高于植物的其他部分。因此,可以用叶片作为样品来测定农作物中微量营养元素的含量。大多数微量营养元素缺乏表现在植物顶部的新叶上,而过量则表现在老叶上。根据Deckers和Steinnes的结论,土壤较为贫瘠的发展中国家与土壤肥沃的欧洲及北美地区相比,微量营养元素缺乏现象较为普遍。许多营养元素缺乏区位于潮湿的热带地区,土壤极度贫瘠、高度风化和/或强淋溶,营养元素十分匮乏。此类其他土壤分部于半干旱及毗邻地区,这些地区的碱性和石灰性土壤条件严重限制了微量营养素对植物的供给。通常,可以满足草料作物生长的Cu、 Fe、Mn、 Zn 、Se含量水平,却不能满足家畜的需要。Se是植物生长所不需要的微量元素,因此草料作物中Se的含量很少。然而,如果动物所食农作物和草料中Se含量偏低,会造成严重的肌肉异常和其他疾病。白肌病是最常见的由于Se缺乏造成的疾病,在牛犊和羔羊中都有发现。本文讨论了与动物需求相关的农作物微量营养元素充足度。  相似文献   

5.
Ironstones from Killara, 56 km northeast of Meekatharra, Western Australia, contain up to 1800 ppm Cu or up to 600 ppm Zn. A Cu anomaly is shown by the plus 8 and 8 to 36-mesh fractions of the soils but no indication is given by the finer fractions. No Zn anomaly is shown by any soil size fraction. Closely spaced percussion drilling along the Cu anomaly showed that the ironstones overlie carbonaceous shales intruded by metadolerites; the maximum Cu content of these rocks is 190 ppm. The shales and, in particular, the dolerites have traces of sulphides, mostly primary and secondary pyrite and, in places, chalcopyrite. The highest Cu contents in the weathered zone occur mostly at contacts between the shales and dolerites, where copper is concentrated in iron oxides and, to a lesser extent, manganese oxides. On artificial weathering, the shales and dolerites give pH readings of 4.3 and 7.0, respectively; the optimum redox conditions for the coprecipitation of copper with goethite and the precipitation of manganese oxides appear to occur close to the contacts, at the interface between the two environmentsThe absence of the common pathfinder elements and the lack of a hydromorphic dispersion halo around the ironstones are indicative of pseudo-gossans but are not diagnostic criteria. However, these features may assist in determining priorities in the selection of drilling targets.  相似文献   

6.
The major, trace and rare earth element (REE) composition of Late Archean manganese, ferromanganese and iron ores from the Iron Ore Group (IOG) in Orissa, east India, was examined. Manganese deposits, occurring above the iron formations of the IOG, display massive, rhythmically laminated or botryoidal textures. The ores are composed primarily of iron and manganese, and are low in other major and trace elements such as SiO2, Al2O3, P2O5 and Zr. The total REE concentration is as high as 975 ppm in manganese ores, whereas concentrations as high as 345 ppm and 211 ppm are found in ferromanganese and iron ores, respectively. Heavy REE (HREE) enrichments, negative Ce anomalies and positive Eu anomalies were observed in post‐Archean average shale (PAAS)‐normalized REE patterns of the IOG manganese and ferromanganese ores. The stratiform or stratabound shapes of ore bodies within the shale horizon, and REE geochemistry, suggest that the manganese and ferromanganese ores of the IOG were formed by iron and/or manganese precipitation from a submarine, hydrothermal solution under oxic conditions that occurred as a result of mixing with oxic seawater. While HREE concentrations in the Late Archean manganese and ferromanganese ores in the IOG are slightly less than those of the Phanerozoic ferromanganese ores in Japan, HREE resources in the IOG manganese deposits appear to be two orders of magnitude higher because of the large size of the deposits. Although a reliable, economic concentration technique for HREE from manganese and ferromanganese ores has not yet been developed, those ores could be an important future source of HREE.  相似文献   

7.
通过对华北地区几种土壤和胶膜中某些性质及元素的相关分析和因子分析。比较了铁锰胶膜和基质土壤的性质及元素含量之间的关系。研究表明,(1)铁锰胶膜的pH值,粘粒含量,K2O,Na2O,MnO2,非晶质铁,铁的活化度,微量元素等的含量均比基质土壤的高,且差异显著;(2)铁锰胶膜富集重金属元素,Co,Ni,Cu和Zn等元素主要富集于胶膜的氧化锰矿物中,而Pb主要富集在氧化铁矿物中;(3)Mg在铁锰胶膜的形成过程中进一步淋溶,以致含量减少。  相似文献   

8.
铁锰氧化物在污染土壤修复中的作用   总被引:22,自引:0,他引:22  
矿物学在环境科学中的应用将是21世纪矿物学研究的一个主要方面。土壤污染作为一个制约人类社会可持续发展的基本问题正受到日益广泛的关注,污染土壤的修复已成为环境科学研究的一个重点。污染土壤的修复技术主要有物理、化学、生物等方法,但是,它们都不同程度地存在着缺陷。众所周知,铁和锰是自然界中少数但常见的变价元素。含有变价元素和带有表面电荷的铁锰氧化物具有良好的表面活性,不仅对有毒有害的无机污染物具有良好的净化功能,而且对土壤中有机污染物具有氧化降解作用。利用这些矿物来修复污染土壤,具有成本低、无二次污染等优点,体现出天然净化作用的特色,展现出广阔的环境矿物学应用前景。  相似文献   

9.
 Sediment and its associated pore water were collected from a zoned, freshwater, riparian wetland, located in the Talladega National Forest, northeastern Hale County, Alabama, to study the porewater chemistry and its spatial changes within and between the wetland ecological zones. Obvious changes in pH, Eh and element concentrations were observed between the different wetland ecological zones. Major cations (Ca, Mg, and Na) and trace elements (B, Ba, Sr, and Mn) have very good spatial correlation with Fe and Mn distributions, both in the pore water and the sediment, suggesting that adsorption on, and desorption from, iron and manganese oxyhydroxides are important processes controlling the distributions of these elements in the wetland sediment. However, an equilibrium adsorption model is not able to explain the distribution of trace elements between the pore water and sediment. A redox kinetic model gives similar vertical profiles for iron and the correlated elements as those measured in the field and thus suggests that the relative rates of ferrous iron oxidation and the reductive dissolution of ferric iron in the sediment are important variables determining the distributions of these elements in the wetland pore waters. Received: 31 October 1996 · Accepted: 27 May 1997  相似文献   

10.
The importance of trace metal scavenging by organic matter in geochemical samples was estimated using an alkaline sodium hypochlorite extraction to leach copper, zinc, molybdenum, iron and manganese from a variety of soils, and stream and lake sediments collected on the Nechako plateau, central British Columbia. The reagent oxidizes or dissolves most forms of organic matter, together with any sulphide minerals, to give strongly coloured extracts containing the associated trace elements at a pH where solution of other sample fractions is at a minimum. Metals precipitated due to alkaline conditions are redissolved by a succeeding distilled-water leach (pH 3.0 ± 0.3).A large fraction of the copper, zinc, molybdenum, and manganese held within the organic fraction of the A soil horizon is liberated whereas only minor amounts of copper, zinc, and manganese are released from inorganic soil (B and C) horizons. Molybdenum, however, is relatively soluble in all soils as the molybdate ion. Despite similar concentrations of organic matter in A horizon soils and stream sediments the latter release a lower proportion of their trace element content. Behaviour of the organic fraction of lake sediments varies from lake to lake and there is great variability in the association of copper, zinc, molybdenum and manganese with organic matter even within the same lake.The presence of organic matter in samples subjected to other partial extractions can be a deleterious factor if the organic fraction is not first removed by a hypochlorite extraction.  相似文献   

11.
The role of both natural weathering and anthropogenic pollution in controlling the distribution of major oxides and several trace elements in soils, stream sediments, and rocks of the Fiume Grande catchment was evaluated. The contents of major oxides and trace elements in soils appear to be governed by weathering and pedogenetic processes, although the use of fertilizers in agriculture could also partly affect K2O and P2O5 contents. Stream sediments have concentrations of major oxides (except CaO) very similar to soils, as relevant amounts of soil materials are supplied to the stream channels by erosive phenomena. In contrast, stream sediments have concentrations of Cr, Co, Ni, Zn, As, and Pb significantly higher than those of soils, probably due to different conditions and rates of mobility of these elements within the three considered matrices and/or disposal of wastes in the drainage network. Comparison of the concentrations of PHEs in soils with the maximum admissible contents established by the Italian law shows that these limits are too restrictive in some cases and too permissive in other ones. The approach of setting these limits with no consideration for the local geological–geochemical framework may lead to improper management of the territory and its resources. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.  相似文献   

12.
溶解态的锰和铁是海洋中重要的生物营养元素,也是探查海底热液活动及其演化的重要示踪剂.由于海底热液活动研究的迫切需求,以及AUV,ROV和HOV等水下运载支撑平台的迅速发展,20世纪80年代以来深海溶解态锰铁原位分析技术得到了快速发展.早期研发的Scanner和SUAVE,可对热液羽流中高含量的锰铁元素实现联合测定,但存在元素之间相互干扰等问题,因此针对锰、铁元素单独测量的原位分析仪应运而生.锰原位分析仪中,ZAPS虽然具有较低的检测限,但是无法在深海高压环境下进行原位校正;GAMOS系列具有原位校正功能,且能耗较低,可长期运行,但是检测限偏高,因此只能应用于热液环境中含量相对高的锰监测.铁原位分析仪中,改进的ALCHIMIST可实现热液喷口异常高含量铁和正常海域水体中低含量铁的检测,但由于能耗较高而难以应用于长期观测中;低能耗的Fe-Osmo-Analyzer和CHEMINI则在长期运行方面有着明显的优势.随着AUV/ROV/HOV等水下移动平台应用的日渐广泛以及海底观测网技术的迅速发展,发展原位分析仪进行长期的自主观测将成为一种必然趋势.  相似文献   

13.
The chemical attenuation of acidity and selected elements (aluminum, arsenic, cadmium, cobalt, chromium, copper, fluorine, iron, manganese, nickel, and zinc) in acidic leachates from coal mineral wastes by four natural subsurface soils has been investigated using laboratory column methods Leachate solutions were allowed to percolate through the soils under simulated natural flow conditions, and the elemental concentrations in the influents and effluents were measured periodically Elemental retentions were substantial for all species except managanese, which was eluted in excess from all soils except the most calcareous Two processes appeared to operate in decreasing influent concentrations: (1) precipitation of solid phases caused by increased pH of the leachate as it percolated through the soil, and (2) adsorption of elements onto exchange and sorption sites naturally present in the soil and on iron and aluminum oxide precipitates formed in situ from leachate components because of the increased pH The soil property most important in retention was its alkalinity Thus, carbonaceous soils provide the best control material for acidic leachates from coal mineral wastes. Results show that natural soils can substantially reduce pollutant fluxes to the environment from acidic coal waste dumps and should be considered when selecting waste disposal sites Performed under the auspices of the U.S. Department of Energy  相似文献   

14.
《Applied Geochemistry》1986,1(1):111-116
Consideration of the geochemistry of Cl and I suggests that both elements would be useful pathfinders for hydrothermal mineralization. The results of published case studies indicate that these halogens form broad dispersion patterns in rocks and soils around many types of such mineral deposits.Simple and reliable automated photometric methods for the determination of these elements have been developed and sample preparation techniques are easily adapted to the rapid throughput of the large numbers of samples required for geochemical prospecting. Cold water extractable Cl and I in soils show strong correlation with total Cl and I concentrations and provide a rapid mthod for the detection of anomalies associated with mineralization.  相似文献   

15.
Soils in New Zealand, and elsewhere, often contain substantial zones of ferro-manganese concretions and pans (laterally continuous layers) that can affect soil quality and management. Soils containing concretions and pans from Southland, New Zealand, were investigated to determine links between microbial ecology and geochemistry. Three soil profiles were sampled at 100-mm intervals to a depth of 1 m and then assayed for nine different populations of bacteria using selective media. Geochemical analysis was performed on the soils at the same intervals, and on shallow groundwater from nearby wells. The largest concentrations of iron (Fe) and manganese (Mn) coincide with concretions. Nitrogen (N) and carbon (C) are not correlated with Fe and Mn but may be depleted due to bacterial metabolism. Fe and Mn concentrations in groundwater are low, suggesting that the source of these elements in the concretions and pans is in situ weathering rather than groundwater. Numbers of iron oxidising organisms increase where concretions and pans are encountered, but manganese-oxidising organisms decrease. Heterotrophic, sulphur-oxidising, and anaerobic populations have relatively consistent numbers at all depths within the profiles. Fifty organisms were selected for phylogenetic characterisation, of which only Pseudomonas sp. is known to have significant interactions with Fe and Mn. These results suggest a link between concretion development and iron-oxidising microbial populations.  相似文献   

16.
Measurements of palaeomagnetic horizontal remanent intensity, saturation isothermal remanence, coercivity of remanence, high field remanence and magnetic susceptibility, have been made on lateglacial and postglacial sediments from two small, inter-drumlin hollow lakes from central Northern Ireland. These magnetic measurements have been compared with pollen and chemical analyses from the same profiles and with complementary mineral magnetic data from local soils. Representative sediment samples have also been divided into a range of particle size fractions and each fraction has been subjected to magnetic investigation. Five distinctive stratigraphic horizons have been identified on the basis of the magnetic mineralogy. Two horizons relate to phases of pronounced erosion. One of these is connected with solifluction processes in the lateglacial and the other to an intensive period of farming activity which started in Medieval times. Two horizons are associated with periods of very high iron and manganese deposition and are possibly related to the precipitation of magnetic minerals within the lake. Hydrological changes during periods of local anthropogenic activity appear to produce magnetic mineral assemblages indicative of stream bed/bank substrate sources. The particle size data also support the suggestion that downcore changes in the mineral magnetic record are mainly caused by changes in the sediment source rather than particle size or sedimentological effects.  相似文献   

17.
The remobilization of iron, manganese, cobalt, cadmium, copper and zinc in the pore water of estuarine sediment cores at Yingkou was assessed using diffusive equilibrium in thin films and diffusive gradients in thin films techniques. A relatively anoxic system (+33.7 to ?224.1 mV) in the sediment cores might cause the reductive release of iron, manganese and cobalt into pore water from the estuarine sediment. High-average concentrations of iron (47.85 μg ml?1) and manganese (3.81 μg ml?1) were observed using diffusive equilibrium in thin films on the sediment core, but the concentration of cobalt (18.02 ng ml?1) was relatively low. A strong correlation between iron and cobalt was observed based on the vertical profiles of the metals. Manganese and iron were more readily released from the solid phase to the solution. The peak cobalt, copper and zinc concentrations were observed in the upper layer (2–4 cm) measured using diffusive gradients in thin films. However, the peak iron, manganese and cobalt concentrations were located in the deeper layer (≥7 cm). In addition, the concentration profiles measured using diffusive gradients in thin films of cobalt, copper and zinc were independent of the iron, manganese and cobalt distribution with respect to depth.  相似文献   

18.
Metal concentrations from stream waters in two geological blocks in Northern Ireland were compared to determine the contributions of catchment characteristics and in-stream conditions. One block is composed of metamorphosed schist and unconsolidated glacial drift with peat or peaty podzol (mainly humic) soils, while the other block consists of tertiary basalt with brown earth and gley soils. Water samples were collected from 52 stream sites and analysed for iron (Fe), manganese (Mn) and aluminium (Al) as well as a range of other chemical determinands known to affect metal solubility. Densities of metal-rich ochre deposit were determined for stream bed stone samples. Higher conductivities and concentrations of bicarbonate, alkalinity, calcium and magnesium occurred on basalt than on schist. Despite higher Fe and Mn oxide concentrations in basalt-derived non-humic soils, stream water concentrations were much lower and ochre deposit densities only one-third of those on schist overlain by humic soils. Neither rock nor soil type predicted Al concentrations, but pH and dissolved oxygen did. Peat-generated acidity and the limited acid neutralising capacity of base-poor metamorphosed schist have resulted in elevated concentrations of metals and ochre deposit in surface waters.  相似文献   

19.
The elemental geochemistry of major, minor and trace elements in iron–manganese cutans and the corresponding matrix soils, collected from three Alfisols in central China, are studied using their chemical compositions as well as correlation and factor analyses. Fe–Mn cutans accumulate high concentrations of MnO2 and Fe2O3. Mean values of these two elements in cutans are about 13.7 and 1.4 times higher than those in the matrix soils. pH, clay contents, extractable X-ray noncrystalline Fe (Feo) and the ratio of Feo to free Fe-oxide (Fed) in cutans are notably higher than those in the corresponding matrices. Cutans are also enriched in some bases and heavy metals. Averages of K, Na, Co and Pb concentrations are about 2.0, 1.4, 15.4 and 6.0 times higher than those in the matrices. Statistical analysis indicates that Co, Ni, Li, Cu and Zn are abundant in Mn minerals of cutans, while Pb exists mainly in iron minerals. Fe–Mn cutans constitute an active microzone of solid–solution–plant–air interaction, element movement and exchange in soils, which cause the contents of Fe- and Mn-oxides, elemental concentrations, and geochemical behavior of cutan to show marked differences in matrix soils.  相似文献   

20.
The Lower Krol sediments consist of intercalations of dolomite with shales in the marginal areas (Solan and Nainital), while limestones are interbedded with marls in the central part of the basin (Massoorie). The Upper Krols are largely composed of dolomites with subordinate limestones and shales.The non-carbonate detrital fraction is dominated by quartz with minor amounts of orthoclase, microcline and plagioclase feldspars. Illite and chlorite constitute the dominant clay minerals, lesser amounts of corrensite and kaolinite are sometimes present. An eastward increase in illite and decrease in chlorite has been ascribed to the supply and distribution of the terrigenum.Zirconium, rubidium, strontium, zinc, nickel and manganese were determined by X-ray fluorescence. Early diagenetic dolomites contain Sr, Zn, Ni and Mn in trace amounts, while the late diagenetic dolomites are characterized by an absence of these elements. The posttectonic dolomites are unusually rich in iron, manganese and sometimes in zinc.Authigenic formation of alkali feldspars, chlorite, illite, quartz and pyrite is not uncommon. The feldspars appear to have formed at early and late diagenetic stages. Potash feldspars dominate over albite in association with dolomite, whereas albite tends to be more common in the limestones.The Krol sedimentation seems to have started in a shallow coastal lagoon behind a barrier beach, upwards changing into tidal-flat deposits.  相似文献   

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