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651.
652.
Soil parent materials and soil properties in two separate catchment areas on the Jos Plateau, Nigeria 总被引:1,自引:0,他引:1
E.A. Olowolafe 《GeoJournal》2002,56(3):201-212
On the Jos Plateau, soils derived from basalt and volcanic ash are much more intensively and extensively utilized for agricultural
purposes than the granite soils. This study was carried out to determine the differences that may have contributed to this
discrimination. Twenty four soil profiles were dug and described in two separate catchment areas that really portray the variance.
Soil samples were analysed using standard procedures. The results show that basalt and volcanic ash-derived soils have relatively
deeper profiles, lower bulk density, higher contents of clay, organic matter, exchangeable bases, micro-nutrients (Cu & Zn)
and weatherable minerals. They are also higher in their CEC and base saturation percentage while available water capacity,
hydraulic conductivity and natural water content are more adequate in them. Hence, the basalt and volcanic ash soils are more
favourable for crop growth while the deficiencies in granite soils present more constraints to agricultural land use. Consequently,
there are differences between the soil types in their crop-yielding capacities. These differences constitute a reflection
of soil parent material influence. Agriculture in the area is mainly low-input. There is the need for improved management
practices for the enhancement of soil conditions of granite areas in particular and the whole area in general.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
653.
654.
Determination of Forty Two Major and Trace Elements in USGS and NIST SRM Glasses by Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry 总被引:39,自引:0,他引:39
Shan Gao Xiaomin Liu Honglin Yuan Bodo Hattendorf Detlef Günther Liang Chen Shenhong Hu 《Geostandards and Geoanalytical Research》2002,26(2):181-196
Forty two major (Na, Mg, Ti and Mn) and trace elements covering the mass range from Li to U in three USGS basalt glass reference materials BCR‐2G, BHVO‐2G and BIR‐1G were determined using laser ablation‐inductively coupled plasma‐mass spectrometry. Calibration was performed using NIST SRM 610 in conjunction with internal standardisation using Ca. Determinations were also made on NIST SRM 612 and 614 as well as NIST SRM 610 as unknown samples, and included forty five major (Al and Na) and trace elements. Relative standard deviation (RSD) of determinations was below 10% for most elements in all the glasses under investigation. Consistent exceptions were Sn and Sb in BCR‐2G, BHVO‐2G and BIR‐1G. For BCR‐2G, BHVO‐2G and BIR‐1G, clear negative correlations on a logarithmic scale exist between RSD and concentration for elements lower than 1500 μg g‐1 with logarithmic correlation coefficients between ‐0.75 and ‐0.86. There is also a clear trend of increasing RSD with decreasing concentration from NIST SRM 610 through SRM 612 to SRM 614. These suggest that the difference in the scatter of apparent element concentrations is not due to chemical heterogeneity but reflects analytical uncertainty. It is concluded that all these glasses are, overall, homogeneous on a scale of 60 μm. Our first results on BHVO‐2G and BIR‐1G showed that they generally agreed with BHVO‐2/BHVO‐1 and BIR‐1 within 10% relative. Exceptions were Nb, Ta and Pb in BHVO‐2G, which were 14‐45% lower than reference values for BHVO‐2 and BHVO‐1. Be, Ni, Zn, Y, Zr, Nb, Sn, Sb, Gd, Tb, Er, Pb and U in BIR‐1G were also exceptions. However, of these elements, Be, Nb, Sn, Sb, Gd, Tb, Pb and U gave results that were consistent within an uncertainty of 2s between our data and BIR‐1 reference values. Results on NIST SRM 612 agreed well with published data, except for Mg and Sn. This was also true for elements with m/z 85 (Rb) in the case of NIST SRM 614. The good agreement between measured and reference values for Na and Mg in BCR‐2G, BHVO‐2G and BIR‐1G, and for Al and Na in NIST SRM 610, 612 and 614 up to concentrations of at least several weight percent (which were possible to analyse due to the dynamic range of 108) indicates the suitability of this technique for major, minor and trace element determinations. 相似文献
655.
656.
Maria Fernanda Gazulla Maria Pilar Gomez Antonio Barba Monica Orduña 《Geostandards and Geoanalytical Research》2004,28(2):203-212
A wide range of natural raw materials is used in the manufacture of traditional ceramic products such as ceramic tiles, frits, glazes and pigments. The chemical composition of these raw materials needs to be strictly controlled to assure end-product quality and enable the identification of the origin of defects caused by impurities or contamination. Six types of ceramic raw materials (silica sand, clays and kaolin, feldspars and related minerals, calcium and magnesium carbonates, sodium and calcium borates, and zirconium silicates) have been analysed in this study. X-ray fluorescence (XRF), potentiometry, coulometry and atomic absorption spectrometry (AAS) were used in this chemical characterisation. A methodology has been established for characterising each studied raw material, by identifying the chemical elements to be determined, selecting the most appropriate technique and validating each measurement. The reference materials used for validation were BCS CRM 267, 313/1, 393 and 388 (BAS), GBW 03103, GBW 07404, NIST SRM 181, 201a and 1835, Euronorm CRM 782-1 and Syenite SY-2. The results showed that most of the elements present in the geological samples used as traditional ceramic raw materials could be determined by XRF. The determination of light elements, such as lithium, fluorine and boron, is more suitably conducted by ICP-AES/AAS, potentiometry or potentiometry/ICP-AES respectively. Organic and inorganic carbon could be determined by coulometry. Inorganic carbon (CO2 ) could also be determined by coulometry or by thermogravimetry, if samples did not contain clay minerals. Loss on ignition was always determined by gravimetry. 相似文献
657.
新疆准噶尔地区金矿床成矿流体稀土元素地球化学特征 总被引:11,自引:0,他引:11
新疆准噶尔地区出现大量不同类型金矿床,为了探讨它们的成因,为金矿床的找矿勘探提供依据。笔者进行了哈图、包谷图、阔尔真阔腊、科克萨依等金矿床包裹体流体中稀土元素及同位素等研究。结果表明,尽管它们成矿形式不同,规模不等,但它们的金均主要来自深源,并有地层物质参与。其中哈图金矿石英脉型矿体与蚀变岩型矿体是两种不同来源的流体叠加成矿,石英脉型矿体主要与哈图岩体岩浆流体关系密切,蚀变岩型矿体与深源流体有关。包谷图、阔尔真阔腊金矿矿、科克萨依金矿成矿流体主要来源于深源,成矿过程中受到浅成流体的综合影响。矿物包裹体流体的稀土元素特征主要反映了原始成矿流体来源,矿物的稀土元素特征可能较多地体现了矿床特有的后期地质作用,这在今后研究中将进一步探讨。 相似文献
658.
659.
Factors affecting the groundwater chemistry in a highly urbanized coastal area in Hong Kong: an example from the Mid-Levels area 总被引:1,自引:0,他引:1
Chi-man Leung Jiu J. Jiao John Malpas Wing-tat Chan Yan-xin Wang 《Environmental Geology》2005,48(4-5):480-495
Coastal areas of Hong Kong Island are one of the most extensively urbanized areas in the world. Groundwater samples in natural
slopes and developed spaces in the regions centered by the Mid-Levels area, Hong Kong Island, were collected and analyzed
to investigate the natural and anthropogenic processes affecting the groundwater chemistry. The results presented may be of
value to other coastal areas in the world for the identification of possible groundwater contamination sources. Groundwater
samples in the natural slopes were in low total dissolved solid (TDS) (<100 mg/l), indicating that the waters were in the
early evolutionary stage. Using chloride as a normalizing factor, the “non-marine” components of different major ions in the
samples were calculated. The correlation analysis indicated the occurrence of weathering of plagioclase feldspars in the natural
slopes. However, the breakdown of biotite and K-feldspar seems to be limited by short groundwater residence time and high
resistance to weathering. The high variety in hydrochemical facies may suggest the presence of extremely heterogeneous subsurface
geological conditions. In the developed spaces, groundwater samples exhibited a high range of TDS (~100–5300 mg/l) and were
mainly dominated by Na–Cl and Na–Ca–Cl water types. Besides water-rock interactions, the groundwater chemistry was significantly
affected by leakage from service pipes and the dissolution of concrete materials. Some chemicals were used as signatures to
identify the leakage from various service pipes. The area generally suffered from widespread, but small amount of leakages,
and no obvious leakage was discovered. The strong correlations among major cations and chloride suggested that even a small
amount of leakage from salty flushing water pipes can significantly affect the groundwater chemistry. Groundwater is found
to be highly aggressive toward concrete as supported by three commonly used aggressiveness indices. Additional Ca2+ may be released to groundwater by corrosion of subsurface concrete materials such as building foundations and basements.
The strength of those subsurface engineering structures may be weakened. Besides, excess Ca2+ may deposit in the dewatering systems in the area, which may affect their performance in lowering high water tables. The
findings regarding leakage from service pipes will be useful for various government organizations such as the Water Supplies
Department and Drainage Services Department. Discussion of the behavior of Ca2+ is instructional to foundation and slope dewatering designs in the area. 相似文献
660.
稀有气体(特别是He、Ar)是一种研究成矿古流体来源的灵敏示踪剂。地球不同圈层的稀有气体同位素具有不同的特征同位素比值。测试样品流体包裹体中的稀有气体同位素值,从测试值中排除掉包裹体形成后各种后生过程对流体初始同位素组成的影响。把得到的结果与前人研究总结的特征值进行比较分析,可以示踪成矿流体来源,从而探讨各种矿床的成矿机制与成矿作用。归纳了近年来用稀有气体同位素来示踪成矿流体的研究进展,概括了其在不同类型矿床中的应用现状,并指出当前该方法存在的问题及发展趋势。 相似文献