Borehole water and hydrologic model around the Nojima fault, SW Japan     

K. Fujimoto  A. Ueda  T. Ohtani  M. Takahashi  H. Ito  H. Tanaka  Anne-Marie Boullier 《Tectonophysics》2007,443(3-4):174

The active fault drilling at Nojima Hirabayashi after the 1995 Hyogoken-nanbu (Kobe) earthquake (M_JMA = 7.2) provides us with a unique opportunity to investigate subsurface fault structure and the in-situ properties of fault and fluid. The borehole intersected the fault gouge of the Nojima fault at a depth interval of 623 m to 625 m. The lithology is mostly Cretaceous granodiorite with some porphyry dikes.The fault core is highly permeable due to fracturing. The borehole water was sampled in 1996 and 2000 from the depth interval between 630 and 650 m, just below the fault core. The chemical and isotopic compositions were analyzed. Carbon and oxygen isotope ratios of carbonates from the fault core were analyzed to estimate the origin of fluid.The following conclusions were obtained. (1) The ionic and isotopic compositions of borehole water did not change from 1996 to 2000. They are mostly derived from local ground water as mentioned by Sato and Takahashi [Sato, T., Takahashi, M., 2000. Chemical and isotopic compositions of groundwater obtained from the Hirabayashi well. Geological Survey of Japan Interim Report No. EQ/00/1, 187–192.]. (2) Geochemical speciation revealed that the borehole water was derived from a relatively deep reservoir, which may be situated at a depth of 3 to 4 km where the temperature is about 80–90 °C. (3) The shallower part of the Nojima fault (shallower than the reservoir depth) has not been healed from the hydrological viewpoints 5 years after the event, in contrast to the rapid healing detected by S wave splitting [Tadokoro, K., Ando, M., 2002. Evidence for rapid fault healing derived from temporal changes in S wave splitting, Geophys. Res. Lett., 29, 10.1029/2001GL013644.]. (4) Precipitation of calcite from the present borehole water since drilling supports the idea of precipitation of some calcite in coseismic hydraulic fractures in the fault core [Boullier, A-M., Fujimoto, K., Ohtani, T., Roman-Ross, G., Lewin, E., Ito, H., Pezard, P., Ildefonse, B., 2004. Textural evidence for recent co-seismic circulation of fluids in the Nojima fault zone, Awaji Island, Japan., Tectonophysics, 378, 165–181.]. (5) Carbon and oxygen isotope ratios of calcite indicated that the meteoric water flux had been localized at the fault core. (6) A difference in the carbon isotope ratio between the footwall and the hanging wall suggests that the fault has been acted as a hydrologic barrier, although the permeability along the fault is still high.  相似文献   

电感耦合等离子体质谱法测定砂岩型铀矿样品中分步提取的铀   总被引：1，自引：0，他引：1  

武朝晖  郭冬发  张彦辉  刘汉彬  郭虹  薛丽丽 《铀矿地质》2007,23(6):371-379

本文研究地质样品中铀形态的分析方法及应用技术,以进一步说明铀形态分析在地球化学找矿中的重要作用。该方法参考Tessier流程,将样品中的铀分为可交换离子态、碳酸盐结合态、铁锰氧化物结合态、硫化物及有机物结合态和结晶态,分别提取,提取溶液用高分辨率电感耦合等离子体质谱仪进行测量。设计的形态提取配方具有良好的可选择性和可重复性,经过国家标准物质、国际形态标准物质和人工模拟样品验证,证明形态提取试剂配方适合所定义的形态分析。通过对实际样品(总量铀为635μg/g)验证表明,碳酸盐结合态铀提取结果的可重复性最好(RSD为2.6%),其次为硫化物及有机物结合态铀(RSD为4.0%)、结晶态铀(RSD为6.0%)和铁锰氧化物结合态铀(RSD为6.1%),可交换离子态铀提取结果的可重复性最差(RSD为26%)。碳酸盐结合态铀与结晶态铀之比,可以用于反映地下铀矿的存在概率。  相似文献   

Partitioning and Speciation of Trace Metal Diagenesis in Differing Depositional Environments in the Sediments of the Oman Margin     

Rengasamy?AlagarsamyEmail author  George?A.?Wolff  Roy?Chester 《Aquatic Geochemistry》2005,11(2):195-213

Organic-rich sediment samples collected from a transect within, and below, the Oman Margin oxygen minimum zone (OMZ) were analysed using a sequential leaching technique to characterise the diagenetic behaviour and speciation of Mn and Fe in operationally defined sediment host fractions. Trace metals showed distinct diagenetic behaviour in the two contrasting environments that were sampled. The absence of non-detrital Mn in the cores below the OMZ site is attributed to the lack of easily reducible oxides in surficial sediments and to the reduction and export of any moderately reducible aged oxides. The reactive form of solid phase Mn showed a classic feature of enrichment in the upper layer of the sediments at the abyssal site, reflecting the presence of an oxidising sedimentary layer which acts as a Mn trap during its recycling. The diagenetic Mn enrichment was inferred from typical downcore colour changes and an upward-increasing Mn content in the upper core sections. An easily reducible Fe oxide layer was observed in the abyssal sediments at an identical depth to the Mn enrichment suggesting that Fe associated with Mn oxides also has undergone sub-oxic diagenesis. However, the association of Fe with organic matter did not indicate diagenetic modification; i.e., the binding strength of the metal with organic materials appears to be sufficiently strong to preserve the trace metal. The speciation signature of non-detrital Fe differed from that of Mn. The association of Fe with organic matter suggests that this metal does not undergo diagenetic modification and is preserved in abyssal sediments. The contrasting behaviour of Mn and Fe observed between cores within the OMZ were particularly interesting. Another interesting observation was that, for cores below the OMZ, the iron oxides were associated with the Mn-oxide peak, rather than deeper in the sediments as observed by earlier studies in the Atlantic [Froelich et al. (1979). Geochim. et Cosmochim Acta 43, 1075–1090].This revised version was published online in May 2005 with corrections to the article title.  相似文献   

Temporal Variability of Iron Speciation in Coastal Rainwater     

Joan D. Willey  Robert J. Kieber  Kelly H. Williams  Jamie S. Crozier  Stephen A. Skrabal  G. Brooks Avery Jr. 《Journal of Atmospheric Chemistry》2000,37(2):185-205

Iron occurs in rain as particulateand dissolved Fe and includes both Fe(II) and Fe(III)species. Model calculations and correlation analysisindicate Fe(II)(aq) occurs almost exclusively as thefree ion whereas Fe(III)(aq) occurs as both ironoxalate and Fe(OH)₂ ⁺(aq) with largevariations over the pH range from 4.0 to 5.0. Complexation with humic-like compounds may also beimportant for Fe(III)(aq); however, the concentrationand structural characteristics of these compounds haveyet to be determined. 112 rain samples were collectedfor iron analysis in Wilmington, North Carolina,between 1 July 1997, and 30 June 1999. Total iron,particulate iron and Fe(III)(aq) were higher inconcentration in summer and spring rain relative towinter and autumn rain. Fe(II)(aq) concentrations, incontrast, did not vary seasonally. Particulate iron,which was approximately half the total rainwater iron,was highest between noon and 6 p.m. (EST), probably dueto more intense regional convection including land-seabreezes during that time. The ratio ofFe(II)(aq)/Fe(III)(aq) was also highest in rainreceived between noon and 6 p.m., which most likelyreflects photochemical reduction of Fe(III)(aq)complexes to form Fe(II)(aq). A conceptual modeldepicting the interplay between iron species, lightintensity and organic ligands in rainwater ispresented.  相似文献   

A comparison of iron limitation of phytoplankton in natural oceanic waters and laboratory media conditioned with EDTA     

L. J. A. Gerringa  H. J. W. de Baar  K. R. Timmermans 《Marine Chemistry》2000,68(4)

The solubility of iron in oxic waters is so low that iron can be a limiting nutrient for phytoplankton growth in the open ocean. In order to mimic low iron concentrations in algal cultures, Ethylenediaminetetraacetate (EDTA) is commonly used. The presence of EDTA enables culture experiments to be performed at a low free metal concentration, while the total metal concentrations are high. Using EDTA provides for a more reproducible medium. In this study Fe speciation, as defined by EDTA in culture media, is compared with complexation by natural organic complexes in ocean water where Fe is thought to be limited. To grow oceanic species into iron limitation, a concentration of at least 10⁻⁴ M EDTA is necessary. Only then does the calculated [Fe³⁺] concentrations resemble those found in natural sea water, where the speciation is governed by natural dissolved organic ligands at nanomolar concentrations. Moreover, EDTA influences the redox speciation of iron, and thus frustrates research on the preferred source of Fe-uptake, Fe(III) or Fe(II), by algae. Nowadays, one can measure the extent of natural organic complexation in sea water, as well as the dissolved Fe(II) state, and can use ultra clean techniques in order to prevent contamination. Therefore, it is advisable to work with more natural conditions and not use EDTA to create iron limitation. This is especially important when the biological availability of the different chemical fractions of iron are the subject of research. Typically, many oceanic algae in the smallest size classes can still grow at very low ambient Fe and are not easily cultivated into limitation under ambient sea water conditions. However, the important class of large oceanic algae responsible for the major blooms and the large scale cycling of carbon, silicon and other elements, commonly has a high Fe requirement and can be grown into Fe limitation in ambient seawater.  相似文献   

Distribution and speciation of mercury in soil in the area of an ancient mercury ore roasting site,Frbejžene trate (Idrija area,Slovenia)     

Tamara Teršič  Mateja Gosar  Harald Biester 《Journal of Geochemical Exploration》2011

In the initial period of mining activities in the Idrija basin (the16^th and the first half of the17^th centuries), Hg ore processing was performed at various small-scale roasting sites in the woods surrounding Idrija, by roasting ore in earthen vessels. The recovery rate of this method was very low; about half of Hg was lost, causing soil contamination and considerable amounts of waste material that could potentially leach Hg into the surrounding environment. The main aims of present geochemical study were to determine the contents, vertical distribution and speciation of Hg in soils at the roasting site at Frbej?ene trate in order to verify the extreme pollution of ancient Hg ore roasting sites in the Idrija area and to establish their significance in the wider spatial contamination of soils and aquatic systems. Soil sampling was performed at the area of the former roasting site. The organic matter-rich surface soil layer (SOM) and underlying mineral soil were sampled at 63 sampling locations. Mercury speciation was performed using Hg thermo-desorption-AAS to distinguish cinnabar from potentially bioavailable forms. The results indicate extremely high Hg concentrations with a maximum of 37,000 mg/kg in SOM and 19,900 mg/kg in mineral soil. The established Hg median in soil was 370 mg/kg and in SOM 96.3 mg/kg. Spatial distributions of Hg in SOM and soil showed very high Hg contents in the central area and decreased rapidly with distance. The results of Hg thermo-desorption measurements indicated the presence of cinnabar (HgS) and Hg bound to organic or mineral soil matter. A significant portion (35–40%) of Hg in the investigated soil and SOM samples was comprised of non-cinnabar compounds, which are potentially bioavailable. It has been shown that soils contain high amounts of potentially transformable non-cinnabar Hg, which is available for surface leaching and runoff into the surrounding environment. Therefore, contaminated soils and roasted residues at the studied area are important for persistent Hg release into the aquatic ecosystem.  相似文献   

长江主要支流与干流沉积物的REE组成   总被引：1，自引：0，他引：1  

杨守业  王中波 《矿物岩石地球化学通报》2011,30(1):31-39

系统采集了长江主要支流与干流从上游到下游不同地区的河漫滩沉积物样品,用1 M盐酸淋滤处理研究了REE在不同相态中的组成特征。研究表明,长江沉积物中REE主要赋存于酸不溶相中,约占总含量的70%。不同REE的酸提取效率不同,酸溶相明显富集REE,主要受磷灰石等磷酸盐矿物和部分Fe-Mn氧化物矿物的控制。主要赋存于粘土矿物中的不同轻稀土元素在酸溶相中百分比接近,而富重稀土元素的重矿物可以明显影响REE在不同相态中的组成和不同地区河流沉积物中REE的配分特征。长江支流沉积物的REE组成变化大于干流,流域源岩组成差异是控制REE组成的基本因素,但干流和支流沉积物全样与酸不溶相的REE配分模式基本类似,反映了各自流域风化上陆壳的平均组成。尽管一些支流对邻近干流沉积物的REE组成贡献较大,但总体上干流样品代表了不同支流水系沉积物的混合,尤其是下游近河口地区细粒级沉积物样品的酸不溶组分可以代表长江入海颗粒物的平均REE组成,用于示踪判别东部边缘海长江沉积物的源汇过程。  相似文献   

水环境及水产品中汞的测定与形态分析进展     

杨桂朋  张启华 《中国海洋大学学报(自然科学版)》2011,41(11):67-80

概要总结了世界各地对水环境及水产品中汞的测定与形态分析的研究成果,涵盖样品采集、储存、传递与处理,各种色谱(薄层色谱、气相色谱、液相色谱、电色谱和离子色谱)分离分析方法及其联用技术,以及分光光度法、电化学法、原子吸收光谱和原子荧光光谱的应用等。并对未来发展提出了改进建议。  相似文献   

Speciation in gall-inducing thrips on Acacia in arid and non-arid areas of Australia     

M. McLeish 《Journal of Arid Environments》2011,75(9):793-801

Habitat modification mediated by abiotic processes imposes consequences for the diversification of plants and plant specialists. Host plant diversification is expected to be dependent on environmental and ecological constraints that are fundamentally connected to physiography (physical geography). A phylogenetic approach is used to reconstruct ancestral host plant affiliation of gall-inducing thrips that specialize on Australian Acacia. Diversification rate models are applied to gall-thrips clades that are affiliated with different Acacia host lineages. Gall-thrips diversification is reconciled with contemporary patterns of species diversity relating to the different host lineages. Results indicate that diversification on host lineages that are mostly distributed in non-arid areas are best explained by a rate-constant model. However, this model disguised additive effects of rate-variable lineage accumulation that indicated diversification decreases in sub-clades within this larger group. Gall-thrips affiliated with hosts distributed mostly in arid areas were best characterized by rate-variable decreasing net diversification. The work infers parent gall-thrips lineages are less species diverse compared to daughter lineages that tend to be distributed away from the arid interior of Australia. Contrasting ecological and environmental interactions unique to parent and daughter lineages are suggested to influence the mode of speciation and phenotypic diversity represented by each.  相似文献   

Spatial and temporal variability in the concentration and speciation of metals in suspended sediment transported by the River Aire,Yorkshire, UK     

Julie Carter  Desmond E. Walling  Philip N. Owens  Graham J. L. Leeks 《水文研究》2006,20(14):3007-3027

In recent years, there has been an increasing awareness of the important role of fine sediment in the transport and storage of metals in fluvial systems. However, there has been little research on the behaviour of contaminated sediment in industrial rivers in the UK. This paper examines spatial and temporal variations in the concentration and speciation of lead, copper and chromium associated with suspended sediment in the River Aire in Yorkshire, UK. An increase in the total concentration of all three metals in sediment was identified in the lower reaches, which reflected inputs of road dust, sewage and industrial effluents. Spatial variations in the chemical speciation of the metals were also identified. The iron–manganese oxides and organic fractions were the most significant for the adsorption of metals by sediment. Both the concentrations and speciation of sediment‐associated metals exhibited substantial temporal variation. Such variation reflected the accumulation of metals and organic matter on the river‐bed during low flows, the subsequent remobilization of the sediment at high flows and the additional supply of sediment from uncontaminated and contaminated sources, including pulse inputs of road dust, sewage and industrial effluent. The findings presented have important implications for the development of effective catchment management strategies for the control of point‐ and diffuse‐source pollution. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献