Characteristics of major and trace elements in surface sediments of the Makran Accretionary Prism,Pakistan and their implications for natural gas hydrates     

Jian-ming Gong  Jing Liao  Yu-xi Zhang  Jie Liang  Jian-wen Chen  Nuzhat Khan  Syed Waseem Haider 《China Geology》2021,4(2):299-310

To accurately identify the natural gas hydrates (NGH) in the sea area of the Makran Accretionary Prism, Pakistan, this paper presents the testing and analysis of major and trace elements in sediment samples taken from two stations (S₂ and S₃) in the area by the China Geological Survey. As shown by testing results, all major elements are slightly different in content between the two stations except SiO₂ and CaO. This also applies to the trace elements that include Sr and Ba primarily and Cr, Ni and Zn secondarily. It can be concluded in this study that the tectonic setting of the Makran Accretionary Prism is dominated by oceanic island arc and that provenance of the Makran Accretionary Prism is dominated by felsic igneous provenance, which is at the initial weathering stage and mainly consists of granodiorite. Besides terrigenous detritus, there are sediments possibly originating from Makran-Bela Ophiolite from the northwestern part and Murray Ridge igneous rocks from the southeastern part. The V/Cr, Ni/Co, and V/(V+Ni) ratios indicate that sediments of the two stations are in an oxidation-suboxidation environment. However, the authors infer that the sedimentary environment of the sediments 3.0 m below the seafloor tends to be gradually transformed into a reduction environment by comparison with the Qiongdongnan Basin in the South China Sea where NGH has been discovered. The sediments in the Makran Accretionary Prism are rich in organic matter, with total organic carbon (TOC) content greater than 1%. According to comprehensive research, the organic matter in the sediments mainly originates from marine algae and has high TOC content, which is favorable for the formation of NGH.  相似文献   

Sorptive Potential of Beach Sand to Remove Ni(II) Ions: An Equilibrium Isotherm Study     

Syed Igleem Haider Taqvi  Syed Moosa Hasany  Mohammad Igbal Bhanger 《洁净——土壤、空气、水》2008,36(4):366-372

The potential to remove Ni(II) ions from aqueous solutions using sea beach sand, a carbonate‐quartz mineral, was thoroughly investigated. The effects of relevant parameters such as solution pH, adsorbent dose, metal ions concentration, and temperature on Ni(II) sorption onto beach sand were examined. The sorption data followed the Langmuir, Freundlich and Dubinin‐Radushkevich (D‐R) isotherms. The adsorption was endothermic in nature at ambient temperature and the computation of the parameters, ΔH, ΔS and ΔG indicated the interactions between sorbate and sorbent to be thermodynamically favorable. Equilibrium was achieved very quickly within 30 min of shaking. A pseudo‐first order Lagergren equation was used to test the adsorption kinetics. Other kinetic models, e. g., the Morris‐Weber and Reichenberg equations, were used to calculate the rate constant of intraparticle diffusion and the fate of the diffusion process, respectively. The influence of some of the common cations and anions were also a subject of this study.  相似文献   

Assessing prospects for shrimp culture in the Indian Sundarbans: A combined simulation modelling and choice experiment approach     

D. Knowler  N. Philcox  S. Nathan  W. Delamare  W. Haider  K. Gupta 《Marine Policy》2009

India's Sundarbans region lies within the state of West Bengal and is part of the world's largest mangrove ecosystem. Low-intensity shrimp aquaculture is present, but the potential exists for more intensive development. We argue for avoiding environmental damage and social conflict by adopting appropriate policies now. In this study, we combine ecological simulations and a choice experiment to evaluate several policy scenarios. Such comparative evaluations combining different disciplinary tools are rare. While our ecological modelling supports severe restrictions on shrimp farming activities, local stakeholders prefer a more diverse strategy. Both models indicate that large-scale commercial shrimp aquaculture is least desirable.  相似文献   

Urban Surface Modification as a Potential Ozone Air-quality Improvement Strategy in California: A Mesoscale Modelling Study     

Haider Taha 《Boundary-Layer Meteorology》2008,127(2):219-239

Two of several surface modification (heat-island reduction) strategies, increased surface albedo and urban reforestation, are evaluated via mesoscale meteorological and photochemical modelling of regulatory episodes in central and southern California. The simulations suggest that these strategies can have beneficial impacts on air quality, with increased albedo being relatively more effective than urban reforestation. The simulations also show that air quality indices, such as regional 1-h peaks, area peaks, 8-h relative reduction factors, 24-h averages, etc., improve for both central and southern California and that for the range of strategies evaluated here, the improvements in air quality can be significant. The simulations of southern California suggest that there may be a threshold beyond which further surface modifications tend to produce smaller net improvements in ozone air quality.  相似文献   

Estimating groundwater discharge to surface waters using heat as a tracer in low flux environments: the role of thermal conductivity          下载免费PDF全文

Carlos Duque  Sascha Müller  Eva Sebok  Kinza Haider  Peter Engesgaard 《水文研究》2016,30(3):383-395

Analytical modelling of heat transport was used to address effects of uncertainty in thermal conductivity on groundwater–surface water exchange. In situ thermal conductivities and temperature profiles were measured in a coastal lagoon bed where groundwater is known to discharge. The field site could be divided into three sediment zones where significant spatial changes in thermal conductivity on metre to centimetre scale show that spatial variability connected to the sediment properties must be considered. The application of a literature‐based bulk thermal conductivity of 1.84 Wm^?1 °C^?1, instead of field data that ranged from 0.62 to 2.19 W m^?1 °C^?1, produced a mean overestimation of 2.33 cm d^?1 that, considering the low fluxes of the study area, represents an 89% increase and up to a factor of 3 in the most extreme cases. Incorporating the uncertainty due to sediment heterogeneities leads to an irregular trend of the flux distribution from the shore towards the lagoon. The natural variability of the thermal conductivity associated with changes in the sediment composition resulted in a mean variation of ±0.66 cm d^?1 in fluxes corresponding to a change of ±25.4%. The presence of organic matter in the sediments, a common situation in the near‐shore areas of surface water bodies, is responsible for the decrease of thermal conductivity. The results show that the natural variability of sediment thermal conductivity is a parameter to be considered for low flux environments, and it contributes to a better understanding of groundwater–surface water interactions in natural environments. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Origin and regional significance of late Precambrian and early Palaeozoic granitoids in the Pan-African belt of Somalia     

J. -L. Lenoir  J. -P. Liégeois  D. Küster  A. Utke  G. Matheis  A. Haider 《International Journal of Earth Sciences》1994,83(3):624-641

Granitoids within the Precambrian basement of north-eastern and southern Somalia are subdivided on the basis of geology, geochronology and petrology into three different assemblages. The post-kinematic assemblage in north-eastern Somalia ( 630 Ma) comprises granodiorites and granites which belong to a medium-K calc-alkaline suite. Average initial Sr, Nd and Pb isotopic ratios [Sr_i = 0.7048, _Nd = –1.8,²⁰⁶Pb/²⁰⁴Pb(i) = 17.704 and²⁰⁷Pb/²⁰⁴Pb(i) = 15.611] indicate that these melts were derived from a mantle or juvenile crustal source with only slight involvement of pre-existing crust as a contaminant. Two different assemblages are found in southern Somalia. The older assemblage is composed of crustal anatectic, synkinematic, parautochthonous granites ( 600 Ma) related to amphibolite facies retrogression of an intensively reworked pre-Pan-African crust [Sr_i = 0.7100, _Nd = –8.4,²⁰⁶Pb/²⁰⁴Pb(i) = 15.403 and²⁰⁷Pb/²⁰⁴Pb(i) = 15.259]. These monzo- and syenogranites are moderately potassic and peraluminous. The younger assemblage ( 470 Ma) consists of post-kinematic monzonites to syenogranites with A-type affinities. Initial Sr, Nd and Pb isotopic data for this metaluminous assemblage [Sr_i = 0.7114, _Nd = –13.1,²⁰⁷Pb/²⁰⁴Pb(i) = 16.913 and²⁰⁷Pb/²⁰⁴Pb(i) = 15.512] indicate a significant lower crustal component but, however, also a mantle signature. The late Proterozoic to early Palaeozoic granitoids in Somalia thus express contrasting regimes, characterized by strong juvenile input in the north, close to the Arabian-Nubian Shield, whereas intense crustal reworking with little addition of juvenile material prevailed in the south. Somalia was definitively not a cratonic area during the Pan-African, but a zone of high crustal mobility.  相似文献   

Using multivariate statistical analyses to evaluate groundwater contamination in the northwestern part of Saudi Arabia   总被引：2，自引：1，他引：1  

Taisser Zumlot  Awni Batayneh  Yousef Nazal  Habes Ghrefat  Saad Mogren  Haider Zaman  Eslam Elawadi  Abdalaziz Laboun  Saleh Qaisy 《Environmental Earth Sciences》2013,70(7):3277-3287

Chemical characteristics of groundwater in the Midyan Basin (northwestern Saudi Arabia) were investigated and evaluated. A total of 72 water samples were collected from existing shallow wells and analyzed for different elements. Two multivariate statistical methods, hierarchical cluster analysis (HCA) and principal components analysis (PCA), were applied to a subgroup of the data set in terms of their usefulness for groundwater classification, and to identify the processes controlling groundwater geochemistry. The subgroup consisted of 46 water samples out of 72 samples and 24 variables included major elements (Ca²⁺, Na⁺, Mg²⁺, K⁺, Cl^?, HCO₃ ^?, NO₃ ^?, SO₄ ^2?), minor and trace element (SiO₂, Al, As, B, Ba, Cd, Cr, F, Fe, Mo, P, Pb, Sb, Sn, Ti, and V). For water samples, four geochemically distinct clusters (i.e., C1, C2, C3 and C4) have been observed by hierarchical cluster analysis. Cr, F and Pb are the dominant ions in cluster C2. Al, As, Cd, Mo, Sb and Ti are the dominant ions in cluster C3, while B, Ca, Cl, HCO₃, K, Mg, Na, SO₄ and V are identified as dominant ions in the cluster C4. In the PCA, a total of five components are extracted form the data set, which explained 73.37 % of the total data variability. Among them the first component reveals strong associations between As, B, Cd, Cr, F, Mo, Pb, Sb and Ti. The second component reveals the associations between Ca, Cl, HCO₃, Mg, Na, SO₄ and V.  相似文献   

Radial distribution of production rates, loss rates and densities corresponding to ion masses ?40 amu in the inner coma of Comet Halley: Composition and chemistry     

S.A. Haider 《Icarus》2005,177(1):196-216

In this paper we have studied the chemistry of C, H, N, O, and S compounds corresponding to ions of masses ?40 amu in the inner coma of the Comet 1P/Halley. The production rates, loss rates, and ion mass densities are calculated using the Analytical Yield Spectrum approach and solving coupled continuity equation controlled by the steady state photochemical equilibrium condition. The primary ionization sources in the model are solar EUV photons, photoelectrons, and auroral electrons of the solar wind origin. The chemical model couples ion-neutral, electron-neutral, photon-neutral and electron-ion reactions among ions, neutrals, electrons, and photons through over 600 chemical reactions. Of the 46 ions considered in the model the chemistry of 24 important ions (viz., CH₃OH⁺₂, H₃CO⁺, NH⁺₄, H₃S⁺, H₂CN⁺, H₂O⁺, NH⁺₃, CO⁺, C₃H⁺₃, OH⁺, H₃O⁺, CH₃OH⁺, C₃H⁺₄, C₂H⁺₂, C₂H⁺, HCO⁺, S⁺, CH⁺₃, H₂S⁺, O⁺, C⁺, CH⁺₄, C⁺₂, and O⁺₂) are discussed in this paper. At radial distances <1000 km, the electron density is mainly controlled by 6 ions, viz., NH⁺₄, H₃O⁺, CH₃OH⁺₂, H₃S⁺, H₂CN⁺, and H₂O⁺, in the decreasing order of their relative contribution. However, at distances >1000 km, the 6 major ions are H₃O⁺, CH₃OH⁺₂, H₂O⁺, H₃CO⁺, C₂H⁺₂, and NH⁺₄; along with ions CO⁺, OH⁺, and HCO⁺, whose importance increases with further increase in the radial distance. It is found that at radial distances greater than ∼1000 km (±500 km) the major chemical processes that govern the production and loss of several of the important ions in the inner coma are different from those that dominate at distances below this value. The importance of photoelectron impact ionization, and the relative contributions of solar EUV, and auroral and photoelectron ionization sources in the inner coma are clearly revealed by the present study. The calculated ion mass densities are compared with the Giotto Ion Mass Spectrometer (IMS) and Neutral Mass Spectrometer (NMS) data at radial distances 1500, 3500, and 6000 km. There is a reasonable agreement between the model calculation and the Giotto measurements. The nine major peaks in the IMS spectra between masses 10 and 40 amu are reproduced fairly well by the model within a factor of two inside the ionopause. We have presented simple formulae for calculating densities of the nine major ions, which contribute to the nine major peaks in the IMS spectra, throughout the inner coma that will be useful in estimating their densities without running the complex chemical models.  相似文献   

Late Cretaceous palaeomagnetic results from Sikhote Alin, far eastern Russia: tectonic implications for the eastern margin of the Mongolia Block   总被引：3，自引：0，他引：3  

Yo-ichiro Otofuji  Takaaki Matsuda  Ryo Enami  Koji Uno  Katsuhiko Nishihama  Nadir Halim  Li Su  Haider Zaman  Ruslan G. Kulinich  Petr S. Zimin  Anatoly P. Matunin  Vladimir G. Sakhno 《Geophysical Journal International》2003,152(1):202-214

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An In‐Depth Characterization of Urban Aerosols Using Electron Microscopy and Energy Dispersive X‐Ray Analysis     

Haider A. Khwaja  Pravin P. Parekh  Adil R. Khan  Daniel L. Hershey  Ronaq R. Naqvi  Abdul Malik  Khalid Khan 《洁净——土壤、空气、水》2009,37(7):544-554

The physical and chemical characterization of aerosols from three large cities, Karachi and Islamabad, Pakistan, and New York City (NYC), USA, was investigated. A scanning electron microscope equipped with an energy dispersive spectrometer (EDS) was used to determine particle morphology and elemental composition of the samples. A Bruker Spirit system in combination with a Sahara detector provided both computer controlled Automated Chemical Classification (ACC) and digital mapping features for analysis purposes. The use of these two features to characterize the elemental composition, particle size, and to determine specific classes or source types is described in this paper. Filters were analyzed for the following elements; Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Br, Sr, Y, Zr, Mo, Pd, Ag, Cd, In, Sn, Sb, Ba, La, Au, Hg, Tl, Pb, and U. The EDS work was qualitative not quantitative. Seven source types (mobile, cement, soil, steel mill, fossil fuel, sea salt and biological) contributed to particulate matter in the ambient air of both cities in Pakistan, whereas there were eight source types (diesel, road dust, automobile, iron, residual fuel oil, sea salt, ammonium sulfate and ammonium nitrate) for NYC. For all three urban centers, vehicular traffic emissions were the main contributor to particle number. Diesel emissions from trucks and buses were relatively more prominent in NYC aerosols, while gasoline emission from automotive exhaust was dominant in the two cities of Pakistan. The cement/limestone component from local cement industries was very evident in both particle surface characteristics and number for both Karachi and Islamabad, but not in NYC air. Sea salt aerosols were seen in the two coastal cities, Karachi and NYC. It was also witnessed in Islamabad aerosols and was attributable to the mining of rock salt at the world's richest salt mine, Khewra, situated upwind from the city.  相似文献