Influence of sea-water intrusion and agricultural production on the Blato Aquifer,Island of Korčula,Croatia   总被引：1，自引：0，他引：1  

Josip Terzić  Tamara Marković  Želimir Pekaš 《Environmental Geology》2008,54(4):719-729

The Blato aquifer is situated on the western side of the island of Korčula, southern Dalmatia, Croatia. The terrain is built of karstified carbonate rocks, mostly of the Cretaceous age. In the Blatsko karst polje there are four water supply wells with a total yield of about 60 l/s. The catchment area is 28 km². The whole terrain is tectonically disturbed and compressed; the most permeable fracture system is perpendicular to the structural “b” axes, which gives rise to a general groundwater direction towards the island’s northern coast. Average precipitation is 850 mm/year, but when there is less than 700 mm/year there is a high possibility of sea-water intrusion during the summer season. The risk significantly increases when dry years repeat. Hydrochemical research has shown that two main pollution sources occur at different hydrological moments: sea-water intrusion happens in the dry summer period when there is maximal extraction and almost no recharge; and the washing of nitrates and other humanly caused pollution indicators from the soil and epikarst belt during the rainy season. All factors must be taken into account when planning management and protection of such a sensitive environment.  相似文献   

海康盐场井水化离子与地震关系初探     

吴运恒 《华南地震》1991,11(3):75-79

本文对广东省海康盐场339^#深井8年来的水化观测资料进行了初步分析，认为该井Cl^-含量和Ca^ Mg^ 合量的下尝稳定型的，它们与气象等外界因素影响无明显关系，对一定范围内的地震活动具有震兆显示能力。  相似文献   

隘高岩体地下水的放射性特征及其找矿效果     

朱基忠  陈仁祥 《铀矿地质》1990,6(2):86-92

本文通过对隘高岩体放射性水化学普查、详查、揭露资料的野外调查和综合分析研究,论述了岩体水化找矿效果好的放射性水文地质条件;研究了水异常的展布特征和控制因素;肯定了岩体的水化找矿效果;给出了水化找矿的标志;进而对放射性水化学普查、详查以及成矿远景预测、水异常点找矿意义的评价提出了看法和建议。  相似文献   

Preliminary Results on Hydrological and Hydrochemical Features of Kartamak Glacier Area in Mt. Muztag Ata   总被引：1，自引：1，他引：0  

ZHAO Huabiao YAO Tandong XU Baiqing 《山地科学学报》2007,4(1):077-085

The variations of the meltwater runoff draining from Kartamak Glacier in Mt. Muztag Ata in China were studied by using the measured hydrological data from 1 June to 25 August 2003. The meltwater runoff is mainly affected by ambient temperature and precipitation. Meltwater and precipitation samples were collected from 10 to 23 August 2003. Their pH, EC (electric conductivity) and the major ions (Na~ , K~ , Ca~(2 ), Mg~(2 ), Cl~-, NO_3~-, SO_~4~(2-)) were determined. pH values showed a positive correlation with EC values for all samples. Meltwater samples were slightly alkaline. Sulfate and calcium were the dominant anion and cation in the measured ions, respectively. All the ion concentrations had inverse relationships with runoff or water level. In order to discuss the origins of dissolved chemical substances in the glacial meltwater, a principal component analysis was carried out. The results showed that water-rock interaction determined the ion components of the meltwater.  相似文献   

柴达木盆地西部狮子沟背斜构造区深部卤水水化学特征及演化分析          下载免费PDF全文

刘溪溪  岳鑫  袁文虎  范增林  于小亮  董启伟  陈金牛 《盐湖研究》2019,27(1):73-81

近年来的调查工作发现,柴达木盆地西部的一些背斜构造区油田卤水具有储量大、品位高的特点,表现出良好的开发和利用前景。在狮子沟背斜构造区深部有含卤层甚至盐岩层的发现。以狮子沟背斜构造区深层卤水为研究对象,采样测试其离子含量,进而分析卤水的离子比例系数,对其水化学特征、物质来源、演化过程进行分析,研究认为深部卤水主要是盐岩溶解作用形成的,其中不乏有沉积卤水的加入;其演化主要受控于蒸发和溶解的双重作用,同时白云岩化、酸性斜长石的溶解以及中酸性热液的淋滤作用也可能对该区卤水有某种程度的影响。  相似文献   

Negative ion chemistry in Titan's upper atmosphere     

V. Vuitton  P. Lavvas  M. Galand  G.R. Lewis  A.J. Coates  J.-E. Wahlund 《Planetary and Space Science》2009,57(13):1558-662

The Electron Spectrometer (ELS), one of the sensors making up the Cassini Plasma Spectrometer (CAPS) revealed the existence of numerous negative ions in Titan's upper atmosphere. The observations at closest approach (∼1000 km) show evidence for negatively charged ions up to ∼10,000 amu/q, as well as two distinct peaks at 22±4 and 44±8 amu/q, and maybe a third one at 82±14 amu/q. We present the first ionospheric model of Titan including negative ion chemistry. We find that dissociative electron attachment to neutral molecules (mostly HCN) initiates the formation of negative ions. The negative charge is then transferred to more acidic molecules such as HC₃N, HC₅N or C₄H₂. Loss occurs through associative detachment with radicals (H and CH₃). We attribute the three low mass peaks observed by ELS to CN⁻, C₃N⁻/C₄H⁻ and C₅N⁻. These species are the first intermediates in the formation of the even larger negative ions observed by ELS, which are most likely the precursors to the aerosols observed at lower altitudes.  相似文献   

Two new V-type asteroids in the outer Main Belt?     

R. Duffard  F. Roig 《Planetary and Space Science》2009,57(2):229-1138

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Methane absorption coefficients for the jovian planets from laboratory, Huygens, and HST data     

Erich Karkoschka  Martin G. Tomasko 《Icarus》2010,205(2):674-694

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The ultraviolet reflectance of Enceladus: Implications for surface composition     

Amanda R. Hendrix  Candice J. Hansen 《Icarus》2010,206(2):608-617

The reflectance of Saturn’s moon Enceladus has been measured at far ultraviolet (FUV) wavelengths (115-190 nm) by Cassini’s Ultraviolet Imaging Spectrograph (UVIS). At visible and near infrared (VNIR) wavelengths Enceladus’ reflectance spectrum is very bright, consistent with a surface composed primarily of H₂O ice. At FUV wavelengths, however, Enceladus is surprisingly dark - darker than would be expected for pure water ice. Previous analyses have focused on the VNIR spectrum, comparing it to pure water ice (Cruikshank, D.P., Owen, T.C., Dalle Ore, C., Geballe, T.R., Roush, T.L., de Bergh, C., Sandford, S.A., Poulet, F., Benedix, G.K., Emery, J.P. [2005] Icarus, 175, 268-283) or pure water ice plus a small amount of NH₃ (Emery, J.P., Burr, D.M., Cruikshank, D.P., Brown, R.H., Dalton, J.B. [2005] Astron. Astrophys., 435, 353-362) or NH₃ hydrate (Verbiscer, A.J., Peterson, D.E., Skrutskie, M.F., Cushing, M., Helfenstein, P., Nelson, M.J., Smith, J.D., Wilson, J.C. [2006] Icarus, 182, 211-223). We compare Enceladus’ FUV spectrum to existing laboratory measurements of the reflectance spectra of candidate species, and to spectral models. We find that the low FUV reflectance of Enceladus can be explained by the presence of a small amount of NH₃ and a small amount of a tholin in addition to H₂O ice on the surface. The presence of these three species (H₂O, NH₃, and a tholin) appears to satisfy not only the low FUV reflectance and spectral shape, but also the middle-ultraviolet to visible wavelength brightness and spectral shape. We expect that ammonia in the Enceladus plume is transported across the surface to provide a global coating.  相似文献   

Shape and obliquity effects on the thermal evolution of the Rosetta target 67P/Churyumov-Gerasimenko cometary nucleus     

M.C. De Sanctis  J. Lasue  M.T. Capria  D. Turrini 《Icarus》2010,207(1):341-494

This work is dedicated to the application to 67P/Churyumov-Gerasimenko of a new quasi-3D approach for non-spherically shaped comet nuclei with the aim to interpret the current activity of the comet in terms of initial characteristics and to predict shape and internal stratification evolution of the nucleus. The model is applied to differently shaped nuclei taking into account the characteristics of Comet 67P/Churyumov-Gerasimenko deduced from observations. We focus our attention on the combined effects that shapes and obliquity have on the comet surface and sub-surface evolution. We discuss the results in terms of activity, local dust mantle formation and disruption, erosion of the surface and internal stratigraphy.The results show that differently shaped nuclei can have different internal structures leading to different activity patterns and behaviors. Our calculations have shown that local variations in the dust and gas fluxes can be induced by the nucleus shape. The distribution of “active” areas on Comet 67P/Churyumov-Gerasimenko is different because of different shapes, reflecting the illumination conditions on the surface. These shapes can influence the structure of the inner coma, but the coma far away from the nucleus is only marginally affected by the nucleus shape. However, different comet behaviors can arise from differently shaped comet nuclei, especially in terms of local activity, surface and sub-surface characteristics and properties. The water flux local distribution is the most influenced by the shape as it is directly linked to the illumination. Irregular shapes have large shadowing effects that can result in activity patterns on the comet surface.The effects of different pole directions are discussed to see the relations with the nucleus activity and internal structure. It is shown that the orientation of the rotation axis plays a strong role on the surface evolution of 67P/Churyumov-Gerasimenko, determining seasonal effects on the fluxes. The activity of the comet changes greatly with the nucleus obliquity leading to pre-post-perihelion differences in the activity and seasonal effects. The effects of the dust deposition and crust formation on the cometary activity have also been simulated and are discussed with respect to 67P/Churyumov-Gerasimenko observations. The dust mantling is also strongly obliquity dependent, with different surface distributions of the dust-covered regions according to the different comet pole orientations. Finally, we show that our model can reproduce the fluxes behavior near perihelion in terms of amplitude and asymmetry, and we estimate 20% of the illuminated surface to be active.  相似文献