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991.
D. Shankar S. S. C. Shenoi R. K. Nayak P. N. Vinayachandran G. Nampoothiri A. M. Almeida G. S. Michael M. R. Ramesh Kumar D. Sundar O. P. Sreejith 《Journal of Earth System Science》2005,114(5):459-474
Hydrographic observations in the eastern Arabian Sea (EAS) during summer monsoon 2002 (during the first phase of the Arabian
Sea Monsoon Experiment (ARMEX)) include two approximately fortnight-long CTD time series. A barrier layer was observed occasionally
during the two time series. These ephemeral barrier layers were caused byin situ rainfall, and by advection of low-salinity (high-salinity) waters at the surface (below the surface mixed layer). These barrier
layers were advected away from the source region by the West India Coastal Current and had no discernible effect on the sea
surface temperature. The three high-salinity water masses, the Arabian Sea High Salinity Water (ASHSW), Persian Gulf Water
(PGW), and Red Sea Water (RSW), and the Arabian Sea Salinity Minimum also exhibited intermittency: they appeared and disappeared
during the time series. The concentration of the ASHSW, PGW, and RSW decreased equatorward, and that of the RSW also decreased
offshore. The observations suggest that the RSW is advected equatorward along the continental slope off the Indian west coast. 相似文献
992.
沙漠沙丘污水处理系统:原理、方法和效果 总被引:1,自引:0,他引:1
“沙漠沙丘系统(DDS)”是以地球化学工程学原理为指导的特殊水处理系统,它利用沙漠沙作为滤料,通过“机械过滤”、“化学作用”和“生物作用”净化污染水,一方面可使沙丘变得湿润而不再移动,以固定移动沙漠;另一方面又能净化污染水,最终起到“以害克害、固沙治水、一举多得”的良好综合生态环境效应。DDS是绿色的水处理系统,所需的原料和生成物都属于自然界存在的物质,无二次污染的发生。在DDS设计中,要注意的主要因素应包括:滤料的种类、湿干时间比、微生物培养方式、滤料层厚度、进水水质、时间、温度和pH等。DDS可以把官厅水库水由V类和超V类处理成2~3类水,从而恢复官厅水库的饮用水功能。 相似文献
993.
994.
本文通过对渭北东部岩溶地下水环境同位素组成特征的研究,分析了大气降水、地表水、地下水三者之间的转化关系,并对研究区岩溶地下水的形成进行了初步探讨,认为大气降水是研究区岩溶地下水的补给源,地表水与地下水之间存在水力联系,地表水对地下水的补给占补给水源的74.3%。西部岩溶裸露区为岩溶水的直接补给区,其周边浅埋区为岩溶水的间接补给区,东南部的岩溶中-深埋区为岩溶水的径流排泄区。 相似文献
995.
A metamorphic petrological study, in conjunction with recent precise geochronometric data, revealed a complex P–T–t path for high-grade gneisses in a hitherto poorly understood sector of the Mesoproterozoic Maud Belt in East Antarctica. The Maud Belt is an extensive high-grade, polydeformed, metamorphic belt, which records two significant tectono-thermal episodes, once towards the end of the Mesoproterozoic and again towards the late Neoproterozoic/Cambrian. In contrast to previous models, most of the metamorphic mineral assemblages are related to a Pan-African tectono-thermal overprint, with only very few relics of late Mesoproterozoic granulite-facies mineral assemblages (M1) left in strain-protected domains. Petrological and mineral chemical evidence indicates a clockwise P–T–t path for the Pan-African orogeny. Peak metamorphic (M2b) conditions recorded by most rocks in the area (T = 709–785 °C and P = 7.0–9.5 kbar) during the Pan-African orogeny were attained subsequent to decompression from probably eclogite-facies metamorphic conditions (M2a).The new data acquired in this study, together with recent geochronological and geochemical data, permit the development of a geodynamic model for the Maud Belt that involves volcanic arc formation during the late Mesoproterozoic followed by extension at 1100 Ma and subsequent high-grade tectono-thermal reworking once during continent–continent collision at the end of the Mesoproterozoic (M1; 1090–1030 Ma) and again during the Pan-African orogeny (M2a, M2b) between 565 and 530 Ma. Post-peak metamorphic K-metasomatism under amphibolite-facies conditions (M2c) followed and is ascribed to post-orogenic bimodal magmatism between 500 and 480 Ma. 相似文献
996.
997.
Using CRD method for quantification of groundwater recharge in the Gaza Strip, Palestine 总被引:1,自引:0,他引:1
Husam Baalousha 《Environmental Geology》2005,48(7):889-900
Rainfall is the main source of groundwater recharge in the Gaza Strip area in Palestine. The area is located in the semi-arid
zone and there is no source of recharge other than rainfall. Estimation of groundwater recharge from rainfall is not an easy
task since it depends on many uncertain parameters. The cumulative rainfall departure (CRD) method, which depends on the water
balance principle, was used in this study to estimate the net groundwater recharge from rainfall. This method does not require
much data as is the case with other classical recharge estimation methods. The CRD method was carried out using optimisation
approach to minimise the root mean square error (RMSE) between the measured and the simulated groundwater head. The results
of this method were compared with the results of other recharge estimation methods from literature. It was found that the
results of the CRD method are very close to the results of the other methods, but with less data requirements and greater
ease of application. Based on the CRD method, the annual amount of groundwater recharge from rainfall in the Gaza Strip is
about 43 million m3.
An erratum to this article can be found at 相似文献
998.
Water soluble components of PM10 Chongqing, China 总被引:1,自引:0,他引:1
The concentrations of water soluble ions (Na+, NH4
+, K+, Mg2+, Ca2+, NO3
-, Cl-, and SO
4
2-
) in PM10 samples collected on cellulose filters by a medium-volume cascade impactor were determined, which were obtained from three
kinds of areas in Chongqing: industrial area (Jiulongpo district), commercial and residential area (Jiangbei district) and
background area (Jinyun Mountain in the Beibei district). The results showed that except for the background site, the annual
average values of PM10 are 23% – 61% higher than the national air quality standard (GradeII) (0.1 mg/m3), even that the value of the control site is still 20% higher than American standard (0.05 mg/m3). This implied that serious pollution of fine particles occurred in Chongqing. Nine kinds of soluble ions in water of PM10 were analyzed by ion chromatography (IC) and the annual average concentrations follow the order of [SO
4
2-
] > [NO3
-] > [Cl-] > [F-], and [Ca2+] > [NH4
+] > [K+] > [Na+] > [Mg2+]. Their values were different in these areas: the industrial area > the commercial and living area > the control area. As
for NH4
+, K+, Ca2+, NO3
- and SO
4
2-
, their seasonal average concentrations show a similar variation trend: the values in spring and fall were higher than those
in summer and winter. The seasonal average concentrations of [Cl-], [F-], [Na+] and [Mg2+] are much lower than those of other ions. However, the concentrations of [Na+] changed more greatly in different seasons than those of the other three ions. Correlation coefficients showed that the three
areas have been polluted by coal smoke and dust to different extents, while some local resources of pollution should be taken
into consideration as well. 相似文献
999.
Development of an integrated conceptual model for the rational management of the transboundary Nestos River, Greece 总被引:1,自引:0,他引:1
This paper provides a detailed analysis of the geologic, hydrologic and hydrogeologic characteristics of Nestos River basin,
which is formed within the Greek mountainous part of the river. The quantitative analysis was mainly based on the data of
the river flow in different gauging points across the rivercourse as well as on the data of groundwater discharge from karst
springs of the mountainous area while important conclusions were made regarding the hydraulic connection between the surface
waters of the river and the groundwater of the karst aquifers of the basin. The qualitative analysis has shown that the quality
of both surface waters and groundwaters of the investigated basin is high, whereas, no sources of contamination were indicated
during this research. The possible effects of the two large dams of Platanovrisi and Thesavros are also analysed as they strongly
affect the quantitative and qualitative regime of the river delta. 相似文献
1000.
Extensive high-grade polydeformed metamorphic provinces surroundingArchaean cratonic nuclei in the East Antarctic Shield recordtwo tectono-thermal episodes in late Mesoproterozoic and lateNeoproterozoicCambrian times. In Western Dronning MaudLand, the high-grade Mesoproterozoic Maud Belt is juxtaposedagainst the Archaean Grunehogna Province and has traditionallybeen interpreted as a Grenvillian mobile belt that was thermallyoverprinted during the Early Palaeozoic. Integration of newUPb sensitive high-resolution ion microprobe and conventionalsingle zircon and monazite age data, and ArAr data onhornblende and biotite, with thermobarometric calculations onrocks from the H.U. Sverdrupfjella, northern Maud Belt, resultedin a more complex PTt evolution than previouslyassumed. A c. 540 Ma monazite, hosted by an upper ampibolite-faciesmineral assemblage defining a regionally dominant top-to-NWshear fabric, provides strong evidence for the penetrative deformationin the area being of Pan-African age and not of Grenvillianage as previously reported. Relics of an eclogite-facies garnetomphaciteassemblage within strain-protected mafic boudins indicate thatthe peak metamorphic conditions recorded by most rocks in thearea (T = 687758°C, P = 9·411·3kbar) were attained subsequent to decompression from P >12·9 kbar. By analogy with limited UPb singlezircon age data and on circumstantial textural grounds, thisearlier eclogite-facies metamorphism is ascribed to subductionand accretion around 565 Ma. Post-peak metamorphic K-metasomatismunder amphibolite-facies conditions is ascribed to the intrusionof post-orogenic granite at c. 480 Ma. The recognition of extensivePan-African tectonism in the Maud Belt casts doubts on previousRodinia reconstructions, in which this belt takes a pivotalposition between East Antarctica, the Kalahari Craton and Laurentia.Evidence of late Mesoproterozoic high-grade metamorphism duringthe formation of the Maud Belt exists in the form of c. 1035Ma zircon overgrowths that are probably related to relics ofgranulite-facies metamorphism recorded from other parts of theMaud Belt. The polymetamorphic rocks are largely derived froma c. 1140 Ma volcanic arc and 1072 ± 10 Ma granite. KEY WORDS: Maud Belt; Pan-African orogeny; geochronology; PTt path, East Antarctica 相似文献