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您的检索式：作者名="Rajesh ASTHANA"
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| 1 | Hydrochemistry and sediment characteristics of polar periglacial lacustrine environments on Fisher Island and Broknes Peninsula,East Antarctica显示文摘Fisher Island and Broknes Peninsula in the Larsemann Hills constitute part of a polar lowland periglacial environment between marine and glacial ecosystems.The landscape is characterized by gently rolling hills and broad valleys interspersed with lakes formed in glacially scoured basins.We analyzed the physicochemical parameters and the ionic constituents of water samples from 10 lakes in each of these two locations.Our results showed considerable differences between the two regions and demonstrated the influence of lithology and processes including weathering,evaporation,and atmospheric precipitation.All major cations and anions in the lake waters showed positive correlations indicating balanced ionic concentrations.Unconsolidated sediments were sparsely distributed and scattered over glacial deposits,valley fills,and occasional moraine ridges.The type and rate of sedimentation was mainly controlled by surface run-off and aeolian influx.The sediment samples from lake beds and the catchment area on Fisher Island were immature and poorly to very poorly sorted,consisting of gravelly sand with negligible silt and finer fractions.Sediments had a polymodal grain size distribution with the two major populations lying between-2 and-1 phi and between 0 and 1.5 phi.The sediments were lithic arenite to arkosic in composition and the microtextures imprinted over quartz grains were dominated by mechanical textures resulting from several stages of glacial crushing and grinding.The presence of deep dissolution cavities,cryptocrystalline precipitation,and euhedral crystal growth signified the effect of chemical activity after the deposition of grains in the lacustrine environment. | Rajesh Asthana Prakash Kumar Shrivastava Hari Bahadur Srivastava Mirza Javed Beg Pradeep Kumar | 2013 | Advances in Polar Science2013，24，4： | 2 |
| 2 | Role of lithology, weathering and precipitation on water chemistry of lakes from Larsemann Hills and Schirmacher Oasis of East Antarctica显示文摘Schirmacher Oasis and Larsemann Hills areas represent two different periglacial environments of East Antarctica. Schirmacher Oasis is characterized by a vast stretch of ice-shelf in the north and East Antarctic Ice Sheet(EAIS) to its south. Whereas, in Larsemann Hills area the northern and north-western boundary is coastal area and EAIS in the southern part,exhibiting polar lowland between the marine and continental glacial ecosystems. Physico-chemical parameters of water samples from different lakes of both of these two distinct locations are quite contrasting and have indicated influence of lithology, weathering, evaporation and precipitation. The lake water chemistry in Larsemann Hills area is mainly governed by the lithology of the area while Schirmacher lakes exhibit influence of precipitation and rock composition. All major ions of lake waters indicate balanced ionic concentrations. The atmospheric precipitation has significantly modified the ionic distributions in the lakes and channels. Carbonation is the main proton supplying geochemical reactions involved in the rock weathering and this is an important mechanism which controls the hydrochemistry. The lake water hydrochemistry differs widely not only between two distant periglacial zones but also within a short distance of a single periglacial entity, indicating influence of territorial climate over hydrochemistry. | Rajesh ASTHANA Prakash K SHRIVASTAVA Hari B SRIVASTAVA Ashit K SWAIN Mirza Javed BEG Amit DHARWADKAR | 2019 | Advances in Polar Science2019，30，1： | 1 |
| 3 | Hydropericardi-um syndrome:current state and future developments显示文摘 | Manu Asthana Rajesh Chandra Rajesh Kumar | 2013 | Arch Vi-rol2013，158，5： | 1 |
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