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Sarkar, Subir
- Human Role in Shaping the Hydromorphology of Himalayan Rivers: Study of the Tista River in Darjeeling Himalaya
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Authors
Affiliations
1 Polish Academy of Sciences, Institute of Geography and Spatial Organization, Św. Jana 22, 31-018 Cracow, PL
2 Polish Academy of Sciences, Institute of Geography and Spatial Organization, Św. Jana 22, 31-018 Cracow, IN
3 North Bengal University, Geography Department, Siliguri 734 430, IN
1 Polish Academy of Sciences, Institute of Geography and Spatial Organization, Św. Jana 22, 31-018 Cracow, PL
2 Polish Academy of Sciences, Institute of Geography and Spatial Organization, Św. Jana 22, 31-018 Cracow, IN
3 North Bengal University, Geography Department, Siliguri 734 430, IN
Source
Current Science, Vol 106, No 5 (2014), Pagination: 717-724Abstract
The aim of the present study is to evaluate the hydromorphological state (the degree of naturalness and anthropogenic transformation) of Himalayan rivers and to determine the role of human activity in shaping their hydromorphology. The study was conducted in the valley of the Tista River in Darjeeling Himalaya. The field research was carried out in selected channel sections with and without noticeable human interference. The assessment of the hydromorphological state was conducted on the basis of the River Habitat Survey method. The analysis of research results shows that the habitat quality of the river sections with noticeable human interference is not significantly different from that in the sections without noticeable anthropogenic pressure.Keywords
Darjeeling Himalaya, Hydromorphology, Human Impact, River Habit Survey Method, Tista River.Full Text
- Redox Structure of Vindhyan Hydrosphere:Clues from Total Organic Carbon, Transition Metal (Mo, Cr) Concentrations and Stable Isotope (δ13 C) Chemistry
Abstract Views :209 |
PDF Views:80
Authors
Affiliations
1 Birbal Sahni Institute of Palaeosciences, Lucknow 226 007, IN
2 Department of Geology, University of Delhi, Delhi 110 007, IN
3 Department of Geological Sciences, Jadavpur University, Kolkata 700 032, IN
1 Birbal Sahni Institute of Palaeosciences, Lucknow 226 007, IN
2 Department of Geology, University of Delhi, Delhi 110 007, IN
3 Department of Geological Sciences, Jadavpur University, Kolkata 700 032, IN
Source
Current Science, Vol 115, No 7 (2018), Pagination: 1334-1341Abstract
Trace metal concentration in black shales can hold valuable information regarding ancient deep-ocean redox state. The size of marine reservoir of redoxsensitive elements (particularly molybdenum and chromium) is principally controlled by the extent of anoxicity in marine conditions following the onset of oxidative weathering post Great Oxygenation Event (~2.5-2.3 Ga). Hence, it is considered that coupled analysis involving redox-sensitive element/s and primary organic productivity (total organic carbon) may provide a clue for redox behaviour of ancient deep ocean. Here, we use the redox behaviour of Mo and total organic carbon values of Vindhyan shales to show that the Vindhyan hydrosphere although initiated as a stratified sea with anoxic and sulphidic deep water as exemplified by the geochemical character of the Arangi Shale, the extent and veracity of anoxicity and euxinicity was never pervasive. It further suggests that the Vindhyan hydrosphere developed euxinic deep water only during deposition of Arangi, Rampur and Bijaygarh black shale and was anoxic but certainly not euxinic during Koldaha and Rewa sedimentation. The low concentration of Mo and Cr, in general, in argillaceous intervals suggests that the Vindhyan Sea behaved as a moderate Mo and depleted Cr reservoir. The consistent low concentration of Cr within the Vindhyan shales also suggests restriction in the availability of Cr in the water column in the absence of any significant detrital supply of Cr at very low atmospheric oxygen level (<0.1% PAL; present atmospheric level).Keywords
Hydrosphere, Primary Organic Productivity, Total Organic Carbon, Transition Metals, Stable Isotope Chemistry.Full Text
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