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Sarin, M. M.
- Hydrogeochemistry of Sambhar Salt Lake, Rajasthan: Implication to Recycling of Salt and Annual Salt Budget
Authors
1 Bhabha Atomic Research Centre, Trombay, Mumbai - 400085, IN
2 Physical Research Laboratory, Earth Science Division, Ahmedabad - 380 009, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 69, No 1 (2007), Pagination: 139-152Abstract
Geochemical analysis of groundwater samples and brines from the Sambhar Salt lake shows a predominance of NaCl with respect to total salt content (TDS), which varies from 0.5 to -400 g/L. All brine (lake + shallow subsurface) samples indicate a Na-Cl type alkaline solutions with pH varying from 8.5 to 10. All this suggests a general provenance for halite or dissolution of desiccated salt minerals in the catchment and drainage areas of the lake. Adjacent groundwaters are mostly neutral Na-Cl type with TDS ranging from 0.5 to 13 g/L. In contrast to groundwaters, the river waters from Roopangarh and Mendha reflect that out of the TDS, the major ions constitute Na, Alk and Cl with an average equivalent Na/Cl ratio of 2.7, indicating dissolution of Na from silicate weathering of rocks. However, the lake water composition overwhelms the river water upon mixing during the recharge period. A complete annual wetting and drying cycles of evolution of lake brine shows generation of Na-Cl type of brine with steady increase in major ions except Ca and Mg ions which decrease in successive stages of evaporation. Relative change in Na and Cl ions is also observed during the late stage of evaporation at or beyond halite saturation stage. Observation of such chemical change in brine composition is in line with the identification of salt minerals in lake sediments and salt encrustation by XRD technique.
In present-day hydrologic set-up, the estimated salt inventory in lake is _106 tons as compared to riverine input of 6x104 tons and an upper limit of aeolian input of about 5xl04 tons. Such an estimate indicates that majority of salt is derived from the recycling and re-solution of salt encrustation from the lake bed during recharge period.
Keywords
Hydrogeochemistry, TDS, Nacl, Brines, Annual Wetting and Drying Cycles, Evaporation, Brine Evolution, Salt Encrustation, Aeolian Salt Input, Recharge Period, Sambhar Salt Lake, Rajasthan.- Geochemical and Pollen Proxy Records from Northeastern Madhya Pradesh: An Appraisal of Late-Quaternary Vegetation and Climate Change
Authors
1 Bhabha Atomic Research Centre, Trombay, Mumbai - 400 085, IN
2 Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow - 226 007, IN
3 Earth Science Division, Physical Research Laboratory, Ahemdabad - 380 009, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 68, No 1 (2006), Pagination: 95-102Abstract
A 15 m deep sedimentary core from Jagmotha swamp in northeastern Madhya Pradesh has been analyzed for reconstruction of Late-Quaternary vegetation and climate change based on distribution of major/Trace elements, organic carbon, nitrogen and pollen grains contained in the sediments. The combined geochemical and palynological results indicate a cool and dry climate between 6000 to 5000 yrs BP representing a tree savannah type vegetation followed by warm and moist climate between 5000 to 3000 yrs BP. Such a drastic change in climate promoted tropical mixed deciduous forests in the region. Subsequently, between 3000 to 1200 yrs BP, the climatic condition got further improved with enhanced precipitation in the region marked by the advent of sal tree in the forest floristics. Since then, the climate has been inferred conducive for development of modern sal forests in the region.Keywords
Palaeoclimate, Palaeovegetation, Late-Quaternary Period, Major/Trace Element Geochemistry, Organic Carbon and Nitrogen, C/N Ratio, Pollen Frequency.- Atmospheric Deposition of Phosphorus to the Northern Indian Ocean
Authors
1 Physical Research Laboratory, Ahmedabad 380 009, IN
Source
Current Science, Vol 108, No 7 (2015), Pagination: 1300-1305Abstract
Air-sea deposition of phosphorus is an important external source of this macronutrient for ocean primary productivity. Although global budgets have shown that atmospheric input of phosphorus is comparable to its riverine supply, studies on regional scale are rather limited. The present article summarizes sources and atmospheric pathway of phosphorus to the ocean surface as a case study of the Northern Indian Ocean. Water-soluble aerosol phosphorus (PInorg) concentrations are significantly high over the Bay of Bengal (BoB) compared to those over the Arabian Sea (ARS). Relative increase in the supply of aerosol-P over BoB is attributed to acid-processing of mineral dust during long-range atmospheric transport in addition to its supply from anthropogenic sources. Our estimate of P-deposition to the Northern Indian Ocean (~1.2 Gmol-P year-1) is comparable to its atmospheric deposition in other oceanic regions such as the North Atlantic and is also consistent with the model-based projections for the Northern Indian Ocean. These results highlight the importance of atmospheric source in influencing the biogeochemical cycle of phosphorus in the Northern Indian Ocean.Keywords
Air–Sea Deposition, Aerosol-P, Atmospheric Deposition, Northern Indian Ocean.- Carbon, Oxygen and Uranium Isotopic Study of Uraniferous Dolostone from Cuddapah Basin, Southern India : Implications to Depositonal Environment and Uranium Alteration
Authors
1 Physical Research Laboratory, Ahmedabad 380 009, IN
2 Atomic Minerals Division, Dept. of Atomic Energy, Hyderabad - 500 016, IN
3 Atomic Minerals Division, Dept. of Atomic Energy, Bangalore 560 072, IN