Uranium isotopes in rivers, estuaries and adjacent coastal sediments of western India: their weathering, transport and oceanic budget

Borole, D.V.; Krishnaswami, S.; Somayajulu, B.L.K.

doi:10.1016/0016-7037(82)90240-x

Cited by 125 publications

(25 citation statements)

References 20 publications

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“…These include U-HCO 3 ) ( Figure 6) and UÀCl. Similar trends between U-HCO 3 ) are also reported for the Narmada, Tapti rivers (Borole et al, 1982) and for the world rivers (Mangini et al, 1979). HCO 3 ) concentration in rivers is an index of chemical weathering of the basin.…”

Section: Uranium and Major Ionssupporting

confidence: 75%

“…An overall positive correlation between dissolved uranium and dissolved cations is expected in rivers if during chemical weathering of rocks and minerals, cations and uranium are released to them in approximately constant ratio. Borole et al (1982) and Sarin et al (1990) have reported such a trend between uranium and SCat* for samples from the Narmada and Tapti basins and from the Ganga-Brahmaputra rivers (SCat* is the sum of Na*, K, Mg and Ca concentrations in mg L )1 in these waters, where Na*=Na total ) Na from NaCl). Scatter plots of dissolved uranium vs. SCat* for samples analysed in this study are given in Figure 5.…”

Section: Uranium and Major Ionsmentioning

confidence: 91%

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Dissolved Uranium and 234U/238U in the Yamuna and the Chambal Rivers, India

2006

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Dissolved uranium concentration and 234 U/ 238 U activity ratio have been measured in two distinctly different Indian drainage systems: the Yamuna headwaters in the Himalaya and the Chambal river system in the plains to study the weathering and mobility of uranium in these watersheds. The dissolved uranium in the Chambal river system ranges from 0.2 to 1.74 lg L )1 during September (tail end of monsoon), whereas in the Yamuna river system, its concentration varies from 0.1 to 3.18 lg L )1 during October (post-monsoon) and from 0.09 to 3.61 lg L )1 in June (summer). In the Yamuna main stream, uranium is highest at its source and decreases steadily along its course, from 3.18 lg L )1 at Hanuman Chatti to 0.67 lg L )1 at Batamandi, at the base of the Himalaya. This decrease results mainly from mixing of the Yamuna mainstream with its tributaries, which are lower in uranium. The high concentration of uranium at Hanuman Chatti is derived from weathering of the Higher Himalayan Crystalline series (HHC) and associated accessary minerals, which may include uranium-mineralised zones. The 234 U/ 238 U activity ratios in the samples from the Chambal watershed are in the range of 1.15±0.05 to 1.67±0.04; whereas in the Yamuna the ratios vary from 0.95±0.03 to 1.56±0.07, during postmonsoon and from 0.98±0.01 to 1.30±0.03, during summer. The relatively high 234 U/ 238 U activity ratios in the Yamuna system are in its tributaries from the lower reaches viz., the Amlawa, Aglar, Bata, Tons and the Giri. It is estimated that $9Â10 3 and $12 Â 10 3 kg of dissolved uranium are transported annually from the Yamuna at Batamandi and the Chambal at Udi, respectively. This corresponds to uranium weathering rates of 0.9 and 0.09 kg U km )2 y )1 in the basins of the Yamuna and the Chambal headwaters. This study confirms that uranium weathering rate in the Himalaya is far in excess (by about an order of magnitude) of the global average value of $0.08 kg U km )2 y )1 .

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Section: Uranium and Major Ionssupporting

confidence: 75%

Section: Uranium and Major Ionsmentioning

confidence: 91%

Dissolved Uranium and 234U/238U in the Yamuna and the Chambal Rivers, India

2006

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“…Although only a few samples were analysed, it seems that the uranium concentrations during high flow are lower than during low flow, which probably is the result of a dilution effect. Compared with other world rivers, such as the Ganga-Brahmaputra system (Borole et al, 1982;Sarin et al, 1990), African rivers (Kronfeld and Vogel, 1991) and European rivers (Dominik and Mangini, 1987;Carvalho, 1990), uranium contents in the Amazon basin waters generally are low. The calculated mean concentration of uranium for the Amazon river system, 0Ð05 µg L 1 , is lower by one order of magnitude than the mean concentration in most world rivers (Ivanovich and Harmon, 1992).…”

Section: Dissolved Phasementioning

confidence: 98%

Uranium and thorium isotopes in the rivers of the Amazonian basin: hydrology and weathering processes

Marques

Al‐Gharib

Bernat

et al. 2002

Hydrological Processes

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Abstract:Two expeditions (October 1989 and May 1992) were carried out to two points of the main Amazon River channel and four tributaries. The Solimões and Madeira rivers, taking their origin in the Andes, are whitewater rivers. The Negro River is a typical acid, blackwater river. The Trombetas River flows through bauxite-rich areas, and is characterized by low concentrations of dissolved humic substances. The 238 U, 234 U, 232 Th and 230 Th activities were recorded from dissolved, suspended particulate phases and river bank sediments. The latter were analysed for their 226 Ra, 228 Ra and 210 Pb contents, and also subjected to leaching with 0Ð2 M hydroxylamine-hydrochloride solution to determine the concentrations of radionuclides bound to amorphous Fe hydroxides and Mn oxides and hydroxides.The dissolved U average concentration in the Amazon system is ten times lower than the mean world river concentration. The uranium concentration observed atÓbidos in the lower Amazon (0Ð095 µg L 1 ), where the U content in the river bank sediments and suspended matter is lowest, suggests U release from the solid phase during river transport. About 485 t of U are transported annually to the Amazon delta area in dissolved form, and 1943 t bound to suspended particulate matter.Total U and Th concentrations in the river bank sediments ranged from 1Ð59 to 7Ð14 µg g 1 and from 6Ð74 to 32 µg g 1 , respectively. The highest concentrations were observed in the Trombetas River. The proportion extracted by means of the hydroxylamine solution (HL) was relatively high for U in the Trombetas river bank sediment (31%) and for Th in the Solimões sediment (30%).According to the alpha recoil effects, the 234 U/ 238 U activity ratios of the Andean river waters and downstream Amazon water (Óbidos) were >1, but were <1 in the Negro River (at Manaus). The activity ratios of dissolved U correlate with pH and also with the U activity ratios in the river bank sediment hydroxylamine extracts. As expected, the 234 U/ 238 U activity ratios in river bank sediments were <1 in the Andean rivers and in the downstream Amazon, but they were >1 in the Trombetas and Negro rivers. Such ratios probably result from the binding of dissolved uranium to solid sediment.The 228 Th/ 232 Th ratios of river bank sediments were close to unity (except for the Negro River, where it is lower), suggesting no significant Th exchanges between the river water and the sediment. The 226 Ra/ 232 Th activity ratios were <1, and the 226 Ra/ 228 Ra activity ratios generally were significantly higher than the activity ratios of their respective parents. This perhaps is the result of easier leaching of the 226 Ra parent, 230 Th, from solid material (owing to the alpha recoil effect) than of the 228 Ra parent. Uranium and thorium isotopes were used as tools to evaluate the chemical weathering rate of rocks in the Amazon system, which was estimated to be 2Ð7 cm 1000 year 1 s 1 .

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“…Agnihotri et al (2003b) proposed that during glacial periods, large areas of continental shelves were exposed due to the fall in sea level. Continental shelves are known to be a major sink of organic carbon and uranium (Borole et al 1982;Somayajulu et al 1994). These exposed shelves provided regions of vigorous erosion, and finer particles were advected and redeposited, leading to the observed increase in C org and U during the LGM, as well as enhanced sedimentation.…”

Section: Regional Climatic Evolution: Comparison With the Eastern Aramentioning

confidence: 99%

Paleoproductivity Variations in the Equatorial Arabian Sea: Implications for East African and Indian Summer Rainfalls and the El Niño Frequency

et al. 2006

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We analyzed a sediment core from the equatorial Arabian Sea, chronologically constrained by accurate accelerator mass spectrometry (AMS) radiocarbon dates on selected planktonic foraminiferal species, for paleoproductivity variations corresponding to the variations in the Indian Ocean Equatorial Westerlies (IEW). The IEW in turn are positively correlated to the Southern Oscillation Index (SOI), which is a measure of El Niño, Southwest monsoon (SWM), and east African rainfall (EAR). The productivity data show that Indian and east African rainfalls declined from 35,000 calendar yr BP up to the last glacial maximum (LGM), with the maximum El Niño frequency during the last glacial period. From ∼14,500 to ∼2000 calendar yr BP (i.e. core top), we find strengthening SWM and EAR along with declining El Niño frequency.

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Uranium isotopes in rivers, estuaries and adjacent coastal sediments of western India: their weathering, transport and oceanic budget

Cited by 125 publications

References 20 publications

Dissolved Uranium and 234U/238U in the Yamuna and the Chambal Rivers, India

Dissolved Uranium and 234U/238U in the Yamuna and the Chambal Rivers, India

Uranium and thorium isotopes in the rivers of the Amazonian basin: hydrology and weathering processes

Paleoproductivity Variations in the Equatorial Arabian Sea: Implications for East African and Indian Summer Rainfalls and the El Niño Frequency

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