Distribution of rare earth elements in the Yamuna and the Chambal rivers, India

Abstract

We report here the first measurements of dissolved rare earth elements (REE) in the headwaters of the Yamuna river draining through the southern slopes of Himalaya. Due to intense weathering of the surface rocks of different lithologies and influence of tributaries, Yamuna river waters have variable dissolved REE contents (87 < ÂREE < 1374 ng L -1 , mean = 288.6 ng L -1 ) and exhibit negative Eu anomaly (0.49 < Eu/Eu* < 0.73, mean = 0.63). While most of the samples do not show discernable Ce anomalies; a negative Ce anomaly, however, found in a few of them, which can be explained by the colloidal pool preferentially enriched in Ce. A comparison among the river waters and bed sediments suggests that dissolved composition of REE is strongly fractionated and is enriched in MREE (Nd-Gd) with respect to sediments; presumably due to preferential dissolution of phosphate minerals such as apatite during weathering processes.Along with the Yamuna river, bed sediments from the Chambal river (a Peninsular river) have also been analyzed for REE composition. Bed sediments in the Yamuna and the Chambal river basins are characterized by ÂREE concentrations in the range of 78 to 291 mg g -1 (mean = 165 mg g -1 ) and 96 to 157 mg g -1 (mean = 134 mg g -1 ), respectively. A characteristic feature observed in the REE-normalized patterns of bed sediments is a strong HREE enrichment and a relatively positive Eu anomaly with respect to the granites in the Yamuna river catchment. In contrast, the bed sediment samples of the Chambal river show significant LREE enrichment and Eu enrichment with respect to the Deccan basalts in its catchment. The feldspars and their secondary products, which are enriched in Eu, might be the cause of the Eu anomaly. In river sediments of both these basins, the enrichment factors (EF), with respect to PAAS are £2 suggesting that REE composition is mainly derived from weathering processes. Keywords: dissolved rare earth element, MREE enrichment, Yamuna river, Chambal river, bed sediment individual cyclonic discharge events (Alexander et al., 2001) or anthropogenic inputs (Douglas et al., 2002) in controlling chemical variability and transport of major and trace elements. Likewise, studies on the dissolved load of the Ganga-Brahmaputra river system draining the

A stream sediment geochemical survey of the Ganga River headwaters in the Garhwal Himalaya

“…The REE trends of MCTZ and PH are also more akin to the average Ganga and Yamuna River bed sediments (Fig. 8(b)) as reported by Rengarajan and Sarin (2004). Ganga catchment area being more laterally spread within PMS terrain compared to narrow catchment of Yamuna, the influence of PMS on Ganga sediments is more prevalent that dilutes the signatures of MCTZ and PH in Ganga average bedsediments.…”

“…Thus, the removal of radioelements as labile forms in fluids followed by sequestration in stable ore-minerals emplaced in veins along the structurally controlled fluid channels seems to be the most likely operative process of secondary enrichment. The high dissolved REE abundance in Ganga river water (Rengarajan and Sarin, 2004) probably heralds its genesis to the presence of secondary U and Th rich ore minerals in MCTZ that are expectedly rich in REEs. Anomalous radon values reported by others are consistent with, and predicted by our geochemical study.…”

“…Occurrence of these vein-hosted minerals in the study area has also been reported by, many workers (Bhattacharya, 1989;Kaul et al, 1991;Singh et al, 1991). Relatively high dissolved REE abundance observed in Ganga and Yamuna river water samples (Rengarajan and Sarin, 2004) may also be due to partial contributions from dissolution of these secondary minerals that are relatively less resistant to weathering compared to zircon. The plot of U+Th versus Zr in MCTZ (Fig.…”

“…Zones of intense deformation and shearing in the MCTZ and PH become more porous and provide pathways for fluid channeling (Selverstone et al, 1991;Essaifi et al, 2004;Keller et al, 2004;and references therein) and their precipitation as ore minerals. Rengarajan and Sarin (2004). Fig.…”

Rare earth element concentrations in dissolved and acid available particulate forms for eastern UK rivers

“…They provide valuable tracers for examining silicate weathering rates, crustal erosion and element fluxes to the ocean (Brooking, 1989;Dupré et al, 1996;Elderfield et al, 1990;Gerard et al, 2003;Oliva et al, 1999;Rengarajan and Sarin, 2004). Furthermore, there are growing issues over pollutant REE inputs to the aquatic environment (Bau and Dulski., 1996;Neal, 2005;Nozaka et al, 2000;Wang et al, 2003;Weltje et al, 2002;Verplanck et al, 2005;Wilkinson et al, 1997).…”