Dissolved rare earth elements in river waters draining karst terrains in Guizhou Province, China

Abstract

Winter seasonal concentrations of dissolved rare earth elements (REE) of two major river systems (the Wujiang River system and the Yuanjiang River system) in karst-dominated regions in winter were measured by using a method involving solvent extraction and back-extraction and subsequent ICP-MS measurements. The dissolved REE concentrations in the rivers and their tributaries are lower than those in most of the large rivers in the world. High pH and high cation (i.e., Na + + Ca 2+ ) concentrations of the rivers are the most important factors controlling the concentrations of dissolved REE in the river water.The dissolved load (<0.22 lm) REE distribution patterns of high-pH river waters are very different from those of low-pH river waters. The shale (PAAS)-normalized REE patterns for the dissolved loads are characterized by light REEenrichment and heavy REE-enrichment. Water in the upper reaches of the Wujiang River generally shows light REE-enriched patterns, while that in the middle and lower reaches generally shows heavy REE-enriched patterns. The Yuanjiang River is heavy REE enriched with respect to the light REE in the same samples. Water of the Wuyanghe River draining dolomite-dominated terrains has the highest heavy REE-enrichment. Most river water samples show the shale-normalized REE patterns with negative Ce and Eu anomalies, especially water from Wuyanghe River. Y/Ho ratios show that the water/particle interaction might have played an important role in fractionation between HREE and LREE.

Rare Earth Element Patterns in the Karst Terrains of Guizhou Province, China: Implication for Water/Particle Interaction

“…We hence used the method of Shabani et al (1990) to increase the concentration of the REE by at least a factor of 100. The procedure of determining the concentrations of dissolved load REE is similar to that described by Han and Liu (2007). The preconcentration of dissolved load REE concentration involves the following steps: REE were extracted from water samples with 65% HDEHP (2-ethylhexyl hydrogen phosphate) and 35% H 2 MEHP (2-ethylhexyl dihydrogen phosphate) in heptane, then back-extracted with 6 N ultra-purified hydrochloric acid and transformed into nitrates of REE for ICP-MS analysis.…”

“…In Han and Liu (2007), the authors investigated the dissolved REE in river waters in Guizhou Province, China. They did not, however, get sufficient SPM in the low-flow season.…”

Geochemistry of rare earth elements in soils under different land uses in a typical karst area, Guizhou Province, Southwest China

“…Regarding REE migration, some studies have shown that REE are immobile during surface processes (Szczepanski and Ilnicki, 2014). However, some researchers have found that the mobility of REE was controlled by pH values (Han et al, 2009;Pazand and Javanshir, 2014) and REE was generally believed to be mobile at a lower pH value (Han and Liu, 2007;Migaszewski et al, 2014). However, there is In karst regions of the Southwest (SW) China, the degradation of ecosystems has led to many ecological problems, such as Karst Rocky Desertification.…”

Geochemical characteristics of rare earth elements (REEs) in the paddy soil and rice (Oryza sativa L.) system of Kočani Field, Republic of Macedonia

“…Their use as proxies is applied in different disciplines of the earth sciences, especially hydrology, geochemistry, and geology (Aubert et al, 2004;Egashira et al, 1997;Han and Liu, 2006;Henderson, 1984;Hu et al, 2006;Li et al, 1998;Protano and Riccobono, 2002;Tyler, 2004;Wang et al, 2004).…”

“…Until recently, little information had been available for estimating the environmental and ecological impacts of REEs, and such information was generally scarce and sometimes contradictory (Aubert et al, 2004;Chen, 1993;Egashira et al, 1997;Han and Liu, 2006;Henderson, 1984;Hu et al, 2006;Li et al, 1998;Markert and Zhang, 1991;Wang, 1991a,b;Wang et al, 2004). Therefore, it is important to obtain more knowledge about the different environmental effects of REEs to predict possible deleterious effects.…”