In this paper, Bioconcentration and elimination of five light rare earth elements(REEs) La, Ce, Pr, Nd and Sm were investigated in carp (Cyprinus carpio L.). The results show that internal organs had high ability to bioconcentrate light REEs. The order of BCFs of REEs was mostly internal organs>>gills> skeleton>muscle, there were slight differences among the BCF values of different REEs in a given tissue. In the elimination process, there were two patterns of elimination, the pattern of elimination in gills, skeleton and muscle could be described by two-compartment model and the pattern of elimination in internal organs could be divided into two periods, the second period could be described by one-compartment model. The biological half-lives (Tb) of each REEs in tissues of carp were obtained. The results also indicated that internal organs were considered to be the most important site of light REEs' detoxification and metabolism Copyright.

Physiological and biochemical perturbations in the liver ofCarassius auratus were investigated in vivo following 40 days ofexposure to ytterbium solutions of di4erent concentration.Glutamate8pyruvate transaminase (GPT) activity in gold5shliver was stimulated at 0.05mg/L Yb3+ and inhibited at higherYb3+ concentrations. Activity of the antioxidant enzymesuperoxide dismutase (SOD) was stimulated at Yb3+ higher than 0.05mg/L, and catalase (CAT) activity was strongly inhibitedafter 40 days of exposure. Detoxifying enzymes glutathioneS-transferase (GST) and glutathione peroxidase (GSH-Px) werestimulated at 0.05mg/L and inhibited at 0.1mg/L after 40 daysof exposure. Among the parameters determined, CATin gold5shliver was most sensitive to Yb3+, indicating that CATmightbe considered a potential tool in the biomonitoring of exposureto Yb3+ in an aquatic ecosystem.

A static laboratory aquatic microcosm was conducted to evaluate the distribution of mixed REEs-rare earth dements (lanthanum, cerium, samarium, gadolinium and yttrium) in natural water bodies. Several kinds of species were used. Duckweed represented phytoplankton, daphnia represented crustacean, shellfish represented benthic species and goldfish represented fishes. Samples from water, sediment and each species were analyzed by ICP-AES to determine their REEs contents. It was found that most REEs was adsorbed by sediment and might be redischarged into water, and the bioconcentration order of REEs in the species is duckweed>daphnia>shellfish>goldfish. The results will be useful to evaluate the environmental impact of the wide use of REEs in China.

In this paper, the species of Rare Earth Elements (La, Gd and Y) complexed with organic ligands EDTA (ethylenediamine tetraacetic), NTA (nitrilotriacetic acid) and Cit (citrate) were calculated in the test medium by MINTEQA-A program to calculate aqueous geochemical equilibrium. The influence of the species on the bioconcentration (kinetics and thermodynamics) processes of REEs by algae (Chlorella Vulgarize Beijerinck) were also studied. The results show that the bioconcentration processes of REEs by algae were highly dependent on chemical species. Adding organic ligands which can form RE-Organic species complex led to a great reduction of the REEs bioconcentration in algae. The order of BCFs from high to low is RE3+>RE-Cit>RE-NTA>RE-EDTA complex. The potential mechanism ofbioconcentration may be the coordination reactions of REEs ions with the active sites on algae surface followed by the slow diffusion into the algae cell.

The bioavailability of rare earth elements (REEs) in soils was evaluated, based on the combination of chemicalfractionation and multiple regression analysis. REEs in soils were partitioned by a sequential extraction procedure intowater soluble (F(ws)), exchangeable (F(ec)), bound to carbonates (F(cb)), bound to organic matter (F(om)), bound toFe