DISTRIBUTION AND MODELING OF RARE-EARTH ELEMENTS IN CHINESE RIVER SEDIMENTS

Fifty-nine sediment samples were collected from the major rivers of Ch ina and analysed using Inductively Coupled Plasma-Mass Spectrometry (I CP-MS). The background rare earth element (REE) concentrations (mu g/g ) of these samples were: Sc, 11.1 (1.3-23.1); Y, 13.7 (3.3-24.8); La, 30.8 (7.6-57.2); Ce, 64.4 (16.5-122.6); Pr, 7.3 (1.6-14.4); Nd, 27.8 ( 5.6-58.5); Sm, 5.74 (1.1-11); Eu, 0.98 (0.05-1.7); Gd, 8.9 (1.6-16.8); Tb, 0.62 (0.12-1.2); Dy, 3.0 (0.53-5.0); Ho, 0.55 (0.09-1.00); Er, 1. 4 (0.26-2.4); Tm, 0.19 (0.06-0.4); Yb, 1.0 (0.22-2.9); Lu, 0.16 (0.05- 0.42). The total REE concentration (Sigma REE), light-REE concentratio n (LREE) and heavy-REE concentration (HREE) were 44.5-315.8, 38.1-264. 6 and 6.36-51.2 mu g/g, respectively. The ratio of LREE to HREE ranged from 3.7 to 7.7. The average ratio was approx. 5.1 and did not show m uch variation with location. Total and individual element concentratio ns were normally distributed. The variation in the average REE concent ration was not greater than 25 mu g/g. A high degree of correlation wa s found between the REEs. Factor analysis indicated that REE concentra tions in sediments were mainly described by two factors and the loadin g of the first two factors could be described by: Y=1-X-2. Factor scor e plots were employed to distinguish between samples of natural and an thropogenic origin. Based on the inter-correlation determined between REEs in sediment samples, a model was developed to predict REE concent rations. (C) 1997 Elsevier Science B.V.