DEVELOPMENT AND APPLICATION OF A SENSITIVE AND RAPID ANALYTICAL METHOD TO DETERMINE THE RARE-EARTH ELEMENTS IN SURFACE WATERS

A new cost-effective method to determine the 14 rare-earth elements (R EE's) in waters to levels as low as 0.2-1.0 ng l(-1) (ppt) has been es tablished. Inductively coupled plasma mass' spectrometry (ICP-MS) is u sed for measurement following automated preconcentration using the Dio nex Registered trademark MetPac CC-1 resin of iminodiacetate functiona lity. The free REE ion is chelated onto the resin while alkali and alk aline-earth elements are washed through and separated, enabling the me thod to be applied to seawater as well as fresh water, The eluant, 0.8 M HNO3, provides an ideal medium for analysis by ICP-MS and the suite of elements determined can be expanded to include first-row transitio n elements, Cd, Pb and U. Based on replicate analyses of control sampl es and data for field and laboratory duplicate samples (lakes and stre ams), relative standard deviations are better than +/- 10% except wher e concentrations are below 5 ng l(-1). Application of this method to 1 35 lake waters in the Bale d'Espoir region of Newfoundland indicates: (a) contamination is not introduced from sampling bottles (Nalgene Reg istered trademark, LPE) or during the filtering and acidification proc ess, even at low ng l(-1) levels; (b) there is a high degree of correl ation in element distribution patterns between lake waters and their c orresponding centre-lake sediments for Yb and Tb; (c) the chondrite-no rmalized plots for water and sediment are similar in shape and show co nsistent patterns within geological units but are distinct between suc h units; and (d) the powerful potential of REE concentrations in surfa ce water for geochemical mapping.