Low-Level Analysis of Lanthanides in Eleven Silicate Rock Reference Materials by ICP-MS After Group Separation Using Cation-Exchange Chromotography

A simple method is described for the determination of lanthanides in depleted rocks based on acid dissolution, cation-exchange chromatography and ICP-MS analysis using a low flow, microconcentric nebuliser. The potential of the method is evaluated by analysis in triplicate of eleven low-concentration level geochemical reference materials (UB-N, NIM-D, BIR-1, DNC-1, JB-2, JGb-1, JGb-2, NIM-N, NIM-P, FK-N and MA-N). The repeatability of the three dissolutions is between 0.2% and 0.6% relative standard deviation (RSD) for basaltic samples BIR-1 and JB-2, with the exception of La in BIR-1 (2.6% RSD), presumably because of blank or memory effects. The results are more scattered for coarsegrained rocks. A good agreement between the results and working values is observed for most mafic samples and the serpentinite UB-N. Significant deviations observed between the data obtained in this work and working values for some reference materials might reflect heterogeneities of the REE distributions in coarse-grained (especially granitic) rocks at the 10 0 mg sub-sampling scale.     

Atmospheric excitation of the annual wobble

Summary. The excitation of the annual wobble due to the atmosphere is computed on the basis of modern global homogeneous atmospheric pressure and temperature fields of 5°× 5°.
The contribution of the oceans is estimated using two hypotheses of the response to the atmospheric load.
The results are compared with estimates by other authors and with data from astronomical observations. The atmospheric excitation computations have now reached their maximum accuracy and the discrepancies with the observations demonstrate the large errors in the estimates of the non-atmospheric contributions for which constraints are given.