Wavelength dispersive X-ray fluorescence determination of major oxides in bottom and peat sediments for paleoclimatic studies.

The wavelength dispersive X-ray fluorescence method was applied to identify the distribution of major oxides within bottom and peat sediments containing organic matter of up to 70 wt.%. Samples were prepared as glass beads by fusing with lithium metaborate. The accuracy of results was assessed by flame photometry, spectrophotometry, and flame atomic absorption techniques. The proposed technique requires a sample weighing only 110 mg, which allows to analyze each centimeter of core collected at high-mountainous sites with undisturbed environment and eventually achieve uniquely high resolution of paleoclimatic reconstructions of global and regional climatic and environmental changes.

Analytical approaches for determination of bromine in sediment core samples by X-ray fluorescence spectrometry.

Bromine has been recognized as a valuable indicator for paleoclimatic studies. Wavelength dispersive X-ray fluorescence (WDXRF) and total reflection X-ray fluorescence (TXRF) methods were applied to study the bromine distributions in lake sediment cores. Conventional WDXRF technique usually requires relatively large mass of a sediment sample and a set of calibration samples. Some analytical approaches were developed to apply WDXRF to small sediment core samples in the absence of adequate calibration samples with a known Br content. The mass of a sample to be analyzed was reduced up to 200-300mg and the internal standard method with correction using fundamental parameters was developed for Br quantification. TXRF technique based on the direct analysis of a solid suspension using 20mg of sediment sample by internal standard method was additionally tested. The accuracy of the WDXRF and TXRF techniques was assessed by the comparative analysis of reference materials of sediments, soil and biological samples. In general, good agreement was achieved between the reference values and the measured values. The detection limits of Br were 1mg/kg and 0.4mg/kg for WDXRF and TXRF respectively. The results of the Br determination obtained with different XRF techniques were comparable to each other and used for paleoclimatic reconstructions.