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An automatic column changing system was developed for preconcentration and measurement of rare earth elements (REEs) in natural water samples, where syringe driven chelating columns (SDCCs) were applied to the hybrid (off-line operation and on-line operation) solid phase extraction of REEs. The sample loading was carried out off-line prior to the measurement. After that, the SDCCs were set into the column holder of the automatic column changing system and REEs were on-line eluted and measured by an inductively coupled plasma mass spectrometer (ICP-MS). The present automatic column changing system permitted continuously automatic measurement of 30 samples, while 3 min was enough for measuring one sample. The reproducibilities of REEs' signals obtained with two kinds of SDCCs showed that both of them are fit for the hybrid solid phase extraction method for preconcentration of REEs. The analytical detection limits (ADL) of REEs were in the range from 0.013 pg mL−1for Tm to 0.15 pg mL−1for Ce when 10 mL of water sample was loaded to each SDCC. The usefulness of the present method was confirmed by analysing NMIJ CRM 7201-a. After that, REEs in Lake Baikal water samples from depth of 50, 100, 150, 200, 250 m were determined. The results showed that dissolved REEs in the sample of 50 m depth were significantly lower than other samples, while the total REEs in the sample of each depth were close to one another. The distribution of REEs in Lake Baikal water samples was also discussed using shale normalized REEs distribution pattern. [ABSTRACT FROM AUTHOR]

The current study examines the potential cyclical nature of the elemental concentration record of silicon in sediments from Lake Baikal site BDP 96-2 in an attempt to clarify trends in periodicity observed for periods from 700 kyr BP to the present, 760 kyr BP to 1.43 Ma, and 1.47 to 2.4 Ma. The results indicate the presence of the 100 kyr cycle during the past 700 000 yr, as identified in other research. They also indicate the presence of a strong 74 kyr cycle from 760 kyr BP to 1.43 Ma, with a weaker 44 kyr cycle. For the period from 1.47 to 2.4 Ma, we observed evidence of strong 465 and 155 kyr cycles, in addition to a moderate 93 kyr cycle and various lesser cycles. This new evidence represents one of the first findings of longer cycles, as predicted by classic insolation theory, and sheds some initial light on Imbrie's 400 kyr question. [ABSTRACT FROM AUTHOR]