Cosmochemical Trace Analysis

Accelerator mass spectrometry (AMS) is useful to measure extremely low-abundance nuclides (isotope ratio of 10 to 10 relative to its stable isotope), such as Be, C, A1, C1, " Ca, and I, in natural samples. Small amounts of C and T can be measured by AMS on mg size samples of carbon and iodine extracted from 500-ml seawater samples (Povinec et al. 2000). Neutron activation analysis (NAA), radiochemical neutron activation analysis (RNAA), and inductively coupled plasma mass spectrometry (ICP-MS) are useful for the determination of ultra-trace Th and U in geological and cosmochemical samples, and for determination of the concentration of Pu and Pu. Reference marine-biological samples are necessary to test the performance of the analytical methods employed in surveying and monitoring radioactive materials in the sea. An ocean shellfish composite material containing 0.1% w/w Irish Sea mussel, 12% w/w White Sea mussel, and 87.9% w/w Japan Sea oyster has been prepared as the NIST SRM 4358 (The National Institute of Standards and Technology, SRM) in the natural-matrix, environmental-level radioactive SRM series (Altzitzoglou 2000). This NIST SRM 4358 sample will be useful for the determination of the activity of K, Cs, Pb, Ra, Th, and Am. 

Analysis of extraterrestrial materials, and in particular meteorites, is an important focus of cosmochemical research, as such samples preserve chemical and isotopic records of early solar system conditions and processes. The first studies of meteorites, which recognized that such samples have an extraterrestrial origin, date back to the late eighteenth century [3], but modem research in cosmochemistry has a much more recent origin. This is traced back by many to the founder of contemporary geochemistry, V.M. Goldschmidt, as he produced early, but well-founded, compilations of cosmic element abundances, based on data acquired for meteorites [4, 5]. Goldschmidt s work was later continued and extended by Suess in collaboration with Urey and their study on the abundances of the elements [5] is still an important milestone in cosmochemistry. 

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