Elemental fractionation of Si, Al, Ti, Fe, Ca, Mn, P, and Ba in five marine sedimentary reference materials: results from sequential extractions Original Research Article

We report on the elemental results from sequential extractions of BCSS-1 (marine sediment), MESS-1 (estuarine sediment), MAG-1 (marine mud), SCo-1 (Cody shale), and NIST-1c (argillaceous limestone) to encourage future comparisons of sequential extraction results within the marine geochemical and paleoceanographic communities. We measured Si, Al, Ti, Fe, Mn, Ca, P, and Ba in sequential de-ionized water (loosely-bound), MgCl2 (exchangeable), acetic acid (carbonate), hydroxylammonium hydrochloride (oxide), H2O2 (organic), Na2CO3 (opal), and residual (lithogenic) leaches. The protocol and selected elements were tailored to be most relevant to paleoceanographic geochemical studies instead of to environmental studies. Our results show that the sequential extraction procedure faithfully yields elemental distributions that are consistent with individual SRM lithologies. Our results also show that the procedure is typically reproducible within approximately 15%. However, in almost all cases, the procedure suffers from a systematic under-recovery of material when compared with the certified, bulk chemical analysis, and the under-recovery appears to be related to the lithology of the SRM. Similar under-recovery appears to be typical of sequential extraction procedures as reported by other previous studies. While this is problematic in assessing closure, it does not diminish the potential of inter-lab comparisons and first-order accuracy comparisons. We found that the elemental totals for the sequential extractions of MAG-1 compared best with the certified, bulk totals, and we recommend using this SRM to facilitate future accuracy assessments and inter-lab comparisons.