The Sr-isotope composition of soils: A case study from Muravera (Se Sardinia, Italy)

This paper presents a case study of applying Sr-isotope geochemistry to a soil, located near the coast in the island of Sardinia, Italy. Therefore, we have measured the Sr-isotope ratios of bulk samples from the three soil horizons as well as correlated acid extracts and insoluble residue obtained by sequential attack of bulk samples. The results indicate that the Sr isotopic compositions of acid extracts vary with depth (“vertical” isotopic trend) as well as within each horizon (“chemical” isotopic trend). Both trends can be explained assuming that bulk Sr in the soil proceeds from two reservoirs: one internal represented mainly by plagioclase of the parent rock, and the other external represented by minerals and salts carried by rainwater and winds. Calculations may provide a quantitative approach to the case study here presented.