Rare earth elements and Sr-Nd isotopes in mosses from Romagna (Italy) and their environmental significance

Sr and Nd isotopes were applied to the study of a large number of moss samples from Romagna, northern Italy, to investigate whether these isotopes can provide useful information on environmental quality. Sr, Ca, and rare earth elements plus Y, i.e. REY, were also determined in selected samples. The REY contents (0.014-2.65 mg/kg) likely correlate with the different age of the samples. The REY patterns normalized to Post-Archean Australian Shale show a middle REY enrichment suggestive of phosphate assimilation by the mosses, whereas the Gd and Y positive anomalies along with the Ce negative anomaly envisage carbonate assimilation and, lastly, the Nd negative anomaly may refer to either Nd retention onto soil clay or Nd substitution for Ca under Ca deficiency. The delta Sr-87 values of the samples (from -1.4 to 0.2) collected from tree canopy-protected areas support the hypothesis of Sr provenance from marine carbonates. In contrast, the uppermost of the samples from open spaces display delta Sr-87 values (0.1-3.6) suggestive of a significant Sr contribution from crustal silicates. The epsilon(Nd) range (from -10.9 to -4.1) supports the hypothesis of a Nd crustal source for all the mosses. As a whole, there is no evidence of contribution of Sr and Nd from pollution sources. Lastly, this paper yields the largest data base ever carried out about the Sr-Nd isotopic composition of a moss species.