Is a Combination of Metals More Toxic to Mosses Than a Single Metal?

Increasing pollution in the environment calls for the precise determination of metal toxicity in plants as they are at the base of the food chain. Mosses are often employed as biomonitors and provide good models for testing metal adsorption. However, species may react differently and many studies only look at one metal at a time, even though toxicity levels are affected by metal combinations. In this study, the effects of CuCl₂, MnCl₂, FeCl₂, and Sb-acetate were examined individually and in combinations on the moss species Pohlia drummondii and Physcomitrium patens. In general, the two species reacted differently to the presence of trace metals; although, for both, the tolerance limit was at 100 µM. Overall, individual metals were less toxic than combinations, with some exceptions for Fe and Mn in P. patens. Additionally, we demonstrate that multiple combinations of metals are especially toxic if Cu is present.