Biogeochemistry of trace and major elements in a surface environment (volcanic rock, soil, mosses, lichens) in the S. Miguel Island, Azores, Portugal

摘要

The distribution of the chemical element during weathering of trachyandesite in S. Miguel Island (Azores, Portugal), and in mosses and lichens growing on these rocks, was studied using instrumental neutron activation analysis. A general enrichment of rare earth elements (REEs), a Ce positive anomaly (partial oxidation after primary apatite dissolution) and a Eu negative anomaly (Eu2+ in plagioclases/clay minerals) are observed with increasing weathering. Mosses and lichens are Ce and Eu depleted, indicating that the main REE uptake is done via absorption from REE3+ secondary phosphates, probably together with P (essential nutrient). Zn, Br and Sb show higher enrichment factors in lichens and mosses.