Solution geochemistry and behaviour of major and trace elements during summer in a moss community at Edmonson Point, Victoria Land, Antarctica

Physical and chemical characteristics and solution geochemistry of major an d trace elements were investigated in an area of volcanic soil colonized by mosses at Edmonson Point (central Victoria Land) during the international BIOTAS (Biological Investigations of Terrestrial Antarctic Systems) expedit ion (BIOTEX) in the 1995-96 summer. The broad objective was to study the en vironmental factors involved in plant colonisation and survival in terrestr ial continental Antarctic ecosystems. The results showed that moss distribu tion and survival throughout the summer was closely dependent on water supp ly. In Antarctic coastal ecosystems the environmental biogeochemistry is la rgely dominated by ions of marine origin. At the drier end of a hydrologica l gradient the dry cushions of Hennediella heimii were encrusted with salts and showed much higher concentrations of soluble ions (Na+, Cl-, K+, Ca2+, Mg2+, SO42-, NO3-) than those in adhering soil particles or in other moss species from wetter parts of the transect. Although salt encrustations may partly derive from sublimation of surface snow, comparisons between concent rations of soluble ions in the dry moss and those in the < 2 mm fraction of surface and deep soil showed an upward migration along the soil profile of soluble ions as the substratum dried out, between December and January, an d their accumulation mostly on mosses. At the wet end of the transect mosse s were less affected by salt encrustations and there was evidence of Ca2+ u ptake and an active cycling of nutrients.