The Concentration of Na, Mg, K and Ca In Epilithic Lichen, Usnea Aurantiacoatra of King George Island, South Shetland Islands, West Antarctica

Abstract

The accumulation pattern of Na, Mg, K and Ca in the epilithic lichen, Usnea aurantiacoatra is reported in the vicinity of the Korea research station located in the Barton Peninsula, King George Island. The elemental concentrations were determined by atomic absorption spectrophotometry (AAS). During the 2006/2007 Korea Antarctic Research Program (KARP) expedition, lichen samples were collected from 25 sites. At each site, collected samples were classified into three age groups based on the size and weight of lichen: young (ca. 0.1 g), middle (ca. 0.7 g) and old (ca. 5 g) groups. Our results show that the concentrations of Na and K increase dramatically with size, reflecting the age of lichen, while no differences were found in those of Mg and Ca among three age groups. It suggests that the amount of Na and K in lichen, Usnea aurantiacoatra is significantly influenced by exposure time, which is age related. Lichen samples of the old group were also divided into three segments: upper, middle and basal segments. The vertical distributions of macronutrients in lichen were clearly observed. The amount of Na, Mg and Ca was concentrated in top segments. In contrast, K was greater in basal segments. Therefore, the upper segment of Usnea aurantiacoatra appears to be strongly influenced by atmospheric wetfall because of its large surface area exposed to air.