In sensitive ecosystems of the Arctic, even slight disruptions may produce serious damage. Therefore, the extent of contamination in such zones should be evaluated. A comparison was made between concentrations of metals in Sanionia uncinata in three areas of the European Arctic: (1) the vicinity of the Polish Polar Station in the SW part of Spitsbergen on Wedel Jarlsberg Land, (2) Longyearbyen (Spitsbergen) influenced by local sources of pollution and (3) Iceland relatively free from local pollution. The tested hypothesis was that S. uncinata from Iceland contains significantly lower concentrations of metals than the same moss from Spitsbergen. The maximum concentrations of metals in the examined moss from Longyearbyen reached values for Cr and Mn higher than those known as harmful for plants and for Ni and Zn values within the harmful ranges with no visible harmful effects. S. uncinata from Iceland contained significantly lower concentrations of Cd, Mn, Pb compared to this species from Spitsbergen. S. uncinata seems to be a useful indicator for metal fallout in the European Arctic. This study presents the effects of local sources of contamination on metal levels in S. uncinata from Longyearbyen, Wedel Jarlsberg Land and Iceland as well as verification of S. uncinata as a suitable bioindicator in this Arctic area. The benefit of the study is a to better understanding contamination problems of Arctic habitats.

The Orravatnsrustir palsa site, located north of the Hofsjokull glacier in Central Iceland, has well developed palsas located in a valley-like depression at 710-715 m a.s.l. and stands in remarkable contrast to the surrounding desert-like highland plateau. The purpose of this paper is to give an overview of the Orravatnsrustir palsa site, geographic distribution and geomorphic statistics related to size and permafrost thicknesses of the palsas, including recent changes. Icelandic palsas exhibit characteristics of both organic palsas and lithalsa (frozen mineral soil). They are subjected to intense aeolian deposition of volcanic materials. The palsas are often 40-200 cm high, with a 40-80 cm thick active layer and permafrost reaching more than 5 m depth. Measurements of the size of the palsas and the thickness of the active layer which started in 2001 indicate that their size is decreasing and the thickness of the active layer is increasing. These results are in agreement with the general warming trend which has occurred in Iceland during the last decade. (c) 2012 Elsevier B.V. All rights reserved.