Adsorption and desorption of mercury was studied under laboratory conditions using moss (Sphagnum girgensohnii) and Rye grass (Lolium perenne) at different temperatures. Desorption was also studied in a transplantation experiment. The adsorption was rapid and strong for both plant species at different temperatures (q10 to q60 8C) and exposure times (1 h, 1 month) while the evaporation was negligible. Also the leaching of adsorbed mercury was of minor importance. The results emphasise the importance of vegetation in removal of mercury from the atmosphere. They also confirm the suitability of moss and grass for biomonitoring purposes. The high retention of mercury in moss even at q60 8C indicates the possibility of using higher temperatures in pretreatment of samples for mercury analyses. ᮊ

-Epilithic diatoms were identified from five small streams and one canal in Ramsar, northwest Iran. A total of 155 diatom taxa belonging to 37 genera were found and only two species remained unidentified (Fragilaria sp. and Nitzschia sp.). Achnanthes, Nitzschia, Navicula, Cocconeis, Melosira, Amphora, Craticula, Diatoma, Surirella, Cymbella, Diploneis and Entomoneis were among the most abundant genera. Eighty seven taxa were recorded for the first time in Iran. Thirty two of the genera belong to the Pennales and 5 to the Centrales. Species richness was rather high ranging from 66 to 95 taxa at the six sites studied. The epilithic diatom species found in Ramsar were dominated by cosmopolitan taxa found in meso-to fairly eutrophic waters with high conductivity and high nutrient concentrations. The abundances found at all six sites were compiled in order to estimate the overall abundance of each taxon in Ramsar. This study includes EM pictures of diatoms observed in Ramsar, Iran.

ABSTRACTthe effects of pollutants, a factor neglected in many investigations.In order to assess the effects of wood ash application to forests on small mammals, we collected bank voles (Clethrionomys glareolus ) and common shrews (Sorex araneus ) from a forest area in southern MATERIALS AND METHODS Finland. Part of the sample population was from sites that had been Three study plots treated with ash and two control plots treated with ash 1.5 years earlier, part from untreated control sites.with no ash applied were chosen around two small lakes,The ash increased the soil pH and gave an average cadmium load in Tavilampi and Nimetö n, located about 1 km apart in Evo, soil of 44 g ha Ϫ1 . When comparing treated and control areas, we found southern Finland (61Њ14Ј N, 25Њ12Ј E). The area of each plot slightly but significantly lower Cd concentrations in vole muscle, liver, was approximately two hectares. The soils at these sites were and kidney from treated plots, whereas the Cd concentrations in shrew formed on moraine deposits and in peat, and the forests con- Approximately 4.8 Mg ha Ϫ1 of wood ash (dry weight) was applied in February 1998. This ash contained 9.2 g g Ϫ1 (dry weight) of cadmium that gave an single average load of 44 g A pproximately 100 000 Mg of wood ash is generated Cd ha Ϫ1 . This amount exceeded the 3 g Cd ha Ϫ1 yr Ϫ1 limit each year in Finland. This ash could be used as Areas subjected to ash application should be monitored Small mammals were collected from 27 July 1999 through over extended periods in order to evaluate the potential and spiders (Pernetta, 1976; Saarikko, 1989). age and not breeding), subadults (23 months, not breeding Small mammals have been used as biological indicaand with delayed maturation), young adults (34 months and tors for several reasons: they are rather easy to collect, breeding), and overwintered (about 1 year and breeding) (Pré -they move within a limited areas, and it is possible to vot-Julliard et al., 1999). The shrews were divided into summer use both herbivorous and carnivorous species (e.g., Ma born, nonbreeding juveniles, and overwintered adults (Churchfield, 1990). The trapped animals were frozen in toto as soon et al., 1991;Pankakoski et al., 1994). Environmental

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