Water striders (Heteroptera, Gerridae) as bioindicators of heavy metal pollution

Heavy metal contents of water striders collected near a steel factory and from control sites were analyzed by AAS. The average concentrations µg/g of dry weight found near the factory vs. the control areas were: Al 76, 65; Fe 840, 330; Mn 49, 37; Zn 310, 280; Cu 44, 42; Cd 1.6, 6.5, respectively. In most cases Ni and Pb concentrations were below the determination limit in both sites. There were significant differences between sites in the concentrations of iron and cadmium. Fifth instar larvae had higher iron content than adults, but sexes did not differ in heavy metal content. There were also significant differences between different water strider species as accumulators of zinc, aluminium and cadmium. It is concluded that water striders seem suitable as bioindicators of heavy metals

Epilithic diatoms (Bacillariophycae) from streams in Ramsar, Iran

Epilithic diatoms were identified from five small streams and one canal in Ramsar, northwest Iran. Atotal 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

Factors Affecting Metal and Radionuclide Pollution In the Baltic Sea

External pollution load in the Baltic Sea originates from urban, agricultural and industrial sources. Emissions of heavy metals have decreased substantially in the catchment area but the temporal trends are not always significant and differ with sample, area and pollutant. The most significant source of anthropogenic radioactivity in the Baltic Sea is fallout from the Chernobyl accident in 1986. Many factors affect the future development of pollutant concentrations including anthropogenic emissions, political decisions and changes in salinity, temperature and water currents, in eutrophication and oxygen status, in fisheries and in atmospheric deposition of pollutants. Large scale changes like eutrophication and climate change affect ecosystems in many ways, directly and indirectly, causing biological and abiotic effects. These factors are interrelated and difficult to predict. Measures aiming to enhance the ecological status of the Baltic Sea will certainly give positive results but this will take at least several decades.Peer reviewe

Cadmium in insects after ash fertilization

Ash fertilization of forests returns nutrients to forest ecosystems and has a positive effect on soil pH, but it also may elevate Cd concentrations of forest biota. Cadmium concentrations of some forest insects (Formica ants, carabids and Coleopteran larvae from decaying wood) were investigated in southern Finland, where two plots were fertilized with wood ash, while two other plots represented unfertilized control plots. In ants, mean Cd concentration was 3.6 ± 1.4 mg/kg, with nest workers having significantly higher concentrations than workers trapped in pitfall traps. Concentrations at fertilized and unfertilized plots were similar. In carabid beetles, the average Cd concentration of Carabus glabratus was 0.44 ± 0.36 mg/kg, with no significant difference between control plots and fertilized plots. In another carabid beetle, Pterostichus niger, mean Cd concentration was higher at fertilized plots compared to control plots. We conclude that the variation of Cd concentrations in the insects studied is more efficiently controlled by species-specific differences than fertilization history of the forest floor

Effects of Ash Application on Cadmium Concentration in Small Mammals

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 Finland. Part of the sample population was from sites that had been treated with ash 1.5 years earlier, part from untreated control sites. The ash increased the soil pH and gave an average cadmium load in soil of 44 g ha1.When comparing treated and control areas, we found slightly but significantly lower Cd concentrations in vole muscle, liver, and kidney from treated plots, whereas the Cd concentrations in shrew tissues were greater in animals from treated plots. In voles we detected an increase in Cd concentrations during the 45-d sampling period in treated and untreated plots. The relative weight of kidneys was greater from the ash-treated areas than untreated areas for both voles and shrews. The difference in Cd concentrations between the voles and shrews could be explained by the different food habits

Diatom and Metal Stratigraphy of a Small and Shallow Lake in Southern Finland

A sediment sequence of 52 cm in length was cored from the deepest point (1.5 m) of Lake Sandöträsket, SW Finland (59° 52’ N, 23° 10’ E) close to a steel plant. The frequency of diatom species and the concentrations of ten elements (Ca, Cd, Cu, Hg, Fe, Mg, Mn, Ni, Pb and Zn) and organic matter were studied. The isolation from the Litorina Sea (now the Baltic Sea) about 3100 years ago was clearly seen in the distribution of diatom species. However, the Cs dating revealed that the upper sediment layers were mixed. The diatom stratigraphy indicates small or moderate changes in pH and trophic status of the lake. The metal distribution was similar for many metals with many fold higher concentrations near the surface compared to the lowest layers. There were strong correlations between metals except for Ca and Mg. Metal concentrations were compared to other lacustrine and marine sediments from the same area. The diatom and metal stratigraphies indicate anthropogenic influence

Shores in the city: opportunities, threaths and challenges : viewpoints of citizens in Helsinki.

The attitudes of citizens in Helsinki towards sea shores were investigated by means of three different surveys in the late summer of 2002. Survey data showed clear evidence that the shores are important to the citizens of Helsinki. People visited the shores often and participated in many different activities including general recreation, sunbathing, nature observation, swimming and physical exercise. Problems mentioned in the surveys were related on the other hand to the purity and tidiness of the water and the shores and on the other hand to the development plans of the growing city. Most people want to keep the shores in natural condition, but at the same time they also ask for services like litter bins, benches and toilets. People using boats would appreciate better garbage management, fire places and landing stages. There was some variation among different age groups and areas, but generally the citizens of Helsinki are quite unanimous in their opinions concerning the importance of shores and archipelago for physical and mental welfare