9 research outputs found
Metal levels in an epiphytic lichen as indicators of air quality in a suburb of Helsinki, Finland
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
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
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
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
In Situ Bioremediation through Mulching of Soil Polluted by a Copper–Nickel Smelter
Received for publication September 8, 2000. Bioremediation of a heavy metal–polluted soil was investigated in a 3-yr field experiment by adding mulch to a polluted forest floor. The mulch consisted of a mixture of compost and woodchips. The remediation treatment decreased the toxicity of the soil solution to bacteria as determined by the [3H]-thymidine incorporation technique, that is, by measuring the growth rate of soil bacteria extracted from unpolluted humus after exposing them to soil solution containing heavy metals from the experimental plots. Canonical correlation analysis was performed in order to identify the chemical and microbiological changes in the soil. The pH of the mulched organic layer increased by one unit. The concentration of complexed Cu increased and that of free Cu2+ decreased in the soil solution from the mulch treatment. According to basal respiration and litter decomposition, microbial activity increased during the 3 yr following the remediation treatment. The [3H]-thymidine incorporation technique was also used to study the growth rate and tolerance of bacteria to Cu. The bacterial growth rate increased and the Cu tolerance decreased on the treated plots. The structure of the microbial community, as determined by phospholipid fatty acid (PLFA) analysis, remained unchanged. The results indicate that remediation of the polluted soil had occurred, and that adding a mulch to the forest floor is a suitable method for remediating heavy metal–polluted soil