Pål A Olsvik

Publications (43)102.91 Total impact

• Source

  Available from: Eiliv Steinnes

  Article: Variations in heavy metal concentrations and speciation in two mining‐polluted streams in central Norway

  Pål Gundersen, Pål A. Olsvik, E. Steinnes
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  ABSTRACT: The dissolved (dialysis in situ), colloidal (filtered minus dissolved), and total concentrations of Cu, Zn, Cd, and Al were determined and compared with pH, Ca concentrations, and alkalinities through seasonal variations in water levels in two streams, Rugla and Naustebekken, in the Røros area of central Norway. The main objective was to monitor the dissolved fraction of the metals during the seasons and to establish the extent to which chemical parameters influencing metal toxicity were unfavorable during episodes of high total metal concentrations. The average dissolved fractions of Cu, Zn, Cd, and Al were lower in Rugla (55, 69, 64, and 17%, respectively) compared with Naustebekken (59, 82, 82, and 30%, respectively). This is probably due to sedimentation of metal particles in a small lake located in the path of Naustebekken. Alkalinity and Ca concentrations were generally low during the flood episodes, when the highest metal concentrations occurred. This is unfavorable since these parameters are assumed to counteract toxic effects of metals. On the other hand, the results indicate that toxic stress during metal concentration peaks was moderated by adsorption of dissolved metal species on colloids and/or particles.
  Environmental Toxicology and Chemistry 04/2001; 20(5):978 - 984. · 2.81 Impact Factor
• Article: Induction and activity of oxidative stress-related proteins during waterborne Cu-exposure in brown trout (Salmo trutta)

  Bjørn Henrik Hansen, Svein Rømma, Liv I.R. Søfteland, Pål A. Olsvik, Rolf A. Andersen
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  ABSTRACT: Induction of gene transcription for proteins and enzymes involved in metal-mediated oxidative stress were studied in brown trout transferred to a Cu-contaminated river in the Røros region in Central Norway. In addition to metallothionein (MT-A), Cu/Zn-superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) gene transcription, protein levels of MT and enzyme activities of SOD and CAT were analyzed in gill, liver and kidney. MT-A, SOD and GR transcription increased significantly along with uptake of Cu in gills, while only transcription of MT-A was found to respond in liver and kidney during the exposure. Already present MT proteins in gills seemed to be oxidized during the exposure, probably caused by Cu-mediated oxidative stress, and no increase in MT protein levels were observed in gills. SOD and CAT enzyme levels were affected in all tissues during the exposure. A negative correlation between SOD and CAT activities was observed in gills, and we suggest that the activities of these enzymes were influenced not only through transcription. GPx and GR transcription levels correlated positively with each other in gills and liver, indicating their shared function in GSH-turnover. Levels of MT and activity of SOD and CAT dealing with metal-induced oxidative stress appear to be regulated not only through gene transcription, but also through post-translational mechanisms.
  Chemosphere.
• Article: Metal accumulation and metallothionein in two populations of brown trout, Salmo trutta, exposed to different natural water environments during a run-off episode

  Pål A Olsvik, Pål Gundersen, Rolf A Andersen, Karl E Zachariassen
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  ABSTRACT: Cd, Cu and Zn concentrations were measured in ambient water as well as in gills, liver and kidney tissues of two natural populations of brown trout (Salmo trutta) during a run-off episode in two rivers with different metal compositions due to mining pollution. Metallothionein (MT) was also measured in these tissues. The two rivers, Rugla (Cu contaminated) and Naustebekken (Cd and Zn contaminated), are located in two neighboring drainage basins separated by the topographic divide near the city of Røros in the County of Sør-Trøndelag, Norway. In Rugla, the Cu concentration increased from 15 μg/l at the low water level to 41 μg/l during the run-off episode. In Naustebekken, corresponding values for Cd were 90–170 ng/l and those for Zn were 49–91 μg/l. Gill concentrations of Cu and Cd/Zn MT in both populations of native trout clearly reflect the presence of these metals in the rivers during the run-off, in accordance with the hypothesis of protection caused by MT induction. When Rugla trout were transferred to Naustebekken and vice versa, both the amounts of MT itself and the Cu contents reflected the concentration of this metal in the new environment, indicating that MT induction also protects against acutely increased metal levels. The measured levels of MT in both native and transferred trout can account for all the Cd present in the tissues, but not for all of the Cu and Zn. The capacity of MT to regulate Cd and Cu in the trout populations in their natural habitat therefore seems clearly present. Our data also indicate that the MT I and II isoforms may bind metals selectively.
  Aquatic Toxicology.