The aim of this study was to examine the metal contributions to and from the lake Råsvalen, in northern Örebro County in Sweden, from incoming and outgoing streams. The main questions were: what is the metal concentration in the streams? How large is the metal transport from the streams, do the concentrations imply a risk for the biota, and can any source be identified. Water was sampled at six locations at six occasions with two-week intervals. The water samples were analyzed for total metal concentrations. The results were compared to environmental quality standards; EQS and from Swedish environmental protection agency suggested class limits. The concentrations were also compared to deviations from background levels and estimations of risk for biological effects. Metal transport was calculated from the average measured concentrations and water flow data from SMHI. Data from sediment analysis in 1989 was included for information about temporal trends. Zn, Cu, and Pb had concentrations above the limits and therefore they could have an effect on biota in water. Zn had a maximum concentration of 39 µg/l in Storån, which is 12 times higher than limits. Pb was found in a maximum concentration of 4,3 µg/l in Hammarskogsån downstream, which is more than twice as high as EQS. Cu was found in concentration of 6,1 µg/l in Storån downstream. Comparison with estimations of biological effects showed no or little effects except for Pb in Hammarskogsån downstream and Storån showing moderate risk. The stream that contributes most to metal influx is Storån. The stream stands for >80% of the total estimated metal transport. Possible sources could be historical mining, and higher levels upstream may contribute to the metal levels found in Storån.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:umu-88247 |
| Date | January 2014 |
| Creators | Warnicke, Caroline |
| Publisher | Umeå universitet, Institutionen för ekologi, miljö och geovetenskap |
| Source Sets | DiVA Archive at Upsalla University |
| Language | Swedish |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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