Restaurering av eutrofierade sjöar i Sverige: metoder, miljöpåverkan och genomförda projekt
Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
Eutrophication and overgrowth in lakes are in general natural processes that occur with sedimentation. Lakes near the northern Swedish coast can also be affected by land rising. Mankind has increased the amount of nutrients circulating in nature, which in some lakes causes an increase in the level of phosphorus and that in turn leads to the lakes becoming eutrophic. These phosphorus sources are foremost sewage, leakage from arable land and surface water. Under many years the lakes also store large amounts of phosphorus in the sediment which can be released back to the water even if the external supply of phosphorus has stopped. This report is based on a literature review with the purpose to gather information about methods used in lake restoration in Sweden. Internet sources and interviews were used to present different projects where restoration methods have been applied. To preserve the environmental quality of lakes in Sweden the government tries to decrease the amount of phosphorus that affects the lakes. There are several methods to do this, such as removing the phosphorus-rich sediments or by chemical additions that help to bind the phosphorus harder to the sediment. The external supply of phosphorus must be minimized for these methods to succeed or the lake will return to its previous stage. Which method to choose depends on the lake, but oftentimes a combination of methods is the best solution to restore a lake. There are numerous things to think about before the restoration in order to minimise the effect on organisms in the lake. For an example geotextiles can be used to prevent muddy water. The restored lakes in this study show, in most cases, a positive change after the restoration with an increased value for organisms and for mankind. Restoration used with the purpose of preventing eutrophication could be a step in the right direction to preserve this biotope and increase the biological diversity.
Place, publisher, year, edition, pages
2006. , 52 p.
Eutrophication, lake restoration, restoration methods, phosphorus, sediment, external supply
IdentifiersURN: urn:nbn:se:umu:diva-31365OAI: oai:DiVA.org:umu-31365DiVA: diva2:292624
Johnson, TorbjörnBacklund, Sten, universitetsadjunkt