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Arctic lakes mirror environmental changes

Last changed: 06 February 2017

In the mountains of Sweden are almost 22,000 artic-alpine lakes which reflect all the changes that are taking place in nature. Professor Willem Goedkoop coordinates the project to develop a pan-arctic network of freshwater monitoring stations.

“The environmental changes taking place in the Arctic are happening rapidly and are widespread," says Professor Willem Goedkoop, who is an aquatic ecologist and one of Sweden's leading freshwater experts.”

Thawing makes slopes collapse

He talks about dramatic, widespread changes in the arctic landscape. About how permafrost thawing is causing entire mega slumps that makes slopes suddenly collapse in north western Canada. About melting glaciers which are making it possible to extract minerals, oil and gas from areas that were previously inaccessible.

A warmer climate will also make transports easier. It will for example be easier to transport goods by vessel when coastlines remain ice-free for longer. However, overland transportation will be hampered, as ice roads may become less accessible.

Lakes receive more pollutants

“The lakes act like mirrors in the landscape by reflecting changes in nature. They receive pollutants from point sources, such as mines, and from other human activity. When the permafrost melts, particle transport into the lakes also increases.“

The researchers currently believe the biggest threats to arctic fauna and flora to be global warming and the increased extraction of natural resources. Countries with land areas north of the Arctic Circle are working together within the framework of the Conservation of Arctic Flora and Fauna (CAFF) to conserve the biodiversity of the arctic environment.

Professor Goedkoop is a member of the freshwater group in CAFF, but similar teams of researchers are working on terrestrial and marine environments.

Warmer and wetter mountains

“Twenty six years ago, we started to carry out water chemistry and biological measurements in eight mountain lakes. This has enabled us to detect changes and gain an understanding of what we can expect as the climate warms.”

Analyses of meteorological data reveal that, since the mid-1990s, the mountains of Sweden have become both warmer and wetter, thus reducing the time that the lakes are covered in ice. Thawing mountain moorland can also release organic pollutants and environmental toxins which were previously bound in the soils, causing them to reach lakes and watercourses.

Rising pH and less phosphate

“The eight lakes from which measurements were taken are situated in Sweden's mountain chain, one of Europe's least affected regions, yet we can still see clear changes in them. One positive change is that the pH of the lakes is rising, caused by the decline in the atmospheric deposition of sulphate and other acidifying compounds across Sweden during the period.”

However, despite the reduction in atmospheric deposition, concentrations of sulphate in a few lakes, particularly high-altitude lakes in the mountain chain, are rising. This is probably the result of previously deposited sulphate reaching the lakes due to the melting of multiannual ice or snow. Another theory is that the melting released and oxidised glacial clays containing sulphides.

“We are also seeing declining trends in phosphate concentrations in the lakes, which is causing the lakes to become even more nutrient-poor. The same trend can be seen in both Finland and Canada, so it appears to be a large-scale change.”

Continuous monitoring shows the changes

Professor Goedkoop points out that it will only be once the researchers have access to long time series that they will be able to see indications of ongoing changes on top of inter-annual variations. The measurements taken in the eight mountain lakes now provide valuable information for purposes which the researchers could not have originally foreseen.

“The aim is an arctic monitoring network, which enables continuous, standard measurements to be taken. This will enable us to monitor ongoing changes in the environment with much greater certainty than is currently possible.”