Arctic glaciers are a source of silica
27 September 2016
Meltwater contains considerable amounts of dissolved silica, an essential nutrient for a healthy coastal food web.
Greenland is covered by the second largest ice sheet in the world. As the large mass of glacier ice is slowly but steadily on the move, the rocks underneath undergo intense weathering. One of the elements that is released with weathering is silica. The Earth crust consists mainly of silicates, and this rock type contains plenty of silica. Nevertheless, glaciers were until now considered inactive in the global silica cycle.
Patrick Meire (Global Change Ecology Excellence Center, Research Group Ecosystem Management) investigated together with Danish, German, Belgian, Canadian and Dutch colleagues whether the glaciers really only release negligible quantities of silica to the Arctic Ocean.
Their research now shows that glaciers cannot at all be considered as inactive in the silica cycle. Lorenz Meire, researcher of the Greenland Climate Research Centre: “Measurements in different glacier fed rivers around Greenland show that the weathering by the ice sheet is a rich source of silica for the ocean. The glaciers actually deliver equal amounts of silica to the ocean as some large rivers around the North Pole region.”
Silica is an essential nutrient for the growth of diatoms. These unicellular organisms are at the base of the coastal food web. Because of their energy- and nutrient-efficient photosynthesis, they often dominate other phytoplankton: they play therefore an essential role feeding the coastal food web.
Lorenz: “There are very strong indications in our observations that silica originating from the glaciers is important for diatoms along the Greenland coasts. The accelerated melting of the glaciers, as a result of climate change, will further increase the weathering rates. This could results in an almost 3-fold increase in silica delivery. This could have an important impact on the diatom productivity.”
The research was published in Geophysical Research Letters, a journal of the American Geophysical Union.