2. Glacial dust carries iron to the Gulf of Alaska
Iron is an essential nutrient for phytoplankton in the ocean. How does iron get to the ocean? In the Gulf of Alaska the sources of iron and the processes that transport iron to the ocean are not well quantified. Crusius et al. combine satellite, meteorological, and other data to infer one source of "bioavailable" iron: dust from the Gulf of Alaska coastline.
Glacial erosion causes large amounts of fine-grained sediment, known as glacial flour, to be deposited near the coast. Some of this material can be resuspended by the wind and transported hundreds of kilometers from shore during dust storm events that occur at least annually, and most often in the fall, when river levels are low and sediments are exposed. The authors find that glacial flour dust storms are a significant source of iron to the Gulf of Alaska. They estimate the amount of iron-containing dust transported to the Gulf of Alaska from the Copper River valley during one 2006 dust storm to be between 25 and 80 thousand metric tons (28 to 88 thousand tons (U.S.)). If glaciers continue their present-day pattern of increasing mass loss due to a warming climate, more glacial flour may be transported to the Gulf of Alaska by this and other mechanisms, affecting phytoplankton growth and Gulf of Alaska ecosystems.
Source: Geophysical Research Letters, doi:10.1029/2010GL046573, 2011 http://dx.doi.org/10.1029/2010GL046573
Glacial flour dust storms in the Gulf of Alaska: Hydrologic and meteorological controls and their import
|Contact: Peter Weiss|
American Geophysical Union