Yukon River

Global warming affect on water quality and hydrology

Concerns that global warming is changing the water chemistry of the Yukon River by causing permafrost regions to melt, thereby transforming the frozen soil into biogeochemically active zones, led to a U.S. Geological Survey study of the Yukon River Basin. Study objectives were a) to establish a baseline describing the general water quality of the Yukon River and its major tributaries as a reference for measuring future changes and b) to examine the processes that affect or control the water quality of the Yukon River and its tributaries.

In recent reports, USGS scientists:

• reported that over 40% of total N (TN) delivered to the Yukon Delta by the Yukon River is dissolved organic N and 98% of the total P (TP) is particulate phosphorus, with about half of the annual export of TN and TP occurring during spring. (Dornblaser and Striegl, 2007)
• noted that total carbon yield was proportional to water discharge; about half of annual dissolved organic carbon (DOC) export occurred during spring; DOC export, when normalized to water discharge, has decreased from the Yukon basin during summer; and that dissolution of suspended carbonates strongly affected dissolved inorganic carbon concentration and carbon isotopic composition. (Striegl and others, 2007)
• determined, in a collaborative effort with the Marine Biological Laboratory PARTNERS project, that the total input of DOC to the Arctic Ocean appears to be 25-36 teragrams (Tg), which is about 5 to 20% greater than previously reported and about 2.5 times greater than temperate rivers with similar watershed sizes and water discharge. A simple model predicts that approximately 50% of DOC exported during the arctic spring thaw is 1-5 years old, 25% is 6-10 years old , and 15% is 11-20 years old. (Raymond and others, 2007)
• indicated that the ground-water contribution to total annual flow, which appears to be dependent on the geology and permafrost coverage, has shown an overall increase, while there has been minimal change in annual flow; they suggest that the increases in ground-water contributions may largely be due enhanced infiltration brought about by permafrost thawing. (Walvoord and Striegl, 2007)

For additional information see the water-quality and sediment-quality data reports and the following cited references: