Recent observations from Arctic Alaska indicate that waters draining permafrost landscapes may be susceptible to iron and carbon mobilization following thaw. One visual indication of the altered iron-cycling processes is the abrupt change in the color of stream and river reaches, reflecting a dramatic shift in water quality. The oxidation of subsurface minerals from thawing permafrost is hypothesized to deliver iron and other toxic metals in dissolved and colloidal forms from thawing soils to streams.

Since 2015, abrupt disturbances have been observed in streams throughout the region. These changes coincide with rapid shifts in air and ground temperature in ARCN since 2014 that indicate the thawing of permafrost. Preliminary observations indicate that the emergence of orange streams reflects a decline in water quality and subsequently in stream biota from an increase in the concentrations of toxic metals.

Dramatic shifts in sulfate and iron concentrations and pH (to < 3) in streams near the mine have been attributed to permafrost thaw. These shifts in chemistry suggest that the oxidation of sulfide minerals may be enhanced in thawing terrain, contributing to acidification of surface waters.

The primary objectives of the proposed work are to:

• Map the spatial distribution of orange streams and the onset of stream color change across ARCN national parks.
• Quantify the effects of iron and other metal inputs on water quality in Arctic streams and determine landscape controls on metal mobilization.
• Assess consequences of shifts in stream water quality on stream biota, including biofilm, macroinvertebrates, and resident and anadromous fish communities.
• Develop tools to predict spatial and temporal impacts to drinking water supplies and subsistence activities.

Project Publications

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  Metal mobilization from thawing permafrost to aquatic ecosystems is driving rusting of Arctic streams.