PACIFIC NORTHWEST STRATOVOLCANO GLACIERS
Washington and Oregon in the Pacific Northwest harbor stratovolcanoes that have formed as a result of melt generated during subduction of the Juan de Fuca oceanic plate under the western edge of the North American plate. These volcanoes can reach over 10,000 feet (or over 3000 meters) in elevation, and built from a diverse range of volcanic material including basalt, andesite, dacite, and rhyolite. The stratovolcanoes of Washington and Oregon started forming about 500,000 years ago, making them relative youngsters in geologic terms. On these peaks, glaciers have scoured and cut the volcanic formations. We were able to explore glaciers on three of these volcanoes during the summer of 2015, and again in 2016.
Gotchen Glacier (center) on the Southeast flank of Mt. Adams in Southern Washington. The summit (12,276 ft or 3,777 m) is just peaking above the ridge (top). Photo by Jeff Havig.
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Eliot Glacier (center) on the Northeast flank of Mt. Hood in Northern Oregon. The summit (11,239 ft or 3,458 m) is partially obscured by clouds. Photo by Jeff Havig.
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Collier Glacier (center right) on the Western flank of the North Sister in Central Oregon. The summit (10,058 ft or 3,095 m) is actually part of a large extinct volcano that also includes the nearby 10,047 ft Middle Sister summit. Photo by Jeff Havig.
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We are studying the geochemistry and ecology of the snow and ice that occupy these volcanic edifices. To do this, we sample snow, ice, supraglacial (or the surface of the glacier) meltwater, and subglacial (or below the glacier) outwash meltwater, contextual rocks and sediments, and the microbial communities that inhabit these environments. Of particular interest is snow algae and ice worms. Our first paper (Hamilton and Havig, 2016, see below) from samples we collected in 2015 is published (open access) in the journal Geobiology, and includes the first carbon uptake rates ever reported for PNW snow algae. A second paper (Hamilton and Havig, 2018, see below) we were able to make the first connection between DIC limitation and snow algae growth, suggesting increasing CO2 concentration in the atmosphere may in fact be driving increased snow algae blooms, which in turn are darkening snow and glacier surfaces, accelerating melting. A third paper (Havig and Hamilton, 2019) greatly expands our understanding of where and how much productivity is occurring across supraglacial and periglacial (around the glacier) terrains, primarily driven by snow algae communities. We also uncovered the source of fixed nitrogen for the snow algae at these sites (primarily anthropogenic), and make connections between supra-glacial primary productivity and subglacial microbial communities that can help drive weathering processes.
Right: Map and Google Earth images showing the areas that we have been sampling in the Pacific Northwest for our snow algae research. We have been focusing our attention on Gotchen Glacier at Mt. Adams in Washington, on Eliot and Palmer Glaciers at Mt. Hood in Oregon, and on Collier and Diller Glaciers at the Three Sisters in Oregon.
We are particularly interested in learning about microbial communities hosted in volcanic terrains as these sorts of sites have been under-studied to date. Volcanic terrains have direct connection to understanding Mars, which is effectively a glacial planet where most of the glaciers are hosted in volcanic terrains. We are working collaboratively with Dr. Alicia Rutledge (now at NAU) and Dr. Briony Horgan at Purdue University who are making links between mineral precipitation at Collier Glacier on the North Sister and remote sensing of mineral assemblages found on Mars. I have linked below to a paper led by Dr. Rutledge on initial results of her work there below. |
First report of carbon fixation rates by PNW snow algae communities, hosted in volcanic terrains =>
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Paper showing a link between increasing dissolved inorganic carbon availability and increasing carbon uptake =>
Paper by Dr. Alicia Rutledge that we collaborated with linking subglacial processes to aqueous geochemistry and mineral precipitation =>
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Paper reporting carbon uptake across supraglacial and periglacial sites, source of fixed nitrogen, and link between supraglacial primary productivity and subglacial chemical weathering =>
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Highlights of Havig and Hamilton (2019) are presented below:
Figure 2 from Havig and Hamilton (2019) showing sampling sites (top), carbon uptake experiment results (middle), and community composition (bottom) from Gotchen Glacier, Mt. Adams, WA.
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Figure 3 from Havig and Hamilton (2019) showing sampling sites (top), carbon uptake experiment results (middle), and community composition (bottom) from Eliot Glacier, Mt. Hood, OR.
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Figure 4 from Havig and Hamilton (2019) showing sampling sites (top), carbon uptake experiment results (middle), and community composition (bottom) from Collier Glacier, North Sister, OR.
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Figure 5 from Havig and Hamilton (2019) showing d15N plotted against d13C for (left) contextual samples (plants, soils, insects, etc.) and (right) snow algae communities. Note that the plants and the snow algae a predominantly near or below -5 per mil for d15N, indicating most of the fixed N is coming from NH3 that is volatilized from dairy lagoons and feed lots to the west. Easter Egg: the crimson dot with the white cross through it represents the first ever reported d13C and d15N values for ice worms!
Figure 8 from Havig and Hamilton (2019) where we present a conceptual model showing our interpretation of the interactions between supraglacial and subglacial systems, and the influence on subglacial chemical weathering.
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Figure 6 from Havig and Hamilton (2019) with plots of P and fixed N present in the different supra- and periglacial sites. The relatively low concentration of P and ammonium in the supraglacial sites contrasts with the relatively higher concentrations in the subglacial sites, indicating release of P and ammonium due to heterotrophic breakdown of organic material in the subglacial system.
Figure 7 from Havig and Hamilton (2019) with plots of dissolved constituents in the supra- and periglacial sites sampled. The increases in dissolved silica (SiO2), Al, Fe, and Ti all reflect dissolution of volcanic materials in the subglacial system.
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Collecting samples at these sites necessitates staying overnight. Here one of our tents is resting on sediments overlaying Eliot Glacier, Mt. Hood, OR. Finding space for a tent that isn't too rocky can be a big challenge. Photo by Jeff Havig.
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Closeup of red snow algae being collected from Palmer Glacier. This biomass sample can be used for incubation studies that can help our understanding of the uptake and use of carbon, nitrogen, and phosphorous by the snow algae and it's associated microbial community. Photo by Jeff Havig.
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A snow worm on the snow surface of Collier Glacier, with my gloved finger for scale. The ice worms are annelids related to earth worms, and feed on snow algae and other organic matter on the glacier surface. Ice worms have a very narrow temperature range that they can survive in, from -6.8 to 5.0°C (or 20 to 40°F). Photo by Jeff Havig.
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Dr. Hamilton collecting ice worms after the sun has set on Collier Glacier, North Sister, Oregon. This view is looking down the valley that Collier Glacier has cut into the flank of the North Sister-Middle Sister volcanic complex. In the middle is a lake at the base of Collier Glacier dammed by Collier Cone, a recent (~1600 years old) cinder cone. In the distance looking north (from left to right) are the stratovolcano remnants Mt. Washington and Three-fingered Jack, and the stratovolcanoes Mt. Jefferson, Mt. Hood, and the very top of Mt. Adams just above Collier Cone. Photo by Jeff Havig.
SNOW ALGAE IN THE ROCKIES
We have been working to sample at some sites in the Rocky Mountains. Specifically, we have been able to sample in the Beartooth Mountains along the Wyoming-Montana border, and in the Medicine Bow Mountains in southeastern Wyoming.
Above: The Beartooth Mountains are Archean-aged rocks that have been thrust up to over 10,000 feet (3080 meters), and host some residual glaciers as well as perennial snow fields. Photo by Jeff Havig.
Above: We have sampled several sites along Highway 212 that connects Silver City, WY and Red Lodge, MT, all at an elevation close to 10,000 feet (3080 m). Here Professor Hamilton (director of The Fringe Lab at UMN) is collecting a sample from a particularly dense bloom of snow algae. Photo by Jeff Havig.
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Above: The Medicine Bow Mountains are Archean to Paleoproterozoic-aged rocks that have been thrust up to between 10,000 and 12,000 feet (3080 to 3700 meters). Though glaciers are long gone, perennial snow fields are still around to host snow algae populations. Photo by Jeff Havig.
Above: We sampled a perennial snow field next to a small unnamed lake at around 10,400 feet (3200 m) elevation, not far from Highway 130. The snow algae here looked orange to pink to green. Photo by Jeff Havig.
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