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- Title
Biogeochemical Responses to Mixing of Glacial Meltwater and Hot Spring Discharge in the Mount St. Helens Crater.
- Authors
Dubnick, A.; Faber, Q.; Hawkings, J. R.; Bramall, N.; Christner, B. C.; Doran, P. T.; Nadeau, J.; Snyder, C.; Kellerman, A. M.; McKenna, A. M.; Spencer, R. G. M.; Skidmore, M. L.
- Abstract
Environments where geothermal waters and glacier meltwater mix are common on Earth yet little is known about the biogeochemical processes that occur when hot, reduced geothermal water mixes with cold, oxidized glacial meltwater in natural systems. Mount St. Helens provides an ideal location to study the interaction between geothermal and glacier waters since the water sources, and their mixing environment in Step Creek, are exposed in the volcanic crater. We find that the two water sources contain distinct major ion, trace element, dissolved organic matter (DOM), and biological signatures. The hot spring contains high concentrations of biogeochemically reactive components (e.g., siderophile and chalcophile trace elements and DOM) compared to the glacier discharge but a large fraction of these solutes do not remain in solution after the waters mix. In contrast, glacier discharge contains fewer solutes but most of these solutes remain in solution after the waters mix. The mixing of glacier and hot spring water in Step Creek supports seston and benthic ecosystems that have higher phototrophic and microbial biomass than those in the source waters, suggesting that the mixing environment in this high‐gradient stream provide a more comprehensive suite of soluble and essential nutrients that promote primary production and DOM cycling. Plain Language Summary: Most of the waters that drain from the crater of Mount St. Helens originate from hot spring seeps or the glacier within the crater. We found these two water sources have distinct chemical fingerprints. When the two water types mix in Step Creek, many of the chemical species from the hot spring either precipitate out of solution or are consumed by the aquatic ecosystem, while most of the chemical species from the glacier flow downstream. The chemical energy and the combination of essential nutrients supplied by the two water sources appear to stimulate a more productive downstream aquatic ecosystem. Key Points: Glacier and hot spring discharges contained distinct major ion, trace element, dissolved organic matter, and biological signaturesMany of the chemical species from the glacier remained in solution after the waters mixed but many of those from the hot spring did notMixed waters supported seston and benthic ecosystems that had higher phototrophic and microbial biomass than either of the water sources
- Subjects
SAINT Helens, Mount (Wash.); HOT springs; MELTWATER; VOLCANIC craters; HOT water; WATER springs; GLACIERS; CHEMICAL fingerprinting
- Publication
Journal of Geophysical Research. Biogeosciences, 2022, Vol 127, Issue 10, p1
- ISSN
2169-8953
- Publication type
Article
- DOI
10.1029/2022JG006852