EGU22-3571, updated on 27 Mar 2022
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Impact of hydrothermal activity on the Si cycle in Yellowstone Lake

Petra Zahajská1,4, Sherilyn Fritz2, Sophie Opfergelt3, Johanna Stadmark1, Rosine Cartier1, and Daniel Conley1
Petra Zahajská et al.
  • 1Department of Geology, Lund University, Lund, Sweden
  • 2Department of Earth and Atmospheric Sciences, School of Biological Sciences University of Nebraska – Lincoln, Lincoln, Nebraska, USA
  • 3Earth and Life Institute, Environmental Sciences, Université catholique de Louvain, Louvain-la-Neuve, Belgium
  • 4Institute of Geography & Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland

Diatoms (unicellular algae forming siliceous tests) are a significant component of the linked carbon-silicon (Si) cycles in that they consume Si released from the weathering of silicate rocks and subsequently sequester carbon and silica when buried in sediments. Thus, regions of diatom-rich sediment yield a window into the conditions that favor high carbon export rates and burial. We studied the Si sources (tributaries, hydrothermal vents) and sinks (diatomaceous sediment) of Yellowstone Lake, which is situated on silicate rich volcanic rocks, to elucidate Si cycling dynamics in the present and during the Holocene. 

Recent lake water, tributaries, and hydrothermal vent fluids from Yellowstone Lake were analyzed for their dissolved Si (DSi) concentration and stable silicon isotopes (δ30Si) to aid in evaluating the sources of variability in the lake’s Si cycle. In addition, elemental composition (XRF), biogenic silica (BSi) content, and the diatom δ30Si were analyzed in two sedimentary core records spanning the Holocene from a hydrothermally influenced area and an undisturbed deep portion of the lake to identify whether past hydrothermal explosions and disturbance by Mazama ash deposition affected Si cycling.

Combinations of the Si and δ30Si mass balance, sedimentary BSi, diatom δ30Si with XRF, and lithology data revealed that Yellowstone Lake has a resilient biogeochemical system influenced by consistently high hydrothermal input throughout the Holocene. Several of the hydrothermal explosions identified in the lithology had no identifiable long-term impact on BSi accumulation or the diatom δ30Si signature. Both cores show similarities that suggest a stable and homogeneous DSi source across the entire lake. Thus, the diatom δ30Si values record changes in the relative proportion of DSi sources, diatom production connected with changes in climate, and hydrothermal inputs.

How to cite: Zahajská, P., Fritz, S., Opfergelt, S., Stadmark, J., Cartier, R., and Conley, D.: Impact of hydrothermal activity on the Si cycle in Yellowstone Lake, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3571,, 2022.