Vertical transport of sediment-associated metals and cyanobacteria by ebullition in a stratified lake
Name
bg-17-3135-2020.pdf
Description
Published version
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723.9 KB
Format
Adobe PDF
Checksum (MD5)
db07192ad252857d1dc5cea97f743b13
Author(s)
Delwiche, Kyle
Gu, Junyao
Hemond, Harold
Preheim, Sarah P
Date Issued
June 19, 2020
Journal
Biogeosciences
Publisher
Copernicus GmbH
Citation
Delwiche, K., Gu, J., Hemond, H., and Preheim, S. P.: Vertical transport of sediment-associated metals and cyanobacteria by ebullition in a stratified lake, Biogeosciences, 17, 3135–3147.
Version
Final published version
Abstract
Bubbles adsorb and transport particulate matter in a variety of natural and engineered settings, including industrial, freshwater, and marine systems. While methane-containing bubbles emitted from anoxic sediments are found widely in freshwater ecosystems, relatively little attention has been paid to the possibility that these bubbles transport particle-associated chemical or biological material from sediments to surface waters of freshwater lakes. We triggered ebullition and quantified transport of particulate material from sediments to the surface by bubbles in Upper Mystic Lake, MA, and in a 15 m tall experimental column. Particle transport was positively correlated with the volume of gas bubbles released from the sediment, and particles transported by bubbles appear to originate almost entirely in the sediment, rather than being scavenged from the water column. Concentrations of arsenic, chromium, lead, and cyanobacterial cells in bubble-transported particulate material were similar to those of bulk sediment, and particles were transported from depths exceeding 15 m, implying the potential for daily average fluxes as large as 0.18 µg arsenic m−2 and 2×104 cyanobacteria cells m−2 in the strongly stratified Upper Mystic Lake. Bubble-facilitated arsenic transport currently appears to be a modest component of total arsenic cycling in this lake. Although more work is needed to reduce uncertainty in budget estimates, bubble-facilitated cyanobacterial transport has the potential to contribute substantially to the cyanobacteria cell recruitment to the surface of this lake and may thus be of particular importance in large, deep, stratified lakes.
MIT Department
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
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Creative Commons Attribution
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DOI of Published Version
https://doi.org/10.5194/bg-17-3135-2020, 2020
