title: Effect of Sediment Gas Voids and Ebullition on Benthic Solute Exchange.
abstract: The presence of free gas in sediments and ebullition events can enhance the pore water transport and solute exchange across the sediment-water interface. However, we experimentally and theoretically document that the presence of free gas in sediments can counteract this enhancement effect. The apparent diffusivities (Da) of Rhodamine WT and bromide in sediments containing 8-18% gas (Da,YE) were suppressed by 7-39% compared to the control (no gas) sediments (Da,C). The measured ratios of Da,YE:Da,C were well within the range of ratios predicted by a theoretical soil model for gas-bearing soils. Whereas gas voids in sediments reduce the Da for soluble species, they represent a shortcut for low-soluble species such as methane and oxygen. Therefore, the presence of even minor amounts of gas can increase the fluxes of low-soluble species (i.e., gases) by several factors, while simultaneously suppressing fluxes of dissolved species.
authors.affiliation: Chemical Analytics and Biogeochemistry, Leibniz-Institute of Freshwater Ecology and Inland Fisheries , 12587 Berlin, Germany.|Nordic Centre for Earth Evolution (NordCEE), University of Southern Denmark , 5230 Odense M, Denmark.
authors.forename: Sabine
authors.initials: S
authors.lastname: Flury
authors.affiliation: Nordic Centre for Earth Evolution (NordCEE), University of Southern Denmark , 5230 Odense M, Denmark.|Scottish Association for Marine Sciences, Scottish Marine Institute , PA37 1QA Oban, United Kingdom.|Arctic Research Centre, University of Århus , 8000 Århus C, Denmark.
authors.forename: Ronnie N
authors.initials: RN
authors.lastname: Glud
authors.affiliation: Chemical Analytics and Biogeochemistry, Leibniz-Institute of Freshwater Ecology and Inland Fisheries , 12587 Berlin, Germany.|Institute for Landscape Biogeochemistry, Leibniz Centre for Agricultural Landscape Research (ZALF) , 15374 Müncheberg, Germany.
authors.forename: Katrin
authors.initials: K
authors.lastname: Premke
authors.affiliation: Chemical Analytics and Biogeochemistry, Leibniz-Institute of Freshwater Ecology and Inland Fisheries , 12587 Berlin, Germany.|Nordic Centre for Earth Evolution (NordCEE), University of Southern Denmark , 5230 Odense M, Denmark.|Institute F.-A. Forel, Section of Earth and Environmental Sciences, Faculty of Sciences, University of Geneva , 1211 Geneva 4, Switzerland.
authors.forename: Daniel F
authors.initials: DF
authors.lastname: McGinnis
mesh_terms: D001965:Bromides / Q000032:analysis; D004058:Diffusion; D017753:Ecosystem; D005740:Gases / Q000032:analysis*; D019015:Geologic Sediments / Q000737:chemistry*; D008697:Methane / Q000032:analysis; D016062:Porosity; D012235:Rhodamines / Q000032:analysis; D012995:Solubility; D014867:Water / Q000737:chemistry
chemical_list: D001965:Bromides; D005740:Gases; D012235:Rhodamines; D014867:Water; C222011:rhodamine WT; D008697:Methane