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Evaluating oxygen fluxes using microprofiles from both sides of the sediment‐water interface
Author(s) -
Bryant Lee D.,
McGinnis Daniel F.,
Lorrai Claudia,
Brand Andreas,
Little John C.,
Wüest Alfred
Publication year - 2010
Publication title -
limnology and oceanography: methods
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.898
H-Index - 72
ISSN - 1541-5856
DOI - 10.4319/lom.2010.8.0610
Subject(s) - sediment , sediment–water interface , oxygen , biogeochemical cycle , soil science , environmental science , diffusion , geology , hydrology (agriculture) , environmental chemistry , chemistry , geomorphology , physics , geotechnical engineering , thermodynamics , organic chemistry
Sediment‐water fluxes are influenced by both hydrodynamics and sediment biogeochemical processes. However, fluxes at the sediment‐water interface (SWI) are almost always analyzed from either a water‐ or sediment‐side perspective. This study expands on previous work by comparing water‐side (hydrodynamics and resulting diffusive boundary layer thickness, δ DBL ) and sediment‐side (oxygen consumption and resulting sediment oxic zone) approaches for evaluating diffusive sediment oxygen uptake rate (J O2 ) and δ DBL from microprofiles. Dissolved oxygen microprofile and current velocity data were analyzed using five common methods to estimate J O2 and δ DBL and to assess the robustness of the approaches. Comparable values for J O2 and δ DBL were obtained (agreement within 20%), and turbulence‐induced variations in these parameters were uniformly characterized with the five methods. J O2 estimates based on water‐side data were consistently higher (+1.8 mmol m −2 d −1 or 25% on average) and δ DBL estimates correspondingly lower (−0.4 mm or 35% on average) than those obtained using sediment‐side data. This deviation may be attributed to definition of the sediment‐water interface location, artifacts of the methods themselves, assumptions made on sediment properties, and/or variability in sediment oxygen‐uptake processes. Our work emphasizes that sediment‐side microprofile data may more accurately describe oxygen uptake at a particular location, whereas water‐side data are representative of oxygen uptake over a broader sediment area. Regardless, our overall results show clearly that estimates of J O2 and δ DBL are not strongly dependent on the method chosen for analysis.