Flux of reduced chemical constituents (Fe2+, Mn2+, NH inf4 sup+ and CH4) and sediment oxygen demand in Lake Erie |
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Authors: | Adams Donald D Matisoff Gerald Snodgrass William J |
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Institution: | (1) Departments of Chemistry and Geology, Wright State University, 45435 Dayton, OH, USA;(2) Department of Geological Sciences, Case Western Reserve University, 44106 Cleveland, OH, USA;(3) Department of Civil Engineering, McMaster University, L8S 4L7 Hamilton, Ontario, Canada |
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Abstract: | Sediment pore water concentrations of Fe2+, Mn2+, NH
inf4
sup+
and CH4 were analyzed from both diver-collected cores and anin situ equilibration device (peeper) in Lake Erie's central basin. Sediment oxygen demand (SOD) was measured at the same station
with a hemispheric chamber (including DO probe and recorder) subtending a known area of sediments. The average SOD was 9.4
mM m−2 day−1 (0.3 g m−2 day−1). From pore water gradients within the near-surface zone, the chemical flux across the interface was calculated indirectly
using Fick's first law modified for sediments. These calculations, using core and peeper gradients, always showed sediment
loss to overlying waters, and variations between the two techniques differed by less than an order of magnitude for Fe2+ and CH4. The transport of these reduced constituents can represent a sizeable oxygen demand, ranging from less than 1% for Fe2+ and Mn2+ to as high as 26% for NH
inf4
sup+
, and 30% for CH4. The average flux of these constituents could account for about a third of the SOD at the sediment-water interface of this
station. |
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Keywords: | sediment oxygen demand interstitial water hypolimnion methane ammonium iron manganese oxidation sediment-water interface |
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