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Oxygen dynamics and evaluation of the single-station diel oxygen model across contrasting geologies
Parker, Simon J.
Parker, Simon J.
Date
2020-1-20
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bg-17-305-2020.pdf
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Parker, S.J. Oxygen dynamics and evaluation of the single-station diel oxygen model across contrasting geologies. Biogeosciences, 2020, 17(2), pp.305-315. https://doi.org/10.5194/bg-17-305-2020
Abstract
In aquatic ecosystems, the single-station, single-stage R diel
oxygen model assumes constant ecosystem respiration and aeration rate
(notwithstanding temperature effects) over the course of a single night. The
validity of this model was assessed for four small streams representing two
geologies (Chalk and Greensand) over a 1-year period, by examining the
behaviour of the nighttime dissolved oxygen (DO) saturation deficit for each
night at points where change in DO is zero. The resulting value was then
compared with the corresponding ratio (the regression quotient) obtained from
nighttime regression analysis (Hornberger and Kelly, 1975). If model
assumptions are correct, then these two values should be equal; where they
diverge therefore gives a method of assessing the suitability of the model
structure. For two streams (one Chalk and one Greensand), the regression quotient
persistently underestimated the observed DO deficit. These two streams showed
similar timing patterns of oxygen dynamics with the point of minimum DO
occurring relatively quickly after sunset in spring and early summer,
although the two Chalk streams were more similar to one another in terms of
DO magnitudes. Comparisons between different streams using the single-station
model with constant R and k on the presumption that it is equally
appropriate in all cases may lead to misleading conclusions.