A numerical dissolved oxygen (D.O.) routing model DORM is developed
to determine• total stream community photosynthesis (P) and community
respiration rates (R) through successive routing of two-station diel
D.O. measurements in a stream. The model differs from existing procedures
for diel curve productivity analysis in that it uses the complete
D.O. transport equation, including D.O. surface exchange, longitudinal
dispersion, dependence of respiratory rates on water temperature and
dissolved oxygen. The model is applied to the experimental field
.channels at the USEPA Monticello Ecological Research Station to compute
P and R values at different seasons and under different conditions of
water temperatures, solar radiation, and pH. A sensitivity analysis
shows that computed P and R values are most sensitive to residence times
and surface oxygen exchange (reaeration) coefficients. New equations for
surface exchange including the effect of wind have been developed and
A graphical simplified routing procedure produced P and R values
which were 82 and 89 per cent, respectively, of those obtained by complete
routing, with a standard deviation of les~ than 5 per cent.
Nighttime longitudinal D.O. gradients were used to derive respiration
Maximum values of P and R in the MERS channels were 14.8 g m- 2
day-1 and 10.7 g -2-1 m day , respectively. P/R ratios ranged from
0.3 to 2.1. A seasonal dependence of P and R values was found as
Hysteresis in plots of hourly P versus photosynthetically active
radiation (PAR) intensity was observed frequently. It was of such
magnitude that it could not be caused by errors in surface exchange
estimates or other physical processes.
Environmental Research Laboratory - Duluth
Office Of Research And Development
U. S. Environmental Protection Agency
Gulliver, John S.; Mattke, Tedd W.; Stefan, Heinz G..
Numerical And Graphical Procedures For Estimation Of Community Photosynthesis And Respiration In Experimental Streams.
St. Anthony Falls Laboratory.
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