1995 Volume 18 Issue 4 Pages 279-289
Free water and incubation methods were applied in order to estimate the net rates of primary production, respiration and gas exchange across the air-water interface using continuously measured dissolved oxygen (DO) and pH data for both outdoor ponds and transparent closed and open boxes (20 cm × 20 cm × 20 cm) suspended in the ponds. The rates of primary production and respiration determined with the closed box agreed well with values obtained in parallel incubations by the standard light bottle method. Gas exchange coefficients were calculated by comparison of the differences in the net rates of change of DO and dissolved inorganic carbon between the closed box and the open box. These gas exchange coefficients varied with wind velocities and those for CO2 were about one order of magnitude larger than those for O2 due to chemical enhancement of CO2 gas exchange. Diurnal changes in the stoichiometry of productivity and the effects of temperature on respiration in the open water of the experimental ponds were estimated and discussed.
