Diurnal fluctuations in oxygen release from roots of Acorus calamus Linn in a modeled constructed wetland

The detailed mechanisms of oxygen release from the roots of plants in constructed wetlands (CW) remains unclear. This study investigated the variation of root oxygen release rate, and the effect of photosynthesis during day and night periods on the rate of oxygen release from the roots of Acorus calamus Linn in a model CW. The maximum oxygen release rate was recorded to be in the range of 215.2-750.8 μmolg-1h-1 and this occurred at 15:00. The maximum value of photosynthetically active radiation(PAR) ranged from 1281.8-1712.0 mmolm-2s-1, and this occurred at 13:00. It was observed that both the oxygen release rate and PAR approached zero at night. The results indicate that the rate of oxygen release depends largely on the light intensity, which exhibits a diurnal periodic variation. Accordingly, there are two time intervals namely: day time and night time, during the former period oxygen is released by plants. This study on dynamics of plant root oxygen release distribution has shown that the variation of root oxygen release during daytime followed the Gaussian function. The Gaussian function can be used to predict the root oxygen release rate in constructed wetlands.