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- PublicationDiurnal fluctuations in root oxygen release rate and dissolved oxygen budget in wetland mesocosmTo assess the role of plants for oxygen offering in constructed wetlands, this study experimentally evaluated the amount of root oxygen release rate using mass balance method. The mass balance calculation is based on the following components: respiratory oxygen consumption of the roots; oxygen required for degradation of the organic matters; oxygen required for nitrification; and the amount of dissolved oxygen in the influent, effluent and substrate water. Experimental results have demonstrated that the root oxygen release rate was ranged from 20.3 to 58.3gO2/m2.d with average value of 38.4gO2/m2.d, which was affected dramatically by light intensity. Only 35% and 9% of the oxygen released by roots were used in the degradation of organic matters and nitrogen-nitrification, respectively, while 56% was used for roots respiration with little to be released to the surrounding medium. The results also showed that diurnal fluctuation of oxygen release and light intensity followed unimodal distribution. Meanwhile, a better understanding of the DO (dissolved oxygen) budget was proposed. Root oxygen release rate could be described by two fractions. One is “net specific oxygen release rate” and the other is “dischargeable oxygen release rate”.
Scopus© Citations 35 1548
- PublicationDiurnal fluctuations in oxygen release from roots of Acorus calamus Linn in a modeled constructed wetlandThe 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.
812Scopus© Citations 9