|Other Abstract||The research investigated the biochemical activities in media system plot of Integrated Vertical-flow Constructed Wetland (IVCW). The substrate oxidoreductase activities, the correlations between the redox potential characteristics and microorganisms activities, as well as the influences of pentachlorophenol (PCP) on the substrate oxidoreductase activities in IVCW were studied, and the results were summarized as follows:
1. There were significant differences in different seasons for the activity of oxidoreductases; the activities of peroxide were significantly higher in spring, summer, autumn than those in winter (P<0.05); the activities of polyphenol oxidase and catalase were highest in autumn; the activity of dehydrogenase was significantly higher in summer and winter than those in spring and autumn (P<0.05); the activities of nitrate reductase was significantly higher in spring and winter than those in summer and autumn (P<0.01). As for the spatial characteristics, the activities of polyphenol oxidase, catalase and dehydrogenase in down-flow chamber were significantly higher than those in up-flow one, except peroxide; meanwhile, the activities of enzyme were degressive with the increase of substrate layer depth, but there was no obvious difference for nitrate reductase activities in the different depths in the substrate of IVCW.
2. Under the 800mm/d of hydraulic loading, the redox potential, numbers of aerobic microorganisms and oxygen consumption rates were the highest respectively in the surface layer, and decreased gradually with the increase of substrate depth. The activities of oxidases in the surface layer were generally higher than those in the middle and lower layers except peroxidates; while the change trends of nitrate reductase and nitrite reductase activities were reverse. There were significantly positive correlations between the redox potential and the numbers of bacteria, fungi, actinomycetes and oxygen consumption rates; there were significantly positive correlations between the redox potential and the activities of polyphenol oxidase, catalase, dehydrogenase. Meanwhile, significantly negative correlations between the redox potential and nitrate reductase, nitrite reductase activities were found in the down-flow chamber.
3. The results showed that the strengths of cellulose decomposition, ammonification and phenol decomposition and oxygen consumption rate were higher in downflow chamber than those in the upflow one, and those in the surface layer were higher than those in the middle and lower layers; all indexes change trends were similar to the spatial distribution of the substrate biomass. The down-flow chamber and the surface layer were the main purification region of the pollutants. The anaerobic environment that in the upflow chamber was better than that in the down-flow one. The Co2+ could affect the anaerobic activity of the substrate; the anaerobic activity of the substrate increased and then decreased with different concentrations of Co2+. These studies would help to disclose the purification mechanisms of IVCW.
4. The influences of PCP on the substrate oxidoreductases were different under different concentrations. The activities of catalase manifested basically “inhibition-stimulation” mode under all the concentraton tested. The activities of dehydrogenase manifested basically “inhibition-stimulation-restoration” mode under the middle and lower concentration (1μg/g, 10μg/g) treatments, while the activities manifested basically “inhibition-stimulation” mode under the high concentration (50μg/g, 100μg/g) treatments. The activities of peroxidases and polyphenoloxidase manifested basically “stimulation-restoration” mode under the middle and lower concentration (1μg/g, 10μg/g) treatments, while the activities basically manifested “inhibition-restoration” mode under the high concentration (50μg/g, 100μg/g) treatments. The stimulation or inhibition intensities changed with the concentrations of PCP.|