Effect of Microorganism-plant Joint Remediation on N2O, N2 and O2 Release Flux from Polluted Waters in Urban River

Considering the remediation of polluted water in urban area, this study investigated the effect of microbial agent(MAP) and aquatic plant combined purification method(MAAPP) on N2O, N2 and O2 releasing characteristics from the water system, using a gas trapping device. The results showed the average N2O releasing flux during MAP and MAAPP period was 10.68 μmol·m-2·h-1 and 5.91 μmol·m-2·h-1, respectively, and decreased by 16.37% and 53.86% in contrast to the control pond. The average N2 releasing flux during the MAP and MAAPP period was 1.49 mmol·m-2·h-1 and 0.87 mmol·m-2·h-1, and decreased by 5.70% and 67.54% in contrast to the control pond, respectively. The average O2 releasing flux during MAP and MAAPP period was 1.14 mmol·m-2·h-1 and 0.69 mmol·m-2·h-1 and decreased by 14.93% and 72.06% in contrast to the control pond, respectively. During MAP and MAAPP period, water transparency was improved and over-saturation dissolved oxygen(17.17 mg·L-1) was significantly reduced to nearly normal level(9.49 mg·L-1), with 50% decreasing rate. The results indicated that both MAP and MAAPP method could reduce N2O, N2 and O2 releasing flux from water system. The microbial agent and aquatic plant absorbed the water nutrients and competed with denitrifying bacteria and phytoplankton, inhibited of N2O, N2 and O2 producing and releasing from the polluted water