Journal of Ecology and Rural Environment ›› 2020, Vol. 36 ›› Issue (2): 227-233.doi: 10.19741/j.issn.1673-4831.2019.0291

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Effects of Cyanobacterial Blooms on Nitrous Oxide Emission From Taihu Lake

CHEN Jing1, LI Xing1, WANG Yi-ping1, CHEN Xiao-feng1,2, YANG Liu-yan2   

  1. 1. School of Environmental Science and Engeering, Yangzhou University, Yangzhou 225127, China;
    2. School of Environment/State Key Laboratory for Pollution Control and Resource Utilization, Nanjing University, Nanjing 210023, China
  • Received:2019-04-26 Published:2020-03-03

Abstract: During a cyanobacterial bloom, surface water nitrous oxide (N2O) concentrations were measured at 12 sites in Taihu Lake, including Meiliang Bay and the open area. It was found that N2O concentration at the sampling sites of Lake Taihu were significantly different. The mean N2O concentration at the estuary area was averagely around 26.8 μmol·m-3, which was much higher than those at the other sites (<11 μmol·m-3), among which the northeast area of Meiliang Bay and the open area were averagely only 4.0 μmol·m-3. N2O concentrations in the surface water were correlated with chlorophyll a (Chl-a) concentrations (P<0.05), indicating that cyanobacterial blooms might promote the production of N2O in Lake Taihu. To test the hypothesis, a microcosm simulation experiment was conducted in laboratory. With sufficient nitrate, N2O release from the treatment with a small amount of cyanobacteria added (about 80 μg·L-1 Chl-a) was significantly higher than that from the control group without cyanobacteria added (about 30 μg·L-1 Chl-a, P<0.001). However, the N2O releases decreased significantly (P<0.001) when Chl-a concentrations increased further. This suggests that when nitrogen is abundant, a certain concentration of cyanobacteria can promote N2O release, but higher concentrations might inhibit it. In an acetylene inhibition experiment, the N2O production rate increased markedly with increasing Chl-a, even with high cyanobacteria concentrations. This indicates that high cyanobacteria concentrations in microcosms did not inhibit N2O production, but rather accelerated the reduction process of N2O to N2.

Key words: N2O, cyanobacterial bloom, Taihu Lake, laboratory simulation experiment

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