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Effects of hydrodynamic disturbance on algal toxins in eutrophic lakes.

ZHANG Hong-liang1, XIE Meng-ping1,2, TIAN Wei2,3, TANG Xiang-ming2*   

  1. (1School of Resource Environment and Tourism, Anyang Normal University, Anyang 455000, Henan, China; 2State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; 3School of Environmental Science and Engineering, Anhui Normal University, Wuhu 241003, Anhui, China).
  • Online:2020-03-10 Published:2020-03-10

Abstract: Taihu Lake is a typical shallow large lake, which is disturbed by wind wave all the year round due to the monsoon. To understand the effect of disturbance from wind and wave on the release of microcystin (MC) by Microcystis spp. in Taihu Lake, water samples containing Microcystis bloom were collected in July 2018. Three treatments including control, intermittent disturbance and continuous disturbance were set up at Taihu Laboratory for Lake Ecosystem Research, Chinese Academy of Sciences to investigate the changes of MC during 19 days. Ourresults showed that the changes of MC concentration under the three treatments were consistent, which increased during 1-13 d and decreased with different margins. The average concentration of MC in control was 1.69 μg·L-1, which is significantly lower (P<0.05) than those in the intermittent(1.81 μg·L-1) and continuous disturbance group (1.86 μg·L-1). The differences of MC concentration between the two disturbance groups were not statistically significant. During 1-7 d, the contents of MC per unit decreased in all the three treatments, with no significant differences among them (P>0.05). During 10-19 d, the contents of MC per unit in all treatments increased and then decreased, with significant differences among groups (P<0.05). The average contents of MC per unit in control, intermittent and continuous disturbance groups were 0.55, 1.20 and 1.98 μg·108 cells-1, respectively. Under this experiment condition, the concentration of MC was significantly negatively correlated with nitrogen and phosphorus, and positively correlated with water temperature, SS and Chla. Our results indicated that hydrodynamic disturbance could increase the MC concentration and MC content per unit in lake waters.