| Nowadays,eutrophication and algal blooms have been one of the most serious environmental problems in the world.Much evidence shows that optimum hydrodynamic conditions would lead to water bloom.Many domestic and international researchers have offered abundant empirical studies about the turbulence effects on the growth of algae.However,owing to the complexity,the mechanism of the effect of turbulence on algae physiology is still unclear.This study manly focuses on the mechanism of the influence of turbulence on the algae physiology,aiming to provide more information for further clarifying the effects of hydrodynamic conditions on the growth of algae,and exploring the mechanism of the algae bloom.In this study,Anabaena flos-aquae was used to simulate the effect of water turbulence on algae's growth in a favorable environmental conditions?e.g.temperature,illumination?.The results prove that the turbulence could promote the growth of algae.With the enhancement of the turbulent dissipation rate,Anabaena flos-aquae specific growth rate increased at first and then decreased,showing a single peak characteristic.The specific growth rate of Anabaena flos-aquae under turbulence was still greater than that in the static state.When the turbulent dissipation rate was 2.92×10-5 m2s-3,the special growth rate is 0.129 d-1,which is 7 times of the growth rate in static state.Through the comparison of elements content in the algal cells under different turbulence,it showed that turbulence would affect the substance absorption process of Anabaena flos-aquae.In the experiments,with the increase of the turbulent dissipation rate,C,N and P absorption of Anabaena flos-aquae increased firstly and then decreased.Low turbulence disturbance intensity had a role in promoting on C,N and P uptake of Anabaena flos-aquae,and higher turbulent disturbance had a certain inhibitory action on the cell of the absorption of C,N and P;when the turbulent dissipation rate was 2.92 ×10-5 m2s-3,C,N and P absorption achieved the maximum value.With the increase of the turbulence dissipation rate,the length of the algae was firstly decreased and then increased,and the length of the algae under the turbulence was lower than that in static state.When the turbulent dissipation rate was 2.92×10-5 m2s-3,the length of the algae was the smallest,which was only 45.5 ?m.Through a chemostat reactor,we established the algae chemostat culture system,providing algae under constant physiological state for photosynthetic oxygen evolution study.The experimental results showed that under the experimental conditions,the algae cells had high tolerance to light and temperature.Under different temperature and turbulence of Anabaena flos-aquae photosynthetic oxygen evolution variation had the same trend: with turbulence increasing,photosynthetic oxygen evolution rate gradually increased and the rate decreased gradually.Turbulence promoted Anabaena photosynthesis efficiency,improved the photosynthesis activities of algae cells,and promoted cell growth.In the turbulent dissipation rate of 9.042×10-10 m2s-3,the maximum photosynthetic efficiency was 2.24.The maximum value of Pm/Rd in Anabaena flos-aquae was-14.49.This study tested the turbulence effect on Anabaena flos-aquae physiological processes influence,and initially studied the mechanism of the effect of hydrodynamic condition on the algal physiology process,and provided a theoretical basis for the algal bloom. |
PDF Full Text Request