Research On The Plume Distribution Of Artificial Upwelling And Its Effect On The Growth Of Skeletonema Costatum

Artificial upwelling is considered to be a potential geoengineering project.It promotes the growth of phytoplankton by increasing deep ocean water to the euphotic layer,to increase the efficiency of biological pumps and thus influence climate warming.Artificial upwelling system can form the plumes of different environmental parameters,including the plume concentration,the total amount and distribution of nutrients,and the turbulence intensity,by adjusting the engineering parameters of artificial upwelling.These changes further influence the growth status and community structure of the phytoplankton stimulated by the plume,thus greatly affecting the carbon sequestration capacity of the artificial upwelling.At present,researches on artificial upwelling mostly focus on the engineering equipment such as improving the reliability and energy utilization rate of equipment.There has been a lack of research on the effects of upwelling plume parameters on biological carbon sequestration and influencing mechanism of artificial upwelling.This thesis studies the effect of artificial upwelling system setting on carbon sequestration capacity from:verifying mathematical model of artificial upwelling,establish algae cultivation equipment capable of producing controlled turbulence and research the influence of turbulence intensity on the growth rate of Skeletonema costatum.The results of our study provide the theoretical experimental methods and the equipment to help understand the changes of biochemical parameters in plumes and accurately assess the effects of artificial upwelling on biological carbon sequestration.The laboratory simulation experiments of artificial upwelling plume were based on the previous theoretical calculation by Fan et al.By establishing a laboratory tank model,we analyzed the dilution process of the deep-water plume and surrounding seawater,as well as the plume trajectory.Through the comparison with the CFD simulation results,the correctness and feasibility of the theoretical formula of controlling the depth plume dilution and the neutral buoyancy depth by artificial upwelling engineering parameters are verified.In order to investigate the effect of artificial upwelling plume on biological carbon sequestration,we studied and designed algae culture equipment that can produce controlled turbulence.Using a single point velocity and energy spectrum analysis,we analyzed the internal turbulence intensity of algae cultivation equipment.And establish the empirical formula of turbulent kinetic energy dissipation rate and vibration parameter-frequency.Using the actually measured turbulence distribution and the STAR-CCM+ simulation results of Yao Zhongzhi,the turbulent algae culture equipment based on orbital vibration is proved to be a stable experimental system that can produce homogeneity and homogeneous turbulence.This system can simulate the sea conditions in the areas of medium and high turbulence intensity and is suitable for the laboratory to study the effects of turbulence on algae.After verifying the mathematical model of artificial upwelling plume,the effects of turbulent intensity on the growth of S.costatum were studied under conditions of adequate nutrient and light.It is observed that within a certain range,as the turbulence intensity increases,the growth rate of the diatom cells will increase.It can be inferred that in the algae community dominated by S.costatum,the artificial upwelling does not only affect nutrient,but changes of fluid parameters can also significantly affect the carbon sequestration of algae.Therefore,a more systematic analysis of the effects of artificial upwelling on biological carbon sequestration is needed.The exploration of this paper is just a small step,and it will be further explored systematically in the future.