| Since the 21st century,the spiny ginseng farming industry has developed rapidly and the farming mode has shown a diversified pattern,with pond farming as one of the main farming modes.However,since 2013,extreme high temperature weather in summer has been frequent,leading to the death of spiny cucumbers by chemical skin,causing heavy economic losses to farmers and seriously restricting the sustainable and stable development of the industry,so it is of great practical significance to establish a pond culture summer high temperature prevention and control technology for the healthy development of spiny cucumber industry.In this paper,we analyzed a new cooling technology based on cold energy micro-nano bubbles,and observed the ponds with cold energy aerosol cooling equipment.It provides data support to explore the cooling effect and mechanism of cold energy aerosol cooling device in the sedge pond system and to promote the cooling technology of pond water in aquaculture ponds.(1)Evaluation of the installation of cold-energy aerosol cooling equipment and its effect on the culture of spiny ginsengIn order to investigate the actual effect of the cold energy aerosol cooling equipment,the pond water temperature of the experimental group with cold energy aerosol cooling equipment and the control group without the equipment were tested in real time,and the results showed that the air exchanged energy with the cooler and the cooling water to form a gas of 16.0-18℃,and the gas was passed into the laid pipe to produce micro-nano bubbles with cold energy,which exchanged heat with the water body to maintain the bottom water temperature.In order to maintain the pool bottom water temperature and other effects.During the high temperature period,the equipment can stabilize the temperature of the bottom of the pool at 26.1-30.5℃,and reduce the temperature by 0.9-4.3℃during the high temperature period.Through the detection of dissolved oxygen:the dissolved oxygen in the experimental group ponds was higher than that in the control group ponds,which could be maintained steadily between 5.1-8.9 mg/L,while the dissolved oxygen in the control ponds varied greatly,with the lowest dissolved oxygen being 2.2 mg/L,which was lower than the dissolved oxygen demand concentration of 4.0 mg/L for spiny ginseng.observation of the health status of spiny ginseng in the ponds revealed that:under the same temperature condition,the Under the same temperature conditions,the experimental group had normal feeding and no abnormal physiological indicators,while the control group had little or no feeding.The yield evaluation of the experimental ponds showed that the average yield of sea cucumbers was 378.1 kg per mu by the acceptance date,and the proportion of finished sea cucumbers(weight≥100 g)was 37.7%,and the largest individual sea cucumber weighed 410.0 g.It shows that the cold energy aerosol cooling equipment can effectively control the bottom temperature and dissolved oxygen to ensure the survival of sea cucumbers in the high temperature period.(2)Characterization of micro and nano bubbles and their attenuating effect on light intensity:The particle size of the observed microbubbles ranged from 1.2μm to 13.3 μm It was found that the observed microbubbles could remain in the water for 14.0 h.During this time variation,the number of microbubbles in the upper layer decreased by81.8%,the number of microbubbles in the middle layer decreased by 57.1%,and the number of microbubbles in the lower layer decreased by 76.9%.In the experimental pond,the difference of light intensity between the experimental pond and the control pond was not significant,and it was speculated that the experimental effect was not obvious because there were many factors affecting the light intensity.Under laboratory conditions,the external light intensity was studied according to the intensity above30,000 LUX(low light),30,000 LUX-60,000 LUX(medium-intensity light)and above60,000 LUX(intense light)by the developed microbubble generation observation device and randomly selected micro-nano aeration discs of different manufacturers,and the results showed that when the external light intensity was less than 60,000 LUX When the external light intensity is less than 60,000 LUX,the microbubbles can attenuate the light intensity to a certain extent,and the difference between the attenuation rate of light intensity of the experimental group and that of the control group is the largest when the position is located at a depth of 140 cm from the water surface,at which time the recession rate of light intensity of the experimental group is 24.4%and that of the control group is 6.9%,with a difference of 17.5%;and when the external light intensity is too strong,the effect of microbubbles is weakened.The external light was able to project directly to the bottom of the pool.The experimental results were examined using different manufacturers’air disks,and it was found that there were differences in the decay rate of light intensity at each level,but the overall trend was consistent.(3)Study on the generation and characteristics of micro and nano bubbles in bulk phaseIn order to explore the influence of the change of water quality index on the micro-nano bubbles,the micro-nano bubbles generated by the micro-bubble aeration tray were firstly examined and found that:when the water temperature was controlled at22℃and the salinity was adjusted to 0,the particle size of micro-bubbles ranged from7.5-7.6μm and the number of particles per unit volume ranged from 2.5×10~5-3.1×10~5;when the salinity was adjusted to 25,the particle size of micro-bubbles ranged from When the salinity was adjusted to 25,the particle size of micron bubbles ranged from12.4-15.3μm and the number of particles per unit volume ranged from 4.1×10~4-6.5×10~4.When the salinity was increased,the stability of micro and nano bubbles was reduced,and the average particle size increased by 67%-101%and the number decreased by 79%-84%.Subsequent observations of micro-and nano-bubbles produced by the ultramicroscopic nano-bubble generation device revealed that the particle size,concentration,and volume of the nano-bubbles differed between 22°C and 32°C water,but still maintained a stable state.The addition of zeolite powder and tea saponin,which are commonly used in aquaculture,was analyzed and found that the concentration of nanobubbles in the water column increased by 3-7 times after the addition of zeolite powder,and the concentration of nanobubbles in the water column increased by 84%-190%after the addition of tea saponin,but the change in particle size was relatively small.For nanobubblesζPotential detection found that micro and nano bubblesζThe potential reaches 30 m V,which can make it stable in the gas water for a long time.After adding zeolite powder,it can cause the formation of nano bubblesζThe potential ranges from-20.1±0.69 m V to-28.6±1.16 m V,indicating the presence of nanobubblesζThe potential decreases slightly,but it is not conducive to the stability of nanobubbles;Adding an appropriate amount of tea saponin can make the nano bubblesζThe potential is stable within the range of-29.9±0.8 m V to-35.0±1.1 m V,which is conducive to the stability of micro and nano bubbles.This article studied the morphological characteristics,charge distribution,retention time in pond water,and light attenuation of micro and nano bubbles in sea cucumber aquaculture ponds.The effects of zeolite powder and tea saponins on the charge and stability of micro and nano bubbles were also studied.The role and mechanism of micro and nano bubbles in reducing the water temperature of aquaculture ponds during high temperature periods were explained,providing theoretical basis and technical support for solving the high temperature disaster of sea cucumber aquaculture ponds during summer high temperature periods. |
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