Study On Physical Adjustment Of High-pH Water In Saline-alkaline Aquaculture Ponds

Saline-alkaline water is characterized by high pH value,high alkalinity,and imbalance of main ion ratios.The high pH value is one of the main characteristics of the saline-alkaline aquaculture water,which restricts the development of saline-alkaline aquaculture.The pH of pond water is mainly affected by chemical and biological factors.As the main component of carbonate balance system,CO₂ plays an important role in pH balance;Biological activities such as photosynthesis and respiration of planktonic algae contributes pH variation.Regardless of chemical factors or biological factors,the concentration of CO₂ in the water is the key link.According to high pH value,this study intended to explore the physical regulatory methods for high pH value water quality in saline-alkaline ponds.We conducted laboratory experiments to test the effects of ventilation on the algae-enriched high pH value water,and a field experiment about the effect of different aerobic methods on the pH regulation of the saline-alkaline ponds.The results of this study will provide technical support for high-pH water quality control in saline-alkaline ponds.1.Ventilation could reduce the pH of the water body.The greater the aeration amount in algae-free water,the more obvious the decrease of pH value.In the algae-containing water,the decrease of pH value is also correlated to the concentration of Chlorophyll-a.The ventilation volume and Chlorophyll-a concentration show some antagonism.The effect of internal ventilation on the pH of the water body is stronger than that of the Chlorophyll-a concentration.2.In laboratory experiments,ventilation may inhibit the pH increase of the water containing cyanobacteria and green algae.In water bodies with high concentration of blue-green algae,ventilation amount and light intensity were proportional to the pH value inhibition effect,the greater the ventilation volume,the better the effect of inhibiting the pH value growth when the light intensity was stronger.When the ventilation rate was 2.4L/min,the temperature was 25°C,and the light intensity was 6000lx,the effect of inhibiting the pH value increase was best.In the water containing green algae,the aeration volume was proportional to the effect of inhibiting the pH growth,and the light intensity was shown.Inversely,when the ventilation rate was 2.4L/min,the temperature was 25°C,and the light intensity was 2000lx,the pH value was the most obvious,and the?pH was-0.41.3.In the field study,compared with the single impeller oxygenation method,the compound aeration method of bottom aeration plus impeller aeration decreased the pH value well.In different weather conditions such as sunny days,cloudy days and rainy days,the pH value of compound aeration pond was lower than that of single impeller pond.In cloudy and rainy days,water pH of the compound aeration pond was significantly lower than that of a single impeller pond?P<0.05?,and it was significant when the aerator was working?P<0.05?.During the farming,the pH of the compound aeration pond was higher than that of the single impeller aerobic pond in the initial stage of monitoring,but the pH was already lower than the latter at the 45th day.Compared with the single aerobic method,the pH value of the water body under the compound aerobic method decreased greatly.In the first 30 days,the pH value was significantly higher than the single impeller aerobic pond?P<0.05?,and reached the maximum on the15th day.The pH value of 9.09 on the 45d was significantly lower than that of the single impeller aerobic pond?P<0.05?,and the lowest value reached8.10 on the 45d.At the same time,the pH reduction value?pH of the compound aeration pond reached the maximum value of 0.89,but the single impeller pond reduction was only 0.64.In addition,the pH value of the water under the compound aeration method tends to be stable after 30days.4.Ventilation had a certain effect on the addition of microecological agents containing algae and high pH value water.Between entilation and microecological agents,they showed a synergistic effect.Ventilation played a certain role in regulating the pH of the water in microecological agents.The effects of Bacillus and Lactic acid bacteria on the pH value of water were obvious under aeration conditions.In summary,increasing the concentration of water CO₂,could suppress or reduce the water pH of the saline-alkaline pond.The effect of the combined aeration method with bottom aeration plus impeller aeration is better than that of the traditional single impeller.In addition,ventilation can enhance the effect of decreasing pH value with microecological preparations on pH regulation in water bodies.Using aerobic physical means to regulate high water pH in saline-alkaline ponds,providing new ideas for the healthy and green development of saline-alkaline ponds aquaculture.