Effects Of Environmental Factors On The Absorption Characteristics And Growth Of Nutrients Of Cdium Repens

The green tide is a kind of phenomenon that some large algae(Enteromorpha Enteromorpha and Codium repens algae,etc.)proliferate in a certain time,or the accumulation reaches a certain level in the sea water,which leads to the abnormal marine ecology.In recent years,the phenomenon of green tide has become a widespread concern in the world.Coral reef ecosystem is a tropical shallow sea ecosystem with high biodiversity and high resource productivity,and also a very fragile ecosystem.In recent years,due to the influence of human activities,a large-scale outbreak of green tides has been caused.Many coral reef ecosystems are facing serious threat of degradation.In this paper,the main dominant algae of the green tide in the coral reef sea area was selected as the experiment object.Using the controlled conditions in the laboratory,the dynamic characteristics of the nutrient absorption and the best conditions for the absorption of nutrients(salinity,light,temperature and nutrient concentration)were studied.Under the conditions,it is the most suitable for rapid growth of Codium repens.It provides a scientific basis for prediction and prevention of pine green tide outbreak.In addition,the determination of nitrate content in water samples is mainly using zinc and cadmium reduction method.At present,the operation rules of the method in the determination of marine water quality are mainly based on the marine survey standard(GB/T 12763.4-2007),but the scope of the specification has a wide range of experimental conditions in the operation process,and it is difficult to guarantee the reduction of the water quality.The reliability of the data is measured by rate.In this paper,the effect of the reaction temperature(20-30 C)and oscillation velocity(200-300r/min)factor on the nitrate reduction rate in seawater under 0-1.5mg/L nitrate concentration was studied.The main results are as follows:1,we studied the nitrogen absorption characteristics of Codium repens under different nitrogen and phosphorus ratios.The results show that the absorption rate of ammonia nitrogen can reach about 60%in 7 days under strong light conditions,and the effect of different nitrogen and phosphorus ratio on the absorption of ammonia nitrogen is little,but the absorption rate of ammonia nitrogen is higher under the light intensity of high intensity 25001ux?45001ux.It can reach the peak faster.2,we studied the phosphorus absorption characteristics of Codium repens under different nitrogen and phosphorus ratios.The results showed that the absorption rate of phosphorus was the highest under the light conditions of 35001ux,but in the process of phosphorus absorption,it was found that there was a problem of phosphorus release in 2?5 days,and phosphorus was in a process of phosphate absorption under the light conditions of 15001ux.There were no significant difference in the absorption of nitrogen and phosphorus ratio after7 days,and the ratio of 2.5:1-17.5:1 to nitrogen and phosphorus had a good absorption rate.3,we studied the absorption characteristics of N under different conditions of N.It was found that nitrate-N release was observed on the second day of the experiment,but not in the absorption of ammonia nitrogen.Moreover,it was found that the uptake rate of ammonia nitrogen by Codium repens was 60%,while that of nitrate nitrogen was only about 20%.It is also found that increasing the intensity of light can speed up the maximum value of ammonia nitrogen absorption by Codium repens,but there is a slight fluctuation in the peak value of the absorption of nitrate nitrogen,and there is no obvious influence on the absorption of nitrite.4,we studied the absorption characteristics of Codium repens under different light conditions.The results show that the enhancement of light intensity can accelerate the absorption rate of ammonia nitrogen,and can reach the peak of absorption faster.However,the enhancement of light intensity has no significant effect on the absorption rate and absorption rate of Codium repens.The amount of nitrite and nitrogen released during the second day absorption of nitrate-N was almost equal to the amount of nitrate nitrogen absorption in the first day,and the phenomenon did not change after the light conditions were changed.The absorption rate of P is the highest under the light condition of 35001ux,but the phosphorus release rate is the highest in the first 5 days of the 7 days,and the phosphorus absorption rate rises abrupt after 6 days,and reaches the peak value in the 7 day.It is also found that under the illumination intensity of 15001ux,Codium repens has the state of absorbing phosphorus.5,The zinc and cadmium reduction method is the most common method for determining the nitrate content in the water samples.The reduction rate of 70%-80%in the zinc and cadmium reduction method in the marine survey standard is 82.3%,under the optimal conditions determined by this experiment.