The Effect Of No On Marine Phytoplankton Growth And The Carbon Dioxide System

Nitric oxide(NO) itself is a colorless,odorless and toxic gas. However,in recent years it has been found that NO plays an important role in the atmosphere. At the same time,it has special and diversiform physiological functions in organisms,especially as an important growth regulator and signal massager in high plants. The study of NO on marine phytoplankton has attracted scientists'attention and some progresses have been made. For further study on the role of NO playing mechanism in the phytoplankton, the red tide algae Skeletonema costatum, Gymnodinium donghaiense and Prorocentrum donghaiense ,and food algae platymonas helgolandica var.tsingtaoensis and P.subcordiformis were chosen to culture by adding two different forms of exogenous NO .This work includes two aspects: (1) The algae were cultured when adding different NO concentrations (l.4×10-6 l.4×10^-9mol / L)one time,then observe changes of microalgae density and the carbon dioxide parameters of the medium during the microalgae cultivation at regular time. (2) The algae were cultured when adding different concentrations of SNP (NO donor) into the medium only once,then observe changes of the carbon dioxide parameters of the medium during the microalgae cultivation at regular time. The main results are as follows:(1) When being continuously affected by NO (adding SNP),the growth of phytoplankton was significantly different from that affected by NO in a short time . It may decrease the threshold that shows negative effect on the growth of marine phytoplankton. Therefore, the qualitative laws of the effects of NO on the growth of marine phytoplankton, two types of"NO threshold", is closely related with the time.(2) Adding two different forms of exogenous NO to the media of 5 species of marine microalgae during cultivation and observing the changes of carbon dioxide parameters during the cultivating process, for the 5 species of marine microalgae, it was found that either red tide algae or food algae, which is closely related to the growth rate of algae.Compared with non-SNP-addition system, the DIC,HCO3 -and Pco2 of the medium during the microalgae cultivation shows reduced tendency ,When exogenous NO promotes the algae growth, while pH shows the trend of increase.It also shows the law of the changes of DIC and pH is opposite and the change of HCO3- has great similarity with the change of DIC during the process of cultivation.(3) Experiments showed that red tide algae exhibit more sensitive to SNP of high concentration than food algae for the 5 species of marine microalgae. SNP of 10μmol/L concentration played a significant inhibition on red tide alga, including Skeletonema costatum, Gymnodinium donghaiense and Prorocentrum donghaiense, so that which are unable to form exponential growth. For food algae, including platymonas helgolandica var.tsingtaoensis and P. subcordiformis, which showed some negative effect only in the early time of cultivation, later the growth of food algae shows a trend of rapid growing. Compared with non-SNP-addition system, the growth period become longer.