Variation Of In Vivo Fluorescence During Diatom Growth And Its Effect On Chlorophyll Measurement

This research took the marine diatom as the main research object, and the calibration method and the data correction method of the chlorophyll sensor were explored. By setting different conditions, such as light, temperature, salinity and turbidity, diatom cultivation experiments were carried out in the laboratory. Chlorophyll fluorescence and extraction chlorophyll of diatom under different environmental conditions were measured using chlorophyll sensor and extraction method. By analyzing the changes of in vivo fluorescence of diatom and the difference with the extraction method, the response of the in vivo chlorophyll fluorescence to environmental factors during the growth process was discussed.The main research contents and results of this paper are as follows:1 Effect of light on chlorophyll fluorescence measurements of diatomLight is a necessary condition for the photosynthesis of diatom. The chlorophyll fluorescence of diatom under the condition of full light intensity was stronger than others. But strong illumination condition could cause the protective mechanism of diatom, which will cause a decrease of in vivo chlorophyll fluorescence of diatom in a short period of time. Chlorophyll fluorescence and extraction chlorophyll of diatom after long-term culture in the optimum light illumination conditions (60001x,12h light/ 12h dark) were higher than other light illuminations. There was a good linear relationship between the chlorophyll fluorescence and the light illumination in the short term change of light illumination. There was a significant change in the in vivo chlorophyll fluorescence of the diatom in the mutation of light. However, short term light mutation did not affect the overall level of in vivo chlorophyll fluorescence. The chlorophyll fluorescence of diatom was affected by the short-term light/dark ratio. The longer the light time, the higher the overall level of in vivo chlorophyll fluorescence. The relationship between the chlorophyll fluorescence and extraction chlorophyll of the diatom was quite different after the short term continuous cultivation of different light and dark ratio.2 Effects of environmental parameters on chlorophyll fluorescence measurements of diatomEffect of short-term temperature change on extraction chlorophyll of diatom was very small, effect of the rapid change of temperature on the chlorophyll fluorescence of diatom depended on the light condition. Effects of short-term salinity change on both the extraction chlorophyll and chlorophyll fluorescence of diatom were very small.Effects of turbidity on chlorophyll fluorescence include fluorescence effect and light shielding effect. The fluorescence effect of suspended matter in water was constant, and light shielding effect on fluorescence measurement was enhanced with the increase of diatom concentration. The correction method of turbidity effect was established. According to the different effect mechanisms, fluorescence effect and light shielding effect were corrected separately by different methods.3 Methods for data quality control of chlorophyll sensorThe calibration method of the chlorophyll sensor based on diatom was established in the laboratory. The diatom solution after four hours light illumination was selected as the calibration solution of chlorophyll sensor. The work curve of chlorophyll sensor was established by the linear regression of chlorophyll fluorescence and extraction chlorophyll.The interspecific difference correction method was established based on analyzing the effect of algal species difference on chlorophyll fluorescence measurement.A simple and feasible method for the overall correction of seawater comprehensive factors was proposed. The sensor data was calibrated with the extraction chlorophyll as reference data.4 Prospects of research direction of chlorophyll sensorChlorophyll sensor data traceability:effects of environmental factors on the determination of the fluorescence of the sensor itself and effects on the in vivo fluorescence of the algae should be distinguished. The research on the influence of sensor data should be based on the combination of laboratory and field.Chlorophyll sensor data indicating significance:the ecological significance of in vivo chlorophyll fluorescence and its application should be fully studied. For example, the in vivo fluorescence difference of algae can be applied to the analysis of replacement of the dominant species of red tide process.Chlorophyll sensor research and development:from the point of view of the quality control of the sensor data, it is inferred that the seawater chlorophyll sensor in the future might be a multi-channel optical measuring instrument. It can simultaneously measure light illumination, chlorophyll fluorescence, turbidity, CDOM and the indicator parameters of the algae, using with other basic environment parameter measuring equipment such as CTD.