Relationship Between Pigment Concentration and Dry Weight in Determining Microalgae Abundance in Artificial Water Samples

Abstract

Microalgae are aquatic organisms that can function as bioindicators of surface water quality. The concentration of chlorophyll a can be measured to determine the level of microalgae abundance in a body of water. Measurement of the dry weight of microalgae biomass is another method that can be used to determine the abundance of microalgae in a body of water. Both methods have their advantages and disadvantages. In measuring chlorophyll concentration, the presence of other compounds besides chlorophyll which can absorb light spectrum at certain wavelengths (wavelengths of 665 nm, 645 nm, and 630 nm) causes the measured absorbance value to be greater than it should be. The level of turbidity due to the content of suspended particles in water is a problem in the dry weight measurement method. Determination of the dry weight of biomass based on the chlorophyll concentration approach is the subject of this study. The results of simple linear regression analysis showed that the concentration of chlorophyll a and the dry weight of microalgae biomass in treatment A had a fairly strong positive correlation (Ra = 0.870), the tendency of which was to follow the linear regression equation Y = 302.35x + 17.121. Determination of dry weight based on the chlorophyll concentration measurement approach can be applied to water samples with suspended solids content that tends to be constant and inert (does not produce substances that can react with organic solvents during the chlorophyll extraction process). In addition, based on the results of data processing it can be concluded that the effect of the content of other suspended particles in the water samples did not show a statistically significant effect.