Preliminary study on the utilization of Ca2+ and HCO3- In karst water by different sources of Chlorella vulgaris

Abstract

By choosing exogenous Chlorella vulgaris and native Chlorella vulgaris which were screened from karst areas as study objects, and making comparison of the utilization of Ca2+ and HCO3- in typical karst water by Chlorella vulgaris of two different origins in a closed system, the relationship between Chlorella vulgaris cell numbers and the utilization rate of Ca2+ and HCO3- and the pH value change are studied. The results show that the native Chlorella vulgaris have higher Ca2+ and HCO3- use ratio than exogenous Chlorella vulgaris, while exogenous Chlorella vulgaris utilized more Ca 2+ than native Chlorella vulgaris, but utilized the same amount of HCO3-. In addition, exogenous Chlorella vulgaris can form CaCO3-rich sediment in the form of extracellular crystal, but native Chlorella vulgaris cannot. Furthermore, the pH value change in the closed system revealed that both algae utilized the dissolved carbon dioxide as photosynthetic carbon source and made use of HCO3-. Exogenous Chlorella vulgaris can absorb 26.3 % Ca2+ and 29.6 % HCO3- of the karst water, and native Chlorella vulgaris makes use of 42.1 % Ca2+ and 40.6 % HCO3-. As a primary producer in the food chain, the two kinds of aquatic algae transform HCO3- into organic matter and take them into the ecological system which shows the net carbon sink effect. © 2013 The Author(s).