Stable carbon isotope signatures of cellulose in macrophytes collected from three eutrophic lakes in China

Aquatic plants are essential for maintaining the diversity and stability of a lake ecosystem. Stable carbon isotopes (delta C-13) of macrophytes have been widely used as a powerful tool to study ecological processes and paleoenvironmental evolution in lakes. Varying results are obtained when using the delta C-13 of macrophytes to study the changes in the lake environment at different spatio-temporal scales. Thus, sample preparation and subsequent laboratory analyses are crucial for studying environmental changes using the isotopic signal retained in the macrophytes, and are essential for the interpretation of isotope-environment relationships. This study analyzed the delta C-13 of different tissue components of macrophytes in three lakes of the lower Yangtze River basin, and a correlation analysis was performed on aquatic environments influencing the delta C-13 values in the different tissue components of macrophytes. The test results showed the difference between the delta C-13 values of the whole sample and cellulose. Relative analyses indicated that the major factors contributing to the delta C-13 variability in macrophytes were pH and the concentration of dissolved inorganic carbon (DIC). The delta C-13 of alpha-cellulose (delta C-13(AC)) is more sensitive to environmental variables than that of the whole sample (delta C-13(W)) and holocellulose (delta C-13(HC)). The results of this study imply that extraction of alpha-cellulose is a prerequisite for research on the changes in lake environment using delta C-13 of macrophytes. This study aims to provide theoretical and data basis for further research on the environmental and ecological change using stable carbon isotopes of aquatic plants.