Carbon Uptake in Aquatic Plants Deduced From Their Natural 13C and 14C Content

Abstract

δ 13 C and 14 C activity measurements were made on terrestrial, marsh and aquatic plants growing in their natural habitat of the Plitvice Lakes in northwest Yugoslavia. δ 13 C values were ca −47 for aquatic mosses, which indicate that the carbon source was dissolved inorganic carbon (DIC) from alkaline karst waters, following a C 3 pathway, and ca −25 for marsh plants, indicating the carbon source was atmospheric CO 2 . 14 C activity of true aquatic plants and submerged parts of helophytes was close to 14 C activity of DIC, whereas that of emergent parts of helophytes and terrestrial plants was similar to atmospheric CO 2 activity. Aquatic plants which use DIC in freshwater for their photosynthesis are not suitable for 14 C dating, unless the initial activity of incorporated carbon is known. δ 13 C values of plant material also depend on the carbon source and cannot be used for 14 C age correction.