The Impact of Nutrient Availability and Algal Community on Carbon Isotope Fractionation in Crystal Lake, Clark County, Ohio
Water samples were collected every 1.5 meters at approximately the deepest location in Crystal Lake. Several important indicators of photosynthesis, such as dissolved oxygen and pH, were measured in situ. Samples were analyzed for nutrient and chlorophyll content, and sent out for carbon isotope analysis.
The measured values of ä13C in Crystal Lake are highest in areas of photosynthesis, and decrease in the hypolimnion where decomposition occurs. There are trends between carbon isotope fractionation, photosynthetic indicators, and several nutrient concentrations. Samples with ä13C values less than -10 V-PDB have pH values below 8 and little dissolved oxygen. Samples with ä13C values between -9 and -6 V-PDB have pH values greater than 8, dissolved oxygen levels between 5-20 mg/L, silica concentrations below 3.25 mg/L, magnesium below 27 ppm, and calcium above 60 mg/L. Samples with ä13C values above -6 V-PDB have a pH between 8-9, dissolved oxygen levels between 10-30 mg/L, silica above 3.25 mg/L, magnesium above 27 ppm, and calcium below 60 mg/L. More research is needed to corroborate these trends and expand our understanding of the affect of nutrient concentrations on carbon isotope fractionation.