Investigating the Effect of Portland Cement Concentration on the Photosynthetic Rate of Hydrilla verticillata

This investigation explores how varying concentrations of Portland cement (0–8 g/L) influence the photosynthetic rate of the aquatic plant Hydrilla verticillata, measured through changes in dissolved oxygen concentration.

Using a PASCO PASPORT Optical Dissolved Oxygen Sensor, the researcher conducted a controlled laboratory experiment, maintaining constant light intensity and temperature. Data analysis involved calculating the rate of change and applying linear regression to identify trends.

Results demonstrated a significant negative correlation (R² = 0.657), where increasing cement concentration led to decreased oxygen evolution. The exemplar is distinguished by its rigorous evaluation of confounding variables like turbidity and pH, alongside a detailed discussion of experimental uncertainties and methodological improvements.