2.4.2. SRP uptake experiment
Benthic algae grown on plastic gauzes were used to evaluate the uptake rate of SRP with different concentrations by benthic algae. Nine perspex vessels (10 cm × 10 cm × 5 cm) were used in the uptake experiment, and divided equally into three groups. Filtered water was obtained by removing suspended particles from the original lake water sample through filter membranes with a pore size of 0.45 μm. For each vessel in the first group, 200 mL of filtered water were added and a piece of plastic gauze without benthic algae was put in, and this experiment group was considered the control group. For each vessel in the second group, 200 mL of filtered water were added and a piece of plastic gauze with benthic algae was put in, and this experiment group was considered the uptake treatment group. For each vessel in the third group, 200 mL of filtered water and SRP with a concentration of 0.015 mg/L, which was the same concentration as that of the pore water in sediments, were added and a piece of plastic gauze with benthic algae was put in, and this experiment group was considered the uptake treatment group with high SRP concentration.
0.4 μCi NaH232PO4 was added to each vessel for all groups and completely stirred. This was used to assess the SRP uptake by benthic algae under different conditions. Water samples of 0.5 mL were taken from every vessel at the first hour, second hour, and third hour, respectively, to measure the 32P activity.