3.2. SRP uptake by benthic algae
The 32P activity was almost at the same level in the control group and in the uptake treatment group (p > 0.05), suggesting that little SRP was directly taken up by benthic algae. Compared with the 32P activity in the control group, the 32P activity in the uptake treatment group with high SRP concentration significantly decreased (p < 0.05), with a decrease rate of 14% in the first hour ( Fig. 2). However, the decrease rate did not change much with time. After three hours, the 32P activity in the water was still at the same level.