2.4. Experiment design
2.4.1. SRP release experiment
Eight prepared sediment cores, of which four had benthic algae and four were without benthic algae, were used to examine the effect of benthic algae on the SRP release rate from sediments. The four sediment cores without benthic algae were considered the control group. The four sediment cores with benthic algae were considered the release treatment group. All sediment cores were injected with 4 μCi NaH232PO4 through the injection hole using a syringe (Zhang et al., 2013). Thereafter, 0.5 mL of water was extracted from the overlying water of each sediment core at the twelfth hour, first day, second day, third day, and seventh day to determine the 32P activity.
At the seventh day, the oxidation status of sediments was examined in the daytime, with a light intensity of 15.8 ± 9.4 μmol/(m2·s), by measuring the DO concentration in the upper sediment layer, using an Unisense microsensor (PA2000, Denmark).ceae).