Impact of aeration disturbances on endogenous phosphorus fractions and their algae growth potential from malodorous river sediment

The present work assessed the impact of aeration disturbances on sediment-bound phosphorus fractions and their algae growth potential from a typical malodorous river. Phosphorus was sequentially extracted by a modified version of Hedley fractionation method. It was found that the mean contents of TP was 1476.1 ± 60.3 mg/kg, consisting mainly of dilute HCl-extractable P (52.6%) and NaOH-P (19.2%). The algae growth potential tests demonstrated that algae growth had varied P-level requirements for different P speciation and NaOH-P promoted algae growth remarkably and its promoting effect was positively related to its concentration. Additionally, intermittent overlying water aeration modes were recommended, and run 1 (7.0 mg/L, 12 h) was deemed as the optimized aerated mode in terms of its relatively low ecological risk and high P retention. It was noted that NaOH-P was most affected by aeration disturbance and exhibited marked increase with the elevated dissolved oxygen (DO) level whether for intermittent overlying water or sediment aeration. This research helps to gain improved understanding of the ecological risk on sediment P, and NaOH-P is recognized as one ecologically important P fraction in the sediments considering its relatively high proportion and bioavailability.