The role of sediment-bound organic
phosphorus (P<sub>o</sub>) on
lake eutrophication was studied using sequential extraction and enzymatic
hydrolysis by collecting sediments from Dianchi Lake, China. Bioavailable
P<sub>o</sub> species including labile monoester P, diester P, and
phytate-like P were identified in the sequential extractions by H<sub>2</sub>O, NaHCO<sub>3</sub>, and NaOH. For the H<sub>2</sub>O–P<sub>o</sub>, 36.7% (average) was labile monoester P, 14.8% was diester
P, and 69.9% was phytate-like P. In NaHCO<sub>3</sub>–P<sub>o</sub>, 19.9% was labile monoester P, 17.5% was diester P, and 58.8%
was phytate-like P. For NaOH–P<sub>o</sub>, 25.6% was labile
monoester P, 7.9% was diester P, and 35.9% was phytate-like P. Labile
monoester P was active to support growth of algae to form blooms.
Diester P mainly distributed in labile H<sub>2</sub>O and NaHCO<sub>3</sub> fractions was readily available to cyanobacteria. Phytate-like
P represents a major portion of the P<sub>o</sub> in the NaOH fractions,
also in the more labile H<sub>2</sub>O and NaHCO<sub>3</sub> fractions.
Based on results of sequential extraction of P<sub>o</sub> and enzymatic
hydrolysis, lability and bioavailability was in decreasing order as
follows: H<sub>2</sub>O–P<sub>o</sub> > NaHCO<sub>3</sub>–P<sub>o</sub> > NaOH–P<sub>o</sub>, and bioavailable
P<sub>o</sub> accounted for only 12.1–27.2% of total P<sub>o</sub> in sediments.
These results suggest that the biogeochemical cycle of bioavailable
P<sub>o</sub> might play an important role in maintaining the eutrophic
status of lakes