Mr. Penn et al., PHOSPHORUS DIAGENESIS IN LAKE-SEDIMENTS - INVESTIGATIONS USING FRACTIONATION TECHNIQUES, Marine and freshwater research, 46(1), 1995, pp. 89-99
A 60-cm sediment core, representing approximately 50 years of depositi
on, was collected from the major depositional basin of Onondaga Lake,
a calcareous, hypereutrophic system in Syracuse, New York (USA). Seque
ntial chemical extractions were performed to obtain fractional phospho
rus (P) profiles, and these suggest that the sediment P available for
solubilization and recycling to the water column is contained within t
he CaCO3-associated, Fe&Al-bound, and extractable biogenic-P fractions
. Corrections were applied to account for the presence of refractory P
within the CaCO3-associated and Fe&Al-bound fractions. Labile phospho
rus comprises similar to 50% of the particulate P at the time of depos
ition. Reductions in labile P with depth suggest losses due to diagene
sis with subsequent release to the lake water column. Rate constants f
or diagenesis were calculated from measurements of labile P on dated c
ores. Two labile components were apparent: one, exhibiting 'fast' deca
y (k = 4.8 year(-1)), was located within the upper 1 cm of sediment, a
nd the other, characterized by 'slow' decay (k = 0.1 year(-1)) was loc
ated throughout the sediment to a depth of similar to 30 cm, below whi
ch sediment P was refractory. The ratio of the 'fast' to 'slow' fracti
ons is approximately 1:1 in freshly deposited sediment. These findings
facilitate sediment P modelling and have bearing on the recovery of l
akes following reductions in external phosphorus loads.