H. Hartikainen et al., COOCCURRENCE AND POTENTIAL CHEMICAL COMPETITION OF PHOSPHORUS AND SILICON IN LAKE SEDIMENT, Water research, 30(10), 1996, pp. 2472-2478
Various chemical approaches were used to characterize P and Si in the
surface sediment of Lake Vesijarvi, Southern Finland. The dynamic equi
librium between solid and solution P in aerobic and anaerobic sediment
was investigated by means of desorption-sorption isotherms. The sedim
ent material was rich in hydrated Al and Fe oxides and, accordingly, h
ad a high P sorption capacity and a very low P concentration (5 mu g l
(-1)) in the interstitial water under aerobic conditions. Approximatel
y 25-30% of total P and almost 90% of total Si were bound in mineral l
attices, i.e. in a stable form not participating in biological and che
mical transformations. Organic P comprised about 20-25% of total P and
was mainly in practically insoluble form not extractable by dilute ba
se or acid. Phosphorus participating in sorption-desorption reactions
was considered to originate from reserves bound on oxide surfaces. Whe
n the oxide bound P reserves were determined by fractionation analysis
, a large amount of Si (corresponding to about 30% of biogenic reserve
s) was also dissolved. Anaerobiosis increased distinctly the occurrenc
e of both elements in the interstitial water. These dissolution patter
ns suggest that P and Si are bound to the same components and, therefo
re, compete with each other for the sorption sites. This chemical comp
etition, in turn, may be of importance in the nutrient exchange betwee
n solid and solution phase in sediment. Copyright (C) 1996 Elsevier Sc
ience Ltd