AVAILABILITY OF SEDIMENT PHOSPHORUS IN LAKE LUGANO
The knowledge of the biological availability of phosphate adsorbed onto the sediment is of crucial importance in the management of eutrophic lakes. From April 1981 to February 1982 sediment samples were collected at three different depths in the shallow basin of Lake Lugano (Ponte Tresa). Total, organic and inorganic phosphorus along with non-apatite and apatite forms of bottom sediments were analyzed. Bioavailability of sedimentary P was determined using Selenastrum tests. The proportions of sediment P available for algal growth averaged 10 % of the total P content in winter, spring and fall and 22 % in summer. The non-apatite inorganic fraction contributed to the largest proportion (42-100 %) of P utilized by algae, with the exception of summer samples when a significant proportion (35 %) of organic P was assimilated by algal cells. The available P content of the sediments ranged from 40 mg/kg (fresh weight). No correlations between the available P and the different forms of sediment P were found because of great variability of P content with season and water column depth. It is concluded that the chemical extraction procedures cannot replace the bioassays to assess algal availability of sediment P.
Bibliographic Reference: XXII CONGRESS OF THE INTERNATIONAL ASSOCIATION OF LIMNOLOGY, LYON (FRANCE), AUG. 21-28, 1983 PROCEEDINGS PUBLISHED BY E. SCHWEIZERBART'SCHE VERLAGSBUCHHANDLUNG, D-7000 STUTTGART 1 (GERMANY), PP. 1113-1118, 1984
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Record Number: 1989123027500 / Last updated on: 1987-01-01
Available languages: en