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During May 1987-March 1988, water samples were taken monthly from the epilimnion and hypolimnion of Lake Varese to determine the limiting factors upon algal productivity. N/P ratios for epilimnion and hypolimnion calculated as ratio between total inorganic nitrogen and orthophosphate phosphorus, ranged from 10 to 3 and from 7.3 to 1.4 respectively. Chemical analysis (N/P ratios) indicated that iron was generally the main growth-limiting factor, with N as secondary limiting factor. A.G.P. values for epilimnetic and hypolimnetic waters ranged from 1.7 to 58.5 mg/l dry weight and from 0.33 to 143 mg/l dry weight respectively. High correlations between A.G.P. and orthophosphate phosphorus and total inorganic nitrogen concentrations (r = 0.91 and r = 0.94 respectively) allowed the calculations of algal growth potential from the N and P concentrations in the lake water. An equation was developed which can be used to predict the average indigenous phytoplankton biomass from A.G.P. A classification of natural waters, based on A.G.P. values obtained during the overturn period, was proposed.

Additional information

Authors: ZILIO P, Istituto di Ingegneria Sanitaria, Polytecnico di Milano (IT);PREMAZZI G, JRC Ispra Estab. (IT);CHIAUDANI G, Dipartimento di Biologia, Universita di Milano (IT)
Bibliographic Reference: EUR 12014 IT (1989) MF, 145 pp., ECU 8, blow-up copy ECU 18.75
Availability: (2)
ISBN: CD-NA-12014-IT-C
Record Number: 198910359 / Last updated on: 1994-12-01
Original language: it
Available languages: it
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