A. Sfriso et al., ANNUAL NUTRIENT EXCHANGES BETWEEN THE CENTRAL LAGOON OF VENICE AND THE NORTHERN ADRIATIC SEA, Science of the total environment, 156(1), 1994, pp. 77-92
The exchange rates of nitrogen and phosphorus compounds between the Ad
riatic Sea and the inner parts of the central lagoon of Venice, highly
populated by macroalgae, have been estimated by monitoring monthly, f
or 1 year, a number of stations located both along the main channels a
nd in shallow areas of the lagoon as well as in the sea. Total inorgan
ic nitrogen (TIN), between February and September, was 3-4 times highe
r in the sea station than in the lagoon. During the same period, the l
agoon inflow of TIN through the two channels (Lido and Malamocco) that
connect the central lagoon with the sea was 1.2 times higher than the
total loads entering the whole lagoon by freshwater sources. In contr
ast, phoshorus concentrations were higher (15-45%) only in April-June.
Four seasonal campaigns were also carried out both in flood and ebb t
ide at the lagoon mouths. Results confirm the TIN and phosphate inflow
from the sea to the lagoon between March and September. On a yearly b
asis, nutrient concentrations were negatively correlated with chlorini
ty. The nutrient concentrations monitored concurrently at two stations
located on a freshwater stream entering the lagoon (Osellino river) w
ere approximately 1 order of magnitude higher than those of the lagoon
and sea stations. The annual mean phosphate concentration of the Osel
lino river, monitored in these campaigns, was approximately 50% of tha
t measured in 1982.