Observations on continuous nutrient monitoring in Venice Lagoon

Abstract

The deployment of WARMER (WAter Risk Management in EuRope) continuous monitoring platform at the Venice Lagoon was the second field test (duration of the field test: ca. 3 months) of the project and this study was conducted with the cooperation of Magistrato alle Acque di Venezia which maintains a continuous monitoring network (SAMANET) with ten stations. SAMANET stations are geared to measure number of parameters (pressure, temp., conductivity, salinity, DO, DO%, pH, Redox, Chlorophyll-a, Turbidity) continuously. In addition to above mentioned parameters WARMER pontoon is equipped with a nutrient analyser to measure dissolved nutrients continuously (SRP, nitrite, nitrate and ammonia). During the field test WARMER project intended to test the newly developed sensors for nutrients and metals. The pollution control division of the Magistrato alle Acque (SAMA) performed parallel field and laboratory controls, both through the continuous monitoring stations and nutrient laboratory analyses on samples collected in the Venice lagoon. Venice Lagoon is a large, eutrophic, shallow, turbid water body (ca.500 km2) with successive algal blooms during the year with large nutrient fluctuations during the summer months. During the field test, WARMER monitoring pontoon was moored at the following SAMANET stations for a period of 3-4 weeks at each station, starting from mid May till end of August 2009 and samples were taken from lm depth for continuous analysis: Ve-4 Fondamenta Nuove: near the city, by the side of Murano Island; affected by pollution from boat traffic and Murano glass industry; Ve-7 Palude di Cona: at the outlet of the Dese river; brings point and diffused pollution from watershed; Ve-5 Porto Marghera: at the outlet of Porto Marghera industrial area, one of the heavily polluted sites. The lagoon with this well established continuous monitoring network, infrastructure with co-operating laboratories makes it an ideal location for field testing of nutrient probes. The results of this three months field experiment are presented in this paper with main focus on continuous nutrient measurements.