Trace metals and nutrients behaviour during the winter phytoplankton bloom in Bahía Blanca Estuary (Argentina)

FREIJE, R.H.; BOTTÉ, S.E.; CONTARDI, E.; ASTEASUAIN, R.; CHIARELLO, M.N.; MARCOVECCHIO, J.E.

Mar del Plata, Argentina

Congreso; 2001: An Ocean Odyssey-Joint assemblies of the IAPSO-IABO; 2001

IAPSO-IABO

A large phytoplankton bloom usually dominated by centric diatoms has been historically recorded during winter within Bahía Blanca estuary. Nutrient concentrations (nitrate, nitrite, ammonium, phosphate and silicate) have generally shown to be very high, even though slowly decreased together with increasing phytoplankton growth. Fluctuation of other associated parameters (i.e., temperature, salinity, pH/ORP, organic matter) were also studied in order to assess possible covariations occurrence. By the way, a large data base of both nutrients and physico-chemical associated parameters for the studied area exists since middle ´70s, obtained on a semi-monthly basis. On the other hand, distribution of several dissolved toxic trace metals (i.e., Cd, Pb, Cu, Cr) has frequently shown to present a nutrient-like behaviour. Thus, the occurrence, concentration and distribution of these elements have also been determined in order to verify if the mentioned trend occurred. Keeping in mind the above mentioned framework, an experimental sampling programme was designed and developed at Cuatreros Port, in the inner area of the estuary, conducted to identify the occurrence of any relationship between nutrients or the associated parameters and/or dissolved trace metals with environmental conditions of the estuary (i.e., tidal level, sampling time, etc). Moreover, toxic trace metal distribution patterns will allow to determine their corresponding presence-time within the system, considering that dissolved forms are extremely short lived ones. Finally, the usefullness of these kind of relationship arrangement as an experimental design tool for environmental assessment programmes is discussed.