Nutrient and trace metal distribution in the Gulf of Astakos, Aetoloakarnania, Greece

Abstract

The Gulf of Astakos is a very important embayment of the Ionian Sea, as it offers an ideal environment
 for extensive aquacultures with tourism, agriculture and commercial activities. In view of the need for
 sustainable development of the region, the state of the gulf's quality was assessed on the basis of determinations
 of nutrients (NO3
 -, NO2
 -, PO4
 3-, SiO4
 4-, and NH4
 +) and trace metals (Cd, Cu, Fe, Pb, Ni and
 Zn) along with physicochemical parameters in the seawater. The samples were collected in three sampling
 cruises during February 2000, May 2000 and July 2000 from ten sampling stations.
 Nutrients were determined by standard colorimetric methods UV-Vis, using a Varian spectrophotometer.
 Dissolved metals were pre-concentrated using Chelex-100 resin. Particulate metals were
 digested following a hot plate digestion in teflon bombs. Metal concentrations were determined by
 Flame or Graphite Furnace Atomic Absorption techniques with a Varian spectrometer equipped with
 Zeeman background correction according to the concentration levels.
 Seasonal fluctuations were recorded in both nutrient and metal concentrations presenting proportional
 fluctuations with those of the marine euphotic zones. The reduction of concentrations can be attributed
 to the low rainfall seasonal height, the reduced flow of the streams and in the bioaccumulation
 and consumption from the phytoplankton cells that bloomed during spring and early summer.