Issue 3

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.

Results of a monitoring project for the water quality of three important rivers of western Greece
(Acheloos, Louros and Acherontas) are presented in this paper. The results include the concentrations
as well as the temporal and spatial distributions of nitrates, nitrites, phosphates, ammonia and dissolved
organic carbon for a period of twelve months (October 2002 to September 2003). Monthly samplings
took place in four sampling sites at the rivers Acheloos and Louros and two at the river Acherontas.
The samples were analyzed by standard spectrophometrical methods.
According to our measurements, Louros is the most polluted river as it concerns nitrogen compounds,
probably due to the increased human activities in its catchment area. It also occasionally accepts pollutants
from the small stream of Vossa.
Although Acheloos is the biggest and most important river for the whole territory, it seems not to be
heavily polluted. The chemical parameters level, indicates the enrichment of its water in nutrients,
from the water of Lisimahia lake that enters the river through the water lock of Dimikos. No significant
inflow of pollutants was observed in river Acherontas, since no remarkable spatial variation
recorded.

Pollutants posing health risks to human health and to the aquatic environment often occur in drinking
and surface waters, as a result of disinfection practices, agricultural and industrial activities, wastewater
discharges. Toxic pollutants belong to different chemical categories, including chlorination by-products,
volatile and semivolatile organic compounds, insecticides (organochlorine and organophosphorous), herbicides
(triazines and substituted ureas), metals and organotin compounds. Optimization of different analytical
methods needed for their laboratory determination is necessary, since most of these pollutants have
toxic effects when they are present even at trace concentrations in water. The investigation described here
includes optimization of analytical methods applied in the Water and Air Quality Laboratory of the
University of the Aegean for determination of 130 toxic pollutants in water, by means of gas chromatography
with ECD, NPD, FPD and MS detection, Purge and Trap concentration, high performance liquid
chromatography (HPLC) with Diode Array Detection (DAD) and atomic absorption spectrometry
(AAS). The methods described were selected for application to surface water and drinking water samples
from Greece, after experimental modifications which resulted in the best analytical performance achievable
with the particular instrumentation, expressed by the calculated recoveries and detection limits.