Issue 3 [November] ( Issue on Water Quality
)
Abstract The levels and the distribution of metals, hydrocarbons and organochlorine compounds were studied
in mussels (Mytilus galloprovincialis) and surface sediments collected from Thermaikos gulf in March
1999. Hydrocarbon values were indicative of moderate pollution, whereas in some cases clear evidence
for the presence of petroleum residues was found. Polycyclic aromatic hydrocarbon, DDTs, PCBs and
metal concentrations were low, but clearly higher than those measured in the same area during the previous
years. Different spatial distribution patterns were observed between organic and inorganic contaminants
bioaccumulated in mussels and between sediment and mussel values. In all cases the contaminant
concentrations in mussels were well below the permissible limits for consuming seafood.
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.
Abstract The establishment of the Wastewater Treatment Plant of Athens is considered as the main factor contributing
to the improvement of water quality and recovery of the marine ecosystem in Saronicos gulf
as it removes significant percentage of pollutants entering the gulf, including heavy metals.
The comparison of concentrations of dissolved and particulate copper during 1993, 1994 (before the
operation of the plant) and 1998, 1999 and 2000 (after the beginning of the operation) revealed that
some changes in the distribution of copper occurred because of this major change concerning the pollution
sources of the gulf.
The effects are both direct, like the increased concentrations in the sediments near Psitalia and the
slight decrease of mean values of dissolved copper and indirect, associated with the decrease of dissolved
oxygen in the deep water of the western basin, i.e. the decrease of dissolved copper in this layer
and the increase of copper concentrations in surface sediments.
The general conclusion of this study is that the overall picture of copper pollution of the gulf has differentiated
but not radically changed.
Abstract 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.
Abstract The formation of chlorination by-products (CBPs) was investigated by bench-scale chlorination experiments
with surface waters from different sources in Lesvos island, Greece. The main factors studied were
organic matter content of water (expressed as UV-272 absorbance), time and chlorine dose. The CBPs,
determined by gas chromatographic techniques, belong to the categories of trihalomethanes (THMs),
haloacetic acids (HAAs), haloacetonitriles, chloral hydrate and chloropicrin. HAAs and THMs were the
most abundant CBPs detected in the chlorinated samples, while haloketones, haloacetonitriles and chloral
hydrate occurred at much lower concentrations. Statistical analysis of the results with multifactor
analysis of variance revealed the influence of the parameters studied on the formation of individual compounds.
Application of principal component analysis (PCA) provided a clear picture of the differentiations
between varying water sources and chlorination conditions. Multiple regression was used for development
of predictive models for CBPs formation. The proposed models are considered satisfactory for
predicting CBPs concentrations for water sources and chlorination conditions similar to those examined.
Abstract 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.
Abstract A pilot-plant study was carried out with the water supply to Athens water works filtered through a granular
activated carbon (GAC) filter- adsorber. The objective of this study was to evaluate the performance
of GAC for the removal from drinking water of the two main groups of disinfection by -products
(DBPs), trihalomethanes (THMs) and haloacetic acids (HAAs), as well as of dissolved organic matter.
The pilot treatment facility is located at the Water Treatment Plant of EYDAP in Galatsi, Athens, and
was operated as a rapid gravity filter - adsorber. It was fed with chlorinated water, coming from the
overflow of the sedimentation tanks, and operated continuously in parallel with a full-scale sand filter.
At regular time intervals water samples were taken from both filters and analysed for THMs, HAAs
and DOC. Other parameters were measured too. The operation of the GAC filter-adsorber continued
until the GAC adsorption capacity for THMs and HAAs was almost exhausted.
The results of the analyses showed that GAC was more effective in removing the dissolved organic matter
than the smaller molecules of THMs and HAAs, fact which is in agreement with the relevant literature.
GAC was also proved more effective in removing HAAs than removing THMs. The removal of
THMs and the most part of the removal of HAAs and DOC must be attributed to adsorption by GAC,
while that of a smaller part of DOC and HAAs may be attributed to biological activity in the filter
bed, where chlorine had been totally removed by the catalytic action of the activated carbon surface.
Abstract The results of a research study about the groundwater quality in western Thessaly, that took place during
the period 2001-2002, are presented in this paper. The study included two samplings during May and
August of 2002. In May the water table is at high level while at the end of the summer the level of the
water table is as low as it can be. Fourteen sampling stations were selected and the samples were received
from deep wells. In addition to nitrogen compounds, several other chemical parameters were measured.
UV-Vis Spectrometry, Atomic Absorption Spectrometry and Emission Spectrometry were used for the
chemical analyses.
The groundwater of region Farsala has been found to contain very high nitrate concentrations and also
high concentrations of calcium, nitrite and bicarbonates. The increased nitrate level in groundwater is a
major problem, caused by the fertilizers that are used in most areas with intensive agriculture like
Thessaly. The concentrations of heavy metals were very low. The ionic ratios of major cations indicate
that the groundwater originates mostly from calcareous aquifers and there is a constant water flow.
The classification according to conductivity, chloride concentration and degree of alkalinity characterizes
the groundwater as water of medium quality that can be used for irrigation at soils with good conditions
of leaching.