1. 353
QUALITY AND POLLUTION OF SURFACE AND GROUNDWATERS
IN THE CHALKIDIKI DISTRICT, MACEDONIA, N. GREECE
M.K. NIMFOPOULOS
1
, K.G. KATIRTZOGLOU
2
, D.A. POLYA
3
, N. VERANIS
2
, I. ANAGNOSTARAS
4
ABSTRACT
The Chalkidiki peninsula, Macedonia, N. Greece, is predominated to the E by metamorphic rocks of the
Serbomacedonian massif, in the middle by rocks of the Circum Rhodope belt and to the W by the Peonia
zone of the Stip Axios belt. The W part is rather a plain crossed by shallow water streams, whereas, the
middle and the E part is mountainous with a sharp relief and a dense network of deep valleys and shears.
The W part was filled with, up to 3.5 km thick, loose sediments of the Neogene-Quaternary period consisting
of marly limestone, marls, sands, red clays, conglomerates, scree deposits and beach sands. Comparative
chemical analyses of groundwater from different aquifer and host rock associations and in relation to
hydrothermal activity, intrusion of seawater, anthropogenic influence, and the chemistry of polluted surface
water from different influence and the formation of brackish surface water by natural processes are given and
explained based on the geological, hydrogeological and hydrological associations.
Keywords: Chalkidiki, groundwater, surface water, quality, pollution, hydrothermal, brackish, seawater.
ΣΥΝΟΨΗ
Η χερσόνησος της Χαλκιδικής δομείται στα Α της από μεταμορφωμένα πετρώματα της Σερβομακεδονικής
μάζας, στο ενδιάμεσο από πετρώματα της Περιροδοπικής ζώνης και στα Δ απ’ αυτά της υποζώνης Παιονίας,
Ζώνης Αξιού. Το Δ τμήμα είναι σχετικά επίπεδο και διασχίζεται από αβαθή υδρορέματα, ενώ το ενδιάμεσο
και Α τμήμα είναι ορεινό με απότομο ανάγλυφο και πυκνό δίκτυο βαθέων κοιλάδων. Το Δ τμήμα πληρώθηκε
με χαλαρά ιζήματα του Νεογενούς-Τεταρτογενούς, πάχους 3.5 km, που αποτελούνται από μαργαϊκούς
ασβεστολίθους, μάργες, ερυθρές αργίλους, κροκαλοπαγή, κορήματα και άμμους. Στην εργασία αυτή
δίνονται, και επεξηγούνται με βάση τα υδρογεωλογικά στοιχεία, οι συγκριτικές χημικές αναλύσεις υπόγειου
νερού διαφορετικών συσχετισμών υδροφορέων και φιλοξενούντων πετρωμάτων, σε σχέση με υδροθερμική
δραστηριότητα, διείσδυση θαλασσινού νερού και ανθρωπογενή δράση, καθώς και η χημεία του ρυπασμένου
επιφανειακού νερού από διαφορετικές επιδράσεις και ο σχηματισμός υφάλμυρου επιφανειακού νερού.
Λέξεις-κλειδιά: Χαλκιδική, νερό, υπόγειο, επιφανειακό, ποιότητα, ρύπανση, υδροθερμικό, γλυφό, θαλασσινό.
INTRODUCTION
The Chalkidiki district geotectonically belongs to the wider N Aegean area which is characterized by
intense neotectonic and seismic activity (Fig. 1). The area of Chalkidiki is influenced by the extensional
movements of the N. Aegean trench. These movements begun during the Mid-Late Miocene and continue
today (Mercier, 1981). The tectonic activity of the eastern and central Chalkidiki was found by landsat images
and aerial photographs to follow E-W, NW-SE to NNW-SSE, NE-SW and N-S orientations (Tsombos, pers.
comm., 2001). The western Chalkidiki belongs to the eastern margin of the large neotectonic depression of
Axios river-Thermaic gulf. This graben is NW-SE orientated and its activity begun in the Eocene times
(Mercier, 1981; Psilovikos et al., 1988). A lateral E-W faulting activity during the Pleistocene affected the
Axios river-Thermaic gulf depression.
The W part of the Chalkidiki district is rather a plain crossed by shallow water streams, whereas, the
middle and the E part is mountainous with a sharp relief and a dense network of deep valleys and shears.
1
IGME, Division of Geochemistry & Environment Protection, 1 Fragon street, 546-26 Thessaloniki, Greece
2
IGME, Division of Hydrogeology & Environment Protection, 1 Fragon street, 546-26 Thessaloniki, Greece
3
The Victoria University of Manchester, Earth Sciences Department, Division of Geochemistry and
Environment, Manchester M13 9PL, England, U.K.
4
Sithonia Borough Council, Division of Hydrogeology & Environment, 630-88 Nikiti, Chalkidiki, Greece

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HYDROLOGICAL DATA
As it gathered from numerous measurements in the past decades, the mean annual air temperature in
the coastal areas of Chalkidiki peninsula is 16C, with the maximum of 29.7C in July and the minimum of
7C in February. The mean annual precipitation is 500 mm in the SW Chalkidiki peninsula and 800 mm in
the Arnaea area. Based on the Haude method, the mean annual evapotranspiration is 800 mm, while based
on the Turck method the actual evapotranspiration is 450 mm. The Chalkidiki peninsula, is crossed by large
water streams such as the rivers Chavrias and Olynthios and the smaller water streams of Asprolakkas-
Kokkinolakkas, Myloi, Smixi and Tripotamos (Fig. 2). The surface drainage flow of the all the above water
streams in their estuaries is zero to minimal for a large period of the year. However, after intense
precipitation, a surface flow is observed for a period of four to six months. On the other hand, in the
mountainous parts of the drainage basins, surface flows are more permanent due to groundwater discharge
on the surface. The two large water streams (Chavrias and Olynthios) are permanently or periodically
charged with processed or raw domestic waste waters, as well as waste waters for oil-milling units. These
waste waters mix with surface stream water, being transported to the lowland part of the drainage basins
where they infiltrate down to the loose formations and part of them is discharged into the sea.
The hydrological conditions of surface discharge from the rivers Chavrias and Olynthios (Table 1) reveal
that a large part of their rainwater load is discharged unexploited into the sea. From these data it can be
concluded that at least for the Chavrias river, the surface rainwater load could be exploited by the use of
small dams that would prevent its discharge into the sea.
Table 1. Surface discharges, of the rivers Olynthios and Chavrias into the sea.
River Basinal
Area
(km
2
)
Mean
Altitude
(m)
Special
Flow
(lit.s
-1
/km
2
)
Discharges of stream water into the sea (in millions m
3
)
1996 1997 1998 1999 2000
Olynthios 239 470 0.64 7.0 1.2 - 5.4 1.2
Chavrias 457 401 1.69 - 16.8 >29.6 - -
The infiltrations and lateral percolations of Chavrias and Olynthios river water into the loose formations
of the two hydrological basins vary between 10 and 50% of the surface discharges. These figures are lower
than those of the Bogdanas river (70 to 80%) of the Migdonia hydrological basin (Nimfopoulos et al., 2002a).
HYDROCHEMICAL DATA
Least affected groundwater
The least affected water from anthropogenic and natural processes (Table 2) contains elevated amounts
Table 2. Quality of the least affected groundwater in the Chalkidiki Peninsula.
n=25 units x ±1σ max min units x ±1σ max min
pH pH units 7.7±0.3 8.4 7.2 NH4 mg/l 0.10±0.03 0.18 0.00
E.C. μS/cm 788±103 1094 400 NO3 11.1±11.5 39.7 1.2
SAR SAR units 1.3±1.0 4.0 0.3 NO2 0.01±0.01 0.06 0.00
T.H. 0
F 37.5±7.8 53.5 12.9 PO4 0.51±0.58 2.27 0.04
Na mg/l 53.5±21.5 112.2 14.5 Fe μg/l 94±26 150 10
K 2.0±1.9 10.6 0.8 Cu 5±4 23 1
Ca 92.5±21.7 134.4 37.6 Zn 62±28 160 10
Mg 34.6±10.1 49.6 8.3 Pb 12±4 20 10
Cl 72.9±36.2 145.3 23.0 Cd <1
F 0.32±0.19 0.64 0.01 Al 87±30 150 10
SO4 40.5±14.7 70.7 8.2 Ni 9±3 10 1
HCO3 363.9±106.8 590.5 72.0 Mn 25±10 60 1
SiO2 19.5±6.5 40.6 7.5 As <10
O.C. mg/l O 0.08±0.04 0.16 0.02 Cr 9±3 10 1
B 455±150 1050 100

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of total dissolved solids which are reflected in its high Total Hardness (T.H.) values (mean of 37.5±7.8)
expressed in French degrees (
0
F). Its electric conductivity (E.C.) however, is relatively average.
To gauge the suitability of groundwater for irrigation purposes, the Sodium Adsorption Ratio (SAR),
determined from the Na, Ca and Mg contens was measured and found to be characteristic of excellent
irrigation waters. In order to gauge the amount of contained reduced matter in the groundwater, the
consumption of KMnO4 oxygen was used (O.C.). The average O consumption is 0.08±0.04 mg/l which is
ranged as low, meaning that the least affected groundwater contains very small amounts of organic or
reduced mater. The rest of the chemical parameters (cations, anions, base metals and toxic elements) were
found to range within normal levels for unpolluted groundwaters.
Groundwater in spatial relation to ultrabasic and basic igneous rocks
Groundwater which resided in ultrabasic and basic massive rocks, and loose rock formations containing
mainly their erosional products (Table 3) has high hardness, and is enriched in Mg, Fe and HCO3 contents.
In some samples, Al and Mn contents are high. This may be due to the increased circulation of groundwater
within the overlying Neogene sediments and its enrichment in Al and Mn. In other samples, an anthropogenic
influence is apparent by the elevated concentrations of NO3 and NO2, which originate from urban sewage
water discharge in the loose rock formations.
Table 3. Quality of groundwater in spatial relation to utrabasic-basic rock aquifers.
n=28 units x ±1σ max min units x ±1σ max min
PH pH units 7.8±0.2 8.3 7.5 NH4 mg/l 0.1±0.2 0.8 0.0
E.C. μS/cm 980±245 1496 543 NO3 12.9±12.2 44.0 0.0
SAR SAR units 1.3±0.6 2.7 0.3 NO2 0.06±0.20 1.05 0.00
T.H. 0
F 53.8±13.7 84.4 31.6 PO4 0.41±0.28 1.52 0.04
Na mg/l 68.5±30.4 129.7 14.2 Fe μg/l 172±273 1200 10
K 2.3±1.6 5.5 0.4 Cu 46±207 1100 2
Ca 77.2±26.8 130.7 16.0 Zn 90±183 1000 10
Mg 83.9±33.1 178.9 47.4 Pb <10
Cl 98.5±43.2 177.2 28.4 Cd <1
F 0.37±0.10 0.48 0.24 Al 145±240 1200 10
SO4 64.9±74.2 252.4 0.0 Ni 10±2 10 1
HCO3 506.1±95.6 716.1 291.6 Mn 32±75 400 1
SiO2 28.0±8.0 45.0 12.8 As <10
O.C. mg/l O 0.22±0.44 1.92 0.02 Cr 10±3 20 1
B 268±233 1000 100
Groundwater affected by hydrothermal activity
The meteoric water which has infiltrated down to the loose rock formations in the areas of Nea
Kallikratia-Olynthos, Agia Paraskevi and Ormylia had mixed with variable quantities of ascending geothermal
water which acted as a pollutant. The main characteristics of these waters are the increased As (mean of
294 ppb) and B (mean of 3764 ppb) contents and the bicarbonates (Table 4). The elevated concentrations of
NO3 and NO2, which originate from urban sewage water discharge in the loose rock formations, constitute an
anthropogenic influence.
The waters are also characterized by increased electric conductivity and total hardness values. Finally, the
meteoric waters of the studied area are similar to the spring waters of the spatially associated area of Agia
Paraskevi, Thessaloniki district but the latter have a much lower As content (up to 85 ppm) (Nimfopoulos et
al., 2002b).
When the above hot waters originate from ultrabasic and basic rock aquifers, a notable increase in their
Mg content is observed (Table 5). In parallel, there is a notable decrease in the As and B contents. This may
be due to a reduced geothermal influence in the ultrabasic rocks which belong to a different geotectonic unit.
Alternatively, there may have been mixing of the ascending geothermal water with larger amounts of
meteoric fluid and dilution of As and B.

6. 358
Table 5. Waters from utrabasic-basic aquifers which have been affected by hydrothermal activity.
n=44 units x ±1σ max min units x ±1σ max min
pH pH units 7.6±0.2 8.1 7.0 NH4 mg/l 0.10±0.12 0.45 0.00
E.C. μS/cm 1131±238 1560 623 NO3 11.6±12.0 44.0 1.2
SAR SAR units 1.6±0.4 2.7 0.6 NO2 0.03±0.09 0.59 0.00
T.H. 0
F 55.6±8.6 75.8 40.2 PO4 0.79±0.66 4.00 0.20
Na mg/l 88.8±25.8 131.0 29.0 Fe μg/l 141±38 218 10
K 6.8±3.9 17.2 0.8 Cu 10±21 140 2
Ca 120.1±45.8 223.6 48.8 Zn 95±226 1400 10
Mg 62.8±13.2 104.3 45.7 Pb <10
Cl 119.7±45.7 193.2 28.4 Cd <1
F 0.53±0.2 1.08 0.19 Al 90±41 200 10
SO4 26.2±13.0 70.7 0.0 Ni 6±5 14 1
HCO3 629.9±107.4 890.6 419.7 Mn 35±78 460 1
SiO2 35.6±9.9 85.6 9.4 As 155±192 750 5
O.C. mg/l O 0.09±0.11 0.48 0.02 Cr 10±2 20 10
B 2725±1587 8700 600
Finally, coastal water boreholes which have been done recently in the Area of Nea Kallikratia-Olynthos
(Fig. 2) yield water which, besides having the intense characteristics of geothermal water, has also high Cl,
bicarbonate and total hardness values (Table 6).
Table 6. Waters from utrabasic-basic aquifers which have been affected by hydrothermal activity
and intrusion of sea water.
n=3 units x ±1σ max min units x ±1σ max min
pH pH units 7.5±0.1 7.5 7.4 NH4 mg/l 0.48±0.29 0.65 0.15
E.C. μS/cm 1450±55 1491 1388 NO3 19.0±12.5 33.5 11.2
SAR SAR units 1.8±0.1 1.9 1.7 NO2 0.02±0.01 0.03 0.01
T.H. 0
F 71.1±2 72.8 69.8 PO4 1.39±0.58 1.96 0.80
Na mg/l 109.8±7.4 116.6 101.9 Fe μg/l <100
K 10.5±0.4 10.9 10.1 Cu 6±1 7 5
Ca 193.7±11.1 204.0 182.0 Zn 20±17 40 10
Mg 55.2±3.4 59.1 52.9 Pb <10
Cl 213.3±8.0 221.6 205.6 Cd <1
F 0.47±0.10 0.56 0.36 Al <100
SO4 33.0±2.7 35.4 30.0 Ni <1
HCO3 717.8±20.9 736.9 695.4 Mn 3±4 8 1
SiO2 38.5±4.3 42.8 34.2 As 203±300 550 20
O.C. mg/l O 0.06±0.02 0.08 0.04 Cr <10
B 5533±1290 6600 4100
Anthropogenic influence on groundwater
Selective sampling and analysis of water from areas with obvious anthropogenic influence on
groundwater are presented in Table 7. Sample 21 has high O.C. values which mean a high organic content
in the groundwater and, combined with the high NH4, NO3, and NO2 contents, are strongly indicative of the
influence of urban sewage water and organic fertilizer (Velemis, 1991, Gantidis, 1991) infiltration down to the
groundwater levels and dilution of pollutants in it. NH4 originates from the organically-bonded aminic nitrogen
which is hydrolyzed to NH4 with the effect of ammonium bacteria according to Anagnostopoulos (1994) as
follows:
NH2
C = O + 3H2O 2NH4
+
+ 2OH
-
+ CO2
NH2

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The produced NH4 is then transformed to NO2, by the effect of nitrobacteria (nitrosomana) as follows
(Anagnostopoulos, 1994):
NH4
+
+ 3/2O2 NO2
-
+ H2O + 2H
+
+ 55 Kcal
Table 7. Anthropogenic influence on groundwater from the Chalkidiki
Peninsula.
units 21 87 units
pH pH units 7.0 7.8 NH4 mg/l 3.40 0.05
E.C. ΜS/cm 378 1060 NO3 1866.8 56.4
SAR SAR units 2.2 1.1 NO2 201.30 0.01
T.H. 0
F 35.3 59.6 PO4 0.33 1.80
Na mg/l 94.3 59.5 Fe μg/l 700 30
K 5.1 1.6 Cu 50 2
Ca 88.0 72.0 Zn 200 30
Mg 32.3 101.1 Pb 10 10
Cl 180.8 113.4 Cd 1 1
F 0.41 0.51 Al 100 100
SO4 24.2 35.4 Ni 1 10
HCO3 298.9 466.0 Mn 100 10
SiO2 12.8 32.1 As 5 6
O.C. mg/l O 8.96 0.02 Cr 10 10
B 1300 10
When the anthropogenic influence is combined with pollution of water from geothermal fields, a
considerable increase in the E.C., HCO3, As and B contents can be observed (Table 8) as a result of
enhanced element input from the geothermal field waters.
Table 8. Anthropogenic influence on groundwater from geothermal fields.
n=4 units x ±1σ max min units x ±1σ max min
pH pH units 7.5±0.2 7.7 7.3 NH4 mg/l 0.05±0.06 0.13 0.00
E.C. μS/cm 1544±114 1620 1374 NO3 65.6±15.3 90.0 46.6
SAR SAR units 2.0±0.2 2.3 1.8 NO2 0.05±0.05 0.12 0.01
T.H. 0
F 66.4±3.5 71.0 63.0 PO4 0.62±0.37 1.10 0.27
Na mg/l 105.4±10.4 115.6 92.0 Fe μg/l 13±5 20 10
K 7.1±2.5 10.1 4.1 Cu 9±10 23 1
Ca 150.0±34.1 177.2 100.2 Zn 24±11 34 10
Mg 45.2±23.8 66.1 11.8 Pb <10
Cl 196.7±46.2 251.8 141.5 Cd <1
F 0.50±0.17 0.75 0.37 Al <10
SO4 48.1±5.7 55.0 43.0 Ni 8±5 10 1
HCO3 580.4±59.8 628.3 492.9 Mn 1
SiO2 29.0±5.0 36.4 25.5 As 433±264 770 130
O.C. mg/l O 0.53±0.44 1.12 0.05 Cr <10
B 2275±650 2900 1400
Finally, when the anthropogenic influence concerns waters originating from ultrabasic and basic rock
aquifers, a notable increase in their Mg content is observed (Table 9). High PO4 contents (up to 8 ppm),
combined with the high NO2 contents (2.64 ppm) in the same sample, are strongly indicative of the influence
of agrochemical (soil improvers) use in the farmlands. Part of the used fertilisers percolates down to the
groundwater levels and is diluted in the groundwater as a pollutant (Dararas et al., 1996). Agrochemicals
have a serious impact on human health according to Simonis (1991). There is also a notable decrease in the
As and B contents. This may be due to a mixing of the ascending geothermal water with larger amounts of
meteoric fluid and dilution of As and B.

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Table 9. Anthropogenic influence on groundwater contained in utrabasic rocks in geothermal fields.
n=8 units x ±1σ max min units x ±1σ max min
pH pH units 7.6±0.2 7.8 7.3 NH4 mg/l 0.04±0.03 0.10 0.00
E.C. μS/cm 1444±175 1780 1264 NO3 61.2±29.5 121.9 26.7
SAR SAR units 1.8±0.3 2.16 1.33 NO2 0.54±0.98 2.64 0.01
T.H. 0
F 63.9±7.8 74.0 50.6 PO4 1.54±2.63 8.00 0.26
Na mg/l 102.9±16.1 123.5 73.0 Fe μg/l 55±48 100 10
K 7.8±2.8 12.1 5.0 Cu 5±2 8 1
Ca 142.1±48.8 210.8 90.5 Zn 35±23 72 10
Mg 68.4±15.4 95.7 52.0 Pb <10
Cl 174.2±34.1 219.9 109.9 Cd <1
F 0.52±0.23 0.87 0.15 Al <10
SO4 42.3±10.2 59.6 27.1 Ni 6±5 10 1
HCO3 627.2±107.0 824.7 494.1 Mn 2±2 5 1
SiO2 30.9±4.8 38.5 24.8 As 242±368 1100 15
O.C. mg/l O 0.29±0.22 0.64 0.04 Cr <10
B 2638±1666 5600 1300
The Chakidiki peninsula is characterized by the intense agricultural activity, mainly in the western
(planal) part of the district (Nea Kallikratia to Olynthos and Ormylia). This farming industry is consuming
groundwater for plant irrigation purposes throughout the whole year. However, in the two summer months of
July and August, the irrigation water demand is coupled with a peak in the number of tourist population in the
same coastal areas, which rises to 800,000 people and so does the water demand. As a consequence,
intense problems on the water supply services are created due to the restricted volume of the underground
aquifers. The continuous over-pumping of groundwater from boreholes of high water supply from the coastal
loose geological formations causes a significant drop in the groundwater table, which allows the intrusion of
seawater (Fig. 2) into the groundwater aquifers. Thus, a characteristic increase in Cl, Na and Mg contents
and the value of T.H. is observed (Table 10).
Table 10. Influence of overpumping on groundwater, intrusion of seawater (Fig. 2).
n=6 units x ±1σ max min units x ±1σ max min
pH pH units 7.8±0.1 7.9 7.7 NH4 mg/l 0.45±0.36 0.90 0.10
E.C. μS/cm 2010±1554 5170 1231 NO3 13.4±5.5 21.1 5.6
SAR SAR units 3.0±2.2 7.2 1.2 NO2 0.01±0.01 0.02 0.00
T.H. 0
F 71.2±42.0 155.8 43.3 PO4 0.31±0.11 0.48 0.17
Na mg/l 199.6±223.2 650.6 63.91 Fe μg/l 422±969 2400 10
K 4.0±4.9 12.9 0.8 Cu 6±3 10 3
Ca 179.1±119.6 4.8 102.4 Zn 22±10 40 13
Mg 60.9±33.1 124.4 38.8 Pb 13±5 20 10
Cl 531.8±696.9 1949.8 184.4 Cd <1
F 0.40±0.01 0.41 0.40 Al <10
SO4 53.8±40.9 136.1 27.13 Ni 9±4 10 1
HCO3 391.9±96.2 473.4 222.4 Mn 6±2 8 5
SiO2 18.0±3.4 20.9 12.8 As 9±2 10 5
O.C. mg/l O 0.20±0.05 0.29 0.14 Cr 12±4 20 10
B 1310±36 1350 1280
Anthropogenic influence on surface water
Surface waters have different chemistry than the groundwater. The surface waters which, are influenced
by anthropogenic activities (urban sewage waters and oil-milling effluents), have characteristic smell and
colour. These and other characteristics can help in the collection of suitable polluted samples in order to
examine their chemistry. The sample locations of selected surface waters are recorded in Fig. 2. The
polluted surface waters have increased E.C., O.C., NH4, NO2, PO4, the metals Fe and Mn, and B (Table 11).
All the villages located into the Chavrias hydrological basin, discharge their sewage waters and olive oil-

9. 361
milling effluents into the basin. A part of them is infiltrated down to the groundwater and another part is
diluted and transported in the surface water heading to the sea.
Table 11. Pollution of surface waters in the Chalkidiki Peninsula.
n=6 units x ±1σ max min units x ±1σ max min
pH pH units 7.9±0.5 8.9 7.5 NH4 mg/l 0.54±0.73 2.02 0.11
E.C. μS/cm 874±508 1700 365 NO3 23.9±24.5 54.1 0.0
SAR SAR units 2.1±1.7 4.2 0.4 NO2 3.33±5.30 12.38 0.00
T.H. 0
F 29.9±7.7 39.4 20.0 PO4 9.99±9.89 27.00 0.58
Na mg/l 88.8±78.5 192.0 14.5 Fe μg/l 374±333 650 10
K 13.7±7.5 22.3 4.7 Cu 3±2 7 1
Ca 72.7±21.3 109.0 50.4 Zn 50±21 71 20
Mg 28.7±10.8 45.7 16.0 Pb 12±4 20 10
Cl 82.4±75.5 187.9 3.2 Cd <1
F 0.75±0.58 1.42 0.35 Al 166±246 600 10
SO4 35.3±14.3 56.0 17.9 Ni <1
HCO3 358.6±200.7 666.1 218.4 Mn 55±73 140 9
SiO2 14.2±7.7 19.3 1.3 As <10
O.C. mg/l O 2.70±3.50 9.50 0.34 Cr 3±4 10 1
B 2133±252 2400 1900
The northeastern part of the Chalkidiki peninsula is characterized by the presence of large volumes of
polymetallic sulphide ores and the intense mining activity which begun during the ancient Greek times and
continues today. Water sampling was done from the Kokkinolakkas water stream (Fig. 2) of this mining area.
The surface water is characterized by increased E.C., T.H. and O.C. values and elevated contents of Mg,
SO4, Fe, Zn, Cd, Al, Ni and Mn (Table 12).
Table 12. Surface water rich in metallic elements.
units 35 Units
PH pH units 7.1 NH4 mg/l 0.10
E.C. μS/cm 2180 NO3 2.5
SAR SAR units 1.3 NO2 0.01
T.H. 0
F 142.4
Na mg/l 115.9 Fe μg/l 12000
K 7.8 Cu 30
Ca 304.0 Zn 9600
Mg 166.0 Pb 31
Cl 147.1 Cd 31
Al 10100
SO4 1210.3 Ni 600
HCO3 23.2 Mn 34000
SiO2 31.7 As 5
O.C. mg/l O 16.5 Cr 10
B 200
The high SO4 and metallic contents are the result of dissolution of polymetallic sulphide-Mn carbonate
protore by the effect of meteoric waters in the surface water environment (Nimfopoulos, 1988; Michailidis et
al., 1997). Also, the high O.C. values are indicative of a prevailing reducing environment in the surface
waters studied due to the dissolution of sulphides and the release of H2SO4 in the waters (Nimfopoulos et al.,
1997).
Brackish surface water
In the area located South of the village of Nea Potidea in the Kassandra peninsula, there are some very
small water streams which have a surface flow only for a few days after strong rainfalls. The chemical

10. 362
analyses of this water show high E.C. values and increased concentrations of Cl and Na. These values are
characteristic of brackish water. They indicate that, in this specific part of the Kassandra peninsula, the wind
currents, owed to the different air temperature between the Thermaic and Kassandra gulfs, transport
seawater in the form of droplets. Some of the seawater droplets are deposited on the Neogene loose
sediments of the Kassandra peninsula and especially in this narrow strip between the two gulfs, where the
proportion of the sea to the land is much higher. Thus, they supply the sediments of this narrow land strip
between the two gulfs with Na and Cl. After a strong rainfall, the sediments are washed with meteoric water
which, is then enriched in Na, Cl and other dissolved elements (Table 13). This water eventually becomes
brackish.
Table 13. Surface waters rich in Na and Cl in the Kassandra Peninsula.
n=5 units x ±1σ max min units x ±1σ max min
pH pH units 7.9±0.2 8.1 7.6 Mg 66.8±30.1 116.7 42.6
E.C. μS/cm 2687±550 4180 1829 Cl 811.8±380.2 1417.9 496.3
T.H. 0
F 59.5±13.9 78.1 44.8 SO4 123.0±16.4 149.9 110.0
Na mg/l 352.3±180.3 613.7 195.9 HCO3 204.2±75.7 269.7 97.0
K 11.8±5.2 18.4 7.4 NO3 mg/l 5.7±4.8 13.0 2.4
Ca 127.7±46.3 191.6 61.7 NO2 0.04±0.03 0.10 0.02
CONCLUSIONS
The Chalkidiki peninsula is crossed by the, big in size, rivers Olynthios and Chavrias, which discharge
large quantities of surface water into the sea. These amounts of water could assist the coastal communities
in the solution of the very demanding water supply problems, especially in the summer months.
The least affected groundwater by anthropogenic and natural processes is characterized by high total
hardness values. When the groundwater resides in ultrabasic and basic rocks and their erosion counterparts
(loose formations), it is enriched in Mg and HCO3. Often, the infiltrating downwards groundwater is
intermixed with water from hydrothermal activity and is enriched in variable concentrations of As, B, and
HCO3. On the other hand, when sewage water and olive-oil milling effluents infiltrate down and intermix in
various proportions with groundwater, they contribute to the increase in its NH4, NO3, NO2 and PO4 contents
and the prevalence of relatively reducing conditions (increase in O.C.).
Borehole over-pumping of water for domestic and irrigation purposes, especially in the summer months,
causes, intrusion of seawater into the groundwater aquifers of the mainland (Fig. 2), which is common in the
coastal areas of the peninsula, where the Quaternary loose geological formations predominate. This water is
very hard and has large concentrations in Cl, Na and Mg.
The Chavrias basinal area is charged with the larger amounts of urban sewage, olive-oil milling effluents
and agrochemicals. A part of these infiltrates down to the groundwater aquifers, while the rest during the
intense rainfall period is transported in the surface water heading to the sea.
Where large polymetallic sulphide ores exist (NE Chalkidiki, e.g. Asprolakkas stream; Fig. 2), the
surface stream water has elevated electric conductivity, high total hardness and is saturated in Fe, Zn, Cd,
Al, Ni, Mn, Mg and SO4 due to the dissolution of sulphides in the meteoric water and prevalence of relatively
reducing conditions (high O.C. values).
Finally, the observed brackish surface waters in the Kassandra peninsula are owed to the air transport
of sea water droplets from the sea into the peninsula mainland.
Acknowledgements
We would like to thank the Director General of IGME for permission to publish this paper and Ananias
Tsirambides, Professor of the University of Thessaloniki, for fruitful discussions and assistance in the
presentation of the manuscript. Mr G.N. Katirtzoglou has done the statistical processing of chemical
analyses. Mr V. Polyzonis is thanked for assistance with the electronic form of this document. Finally, we
would like to thank the mayors of the local communities for assistance with the sampling locations and the
British Council for financial support to M.K.N. and D.A.P. enabling collaboration visits in Great Britain and
Greece.

11. 363
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