Investigation of sediment pollution in the Gulf of Elefsina using

environmental indicators

CHRISTINA PASCHALIORI

Department of Industrial Design & Production Engineering

University of West Attica

Egaleo, Athens

GREECE

DIMITRIOS PALMOS

School of Sciences & Technology

Hellenic Open University

Patras

GREECE

KORALIA PAPAKITSOU

Department of Animal Science & Aquaculture

Agricultural University of Athens

Athens

GREECE

ANASTASIOS MAVRAKIS

Department of Civil Engineering

University of West Attica

Egaleo, Athens

GREECE

EVANGELOS PAPAKITSOS

Department of Industrial Design & Production Engineering

University of West Attica

Egaleo, Athens

GREECE

NIKOLAOS LASKARIS

Department of Industrial Design & Production Engineering

University of West Attica

Egaleo, Athens

GREECE

Abstract: - In this paper, the sediment pollution in the Gulf of Elefsina, over the period 1986-2010, has been

measured and presented. The pollution had been measured regarding heavy metals, like cadmium (Cd), chromium

(Cr), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), nickel (Ni) and zinc (Zn). Initially, the measured area

is presented, along with the sources of pollution in the historical background and the wider region. Three pollutant

indicators had been calculated for the investigation of Sediment Pollution: The Pollution Load Index (PLI), the

Enrichment Factor (EF) and the Geo-accumulation index (Igeo). The results of the Pollution Control and

Environmental Quality Office measurements had been used for the calculation of these indicators, taken at six

locations of the coast and three locations in the center of the Gulf of Elefsina. The study of these indicators reveals

that there is heavy metal pollution at all sampling locations, while the most heavily affected areas of the Gulf are

these near Skaramangas Shipyards and Elefsis Shipyards. More intense pollution is recorded for Cd, Cu, Fe, Pb,

Zn. More specifically, high values of Cd had been measured at all sampling points, while for Cu, Fe, Pb and Zn

high values had been measured in areas that are active in shipbuilding-repair and dismantling units. In contrast,

there is no pollution for Mn.

Key-Words: - Gulf of Elefsina, sediment pollution, heavy metals, pollution indicators.

Received: December 29, 2022. Revised: September 14, 2023. Accepted: October 15, 2023. Published: November 27, 2023.

International Journal of Environmental Engineering and Development

DOI: 10.37394/232033.2023.1.22

Christina Paschaliori, Dimitrios Palmos,

Koralia Papakitsou, Anastasios Mavrakis,

Evangelos Papakitsos, Nikolaos Laskaris

E-ISSN: 2945-1159

239

Volume 1, 2023

Thriasio Field is located 20km from the center of

Athens (Greece) and consists of the Municipalities of

Elefsina, Mandra-Idyllia, Aspropyrgos and the

Community of Magoula. The lowland area is

approximately 100,000 acres, crossed by two rivers

(Sarantapotamos, Aghios Georgios) and in it the

above settlements have been developed, along with

agricultural crops, craft and industrial units and a

military airport. The sea area that wets its shores is

called the Gulf of Elefsina (alias Elefsis), after the

name of the largest and oldest city in the area [1].

The Gulf of Elefsina is part of the Saronic Gulf,

which has an area of 2,600 km2 (Fig. 1). The Saronic

Gulf (alias Saronikos) is bounded to the north and

east by the coasts of Attica, to the west by the coasts

of Corinth and to the southwest by the coasts of

Argolis. The boundary of the Saronic Gulf with the

Aegean Sea can be considered the imaginary line of

Poros – Sounio (about 45 km). Saronic extends from

38° 03΄N to 37° 27΄N latitude and from 23° 00΄E to

24° 02΄E longitude [2].

Figure 1. Saronikos Gulf – Gulf of Elefsis [3].

The Saronic Gulf can be considered to consist of

four sub-regions: The South Saronic, which is in

direct communication with the S. Aegean Sea, with a

maximum depth of 200 m; the Western Saronic, with

the maximum depth of about 450 m; the Eastern

Saronic, where the islet of Psytallia is located, where

the Athens wastewater treatment center of the same

name (KELP) operates; and the Gulf of Elefsina,

which is located in the northern part of the Saronic

Gulf [4].

The Gulf of Elefsina has a surface area of 67 Km2

and a total water volume of approximately 1.3·106

m3, with a maximum depth of 33 m, while its average

depth is 18 m. The volume of water is distributed by

77% up to a depth of 18 m and by 23% at a depth

between 18 and 33 m. In other words, it is a shallow

basin (Fig. 1), which communicates with the rest of

the Saronic Gulf through two narrow channels,

formed between the coasts of Attica and Salamis

Island, i.e., the Megara Channel in the west with a

depth of 8 m, a surface width of 600 m and a bottom

width of 170 m, and the Keratsini Channel with a

depth of 12 m, a surface width of 1200 m and a

bottom width of 250 m, which is located east of

Salamis [1].

The morphology of the closed shallow basin

directly affects the water circulation and its renewal

time. Specifically, it has been established that the

circulation of water is thermohalo, controlled by low

temperatures in winter and high salinities in summer,

compared to the rest of the Saronic. The waters are

fully mixed in winter and stratified in summer, the

thermocline is clear and placed at about 15 m. The

direction of traffic changes seasonally and is

significantly affected by prevailing winds. The net

flow in winter is 240 m3/s from W to E, while in

summer it reverses and is 450 m3/s. The average

water renewal time is estimated at 2 – 3 months, a

fact that favors the concentration of pollutants mainly

in the bottom sediments [1].

2 Pollution Sources

The rapid residential and industrial development of

Athens, Piraeus and, in general, Attica led to the

discharge of a very significant polluting load into the

Saronic Gulf, with the result that it is the first marine

area in the Greek territory to show severe

environmental problems. It is worth noting that about

40% of the Greek population has gathered around the

Saronic coast, as well as a large number of industrial

and port activities. Most and the largest industries of

Attica are concentrated on the Saronic coast,

including oil refineries, shipyards, foundries, cement

industries, chemical industries, small tanneries,

1 Introduction

International Journal of Environmental Engineering and Development

DOI: 10.37394/232033.2023.1.22

Christina Paschaliori, Dimitrios Palmos,

Koralia Papakitsou, Anastasios Mavrakis,

Evangelos Papakitsos, Nikolaos Laskaris

E-ISSN: 2945-1159

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spinning mills, food and beverage processing plants,

such as dairy plants, soft drink bottling plants,

distilleries, etc. There are also located the most

important port, naval and shipbuilding facilities of

Greece. Piraeus is one of the most important ports in

the Mediterranean, with approximately 24,000 ships

a year anchoring there (www.olp.gr). In addition,

both on the coasts of Attica and on the coasts of the

Peloponnese (see Fig. 1: Corinth and Argolis), tourist

activities have been particularly developed, which

also contribute to the pollution of the Saronic. To the

above sources of pollution, we must add the coastal

boulevards with heavy car traffic, as well as the

airports of Attica [4] [5].

The Saronic Gulf and especially the Gulf of

Elefsina is one of the few regions in Greece where

seawater quality has been systematically monitored

since 1985, within the framework of national and

regional programmes. From 1985 to 2004 with the

“National Monitoring Program for the Assessment

and Control of Marine Pollution in the

Mediterranean” (MED-POL) MAP / UNEP and from

2004 to the present day with the program

“Monitoring of the Saronic Ecosystem under the

influence of the Psyttalia Sewage Outflow Pipeline”.

At the same time, from 2011 Saronic joined the

National Water Quality and Quantity Monitoring

Network (Government Gazette 2017/2011), in the

framework of the implementation of the WFD (Water

Framework Directive), while systematic sampling

began in 2012 [2] [4] [5]. Because of the importance

of the Gulf of Elefsina and Thriasio Field as the first

historically and still major industrial area of Greece,

the environmental interest and monitoring is

continuous, until nowadays [6] [7].

2.1 Industrial waste pollution

In the Gulf of Elefsina the sources of pollution are

due to various anthropogenic activities, mainly due to

the existence of the industrial zone in the area. The

legislated area of the industrial zone of Thriasio Field

adjacent to the sea is 2500 acres. Of the 15 kilometers

of coastline, 12 kilometers have been occupied by

port activities of craft industries [8]. Indicatively,

1623 industrial units have been developed here and

there. In the wider area of Triasio Field, many smaller

industries of oil, plastics, chemicals, paper industry,

quarries, mineral oil regeneration units, etc. operate.

The environmental burdens related to the above

activities are summarized as follows [4] [5] [9]:

 Industrial waste, originating either from

land leakages or from atmospheric

deposition, such as atmospheric suspended

particles and photochemical pollution

(nitrogen oxides, ozone and total

hydrocarbons).

 Handling, repair and construction of ships,

decommissioned anchored ships,

shipwrecks, ship breakers, oil spills from

accidents and decontamination of these

through submersion using special

detergents.

 Landfill operations with metallurgical rusts

and inert materials from various industries

(approx. 1000 acres of sea).

 Focal points (such as the stream of Aghios

Georgios, which carried the liquid waste of

the tanneries, the paper industry, the

bituminous industries, as well as the

drainage from the Ano Liosia Waste Burial

Ground).

 Washing away by the rains of the

agricultural fertilizers, used in the

agricultural crops of the region.

2.2 Heavy metals sources

The natural sources of metals in the sea are soil

erosion and volcanic activity. Anthropogenic sources

are mining, industrial activity, fuel use, combustion

processes at high temperatures. Also, deforestation,

the construction of deep harbors and artificial lakes

increase the transport of metals with particles [2]

[10]. Thus, the investigated heavy metals in the

present study were the following: Copper (Cu),

Cadmium (Cd), Iron (Fe), Chromium (Cr),

Manganese (Mn), Lead (Pb), Zinc (Zn) and Nickel

(Ni).

2.3 Sampling Points

The measurements for pollution control in the marine

area of the Gulf of Elefsina were carried out at three

(3) locations in the center of the bay and at six (6)

locations along the coasts [8]. More specifically, the

three locations at the center of the bay where:

 800m away from Skaramangas Shipyards

(K1),

 1500m away from the local steel industry

(K3),

 1500m away from Eftaxias area (K5).

The six locations along the coast where at:

 Skaramangas’ Shipyards (A1),

 Aspropyrgos’ Refineries (A2),

 Elefsina’s Refineries (A4),

 Aghios Georgios stream (estuary) (A5),

 Bakopoulos dismantling unit (A8),

International Journal of Environmental Engineering and Development

DOI: 10.37394/232033.2023.1.22

Christina Paschaliori, Dimitrios Palmos,

Koralia Papakitsou, Anastasios Mavrakis,

Evangelos Papakitsos, Nikolaos Laskaris

E-ISSN: 2945-1159

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 Elefsina’s Shipyards (A11).

Therefore, the coastal sampling sites were chosen to

be at points where a variety of industrial and craft

units are active. The measurements had been

conducted on sediment samples, a practice still

followed until recently [11].

3 Heavy Metals Pollution Indicators

The estimation of the pollution levels in the sediment

of the bottom of the Gulf of Elefsina was based on

the calculation of three pollution indices, i.e., the

Pollution Load Index (PLI), the Enrichment Factor

(EF) and the Geo-accumulation index (Igeo). Different

environmental tracers have been also used in other

studies, for different purposes (e.g., see [12]).

3.1 Pollution Load Index (PLI)

PLI was proposed by Tomlinson et al. [13] and is

derived as the concentration in the sample of each

metal from the heavy metals, in relation to the

background concentration value of the metal in an

average uncontaminated sediment, according to the

mathematical relationship:

n1 2 1 n

PLI CF CF CF ... CF    

(1)

where CFi is the enrichment index for each metal, as

the quotient of the concentration of the metal in the

sample Ci to the concentration of each metal in an

average uncontaminated sediment (Cbackground), and n

is the total number of heavy metals analyzed in each

sample [14].

PLI was proposed in order to estimate the levels

of metal pollution in the samples to be studied. It is a

simple and quick tool to estimate the level of heavy

metal pollution, in order to compare the pollution

situation in different areas. According to Tomlinson

et al. [13], a value of zero indicates perfection for the

area, a value of one indicates a baseline level of

pollutants, while values above one indicate

progressive degradation of environmental quality.

Zhao et al. [15] further categorized the scale of PLI

as presented in Table 1.

Table 1. PLI sediment classification index [15].

Class

PLI

Sediment Quality

0 < PLI ≤ 1

Zero-burden

1 < PLI ≤ 2

Zero-burden to

moderate pollution

2 < PLI ≤ 3

Moderate pollution

3 < PLI ≤ 4

Moderate to high

pollution

4 < PLI ≤ 5

High pollution

PLI > 5

Very high pollution

PLI cannot provide information about the effects

of pollutant combination for the area under

consideration. It is also possible to calculate low

index values if only one pollutant is at high levels,

while the others have values close to background

concentrations.

3.2 Enrichment Factor (EF)

The enrichment factor EF is the quotient of the ratio

of the concentration of the metal of interest (Xn) to

the concentration of a reference element (Cn) in the

sample in mg/Kg, to the same ratio for a reference

material [14] [16]. We usually use as a reference

metal a metal whose concentration is not due to

anthropogenic influence. Such metals are iron and

aluminum. In this paper, iron is considered as the

reference metal. The classification of sediments

based on EF is presented in Table 2.

Table 2. Sediment classification index EF [14].

Class

Sediment Quality

EF< 1

Zero-burden

1≤ EF < 3

Low pollution

3 ≤ EF < 5

Moderate pollution

5 ≤ EF< 10

Moderate to high

pollution

10 ≤ EF< 25

High pollution

25 ≤ EF < 50

Very high pollution

EF > 50

Extremely high

pollution

3.3 Geo-accumulation index (Igeo)

Igeo was proposed by Müller (in [17]). It is a common

approach to estimate the increase in metal

concentrations in an area, above baseline

concentrations. The method assesses the degree of

heavy metal pollution and categorizes areas into

seven pollution classes, based on increasing

numerical values of the index. The Igeo index is

calculated as follows:

geo 2

I log 1,5 B



(2)

where Cn is the measured concentration of the

examined metal n in the sediment, Βn is the reference

geochemical concentration in pre-industrial sediment

for that element. The factor of 1.5 is introduced to

minimize the effect of possible changes in

background values, attributable to lithological

changes in the sediments [16]. The classification of

sediments based on Igeo (according to Müller) is

presented in Table 3.

International Journal of Environmental Engineering and Development

DOI: 10.37394/232033.2023.1.22

Christina Paschaliori, Dimitrios Palmos,

Koralia Papakitsou, Anastasios Mavrakis,

Evangelos Papakitsos, Nikolaos Laskaris

E-ISSN: 2945-1159

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Table 3. Igeo Sediment classification index [14].

Class

Igeo

Sediment Quality

Igeo< 0

Zero pollution

0≤ Igeo < 1

From zero pollution to

moderate pollution

1≤ Igeo < 2

Moderate pollution

2 ≤ Igeo < 3

Moderate to high

pollution

3 ≤ Igeo < 4

High pollution

4 ≤ Igeo < 5

From high to

extremely high

pollution

Igeo > 5

Extremely high

pollution

4 Calculation of Pollution Indices per

Metal

The aggregated PLI, EF and Igeo indices per metal

were calculated and studied for the various sampling

points and for five five-year periods (1986-1990,

1991-1995, 1996-2000, 2001-2005, 2006-2010),

until the official recording was stopped (2010). All

sampling points have PLI values >1 and according to

Tomlinson et al. [13], we are led to the conclusion

that there is pollution. Therefore, a more careful

study of the sediments in the area of the Gulf of

Elefsina is required. It is also observed that there is a

tendency to decrease the values for PLI and in fact a

stronger decrease is observed in the points of the two

most burdened areas of the coast. More specifically,

two areas are characterized by very high pollution,

despite the very strong drop in PLI values, according

to the scale presented by Zhao et al. [15], with mean

values ranging from 16.8 for the 1986–1990 five-year

period to 7.1 for the 2006–2010 five-year period.

According to the same scale, two more areas in parts

of the coast are characterized as moderately to highly

polluted, with the exception of the five years 1996–

2000, in which they show maximum values of 4.5

and 4.4 respectively and are classified as highly

polluted areas. In one area of the coast, very high

pollution appeared for the period 1986–2000, with

values of 5.5-5.7, while in the period 2001-2010 that

area is characterized by high pollution, since PLI

decreased to the value of 4.4. In another area, there is

an increase in pollution from moderate pollution with

a value of 3.2 in the five-year period 1986–1990 to

very high pollution with a value of 5.2 in the five-

year period 1996–2000. Afterwards, the PLI index

decreases to a value of 4.4 (2005–2010), but this area

is classified among the highly polluted areas. The

central point area with a PLI value of 3.0 in the five

years 1986–1990 has values consistently above 4.0,

with a slight drop for the five years 2005–2010,

therefore it is characterized as a highly polluted area.

Finally, in the other two central areas, the PLI values

are 2.6 and 2.8 respectively (low pollution) in the five

years 1986–1990, while afterwards an increase in PLI

values is observed to 3.2 and 3.7 (moderate to high

pollution).

4.1 Copper (Cu)

According to EF, the most polluted area of the Gulf

in terms of copper is the area where the Elefsina

Shipyards are located (Fig. 2, A11). The values of

this index start from 2.9, i.e., at the upper limit of the

low pollution classification in the five years 1986-

1990, and end at the value of 10.3 at the lower limit

of the high pollution area. For the last period of five

years, the areas where the Skaramangas Shipyards

and the Elefsina Refineries are located are

characterized by low pollution, with index values of

1.9 and 1.4 respectively. The areas in the remaining

sampling points for EF are areas of zero-burden.

Figure 2. EF Index for Cu [17].

According to Igeo, the most polluted area in copper

is Elefsina Shipyards (Fig. 3, A11), with index values

around 5.5, i.e., stable in the area from high to

extremely high pollution in the first twenty years,

while in the last five years period the index value is

6.7, i.e., in the area of extremely high pollution.

Figure 3. Igeo Index for Cu [17].

International Journal of Environmental Engineering and Development

DOI: 10.37394/232033.2023.1.22

Christina Paschaliori, Dimitrios Palmos,

Koralia Papakitsou, Anastasios Mavrakis,

Evangelos Papakitsos, Nikolaos Laskaris

E-ISSN: 2945-1159

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At Skaramangas Shipyards, in the five-year

period 1986-90, the value of the index is 3.9 at the

upper limit of high pollution. Then, while initially

there is a sharp drop to a value of 2.6 (moderate to

high pollution) in the five years 1991–1995, the

values then increase with a final value of 4.5 in the

high to extremely high pollution range. At Elefsina

Refineries, we observe a continuous increase in the

index values for copper, with a final value of 3.1

(high pollution). In the rest of the regions, Igeo’s

values for copper show an increase, with the final

values in the area of moderate pollution.

4.2 Cadmium (Cd)

The values of EF for cadmium do not show large

deviations in the different sampling points, remaining

in the area of low pollution (Fig. 4).

Figure 4. EF Index for Cd [17].

However, comparing the values of the index in the

first five years 1986–1990 and the last five years

2006–2010 for the same point, we notice that there is

an increasing trend in almost all regions. The most

intense increase is observed at the central point of the

Gulf, located at a depth of 33 m, where the EF value

in the five years 1986–1990 was 1.8, while in the five

years 2006–2010 the value of the index reached 3.2.

The only point where a small drop is observed is that

of the coast in the stream of Aghios Georgios, from

3.0 to 2.8.

The values of Igeo for the sediments of the Gulf of

Elefsina show even greater stability than their EF

counterparts (Fig. 5). But almost all Igeo values are in

the high pollution area. The upward trend in values

over time is also observed in Igeo’s values, although it

seems to be less pronounced. The strongest increase

in the values of this index over time is observed at a

central point, from 2.9 to 3.8.

Figure 5. Igeo Index for Cd [17].

4.3 Chromium (Cr)

The EF values for almost all sample points are less

than one (Fig. 6). Only at the point of the Aghios

Georgios stream and for the five-year period 1986-

1990, a value at the upper limit of low pollution (2.8)

is calculated (A5), which, however, decreases rapidly

in the following five years period, to reach a value of

0.5 in the five-year period 2006-2010.

Figure 6. EF Index for Cr [17].

The three sampling points located in the center of

the Gulf of Elefsina are zero-burden points for

chromium, according to Igeo values (Fig. 7).

Figure 7. Igeo Index for Cr [17].

We come to the same conclusion for the locations

of the ship breakers and the Elefsina Refineries. For

International Journal of Environmental Engineering and Development

DOI: 10.37394/232033.2023.1.22

Christina Paschaliori, Dimitrios Palmos,

Koralia Papakitsou, Anastasios Mavrakis,

Evangelos Papakitsos, Nikolaos Laskaris

E-ISSN: 2945-1159

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the rest of the coastal points, a moderate pollution is

initially calculated, which however decreases over

time. The only area in which a moderate burden is

calculated in the five years 2006–2010 is the area of

the Elefsina Shipyards (A11).

4.4 Manganese (Mn)

According to the EF values, the sediments in the Gulf

of Elefsina are characterized as an area of zero-

burden, throughout the time period of the

measurements.

The sediments in the Gulf of Elefsina are also

characterized as a zero-burden area by the values of

Igeo. Only in the areas near the two shipyards (A1,

A11) and for the five years 1986 – 1990, moderate

pollution is calculated which, however, subsequently

decreases to the levels of zero-burden.

4.5 Lead (Pb)

The EF values for lead at the sampling site of the

Skaramangas Shipyards show a decline from a value

of 4.1 (moderate pollution) in the five-year period

1986–1990 to a value of 2.3 (low pollution) in the

five-year period 2006-2010 (Fig. 8). At the

shipbreaking site (A8), the index values are stable

over time near the lower limit of low burden. In the

rest of the points, an increase in values is recorded in

the first three five-year periods, while in the next two

there is a decrease, but remaining in the area of low

pollution. The only point where values of 3.7 and 3.5

(moderate pollution) are calculated in the five years

1991–1995 and 1996–2000 is the point where the

Elefsina Shipyards are located (A11). The worst five-

year period for the Gulf is the five-year period 1996–

2000, since the highest values are recorded in most

sampling points.

Figure 8. EF Index for Pb [17].

The Igeo’s values for lead are decreasing over time

at the sampling points of the Skaramangas Shipyards,

the ship breaking site and the Elefsina Shipyards

(Fig. 9).

Figure 9. Igeo Index for Pb [17].

More specifically, in the first point, in the five-

year period 1986-1990, the value of this index was

calculated at 4.9, very close to the upper limit of the

designation high to extremely high pollution, while

in the five-year period 2006-2010, the value was 3.9,

very close to the limit of the designation high

pollution. For the second point, the values in the

corresponding time periods are 4.1 (near the lower

limit of high to extremely high pollution) and 3.1

(near the lower limit of high pollution). For the third

point, in the time period 1991–1995, the value is 5.4

(extremely high pollution), which is also the

maximum Igeo value for lead over time, while in the

five years 2006–2010 the value is reduced to 3.5

(high pollution). At the point of the Aspropyrgos

Refineries (A2), this index values show an increase

from a value of 2.0 (the limit of moderate pollution)

in the five years 1986-1990 to 2.8 (moderate to high

pollution) in the five years 1996 -2000, and then a

drop to a value of 2.3 (moderate to high pollution).

We have a similar behavior of this index at the point

of the Aghios Georgios stream (A5) and the Elefsina

Refineries (A4). For the areas of the center of the

Gulf, an increase is observed from a value of 2.6

(moderate to high pollution) in the five years 1986–

1990 to a value of 3.1 (high pollution) in the five

years 2006–2010, while in two places, a stability of

values is also observed.

4.6 Zinc (Zn)

The values of the EF index at five points of the coast

correspond to a zero-burden area (Fig. 10). At one

point, the value of the index in the five years 1986–

1990 is 4.2 (moderate pollution). In the five years

1991–1995, the value increases sharply to 8.1

(moderate to high pollution) and then decreases to the

value 2.0 (low pollution) in the five years 2001–2005,

to end up with the value 2.9 (low pollution) in the five

years 2006–2010. At the other points of the coast, the

value of EF increases from 0.8 (zero-burden) in the

five-year period 1986–1990 to 3.0 (the limit of low-

International Journal of Environmental Engineering and Development

DOI: 10.37394/232033.2023.1.22

Christina Paschaliori, Dimitrios Palmos,

Koralia Papakitsou, Anastasios Mavrakis,

Evangelos Papakitsos, Nikolaos Laskaris

E-ISSN: 2945-1159

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Volume 1, 2023

moderate pollution) and then decreases to 0.5 (zero-

burden). We have a similar fluctuation in values

elsewhere.

Figure 10. EF Index for Zn [17].

The Igeo values for a point on the coast are high,

but show a downward trend from 5.6 (extremely high

pollution) in the five-year period 1986–1990 to 4.1

(high to extremely high pollution) in the five-year

period 2006–2010 (Fig. 11). We also observe a

downward trend in Igeo values in other places, with

values of 2.2 (moderate to high pollution) in the five-

year period 1986–1990 to 1.0 (the lower limit of

moderate pollution) for the time period 2006–2010.

For two points we have values from 2.8 (moderate to

high pollution) for the five years 1986-1990 to 1.9

(moderate pollution) for the period 2006–2010, and

from 1.2 (moderate pollution) to 0.8 (zero-burden) in

the corresponding periods. In the rest of the points,

Igeo’s values initially increase and then decrease.

Figure 11. Igeo Index for Zn [17].

4.7 Nickel (Ni)

We observe that the values of the EF index for all

sampling points and in each time period of the study

are less than unity. Based on these values, we

conclude that the area of the Gulf of Elefsina is a

zero-burden area.

We observe that the values of Igeo for all sampling

points, except one (A11), and in every time period of

the study are less than unity. Based on these values,

the areas of the Gulf of Elefsina, except for the area

at the Elefsina Shipyards (A11), are characterized as

of zero to moderate pollution. The area in Elefsina

Shipyards with index values from 1.4 to 1.8 is

characterized by moderate pollution.

4.8 Iron (Fe)

For iron, only Igeo is calculated, since it is considered

a reference metal for the EF index (Fig. 12). The

lowest value of Igeo starts from 3.4 (high pollution) in

the 1986-1990 five-year period, then decreases to 1.7

in the 1991-1995 five-year period, then increases to

2.2 (moderate to high pollution) in the 1996-2000

five-year period, followed by increasing trends until

the 2006-2010 five-year period.

Figure 12. Igeo Index for Fe [17].

5 Summary

The above study was carried out in order to assess the

level of pollution of the sediments of the Gulf of

Elefsina by the heavy metals Cu, Cd, Cr, Pb, Zn, Mn,

Fe and Ni. For this purpose, the values of the PLI

index were initially calculated at nine sampling

points, six on the coasts and three in the center of the

Gulf of Elefsina. PLI estimates pollution as a whole,

taking into account the concentrations for each of the

above metals equally. If its value is greater than unity,

we conclude the existence of pollution and therefore

the necessity of further study.

At all sampling points, PLI values greater than

unity, and in some cases much greater, were

calculated. We are therefore led to the conclusion that

pollution occurs at all sampling points. The highest

values of this index were recorded at the points of the

Elefsina Shipyards and the Skaramangas Shipyards.

However, it should be noted the tendency to decrease

the values of PLI, which concerns all the points, but

is more intense in the points of the most burdened

areas of the coast. In order to specify the PLI results,

the EF and Igeo indices were calculated for each of the

studied metals.

International Journal of Environmental Engineering and Development

DOI: 10.37394/232033.2023.1.22

Christina Paschaliori, Dimitrios Palmos,

Koralia Papakitsou, Anastasios Mavrakis,

Evangelos Papakitsos, Nikolaos Laskaris

E-ISSN: 2945-1159

246

Volume 1, 2023

The Igeo values show more intense pollution than

the EF values in the corresponding areas. This is

probably due to the choice of iron as the reference

metal for calculating EF. Igeo for iron, however,

shows that the sediments contain iron at

concentrations greater than the background

concentration. Therefore, Igeo is judged to be the most

reliable index for the assessment of sediment

pollution for each metal.

For copper, both indicators show pollution in the

area of Elefsina Shipyards. Igeo shows intense

pollution both at Skaramangas Shipyards and at

Elefsina Refineries, which are very close to Elefsina

Shipyards. It is also observed that the values of the

indices for copper are increasing at all points over

time.

For cadmium, the EF values are in the low

pollution area, while for Igeo in the high pollution

area, throughout the Gulf. Both indicators show

increasing trends in most sampling points.

For chromium, the EF index only in the stream of

Aghios Georgios, which is the recipient of

wastewater from many industrial units, and for the

five years 1986–1990, has a value at the upper limit

of low pollution, which, however, decreases rapidly

in the following five years. Igeo shows moderate

pollution in addition to the stream of Aghios

Georgios and at the Aspropyrgos Refineries, which

are located next to the mouth of the stream, but also

at Elefsina Shipyards; but these values are also

decreasing over time.

For lead, the highest index values are calculated at

the two Shipyards. But over time the values decrease.

For the rest of the points, Igeo has high values that

generally show stability.

For zinc, the highest index values are calculated at

the two Shipyards. The very high values of EF in the

five years 1991–1995, both in the areas of the two

Shipyards and in the central area of the Gulf, are

noteworthy. For zinc, as well, the index values

generally decrease over time except for one central

point.

For manganese, the values of both indicators show

no pollution.

For nickel, the EF values show no pollution, while

the Igeo values show moderate pollution only for the

area of Elefsina Shipyards.

For iron, Igeo values are elevated at all sampling

points. The highest values are calculated for the two

Shipyards and for the ship breakers. This is to be

expected due to the activities that take place in the

specific units (construction, maintenance,

dismantling of ships).

If we want to summarize the above conclusions

from the study of the EF and Igeo indices, we can

conclude that the most serious problems of heavy

metal pollution in the sediments of the Gulf of

Elefsina are located in the areas of the two Shipyards,

which are located at its two ends. The sediments in

these areas appear enriched in copper, cadmium, iron,

lead and zinc. Moreover, in Elefsina Shipyards

pollution appears, in addition to the above metals, in

chromium and nickel, as well.

In the areas of the two Refineries, more intense

pollution is recorded for cadmium. Additionally, in

the area of Aspropyrgos Refinery we have higher

values for chromium, while in the area of Elefsina

Refinery we have higher values for lead and copper.

For the area of the mouth of the Aghios Georgios

stream, we notice that we have more pollution in the

sediments for cadmium. At the same time, there is a

strong downward trend in values for chromium and

zinc.

In the area of the ship breakers, there is intense

pollution for cadmium, iron, lead and zinc. For the

first two metals we have approximately the same

pollution over time, while for the next two there is a

strong downward trend.

Finally, for the points in the center of the Gulf, the

most intense pollution is recorded for cadmium.

Milder pollution for all three of these points is

observed for lead and iron. Especially at one central

point, we also have high index values for zinc, which

are likely due to the short distance of this point from

Skaramangas Shipyards.

6 Conclusion

Concluding this study and regarding the heavy metal

pollution indices, and especially for the EF index,

aluminum, which is provided in the literature, or

manganese for which, according to Igeo, the pollution

levels are almost negligible, could be used as a

reference metal in future studies. We could also say

that it is a blow to a region, such as the region of

Elefsina and Western Attica in general, the

degradation of the Office of Pollution Control and

Environmental Quality, which led to the interruption

of measurements in the Gulf of Elefsina in 2010.

In general, all the necessary actions must be taken

in order to carry out measurements for the pollution

of the marine environment, in every area of high

industrial activity. Practical applications of this

direction are the mapping of high industrial activity

areas, the installation of pollution measurement

devices at crucial points there and the setting of

monitoring agencies for processing the data collected

by these devices. In this respect and to facilitate the

collection of environmental data, a robotic system is

being developed at the Department of Industrial

Design and Production Engineering of the University

International Journal of Environmental Engineering and Development

DOI: 10.37394/232033.2023.1.22

Christina Paschaliori, Dimitrios Palmos,

Koralia Papakitsou, Anastasios Mavrakis,

Evangelos Papakitsos, Nikolaos Laskaris

E-ISSN: 2945-1159

247

Volume 1, 2023

of West Attica, in the form of an Unmanned Sea

Vessel (USV). This robotic USV is being designed to

take measurements with results in situ, following

instructions given in natural language that are

processed by semantic modelling software [18] [19].

In conclusion, the present work shows that

significant heavy metal pollution is observed in the

sediments of the Gulf of Elefsina, at least for the time

period of the study. It is therefore necessary to carry

out measurements over time and to take the necessary

measures in order to improve the quality of the area’s

environment.

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International Journal of Environmental Engineering and Development

DOI: 10.37394/232033.2023.1.22

Christina Paschaliori, Dimitrios Palmos,

Koralia Papakitsou, Anastasios Mavrakis,

Evangelos Papakitsos, Nikolaos Laskaris

E-ISSN: 2945-1159

248

Volume 1, 2023

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Contribution of Individual Authors to the

Creation of a Scientific Article (Ghostwriting

Policy)

The authors equally contributed in the present

research, at all stages from the formulation of the

problem to the final findings and solution.

Sources of Funding for Research Presented in a

Scientific Article or Scientific Article Itself

No funding was received for conducting this study.

Conflict of Interest

The authors have no conflicts of interest to declare

that are relevant to the content of this article.

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(Attribution 4.0 International, CC BY 4.0)

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International Journal of Environmental Engineering and Development

DOI: 10.37394/232033.2023.1.22

Christina Paschaliori, Dimitrios Palmos,

Koralia Papakitsou, Anastasios Mavrakis,

Evangelos Papakitsos, Nikolaos Laskaris

E-ISSN: 2945-1159

249

Volume 1, 2023