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Environmental Geochemistry andHealthOfficial Journal of the Society forEnvironmental Geochemistry andHealth ISSN 0269-4042 Environ Geochem HealthDOI 10.1007/s10653-013-9558-3

Metal contamination recorded in thesediment of the semi-closed Bakar Bay(Croatia)

N. Cukrov, S. Frančišković-Bilinski &D. Bogner

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ORIGINAL PAPER

Metal contamination recorded in the sedimentof the semi-closed Bakar Bay (Croatia)

N. Cukrov • S. Franciskovic-Bilinski •

D. Bogner

Received: 30 August 2012 / Accepted: 17 July 2013

� Springer Science+Business Media Dordrecht 2013

Abstract This study presents metal levels in the

sediments of the Bakar Bay, with its main goal to

evaluate recent anthropogenic influence, as well as

over previous decades. Sediment profiles at 7 sam-

pling points were taken. Chemical contents in bulk

sediment were obtained using ICP, ICP-MS, and AAS

methodologies, and 20 most significant elements were

presented. Concentrations of selected elements were

evaluated by factor statistical analyses to identify their

source. Also, metal enrichment factor and geoaccu-

mulation index were calculated, and spatial distribu-

tion maps for three sediment layers were constructed.

Measured metal concentrations in sediment were

compared with concentrations in other sediments

from the Adriatic Sea. In addition, a set of sediment

quality guidelines were also applied in order to predict

the probability of adverse biological effects on the

benthic community: This was found not to be very

serious. Factor analysis clearly demonstrates the

segregation between metals of natural origin resulted

from soil and bedrock weathering (Li, Al, Cr, Sc), and

with two anthropogenic sources originating from the

city of Bakar and bulk cargo terminal (Hg, Pb, Zn, Ag,

Sn, and Fe). Mercury (max 0.65 lg g-1) is found to be

the heaviest contaminant, followed by lead (max

71.5 lg g-1), copper (89.3 lg g-1), and zinc

(156 lg g-1). However, this study shows that Bakar

Bay is considerably less polluted with toxic metals

than it was believed.

Keywords Adriatic Sea � Bakar Bay � Croatia �Geochemistry � Metals � Sediments � Statistical

analysis

Introduction

The rapid urban and industrial development in coastal

areas during the last century has had a negative impact

on the quality of marine environments in close

proximity. Among many pollutants introduced into

the marine environment, heavy metals are of particular

concern globally due to their environmental persis-

tence and their poor biodegradability (Burton 2002).

Once introduced into the aquatic environment, metals

are redistributed throughout the water column, depos-

ited or accumulated in sediments, and consumed by

biota. However, sediments are not only a sink, but they

can be a delayed source of these contaminants into the

aquatic phase, due to desorption and remobilization

processes (Fichet et al. 1998; Monterroso et al. 2007;

N. Cukrov (&) � S. Franciskovic-Bilinski

Division for Marine and Environmental Research, Ruder

Boskovic Institute, Bijenicka c. 54, POB 180, 10000

Zagreb, Croatia

e-mail: Neven.Cukrov@irb.hr

D. Bogner

Institute of Oceanography and Fisheries, Setaliste I.

Mestrovica 63, 21000 Split, Croatia

123

Environ Geochem Health

DOI 10.1007/s10653-013-9558-3

Author's personal copy

Sakellari et al. 2011; Saulnier and Mucci 2000;

Tankere-Muller et al. 2007). Sediments constitute a

long-term source of contamination to the food web

(Burton 2002). Therefore, the evaluation of metal

distribution in recent sediments is the first step in order

to assess the degree of pollution of the marine

environment (Acquavita et al. 2010; Covelli et al.

2006; Cukrov et al. 2008, 2011; Franciskovic-Bilinski

et al. 2011; Lourino-Cabana et al. 2011; Monterroso

et al. 2007; Sakellari et al. 2011; Tessier et al. 2011). In

order to evaluate the trace metal pollution in sedi-

ments, it is very important to be able to distinguish a

difference between the natural trace element record

derived from sedimentation and records that may

reflect the anthropogenic impact.

In this work, we examined depth profiles of metals

in core sediments collected in the area of the Bakar

Bay, with the intention of evaluation of the anthropo-

genic inputs. Moreover, we compared data from the

Bakar Bay with the nearby Rijeka harbor (Cukrov

et al. 2011) and with other Adriatic sediments

(Acquavita et al. 2010; Bogner et al. 2005; Cuculic

et al. 2009; Cukrov et al. 2008; Dolenec et al. 1998;

Martincic et al. 1989; Obhodas and Valkovic 2010;

Pikelj et al. 2009; Prohic and Juracic 1989; Spagnoli

et al. 2010).

To assess the potential sediment toxicity derived

from metal concentrations in the studied area, bulk

sediment values were compared with the published

sediment criteria and standards (Burton 2002). Also,

metal enrichment factors (EF) were calculated.

The goal was to investigate a possible correlation

between the industrial activities in the past and

environmental quality of the Bakar Bay area, as well

as the asset level and type of contamination in relation

to the geographical distribution and the main source of

pollution.

Moreover, this study will serve to inform decision-

makers of the sources and distribution of sediment-

associated contaminants and their potential environ-

mental impacts in the region and to assess the

potential sediment toxicity deriving from metal

concentrations. The results will also be applicable

to science-based policy in an integrated coastal

management (ICM) and development of Croatian

sediments quality guidelines, because contaminated

sediment management is complex and multivariate,

involving a need for careful balance of science,

politics, and economics.

The studied region of the Bakar Bay is located in

the northern part of the eastern Adriatic coast (Fig. 1),

in the Kvarner area, which is itself a semi-closed part

of the Adriatic Sea located between the Istrian

peninsula and the Vinodol–Velebit coast. The esti-

mated annual load of industrial wastewater to this

relatively closed area is approximately 560 million m3,

whereas the load of urban wastewater is approxi-

mately 23 million m3 (Srut et al. 2011).

In the terrestrial part of Kvarner, Cretaceous

carbonate sedimentary rocks (limestone, dolomites,

and carbonate breccias) are present and Paleogene

limestone prevail, while Paleogene flysch is restricted

Fig. 1 Map of the sampling area

Environ Geochem Health

123

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(Juracic et al. 2009). The Bakar Bay area has

‘‘Dinaric’’ direction of elongation NW–SE with flysch

in central part (Juracic et al. 2009; Susnjar et al. 1970);

the bottom of this sheltered bay is covered with fine

sediments from direct coastal weathering, and under-

water springs ‘‘vrulje’’ are present (Juracic et al.

1999).

Regarding its natural properties, the Bakar Bay is

one of the most picturesque bays of the Adriatic Sea

with cultural and historical heritage. This sheltered

bay is used as a port from Roman times and heavy

anthropogenic pressure started at the middle 1970’s. In

that time, at northern coast of bay, bulk cargo facilities

were built, and at opposite coast, the coke plant was

built. Today, the Bakar Bay is a typical industrial area

with petroleum industry, coke industry, thermo-elec-

tric power plant, transshipment service (harbor), and

production of chemicals (Pravdic 1995). This bay is

known as a high-polluted area, but little research was

actually really done (Obhodas and Valkovic 2010;

Srut et al. 2011).

Materials and methods

Sampling

Sediment samples were collected at 7 sampling points

in October 2010, using Uwitec gravitational corers (u9 cm) with PVC tube (60 cm). Their accurate posi-

tions were determined by GPS instrument Garmin

GPSMap 76 CSx (Kansas City, MO, USA) with the

accuracy of ±5 m and are shown in Fig. 1.

The uppermost 15 cm of sediment was sampled.

Sampling density was adapted to assumed points of

anthropogenic inputs and characteristic of the Bakar

Bay (Fig. 1). Sediment cores were cut in 5-cm slices

and were kept in plastic bags at 3 �C until analysis.

The sediment slice thickness was found to be optimal

to determine relevant sediment dating related to

particular sedimentation conditions.

Sediment analysis

The grain size of the sediment samples was deter-

mined by sieving ([63 lm) and hydrometric accord-

ing to Casagrande method (\63 lm) (Strmac 1952). A

sediment type was determined according to the

Shepard classification (Shepard 1954). Granulometric

parameters were calculated according to Folk and

Ward (Folk and Ward 1957).

The organic matter content, in the same sediment

sections as cadmium and lead, was determined by H2O2

treatment of the samples at 450 �C for 6 h. The loss of

weight after treatment was assumed to be due to the

organic matter content (Bogner et al. 2005). The

carbonate content was determined as weight loss after

the treatment with 4 M HCl (Loring and Rantala 1992).

Chemical analyses were performed in the ACTL-

ABS laboratories (http://www.actlabs.com), Ontario,

Canada, by ICP/OES, ICP-MS, and cold vapor AAS for

Hg determination in a process called Ultratrace

2—Aqua Regia. A 0.5 g sample was digested in aqua

regia at 90 �C in a microprocessor-controlled digestion

block for 2 h. Generally, this digestion is not total

because silicates, some oxides, and resistant minerals

(e.g., zircon, monazite, sphene, etc.) are not dissolved,

but in our case of predominantly carbonate samples, the

technique approximates total digestion. The solution

was diluted and analyzed by ICP/MS using a Perkin

Elmer SCIEX ELAN 6000, 6100, or 9000. After 15

samples, a digestion duplicate was analyzed. One

control sample was run following every 33 samples,

and after 68 samples, a new blank sample was run. After

each blank sample, digested standards were determined

and the instrument was recalibrated. Internationally

certified reference materials USGS GXR-1, GXR-2,

GXR-4, and GXR-6 were analyzed at the beginning and

end of each batch of samples. Internal control standards

and duplicates were analyzed every 10 samples.

Additional elements (Ti, P, and S) were analyzed by

ICP/OES using a Varian 735 ES.

From obtained elements, 20 most significant ele-

ments were chosen for presentation within the current

paper: Ag, Al, As, Ba, Be, Cd, Ce, Cr, Cu, Eu, Hg, La,

Li, Ni, P, Pb, Sb, Sc, Sn, and Zn.

To identify origin(s) of the elements more pre-

cisely, enrichment factor (EF) were used (Cukrov et al.

2011; Franciskovic-Bilinski 2008).

Results and discussion

Grain size and percentage of carbonates

and organic matter

Grain size, sediment type, and percentage of carbon-

ates and organic matter are presented in Table 1. At all

Environ Geochem Health

123

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Ta

ble

1G

rain

size

and

gra

nu

lom

etri

cp

aram

eter

s(S

o—

sort

ing

;S

k—

skew

nes

s;K

g—

ku

rto

sis;

Mz—

mea

nsi

ze;

Md

—m

edia

n;

U=

-lo

g2

‘‘d

,’’‘‘

d’’

—g

rain

ssi

zein

mm

),

sed

imen

tty

pe

acco

rdin

gto

Sh

epar

d(1

95

4)

clas

sifi

cati

on

,p

erce

nta

ge

of

org

anic

mat

ter,

and

carb

on

ates

inse

dim

ents

of

Bak

arB

ay

Sta

tio

nS

oS

kK

gM

z

(lm

)

Mz

(U)

Md

(lm

)

Md

(U)

Gra

vel

(%)

San

d

(%)

Sil

t

(%)

Cla

y

(%)

Sh

epar

dO

rg.

mat

ter

(%)

Car

b

(%)

B1

/13

.10

.21

.03

.88

.15

.97

.40

.87

.65

3.1

38

.5C

lay

ely

silt

9.7

23

.9

B1

/23

.20

.21

.62

.08

.94

.57

.81

.37

.94

4.5

46

.3S

ilty

clay

9.2

25

.3

B1

/33

.90

.01

.76

.77

.27

.87

.07

.19

.23

9.7

44

.0S

ilty

clay

10

.23

0.3

B2

/13

.10

.31

.24

.77

.78

.36

.90

.11

0.3

54

.93

4.7

Cla

yel

ysi

lt1

2.2

31

.1

B2

/23

.00

.21

.23

.88

.05

.67

.50

.29

.64

9.4

40

.8C

lay

ely

silt

9.3

33

.5

B2

/33

.10

.21

.22

.98

.44

.27

.90

.21

1.0

40

.84

8.0

Sil

tycl

ay7

.43

4.9

B3

/14

.5-0

.11

.97

.37

.17

.87

.01

2.2

6.0

47

.03

4.8

Cla

yel

ysi

lt1

3.0

23

.7

B3

/22

.80

.31

.03

.58

.25

.47

.50

.35

.55

1.5

42

.7C

lay

ely

silt

11

.62

1.2

B3

/32

.70

.41

.15

.07

.77

.87

.00

.34

.06

1.5

34

.2C

lay

ely

silt

9.2

20

.6

B4

/12

.90

.31

.25

.17

.68

.66

.90

.46

.86

1.6

31

.2C

lay

ely

silt

8.4

21

.2

B4

/22

.60

.41

.36

.37

.39

.56

.70

.06

.06

5.2

28

.8C

lay

ely

silt

10

.52

0.5

B4

/32

.70

.31

.14

.87

.77

.07

.20

.84

.65

8.2

36

.5C

lay

ely

silt

9.5

19

.6

B5

/13

.50

.21

.17

.07

.29

.66

.70

.71

6.8

47

.93

4.6

Cla

yel

ysi

lt1

8.3

17

.8

B5

/23

.30

.21

.15

.57

.57

.67

.00

.21

4.0

49

.53

6.3

Cla

yel

ysi

lt1

6.2

15

.5

B5

/33

.00

.31

.14

.97

.77

.77

.00

.21

0.6

52

.63

6.7

Cla

yel

ysi

lt1

5.2

20

.4

B6

/13

.10

.20

.95

.37

.67

.67

.10

.01

0.3

51

.43

8.3

Cla

yel

ysi

lt1

4.0

20

.1

B6

/23

.10

.21

.05

.57

.57

.97

.00

.11

0.1

51

.23

8.7

Cla

yel

ysi

lt1

4.5

19

.0

B6

/33

.00

.31

.14

.47

.87

.37

.10

.29

.65

1.7

38

.5C

lay

ely

silt

14

.12

0.2

B7

/13

.20

.40

.76

.17

.49

.86

.70

.33

.16

1.9

34

.6C

lay

ely

silt

10

.82

1.6

B7

/23

.00

.31

.03

.28

.35

.37

.61

.74

.84

9.5

44

.0C

lay

ely

silt

10

.92

1.4

B7

/32

.90

.31

.13

.68

.15

.57

.50

.46

.47

0.8

22

.4C

lay

ely

silt

9.8

20

.1

Beh

ind

the

stat

ion

cod

e,se

par

ated

by

asl

ash

,n

um

ber

sin

dic

atin

gth

e5

cmlo

ng

sub

-sam

ple

so

fse

dim

ent

(1—

fro

msu

rfac

eto

5cm

dee

p;

2—

fro

m5

to1

0cm

;3

—fr

om

10

to

15

cm)

Environ Geochem Health

123

Author's personal copy

stations, sediments were found to be poorly sorted

(So [ 2), indicating, therefore, a different origin of

settled particles (terrigenous, anthropogenus, and

biogenous). Prevailing of positive skewed (Sk [ 0.1)

and leptokurtic (1.11 \ Kg \ 1.5) curves indicated

that coarser particles prevail in sediment which is

distributed along one particles size. Mean size of

particles is in the range from coarse clay to fine silt,

while median of particles is in narrow range from very

fine silt to fine silt.

Sediment type is determined according to Shepard

(1954) and at almost all locations is classified as

clayey silt. Only three samples (middle and deeper

layer of location B1 and deepest layer of location B2)

are classified as silty clay, due to somehow increased

percentage of clay. At all locations, percentage of

gravel is very low, and only in the shallowest layer of

B3 location, it is 12.2 %, what could be due to past

bulk cargo port activities. Percentage of sand is rather

low on all locations. Only on locations B2, B5, and

B6, percentage of sand is somehow increased, which

could be also due to anthropogenic influence. Silt

fraction prevails in most of samples, after what

follows clay, which is also obvious from Shepard’s

classification of material (Shepard 1954). The per-

centage of carbonates varies from about 15 to 35 %

and is in all samples higher than percentage of

organic matter.

Sedimentation rate

Sedimentation rates in the Bakar Bay could be

assumed from the literature (Cukrov et al. 2011).

They determined sedimentation rates in the nearby

area of Rijeka port using vertical distribution of 137Cs

activities in sediment columns (Cukrov et al. 2011).

For the principal harbor area of the Rijeka port,

estimated sediment rates are 5–6 and 6–7-mm annual

in second part, while at referent point, 2 km from

harbor, sedimentation rate was 3–4-mm annual. From

that, it would be possible to assume that the average

sedimentation rate in the sheltered Bakar Bay, without

river input, could be about 5 mm annually. As our

investigated sediment layers are of 5 cm depth, it

could be estimated that each layer represents about one

decade. So deepest layers of our samples are about

30-year old, which reflects the time of maximum

industrial activity and less attention for environmental

protection.

Spatial distribution of metals

Fourteen of the environmentally most significant toxic

metals were selected for detailed interpretation: Hg,

Cd, Pb, Cu, Zn, Ni, Cr, As,Ag, Co, Mo, Sn, Ba, and Fe.

Spatial distributions of the total metal content in the

Bakar Bay sediments are presented as contour maps in

Fig. 2a–j for all three analyzed sediment layers (0–5,

5–10, and 10–15 cm). Each element will be discussed

separately.

Mercury (Hg)

Measured concentrations of Hg in bulk sediments of

the Bakar Bay varied between 0.33 and 0.65 lg g-1

(mean value of 0.45 lg g-1). From the distribution

maps (Fig. 2a), it is clear that the source of mercury

did not change during the sedimentation of the

observed three layers. Moreover, intensity of mercury

input into the aquatic environment and finally to

sediments did not change significantly during this

period, as all three layers show similar concentrations.

The highest Hg concentrations are determined in the

B4 sediment column sampled in front of the Bakar

town, what could be due to municipal sewage waters

and runoff water. The lowest Hg concentrations are

determined in sediments at locations B2 and B7 near

the exit of the Bakar Bay. It is interesting to note that

sediment at location B1, located at the exit from the

bay, has a bit higher concentrations than sediments at

B2 and B7 locations, what could be due to influence of

the nearby oil refinery in Urinj (Fig. 1).

Cadmium (Cd)

In sediments of the Bakar Bay, measured concentra-

tions of Cd varied from 0.17 to 0.40 lg g-1 (mean

0.24 lg g-1). The distribution map (Fig. 2b) indicates

that the source of Cd to the Bakar Bay remained the

same during sedimentation of all three layers, but its

intensity decreased significantly. The highest concen-

trations were measured in deeper layers of station B7.

Lead (Pb)

Pb concentrations were in the range of 41.2–71.5 lg g-1

(mean 53.3 lg g-1). The source of Pb to the Bakar Bay

did not change in time of sedimentation of three

investigated layers, but concentrations significantly

Environ Geochem Health

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decreased in time (Fig. 2c). The highest concentrations

are measured in the deepest layers of locations B4 and

B5, indicating that Pb has its source at NW side of the

Bakar Bay. The lowest concentration measured in the

deepest layer of all sediments is determined at the B7

station, at the exit from the bay, while in two upper

layers, the lowest concentrations were at the B2 station.

Copper (Cu)

Measured concentrations of Cu in bulk sediments of

the Bakar Bay varied from 30.7 to 89.3 lg g-1 (mean

42.9 lg g-1). From the distribution map (Fig. 2d), it is

obvious that the source of Cu as for Pb to the Bakar

Bay did not change in time of sedimentation of three

investigated layers, but intensity of Cu input gradually

decreased in time. The highest Cu concentrations are

measured in the deepest layers of sediments from

stations B4 and B5, which indicated that the position

of the Cu source in the northern part of the Bakar Bay

during the sedimentation of 10–15 cm layer. The

lowest Cu concentrations are measured at the southern

shore near the exit from the bay at locations B1 and

B2.

Zinc (Zn)

In the bulk sediments of Bakar Bay, measured

concentrations of Zn were in the range of

85.5–156 lg g-1 (mean 109 lg g-1). The source of

Zn in the Bakar Bay remained the same during time,

but its intensity significantly decreased in time

(Fig. 2e). The highest Zn concentrations are measured

in deepest layer at B4 station in front of the Bakar

town, what indicates its origin from Bakar municipal

sewage waters. A positive is that Zn input drastically

decreased in time with better treatment of sewage

waters, and in the recent (uppermost) layer, concen-

trations are much lower than in deeper layers which

originate from the past decades. The lowest Zn

concentrations are measured at the B7 station near

the exit from the Bakar Bay.

Fig. 2 Spatial distributions of metals concentrations in the first 3 layers: 0–5 cm (2010–2000); 5–10 cm (2000–1990); 10–15 cm

(1990–1980) of the Bakar Bay sediments

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Nickel (Ni)

Ni concentrations were in the range of 56.3–80.7 lg g-1

(mean 66.2 lg g-1). The spatial distribution maps

(Fig. 2f) indicate that the source of Ni remained the

same during sedimentation of the analyzed layers, but its

intensity was decreasing in time. The distribution of

nickel is very similar to the distribution of zinc. The

highest Ni concentrations are measured in the deepest

layer of B4 station, in front of the Bakar town. Thus, it

could be concluded that it originates from Bakar

municipal sewage water. The situation with Ni contam-

ination drastically improved, as in the uppermost layer, it

is almost not detectable. The lowest Ni concentrations

are measured at B6 location, which indicate that

distribution of nickel concentrations was not influenced

by transshipment at the bulk cargo terminal.

Chromium (Cr)

Measured concentrations of chromium in bulk sedi-

ments of the Bakar Bay varied from 52.8 to 69.8 lg g-1

(mean 60.2 lg g-1). From the spatial distribution map

(Fig. 2g), it is obvious that the source of chromium

changed its location and intensity during time. From the

oldest (the deepest) layers of the investigated sediments,

it is obvious that during time of their sedimentation, Cr

source was at the NW side of the bay. Later Cr input to

the bay had decreased, but also changed its sink

location. In two upper sediment layers, the highest

chromium concentrations are found at the station B7,

where concentrations are higher in the uppermost than

in the middle layer. It is interesting that at B7, the oldest

layer has the lowest concentrations, which indicates an

increase in Cr pollution at this location.

Arsenic (As)

Arsenic concentrations in bulk sediments of the Bakar

Bay varied from 10.3 to 19.0 lg g-1 (mean

14.5 lg g-1). The spatial distribution map (Fig. 2h)

indicates that the arsenic source was in the north part

of the bay, with increasing intensity over the recent

sedimentation period. The lowest concentrations of As

are measured in sediments from stations located in the

base of the Bakar Bay (B4) or near its entrance (B1 and

B7), what also indicates the location of the arsenic

source somewhere at the middle of NE shore of the

bay.

Silver (Ag)

Silver concentrations in bulk sediments of the Bakar

Bay varied from 0.09 to 0.23 lg g-1 (mean

0.13 lg g-1). The Ag source remained the same

during time, but its intensity decreased in time

(Fig. 2i). The highest Ag concentrations were mea-

sured in the deepest layer of sampling station B4 in

front of the Bakar town. It could be assumed that Ag in

the Bakar Bay originates from municipal sewage

waters of the Bakar town, similar to Hg, Cr, and Zn.

The lowest Ag concentrations are found in sediments

at stations B1, B2, B6, and B7 close to the exit form the

bay.

Iron (Fe)

Iron concentrations were in the range of 3.61–8.31 %

(mean 4.85 %). The source of Fe remained the same

during time, but its intensity decreased in time

(Fig. 2n). The highest Fe concentrations are measured

in the deepest and middle layers of B5 station in front

of bulk cargo terminal. From that, it could be assumed

that Fe in the Bakar Bay is partly of anthropogenic

origin due to transport of iron ores at bulk cargo

terminal, intensity of which decreased in time corre-

sponding more with less transshipment in iron ore.

Molybdenum (Mo)

Molybdenum concentrations in bulk sediments of the

Bakar Bay varied from 1.06 to 2.03 lg g-1 (mean

1.35 lg g-1). In the recent sediment layer, its con-

centrations are almost equally distributed throughout

the bay (Fig. 2k). During the past, there was a source

of Mo around the station B7, close to the exit from the

bay, what is obvious from distribution map for the

deepest sediment layer. In the middle layer, this

contamination source lost its intensity, but still around

B7 are visible somehow increased Mo concentrations.

In the recent sediments, this Mo source completely

disappeared.

Tin (Sn)

Tin concentrations in bulk sediments of the Bakar Bay

varied from 2.36 to 5.58 lg g-1 (mean 3.57 lg g-1).

Contrary to most other toxic metals, Sn concentrations

did not change significantly during the past. In all three

Environ Geochem Health

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studied layers, situation is almost identical—there is

obvious a rather strong source of Sn contamination

around the B4 station in front of Bakar town (Fig. 2l).

Barium (Ba)

Barium concentrations in bulk sediments of the Bakar

Bay vary from 40 to 121 lg g-1 (mean 65.4 lg g-1).

In the recent and middle sediment layer, its concen-

trations are rather equally distributed throughout the

bay, with slightly higher concentrations in front of

Bakar town (Fig. 2m). But, in the deepest sediment

layer, there was an obvious source of Ba contamina-

tion, located around the B5 station in front of bulk

cargo terminal.

Cobalt (Co)

Cobalt concentrations in bulk sediments of the Bakar

Bay varied from 11.5 to 14.3 lg g-1 (mean

12.6 lg g-1). In the recent and middle sediment layer,

its concentrations are almost equally distributed

throughout the bay (Fig. 2n). In the deepest sediment

layer, there was a Co contamination source around B4

sampling station in front of Bakar town. It could be

assumed that it originated from municipal sewage, but

this contamination was not intensive, and concentra-

tions were only a bit increased.

Enrichment factor (EF)

Geochemical normalization of metal concentrations

data to a conservative element such as Fe is commonly

used to identify anomalous metal concentrations. The

enrichment factor (EF) is defined as the ratio between

the observed metal and some conservative element

ratio in the sample of interest, divided by the

background metal/used conservative element ratio

(Cukrov et al. 2011; Guerra-Garcia and Garcia-Gomez

2005; Hilton et al. 1985; Lourino-Cabana et al. 2011;

Tessier et al. 2011). Because Fe is one of the most

abundant elements on Earth and usually poses no

contamination concern, it is the frequent choice for

normalization purposes. But, in the case of its

anthropogenic enrichment in some region, as we have

in the Bakar Bay due to iron ore transport in bulk cargo

terminal, another element could be selected for

normalization, usually Al or Li. In our case, Al was

used, and as the background sample to which the

Bakar Bay values were normalized, we used referent

sample LR7-6 from Cukrov et al. (2011). This referent

sample is an example of unpolluted marine sediment

from the nearby area, taken from the sediment depth of

25–30 cm. EF was calculated for 14 selected ele-

ments: Hg, Cd, Pb, Cu, Zn, Cr, Ni, Co, As, Ag, Mo, Sn,

Ba, and Fe, because those elements are of highest

environmental importance.

Five degrees of contamination are commonly

defined (Sutherland 2000):

EF\2 deficiency to low enrichment

EF 2–5 moderate enrichment

EF 5–20 significant enrichment

EF 20–40 very high enrichment

EF[40 extremely high enrichment

Majority of the Bakar Bay sediment samples show

very low degree of enrichment, with exemption of Hg.

Each element will be discussed separately:

Hg is the only element which shows higher values

of EF. Majority of studied samples are within the

category of moderate enrichment, while all layers of

B4 station belong to a category of significant enrich-

ment. The highest value (6.49) is present in the middle

layer of B4 station in front of the Bakar town.

Cd shows moderate enrichment values on locations

B2 (all layers), B4 (middle layer), B5 (all layers), B6

(deepest layer), and B7 (middle and deepest layer).

Those locations are spread in almost all parts of the

bay. On all other stations, values are \2, indicating

deficiency to low enrichment.

Pb shows moderate enrichment values on loca-

tions B3 (middle and deepest layer), B4 (all layers),

B5 (all layers), and B6 (upper and middle layer). All

those locations are in the part of the bay furthest from

the exit to the open sea. It is assumed to originate

from fuel. On all other locations, Pb EF shows low

values, belonging to deficiency to low enrichment

category.

Cu shows moderate enrichment value only in the

deepest layer of B5 location, located in front of the

bulk cargo terminal, reflecting losses in ores transport

during past decades. On all other locations, Cu EF

shows low values, belonging to deficiency to low

enrichment category.

Zn shows moderate enrichment value only in the

middle layer of B4 location, in front of the Bakar town.

At all other locations, Zn EF shows low values,

belonging to deficiency to low enrichment category.

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As shows moderate enrichment values at two

locations: B5 (in the upper layer) and B6 (upper and

middle layer). At all other locations, As EF shows low

values, belonging to deficiency to low enrichment

category.

Ag shows moderate enrichment values in majority

of locations and sediment layers. Ag shows low EF

values, belonging to deficiency to low enrichment

category in all layers of B1 and B7 locations, the

closest stations to the exit from the bay.

Mo shows moderate enrichment values only in the

deepest layer of station B7, while at all other locations,

Mo EF values are belonging to deficiency to low

enrichment category.

Sn shows similar behavior as Ag: Moderate

enrichment values are present at almost all locations

except those closer to exit from the bay, where Sn

shows low EF values, belonging to deficiency to low

enrichment category.

Ba shows moderate enrichment values at only one

location, B4, where it is present in the upper and

middle layer. At all other locations, Ba EF values are

belonging to deficiency to low enrichment category.

Cr, Ni, Co, and Fe show very low EF values on all

locations and all sediment layers indicating their

natural origin.

Statistical interpretation of results

Basic statistical parameters

Basic statistical parameters for all analyzed elements

were determined, and the results are presented in

Table 2 for bulk sediments of the Bakar Bay. Param-

eters are obtained for 20 analyzed elements from the

whole dataset: Ag, Al, As, Ba, Ce, Fe, Cd, Cu, Cr, Hg,

Mo, La, Li, Ni, P, Pb, Co, Sc, Sn, and Zn, including all

samples from all sediments layers and localities. In the

table are presented data for mean, median, minimum,

maximum, and standard deviation, to get a brief

insight into the concentration ranges of studied

elements in the Bakar Bay.

Factor analysis

Factor analysis (Davis 2002) was performed on bulk

sediment, using data for 20 analyzed elements (Ag, Al,

As, Ba, Ce, Fe, Cd, Cu, Cr, Hg, Mo, La, Li, Ni, P, Pb,

Co, Sc, Sn, and Zn). The most important elements

were selected as representatives for both natural and

anthropogenic sources, as the idea of factor analysis is

to reduce the total amount of data and to present the

data in a simplest way. Totally, 3 factors were

extracted and data were varimax normalized. About

81.49 % of total data were explained with the used

model. In Table 3a are presented factor loadings data

and in Table 3b are presented factor scores.

Factor 1 has excellent correlations with Hg, and Sn

and very good correlations with P, Zn, Ag, Ba, and Pb

(Table 3a). It is an anthropogenic factor, strongly

related to a municipal sewage water output from the

Bakar town and some urban runoff waters. This is

supported by the fact that the highest factor scores of

Factor 2 are observed in all layers of B4 station, in

front of the Bakar town (Table 3b).

Factor 2 has excellent correlations with Al, Cr, Sc,

and Ce and very good correlations with Li and La

(Table 3a). It is a lithogene factor, indicating terrigene

influence introduced into aquatic environment by

runoff water mostly from flysh. Chromium within this

factor is assumed to be of natural source, originating

Table 2 Basic statistical parameters for 20 elements analyzed

in sediments of the Bakar Bay

Mean Median MIN MAX SD

Ag 0.13 0.117 0.088 0.225 0.037

Al % 2.11 2.02 1.81 2.67 0.25

As 14.5 13.9 10.3 19 2.6

Ba 65.4 60.9 40 121 19.4

Cd 0.241 0.22 0.17 0.4 0.057

Ce 27.3 27.1 24.1 31.8 2.4

Co 12.6 12.4 11.5 14.3 0.7

Cr 60.2 59.3 52.8 69.8 5

Cu 42.9 38.9 30.7 89.3 14.1

Fe % 4.85 4.41 3.61 8.31 1.42

Hg 0.45 0.443 0.332 0.65 0.09

La 12.5 12.4 10.8 14.3 1.1

Li 40.1 40.2 34.1 46.9 4

Mo 1.35 1.27 1.06 2.03 0.23

Ni 66.2 66.8 56.3 80.7 5.2

P % 0.058 0.059 0.043 0.076 0.01

Pb 53.3 53.4 41.2 71.5 8.1

Sc 5.53 5.4 4.8 6.4 0.48

Sn 3.57 3.41 2.36 5.58 0.93

Zn 109 104 85.5 156 18.5

Concentrations are in lg g-1 if not indicated differently

Environ Geochem Health

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from flysch underlying the Bakar Bay and terra rossa

(Miko et al. 1999; Prohic et al. 1997). This is also

supported by the fact that Cr neither shows the

increased values of EF, suggesting its natural origin.

Higher values of this terrigene factor are present in

some layers of several profiles (Table 3b), which

could indicate periodic influence of terrigene material

to the Bakar Bay.

Factor 3 has excellent correlation with Fe and very

good with As, while somewhat feeble correlation with

Cu (Table 3a). It is also an anthropogenic factor,

related to transshipment at the bulk cargo port, located

at the northern coast of the Bakar Bay. As support to

that, the highest factor scores of Factor 3 are present in

all layers of B5 station, middle layer of B7 station, and

somehow less intensive in layers of location B6

(Table 3b). All those locations are located along the

northern shore of the Bakar Bay, in front of the bulk

cargo facilities. There is a notable trend of improve-

ment with respect to pollution with elements corre-

lated with Factor 3, as generally in older (deeper)

layers, factor scores are higher than in more recent

(shallower) layers of sediment columns.

Ecotoxicological assessment of metals

in the sediments of the Bakar Bay

The determination of total metal concentrations in the

sediment is the first step in contamination evaluation

of some water ecosystem. However, it does not

provide information on the potential toxicity for

organisms living in this ecosystem, especially for

those which live near or in the sediments. For this

purpose, several sediment quality guidelines (SQGs)

have been developed (Burton 2002) to predict biolog-

ical effect of present metals on benthic organisms. A

concern with SQGs is that they are not predictive of

bioaccumulative effects that may have higher trophic

levels (Burton 2002). The most commonly used SQGs

are with two defined thresholds: the effects-range-low

(ERL) and the effect-range-median (ERM). ERL

corresponds to the concentrations limit for each

Table 3 Factor loadings

(a) and factor scores for

sampling locations (b)

Bold numbers symbolize

significant correlations

Factor 1 Factor 2 Factor 3 Factor 1 Factor 2 Factor 3

(a) (b)

Ag 0.89 0.27 -0.09 B 1-1 -0.27 -0.66 -0.30

Al -0.06 0.90 0.12 B 1-2 -0.54 0.36 -0.50

As -0.02 0.03 0.79 B 1-3 -0.66 1.12 -1.08

Ba 0.79 0.30 0.39 B 2-1 -0.62 -0.87 -0.80

Cd -0.47 0.43 0.31 B 2-2 -0.41 -0.85 -0.76

Ce 0.25 0.91 0.13 B 2-3 -0.91 -0.57 -0.83

Co 0.26 0.62 -0.25 B 3-1 0.28 0.85 -0.83

Cr 0.20 0.95 0.06 B 3-2 0.12 -0.21 -0.40

Cu 0.54 0.29 0.70 B 3-3 0.30 -0.38 -0.55

Fe 0.21 0.09 0.94 B 4-1 1.81 -0.51 -0.43

Hg 0.96 0.12 -0.01 B 4-2 2.00 -0.43 -0.89

La 0.11 0.90 0.16 B 4-3 1.95 1.54 -0.95

Li -0.04 0.89 0.03 B 5-1 0.44 -1.14 1.49

Mo -0.60 0.17 0.28 B 5-2 0.43 -0.07 1.57

Ni 0.45 0.56 -0.54 B 5-3 0.64 1.63 2.47

P 0.87 0.05 0.33 B 6-1 -0.13 -1.65 0.96

Pb 0.80 0.21 0.47 B 6-2 -0.07 -1.13 0.83

Sc 0.25 0.94 0.13 B 6-3 -0.33 0.72 0.93

Sn 0.95 0.13 -0.01 B 7-1 -0.98 1.69 -0.19

Zn 0.84 0.38 0.24 B 7-2 -1.51 1.04 0.49

Expl.var 6.75 6.41 3.14 B 7-3 -1.56 -0.46 -0.22

Prp.totl 0.34 0.32 0.16

Environ Geochem Health

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contaminant from which negative effect on biota could

appear, and ERM corresponds to the concentrations

limit from which significant adverse effect on biota is

expected (Burton 2002). ERL and ERM values

produced by NOAA (National Oceanic and Atmo-

spheric Administration) were chosen as the most

appropriate values, and values for each metal are

presented in Table 4.

Only nickel had all values above the ERM value

with the mean value of 66.2 lg g-1, but those

concentrations are interpreted as a background levels

because the same values were found in preindustrial

sediments 2 km from nearby port of Rijeka (Cukrov

et al. 2011) and in other northern Adriatic sediments

(Table 4). Mean concentrations of nickel in the Bakar

Bay sediments are in the same concentrations range

like preindustrial sediments from the Rijeka Bay

(Table 4). Similar situations were with As concentra-

tions in sediments of the Bakar Bay, where all values

were above the ERL value (Tables 2, 4), but compar-

ison with other Adriatic sediments indicates natural

origin (Dolenec et al. 1998; Obhodas and Valkovic

2010). Mean As concentrations in sediments from the

Bakar Bay were only 20 % higher in comparison with

preindustrial sediments from the Rijeka Bay. EF also

indicates prevailing natural origin of As in sediments

of the Bakar Bay. It appears that mercury, which is

classified as a priority hazardous substance (Chon

et al. 2010), was the principal contaminant in terms of

toxicity for marine organism, with values above the

ERL value in all samples (Table 2, 4), and with values

at sampling station B4 very close to the ERM value.

Mean mercury concentrations in the Bakar Bay

sediments were fifteen times higher than in preindus-

trial sediments from the Rijeka Bay, but five times

lower than the mean values of the Rijeka harbor

(Table 4) and considerably lower than at other

polluted Adriatic spots (Acquavita et al. 2010; Mar-

tincic et al. 1989). Moreover, mean mercury concen-

trations were comparable with concentrations in

sediments from other semi-closed Adriatic areas

(Cuculic et al. 2009). The next contaminant was found

to be lead with 16 from 21 samples above the ERL

value (Table 2, 4). Mean lead concentrations from the

Bakar Bay were three times higher than those found in

preindustrial sediments from the Rijeka Bay and mean

concentration of unpolluted sediments from northern

Adriatic, but five times lower than in sediments from

nearby the Rijeka harbor (Table 4) and notably lowerTa

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Environ Geochem Health

123

Author's personal copy

than some polluted Adriatic sediments (Bogner et al.

2005; Martincic et al. 1989; Obhodas and Valkovic

2010). Furthermore, mean lead concentrations were

comparable with concentrations in sediments from

other semi-closed Adriatic areas, either polluted

(Acquavita et al. 2010) or unpolluted (Cuculic et al.

2009). About 15 from 21 samples had copper

concentrations above the ERL value, with mean

concentrations of 26 % above the ERL value and

more than two times higher when compared to

preindustrial sediments from the Rijeka Bay (Table 2,

4). However, those concentrations were more than

eight times lower than medium concentrations in the

polluted sediments of the nearby Rijeka harbor

(Table 4). Additionally, we may conclude that Cu

concentrations are anthropogenically influenced and

that they are about two times higher than in unpolluted

Adriatic sediments, but also that there are many spots

in the Adriatic Sea with much higher copper concen-

trations (Acquavita et al. 2010; Cuculic et al. 2009;

Cukrov et al. 2008; Dolenec et al. 1998; Martincic

et al. 1989; Obhodas and Valkovic 2010; Spagnoli

et al. 2010). Two from 21 samples had zinc concen-

trations above the ERL value and more than two times

higher comparing with preindustrial sediments from

the Rijeka Bay (Table 2, 4), but, like other toxic

metals, these concentrations were considerably (eight

times) lower than medium concentrations in the

polluted sediments of the nearby Rijeka harbor

(Table 4). Like copper, zinc mainly originates from

anthropogenic sources, but its concentrations were not

very elevated, and they are comparable with other

Adriatic surface sediments (Acquavita et al. 2010;

Cuculic et al. 2009; Cukrov et al. 2008; Dolenec et al.

1998; Martincic et al. 1989; Obhodas and Valkovic

2010; Spagnoli et al. 2010). Cadmium, chromium, and

silver concentrations in the sediments of the Bakar

Bay present no threat for benthic communities.

Conclusions

In this study, for the first time, the metal concentra-

tions in recent sediments (up to 30 years) of the

Bakar Bay were investigated. The data obtained

allowed production of spatial distribution maps

indicating the sources of anthropogenic inputs in

the last 30 years. These maps demonstrated that

northwestern part of the Bakar Bay is the most

contaminated part, including the area in front of the

bulk cargo terminal and that, with the exception of

mercury, metal concentrations decreased during

recent period. The distribution of pollutants indicated

two main anthropogenic sources: the city of Bakar

and the bulk cargo terminal. In order to distinguish

anthropogenic pollutants from natural content in the

sediment, enrichment factors (EF) were calculated.

In terms of metals stock and in comparison with the

natural contents, mercury enrichment was the most

important, followed by lead, copper, and zinc.

The factor analysis clearly demonstrated the seg-

regation between metals of natural origin that arise

from soil and bedrock weathering (Li, Al, Cr, Sc0),

and those that originate from two anthropogenic

sources: the city of Bakar and the bulk cargo terminal

(Hg, Pb, Zn, Ag, Sn, Fe).

The potential risk for benthic organisms has been

estimated using sediment quality guidelines values.

Results revealed that the risk for benthic organisms is

negligible; the exception is small area in front of the

city of Bakar where this risk exists.

Acknowledgments We gratefully acknowledge the financial

and logistical support of the Port of Rijeka Authority and the

Ministry of Science, Education and Sports of the Republic of

Croatia under Projects 098-0982934-2720, ‘‘Interactions of

trace metals in aquatic environments.’’ Also, we like to thank

Ivan Grabar and Nusa Cukrov for help with sampling.

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