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Environmental Earth Sciences ISSN 1866-6280 Environ Earth SciDOI 10.1007/s12665-014-3282-x

Magnetic, geochemical and mineralogicalproperties of sediments from karstic andflysch rivers of Croatia and Slovenia

Stanislav Frančišković-Bilinski, RobertScholger, Halka Bilinski & Darko Tibljaš

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ORIGINAL ARTICLE

Magnetic, geochemical and mineralogical properties of sedimentsfrom karstic and flysch rivers of Croatia and Slovenia

Stanislav Franciskovic-Bilinski • Robert Scholger •

Halka Bilinski • Darko Tibljas

Received: 30 December 2013 / Accepted: 12 April 2014

� Springer-Verlag Berlin Heidelberg 2014

Abstract The aim of the present work was to investigate

links between the low-field magnetic susceptibility (MS)

and chemical and mineral composition of sediments from

several Croatian and Slovenian rivers, as well as to deter-

mine possible anthropogenic influence on these sediments.

MS measurements are a fast and simple method, which

serves as a proxy for the estimation of pollution in different

environmental systems. The investigated rivers are pre-

dominantly unpolluted rivers from Croatian and Slovenian

karstic and flysch areas, which belong to the Adriatic or the

Black Sea watersheds: the Dragonja, the Mirna, the Rasa,

the Rizana, the Reka, the Rak, the Cerknisnica, the Unec

and the Ljubljanica rivers. It was assumed that, due to their

mostly unpolluted status, they could serve as a database for

natural MS background values for this region. For com-

parison, several rivers and a lake from the Celje old met-

allurgic industrial area (Slovenia) were also investigated:

the Savinja, the Hudinja, the Voglajna rivers and Slivnisko

Lake. They form a sub-basin of the Sava River drainage

basin. Sediments of the clean karstic and flysch rivers

showed extremely low MS values, with mass susceptibility

values ranging from 0.58 9 10-7 to 5.11 9 10-7 m3/kg,

and isothermal remanent magnetism (IRM) values ranging

from 0.71 to 7.88 A/m. In the Celje industrial area, river

sediments showed much higher MS values, with mass

susceptibility values ranging from 1.31 9 10-7 to

38.3 9 10-7 m3/kg, and IRM values ranging from 0.91 to

100.42 A/m. The highest MS value was found in the Vo-

glajna River at Teharje-Store, a point which showed a

significant number of anomalies of toxic metals in earlier

investigations. Semiquantitative determination of relations

between grain size and concentration of magnetite was

performed using the Thompson-Oldfield method. X-ray

diffraction (XRD) mineralogical analysis showed that

sediments of the Celje area have mostly quartz as major

mineral, with relatively small amount of carbonate miner-

als, while in sediments of karstic rivers carbonate minerals

prevail. Statistically significant correlations were obtained

between MS and Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd and Ba in

the Slovenian karstic region and between MS and Cr, Fe,

Co, Ni and Zn in flysch drainage basins. On the contrary,

no correlation of MS and Hg content was obtained.

Keywords Karstic and flysch rivers � Croatia � Slovenia �Magnetic susceptibility � Trace elements � Heavy metals �Sediments � Mineralogy � Anthropogenic influence

Introduction

Magnetic susceptibility represents the ease with which

material can be magnetized in an external magnetic field.

Determination of volume susceptibility is a cheap and fast

method, and it is possible to use it as an indicator of

potential anthropogenic contamination with certain metals.

The development of magnetic measurement application

in environmental research begun in the ninth decade of the

S. Franciskovic-Bilinski (&) � H. Bilinski

Division for Marine and Environmental Research, Institute

Ruder Boskovic, POB 180, 10002 Zagreb, Croatia

e-mail: francis@irb.hr

R. Scholger

Department of Applied Geosciences and Geophysics,

Montanuniversitat Leoben, Peter-Tunner-Straße 25,

8700 Leoben, Austria

D. Tibljas

Institute of Mineralogy and Petrology, Department of Geology,

Faculty of Science, University of Zagreb, Horvatovac 95,

10000 Zagreb, Croatia

123

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DOI 10.1007/s12665-014-3282-x

Author's personal copy

twentieth century. The application of this method to sedi-

ments was initiated by Thompson and Oldfield (1986), and

a whole series of authors have been using it for different

investigations in geosciences. Shortly after that, the appli-

cation of magnetic measurements as proxies and indicators

of anthropogenic contamination, which reduced the need

for expensive and complicated chemical analyses, became

one of the main research topics in contamination research

(Oldfield et al. 1985; Strzyszcz 1993; Strzyszcz et al. 1996;

Hay et al. 1997; Heller et al. 1998; Scholger 1998; Plater

et al. 1998; Kapicka et al. 1999; Petrovsky et al. 2000;

Hanesch and Scholger 2002; Hanesch et al. 2003; Boyko

et al. 2004; Fialova et al. 2006; Shoumkova 2006; Botsou

et al. 2011; Novakova et al. 2012). Investigations per-

formed in industrial areas have also shown that the distri-

bution of magnetic susceptibility in soils is closely

connected with deposition of industrial dust and that

magnetic measurements could be used as a method for

detection of heavy metals in soils. A detailed overview of

magnetic monitoring methods in pollutant research was

given by Petrovsky and Ellwood (1999).

Numerous authors are in accordance with the conclusion

that this method is promising and confident for the dis-

crimination of polluted areas. Because this method is fast

and cheap, it is possible to handle a dense network of

sampling sites and construct magnetic susceptibility maps,

which enable an efficient selection of the most important

points on which chemical analyses will also be performed.

This procedure cuts significantly the costs of heavy metal

screening in the environment and contributes significantly

to the quality of environmental research.

Until recently, magnetic susceptibility measurements of

stream sediments have not been used with the purpose of

environmental quality assessment in Croatia. First such

measurements in Croatia have been performed by Fran-

ciskovic-Bilinski (2008a) on samples from the Kupa River

watershed. The area with the highest values of magnetic

susceptibility was found to be the lower flow of the

Mreznica River, and it was shown that this anomaly orig-

inates from careless coal burning products disposal.

Increased values of magnetic susceptibility were observed

in stream sediments of the upper flow of the Dobra River,

which are suggested not to be of anthropogenic influence

(Franciskovic-Bilinski et al. 2014).

To our knowledge, in Slovenia, there have been no

previous investigations of magnetic susceptibility in sur-

face sediments to assess the quality of rivers.

The aim of the present work was to perform measure-

ments of the low-field magnetic susceptibility (MS) of

stream sediments from several Croatian and Slovenian

rivers and to find links with their chemical and mineral

composition, as well as with possible anthropogenic

influence. The results could serve as a database for natural

MS background values for two presumably relatively

unpolluted regions (Slovenian karstic rivers; flysch and

alogene rivers of Croatia and Slovenia) in comparison with

those from the Celje industrial region with intensive metal

manufacturing processes.

Study area

The study area is composed of three regions (a, b and c) in

Slovenia and Croatia (Fig. 1; Table 1). Region a, with 16

sampling points, is the Celje industrial region (Slovenia)

drained by the Voglajna, Hudinja and Savinja rivers

(Fig. 2). Region b (Fig. 3) is a karstic region in Slovenia

with karstic rivers (the Rak, Cerkniscica, Unec and

Ljubljanica) belonging to the Sava River drainage basin,

represented by 8 sampling stations. Region c comprises

drainage basins of rivers that flow through flysch with total

31 sampling stations (the Reka from Brkini Hills; the

Rizana, Dragonja, Mirna and Rasa from Istria) (Fig. 4).

(a) Details about the study area of the Savinja, Voglajna

and Hudinja drainage basins are given in Francisko-

vic-Bilinski et al. (2006). This area is located in the

eastern part of Slovenia. The studied area represents

a young tectonic basin, which is filled with Quater-

nary deposits of the Savinja, Voglajna and Hudinja

rivers. In the northern part, there are Pleistocene

clays, quartz gravel and sand. In the SE part,

Miocene sand, sandstone, marly limestone and

lithothamnium limestone are also exposed as part

of the Celje syncline. The oldest rocks (Triassic

dolomite and limestone, as well as andesite and their

tuff and Carboniferous and Permian shale, sandstone

and conglomerate) crop out in the southern part.

These rivers were poorly studied in terms of

geochemistry; even though they are significantly

Fig. 1 Location of three study areas within Slovenia and Croatia:

a Celje industrial region (Slovenia); b karstic region in Slovenia;

c flysch areas of Croatia and Slovenia

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Table 1 Sample no., river and locality name, geographic coordinates

(datum WGS 84), altitude and results of laboratory magnetic

measurements (mass magnetic susceptibility–vmass, volume magnetic

susceptibility–vv and isothermal remanent magnetism—IRM) of

sediments (fraction \63 lm) from Croatian and Slovenian rivers

No. River and locality name N E m a.s.l. Vmass (m3/kg) Vv (SI) IRM (A/m)

(a) Celje industrial region (Slovenia): mean: 6.50 9 10-7 1.30 9 10-3 15.80

1 Slivnisko Jezero 46�11020.5500 15�27022.1800 293 1.31 9 10-7 2.63 9 10-4 0.91

2 Voglajna, Gorica 46�11053.5900 15�25052.2800 285 3.15 9 10-7 6.29 9 10-4 7.81

3 Voglajna, Vrbno 46�12044.6600 15�22008.3200 255 4.63 9 10-7 9.26 9 10-4 18.31

4 Voglajna, Teharje-Store 46�13047.0400 15�17046.2600 239 3.83 9 10-6 7.65 9 10-3 100.42

5 Savinja, Temerje 46�11040.9200 15�13053.1500 222 4.66 9 10-7 9.32 9 10-4 9.76

6 Savinja, Letus 46�18058.1500 15�01015.6400 312 2.53 9 10-7 5.06 9 10-4 3.99

47 Dobrinjski Potok, Hrastje 46�09052.4200 15�27057.9000 317 1.53 9 10-7 3.06 9 10-4 1.54

48 Locnica, Lipovec 46�11038.4300 15�27025.1800 296 5.58 9 10-7 1.12 9 10-3 13.48

49 Voglajna, Celje 46�13056.4100 15�16040.7800 233 1.10 9 10-6 2.19 9 10-3 28.10

50 Savinja, Celje 46�13046.000 15�15022.300 230 4.86 9 10-7 9.71 9 10-4 10.83

79 Hudinja, Celje 46�13058.4100 15�16041.2500 234 4.63 9 10-7 9.26 9 10-4 8.71

80 Hudinja, Sp. Hudinja 46�14006.3600 15�16043.8900 237 4.60 9 10-7 9.19 9 10-4 9.04

81 Hudinja, Skofja Vas 46�16011.2800 15�17023.9400 251 3.59 9 10-7 7.18 9 10-4 6.57

82 Hudinja, Visnja Vas 46�17058.1300 15�18000.1700 268 4.09 9 10-7 8.18 9 10-4 8.16

83 Savinja, Debro 46�09059.3000 15�14000.9500 219 5.68 9 10-7 1.14 9 10-3 12.54

84 Savinja, Rimske Toplice 46�07037300 15�11050.800 199 5.43 9 10-7 1.09 9 10-3 12.39

(b) Slovenian karstic rivers: mean: 2.40 9 10-7 4.79 9 10-4 3.78

8 Rak, Veliki most 45�47044.2800 14�17019.5000 509 2.27 9 10-7 4.55 9 10-4 n.m.

58 Rak, upstream Kotlici 45�47024.3500 14�17059.3000 509 2.32 9 10-7 4.64 9 10-4 3.54

10 Strzen, Gorica 45�45055.1900 14�21040.2300 545 6.48 9 10-8 1.30 9 10-4 5.37

11 Cerkniscica, Med. Mlin 45�48047.6700 14�22059.4900 580 8.56 9 10-8 1.71 9 10-4 2.25

9 Kotlici, springs 45�47028.300 14�17037.700 513 3.64 9 10-7 7.29 9 10-4 4.38

38 Unec, near Planina 45�49044.0200 14�15049.7000 449 2.58 9 10-7 5.17 9 10-4 3.43

39 Unec, Ravbarjev stolp 45�49019.6900 14�14051.3600 457 3.22 9 10-7 6.43 9 10-4 3.69

17 Ljubljanica, Mocilnik 45�57007.5500 14�17051.8600 303 3.63 9 10-7 7.25 9 10-4 n.m.

(c) Croatian and Slovenian flysch and alogene rivers: mean: 1.70 9 10-7 3.40 9 10-4 2.07

12 Reka, Zabice 45�30027.6200 14�20046.1000 444 2.55 9 10-7 5.10 9 10-4 1.79

13 Reka, Topolc 45�35002.4300 14�12043.4700 395 5.11 9 10-7 1.02 9 10-3 7.88

14 Reka, Ribnica 45�37045.2500 14�09000.2600 369 2.56 9 10-7 5.12 9 10-4 2.75

15 Reka, Gornje Lezece 45�39027.0000 14�04007.7900 362 2.65 9 10-7 5.30 9 10-4 3.23

16 Reka, Vreme 45�38053.700 14�01053.100 346 2.25 9 10-7 4.50 9 10-4 2.43

53 Reka, Donja Bitnja 45�36030.4400 14�10045.6000 385 2.73 9 10-7 5.46 9 10-4 2.69

54 Reka, Suhorje 45�38053.3400 14�05048.3700 361 2.47 9 10-7 4.94 9 10-4 n.m.

56 Suhorica, near Padez 45�38015.700 14�05038.200 439 2.29 9 10-7 4.57 9 10-4 1.83

99 Mirna, Kotle 45�22005.1800 14�01002.9900 157 1.16 9 10-7 2.31 9 10-4 1.48

100 Mirna, Buzet 45�23056.0700 13�58030.6800 49 1.59 9 10-7 3.18 9 10-4 1.29

101 Mirna, Veliki Mlun 45�23012.0300 13�55043.1700 34 1.41 9 10-7 2.83 9 10-4 1.17

102 Mirna, downs. Butoniga 45�21025.6400 13�51026.5800 18 1.06 9 10-7 2.12 9 10-4 0.71

104 Mirna, Novigrad 45�19005.5900 13�35056.5400 0 1.84 9 10-7 3.68 9 10-4 1.71

105 Mirna, Stuparic 45�20007.9700 13�39010.3700 3 1.50 9 10-7 3.00 9 10-4 1.40

106 Mirna, Ponte Porton 45�21028.2500 13�44013.3700 3 1.29 9 10-7 2.58 9 10-4 0.97

114 Butoniga, before Vrh 45�20035.8500 13�53022.1200 21 1.16 9 10-7 2.32 9 10-4 1.57

107 Gologoricki Potok, Gologoricki Dol 45�14014.0200 14�03000.1700 66 1.23 9 10-7 2.46 9 10-4 1.52

108 Gologoricki Potok, Bati 45�14034.8500 14�02025.8000 86 9.34 9 10-8 1.87 9 10-4 0.65

109 Vlaski Potok, Tupljak 45�12034.1400 14�06022.5500 28 1.04 9 10-7 2.07 9 10-4 0.78

110 Rasa, Potpican 45�11014.2400 14�04040.9700 21 8.59 9 10-8 1.72 9 10-4 0.85

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affected by metallurgical industry around Celje.

According to Stern and Forstner (1976), Voglajna

was one of the most polluted water flows in

Slovenia. They found that in the sediments of

Voglajna River, chromium and zinc were enriched

by a factor of more than 100, copper, lead and

cadmium by a factor of 25–50, compared with the

geochemical background. It was assumed that efflu-

ents from the old waste dumps of zinc works, from

iron works near Store, from a TiO2 factory and from

an enamel pottery factory are the contributors to the

unusually high metal contamination in Voglajna.

Also, the consequence of more than 100 years of

smelting of the sphalerite ore in Cinkarna Celje

factory is heavy contamination of the Celje region

with zinc and cadmium. In spite of the fact that

industrial pollution was reduced in meantime,

Table 1 continued

No. River and locality name N E m a.s.l. Vmass (m3/kg) Vv (SI) IRM (A/m)

111 Rasa, upstr. Most Rasa 45�04048.5200 14�01055.6900 2 1.91 9 10-7 3.83 9 10-4 1.89

112 Rasa, dstr. Most Rasa 45�02051.000 14�02059.000 2 1.75 9 10-7 3.50 9 10-4 6.40

113 Rasa, estuary, Brsica 45�01050.8200 14�02057.9000 0 1.81 9 10-7 3.62 9 10-4 1.98

18 Rizana, under Crni Kal 45�31058.1500 13�52020.3900 67 2.16 9 10-7 4.33 9 10-4 3.11

24 Rizana, Skofije 45�33024.1600 13�47008.0600 3 1.82 9 10-7 3.65 9 10-4 3.08

103 Dragonja, Skudelini 45�27031.6100 13�38038.7500 6 1.06 9 10-7 2.11 9 10-4 4.14

19 Dragonja, Trsek 45�28037.5300 13�50000.1500 184 9.23 9 10-8 1.85 9 10-4 0.79

20 Pinjevec, under Borst 45�29042.2900 13�47009.1800 140 4.69 9 10-8 9.38 9 10-5 0.49

21 Dragonja, Kostabona 45�28020.3300 13�44041.1200 69 6.57 9 10-8 1.31 9 10-4 1.08

22 Dragonja, Krkavcani 45�27025.1800 13�42021.0000 37 5.80 9 10-8 1.16 9 10-4 0.71

23 Dragonja, estuary 45�28042.800 13�35009.500 0 1.84 9 10-7 3.68 9 10-4 1.76

Data are first presented as mean values for the whole region, after that follow individual values for each studied sample

n.m. not measured

Fig. 2 Celje industrial region (Slovenia) drained by the Voglajna,

Hudinja and Savinja rivers: geological map (simplified after FGI

1970) with position of sampling locations. C,P Carboniferous and

Permian shale, sandstone and conglomerate; T triassic dolomite and

limestone; g triassic andesite and tuff; Ol oligocene sand, sandstone,

sandy marl; M Miocene sand, sandstone, marly limestone and

lithothamnium limestone; Pl,Q Pliocene and Quaternary clay, quartz

gravel and sandFig. 3 Karstic region in Slovenia drained by the Rak, Cerkniscica,

Unec and Ljubljanica rivers, belonging to the Sava River drainage

basin: geological map (simplified after FGI 1970) with position of

sampling locations. T Triassic, mainly dolomite; J Jurassic, mainly

limestone; C Cretaceous, mainly limestone; E1,2 Eocene, flysch;

Q Quaternary sediments

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Franciskovic-Bilinski et al. (2006) in samples taken

during 2001–2002 still registered elevated Zn and

Cd concentrations in river sediments (Table 2).

(b) The investigated system of Slovenian karstic rivers

(rivers which flow mostly through karstic areas)

from Notranjsko podolje region stretches from the

Cerknisko Lake in the south to the Ljubljanica River

in the north. The most distant source branch of this

system is the Trbuhovica, which springs on Prezid

Polje in Croatia. Two main branches which are

feeding the periodic Cerknisko Lake are the Cer-

kniscica and Strzen. The Cerknisko Lake has an area

of 38 km2 when it is full, the maximal depth is 10 m,

and it is 10.4 km long and 4.7 km broad. The Rak

River drains underground the lake area, and it flows

through the famous Rakov Skocjan valley and

canyon. Rakov Skocjan is a protected area, known

to its natural beauty, and the valley was basically a

huge cave, whose ceiling has collapsed long ago as

the karst surface slowly but steadily dissolved and

cut it. There are two ‘‘natural bridges,’’ which are

remnants of the cave ceiling. Then the river flows

underground until the Planinska Jama cave. Within

this cave, it unifies with the Pivka River and reaches

the surface as Unica. This river sinks and, when it

again reaches the surface near Vrhnika at Mocilnik

spring, it has the name Ljubljanica. It flows to

Ljubljana, where it inflows the Sava River. The

hydrology of this karstic system is explained by

distribution of areas built of the Triassic semiper-

meable dolomites and permeable Jurassic and Cre-

taceous limestones (Gams 2004). Ljubljanica River

was described earlier by Franciskovic-Bilinski

(2008b). The whole investigated area of Slovenian

karstic rivers is very sparsely inhabited, without any

bigger cities. Postojna, the largest settlement in the

area with 8,500 inhabitants but without bigger

industry, can influence quality of waters in the Pivka

River. In the upper part of the drainage basin (in the

area of the periodic Cerknisko Lake), the biggest

settlement is Cerknica with about 3,500 inhabitants

and the biggest settlement in the lower part of this

drainage basin (near upper flow of the Ljubljanica

River) is Vrhnika with about 7,500 inhabitants.

There are no larger pollution sources in this region,

there are no mining activities, neither heavy indus-

try. Higher karstic areas (hills and mountains) are

covered almost completely by forest and almost

uninhabited, while smaller, mostly rural settlements

are situated in karst poljes which are partly agricul-

turally cultivated. Smaller estates and mixed farming

prevail, so it would not be expected that agriculture

is larger source of pollution. The fact that the water

from the karst spring, which receives among others

waters from the Cerknisko Lake and the Rak River,

is used for water supply (Poje 2008) indicates that

water from this hydrological system can be consid-

ered as almost unpolluted.

(c) Flysch (rivers which flow mostly through flysch) and

alogene (rivers which have spring and part of its

course in a non-karstic area and then enter karst)

rivers of Croatia and Slovenia which were studied

within this paper are located in the Istria peninsula,

the Rasa and Mirna in its Croatian part, the Dragonja

at or close to the Croatian–Slovenian border and the

Rizana in Slovenian part. Another studied river (the

Reka) is located in nearby Brkini hills flysch area in

SW Slovenia. The flysch of the Istrian peninsula is

one of the three main flysch areas in the outer

Dinarides, the other two occurring in the northern

Dalmatian and Split areas. The flysch units in Istria

have been considered as Middle to Late Eocene in

age (Babic et al. 2007). From these rivers, Rasa was

studied earlier by Sondi et al. (1994, 1995), with

respect to trace metal transport and sedimentation

processes. Some results of contamination status of

the Rizana, Dragonja, Mirna and Rasa Rivers were

Fig. 4 Flysch areas of Croatia and Slovenia drained by the Reka

from Brkini Hills and the Rizana, Dragonja, Mirna and Rasa from

Istria: geological map (simplified after FGI 1970) with position of

sampling locations. J Jurassic, mainly limestone; C Cretaceous,

mainly limestone; Pc,E Paleocene, Eocene limestone; E2,3 Eocene,

flysch; Q Quaternary sediments

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Table 2 Concentration (in lg g-1, except when stated otherwise) of selected elements in \63 lm fraction of sediment samples from Regions a,

b and c obtained by ICP-MS analysis

Sample Mg % Al % Ca % S % K % Fe % Cr Mn Co Ni Cu Zn As Cd Ba Pb Hg (ng

g-1)

Region a

1 0.62 1.39 0.6 0.023 0.126 3.89 39.2 708 19.5 56.9 22.9 67.8 10.9 0.2 67 17.4 178

2 0.56 1.34 1.3 0.086 0.152 5.53 35.5 13,700 24.7 61.2 24.2 111.2 28.6 0.8 238 33.9 304

3 0.59 1.06 3.1 0.117 0.122 5.19 43.9 1,140 20.4 55.4 30.5 135.9 16.6 0.7 125 43.9 606

4 0.90 1.21 4.9 0.323 0.151 5.65 71.8 1,490 19.4 68.2 138.7 488.7 18.1 2.7 166 133.4 914

5 1.27 1.17 8.5 0.286 0.116 2.95 42.2 1,030 17.9 46.5 52.5 2,760 13.1 3.8 274 66.7 569

6 2.08 1.15 9.4 0.147 0.092 2.84 19.4 643 11.6 36.3 19.8 66.0 10.9 0.3 65 23.9 333

47 1.28 2.35 3.1 0.171 0.346 4.95 59.0 2,590 20.6 84.6 33.3 112.3 16.3 0.4 92 32.5 1,260

48 0.36 1.19 0.6 0.061 0.158 6.98 66.0 2,460 29.4 71.1 36.7 171.3 26.4 0.8 127 62.6 1,113

49 1.46 1.66 5.2 0.188 0.253 4.08 53.9 1,270 51.8 91.2 147.9 2,360 46.0 12.4 189 229.0 2,411

50 1.45 1.70 6.9 0.232 0.194 3.17 41.8 1,240 15.8 52.9 43.9 198.6 10.9 0.7 162 52.2 1,087

79 1.60 2.02 5.5 0.136 0.25 3.74 45.0 861 34.3 82.9 114.7 1,040 30.5 7.3 988 86.9 345

80 1.71 1.68 5.5 0.122 0.227 3.37 35.7 775 17.4 43.0 72.7 469.8 30.3 1.4 1,010 63.9 292

81 1.82 1.62 5.7 0.106 0.244 3.28 36.2 607 13.6 43.3 37.1 144.8 16.3 0.5 108 38.5 211

82 1.68 1.71 4.7 0.103 0.271 3.33 40.2 625 14.9 45.4 38.0 128.3 17.0 0.4 113 35.6 122

83 1.51 1.53 5.6 0.168 0.158 2.88 41.8 1,160 17.4 49.2 47.0 500.3 14.4 1.9 569 63.8 276

84 1.83 1.48 6.7 0.229 0.147 3.20 42.1 1,160 18.7 53.3 50.9 469.1 14.7 2.0 674 69.0 312

Region b

8 1.93 2.18 6.8 0.104 0.162 4.29 42.6 596 16.4 40.3 17.8 88.1 15.8 0.7 89 50.9 446

58 2.12 2.20 13.0 0.083 0.235 2.82 33.7 889 12.3 36.3 25.6 103.6 19.5 1.0 74 46.0 751

10 2.60 1.06 20.6 0.090 0.076 1.88 22.3 252 8.1 28.1 11.2 40.5 8.9 0.6 50 23.0 134

11 4.83 1.01 12.0 0.087 0.14 1.67 15.5 372 5.9 16.0 8.5 38.6 9.2 0.5 57 28.2 482

9 0.85 2.68 4.2 0.054 0.149 5.05 58.4 2,070 16.7 55.2 21.1 90.4 22.7 1.1 90 27.2 236

38 2.65 1.51 9.2 0.110 0.108 3.55 42.3 1,190 21.2 55.2 23.0 82.0 13.0 0.8 66 50.5 8,480

39 1.46 1.69 6.0 0.124 0.124 4.00 53.2 2,740 24.4 80.6 32.9 110.1 13.8 0.9 110 57.7 2,203

17 2.00 1.68 4.7 0.104 0.108 3.56 40.4 1,650 18.0 49.7 25.2 110.2 12.3 1.1 90 46.6 346

Region c

12 0.71 1.59 0.5 0.034 0.106 3.44 59.7 1,520 33.8 121.1 31.0 62.7 6.3 0.2 77 29.1 1,162

13 0.77 1.56 5.7 0.124 0.114 4.66 69.5 1,290 38.0 144.1 39.3 117.3 12.7 0.3 93 48.6 2,142

14 0.75 1.61 3.7 0.096 0.13 3.86 61.0 1,170 28.3 129.2 41.2 101.3 7.6 0.4 94 44.0 1,976

15 0.76 1.57 3.0 0.082 0.119 3.97 77.8 2,070 29.7 141.4 37.2 118.6 7.5 0.4 115 51.5 57,806

16 0.54 1.29 5.9 0.105 0.106 3.18 45.5 1,150 21.4 95.3 28.4 71.5 7.4 0.3 115 26.4 854

53 0.90 2.15 2.1 0.096 0.229 4.20 73.5 1,500 28.7 140.4 52.5 127.5 6.5 0.3 93 36.7 4,805

54 0.96 2.28 2.1 0.098 0.243 4.41 75.2 1,740 33.9 149.5 54.2 130.0 6.7 0.4 106 39.0 2,226

56 0.84 2.07 1.4 0.053 0.252 3.96 72.6 1,110 26.0 138.9 48.4 95.9 7.7 0.2 113 25.0 197

99 0.53 1.15 10.6 0.112 0.14 2.22 39.0 782 14.1 82.8 25.1 66.6 4.1 0.2 239 12.2 73

100 0.48 1.26 11.9 0.116 0.16 2.46 42.1 1,110 19.8 85.6 26.5 63.5 7.3 0.4 201 15.3 220

101 0.46 1.33 10.6 0.096 0.15 2.50 43.9 1,270 23.2 91.2 28.5 75.7 6.5 0.3 174 18.2 334

102 0.49 1.85 7.4 0.053 0.19 2.84 53.0 701 13.1 86.5 30.6 78.9 4.5 0.2 149 12.3 247

104 0.49 1.71 9.7 0.100 0.23 2.25 48.4 722 12.9 71.5 26.1 74.6 3.8 0.3 103 13.1 150

105 0.56 1.73 9.1 0.288 0.28 2.27 48.7 553 12.4 70.7 25.8 69.6 6.0 0.2 80 13.5 114

106 0.46 1.92 7.6 0.085 0.23 2.60 52.6 974 16.0 76.6 27.6 74.4 4.7 0.3 146 17.2 151

114 0.43 1.14 14.0 0.100 0.15 2.24 41.6 1,210 15.6 69.1 23.1 54.7 5.1 0.2 137 16.1 102

107 0.52 1.26 14.2 0.123 0.2 2.04 39.1 787 15.3 70.6 23.7 60.6 6.0 0.2 284 13.5 62

108 0.53 1.00 10.5 0.109 0.14 1.71 29.2 600 9.8 53.1 23.7 71.3 3.6 0.2 90 10.1 98

109 0.44 1.00 10.6 0.097 0.11 1.94 30.3 849 11.7 59.3 24.3 56.9 3.5 0.2 107 11.7 152

110 0.45 1.03 10.7 0.085 0.1 1.90 30.6 732 11.1 61.9 24.6 58.6 3.3 0.2 120 12.2 115

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earlier reported in two brief conference papers by

Franciskovic-Bilinski et al. (2003, 2007). The Drag-

onja River flows through the sparsely inhabited hilly

area at the border between Slovenia and Croatia,

with several small rural settlements and some

Mediterranean agriculture. Small and short, the

Rizana River has its spring in similar area, but its

lower flow is surrounded by industrial areas of Koper

(50,000 of inhabitants), which is center of the whole

coastal region of Slovenia and one of the biggest

Slovenian cities. The Mirna River flows through a

sparsely inhabited valley, through a rural area with

some Mediterranean agriculture. Only bigger settle-

ment in the Mirna valley is town Buzet in its upper

flow, with about 6,000 inhabitants, with a brewery,

but without other heavier industry. The Rasa River

flows through sparsely populated hilly area and

valley. It is a rural area with some Mediterranean

agriculture. Also, coal-operated power plant in

Plomin at eastern Istrian coast is located close to

Rasa valley, so its influence could be expected,

especially due to careless disposal of slag, which is

known to be radioactive and rich with heavy metals

(Barisic et al. 2001). The Reka River valley in

Slovenia is also a rather sparsely populated rural

area, with some agriculture (mostly fruit growing),

except in the middle flow of the Reka River, where

Ilirska Bistrica, town with some 5,000 inhabitants,

and small industry is located. Factory of organic

acids, which operated in the town from 1955 till

1990, was known as a contamination source influ-

encing the Reka River and turning it from source of

drinking water to waste water channel. Since the

closure of the factory, the situation has significantly

improved (Kogovsek 2001).

Materials and methods

Sampling and sample preparation

Sampling of 55 stream sediments sites from Croatian and

Slovenian rivers was performed during 3 years

(2001–2003), in the frame of a Croatian–Slovenian bilat-

eral project, in which geochemistry and mineralogy of river

sediments was studied. Sediments were air-dried and dry

sieved using standard sieves. Sieved samples were pul-

verized using a mortar grinder Pulverisette 2 (Fritsch,

Germany).

Measurements of magnetic susceptibility

and isothermal remanent magnetization

For measurements of mass susceptibility (v in m3/kg),

samples were placed in a standard cylindrical sample

container (10 cm3) and weighed. A multifunction kappa-

bridge MFK1-FA (AGICO, Brno, Czech Republic, Field

200 A/m, Frequency 976 Hz) was used. The procedure was

earlier described in Hanesch et al. (2003).

A direct magnetic field of 1T was introduced, using a

Pulse Magnetizer Model 660 (2G Enterprises, Ca, USA).

After the magnetization step, IRM was measured on a DC-

Squid Magnetometer (2G Enterprises, California, USA).

Mineralogical analysis using XRD

The mineral composition of the sediments (frac-

tion \63 lm) was determined by X-ray powder diffraction

using a Philips X-Pert MPD diffractometer (Cu tube,

graphite monochromator, generator settings: 40 kV,

40 mA, range scanned 4–6382h). Crystalline phases were

identified by comparison with Powder Diffraction File

Table 2 continued

Sample Mg % Al % Ca % S % K % Fe % Cr Mn Co Ni Cu Zn As Cd Ba Pb Hg (ng

g-1)

111 0.43 1.06 10.8 0.112 0.11 1.77 30.6 686 11.1 51.0 21.7 50.3 4.3 0.3 83 14.5 202

112 0.49 1.11 10.8 0.121 0.14 1.80 32.7 563 10.4 55.9 24.2 56.3 3.7 0.2 70 13.1 166

113 0.51 0.99 11.5 0.146 0.14 1.80 31.3 565 10.2 53.4 22.7 55.6 4.8 0.2 55 12.9 358

18 0.67 1.14 14.2 0.096 0.11 2.85 45.2 1,790 20.3 96.4 29.8 86.5 9.4 0.7 90 46.6 717

24 0.48 0.93 18.0 0.087 0.1 2.60 38.4 852 18.1 81.0 25.7 63.8 10.1 0.4 36 19.7 1,144

103 0.28 0.53 10.7 0.128 0.05 1.24 18.1 498 8.0 37.9 14.5 34.6 3.4 0.2 70 9.1 80

19 0.73 1.00 16.0 0.128 0.12 2.86 38.8 1,050 18.5 92.0 20.3 47.7 9.2 0.2 103 28.1 109

20 0.44 0.63 33.3 0.107 0.09 1.83 23.9 544 9.8 58.7 15.7 28.2 9.2 0.1 153 17.8 186

21 0.36 1.09 18.4 0.105 0.12 2.31 33.2 359 9.2 63.1 19.5 42.5 7.8 0.1 87 8.5 347

22 0.32 0.65 30.5 0.122 0.08 1.76 21.4 756 9.5 46.8 33.1 30.2 8.7 0.1 132 10.9 690

23 0.77 1.26 9.6 0.303 0.25 2.94 45.0 530 15.3 78.0 26.4 57.3 11.2 0.1 92 9.5 346

Data for Region a are from Franciskovic-Bilinski et al. (2006)

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(1997) using the computer program X’Pert High score

(Philips Analytical 2001).

ICP-MS analysis of sediment fraction \63 lm

Chemical analysis was performed by ACTLABS com-

mercial laboratories, Ontario, Canada, in the frac-

tion \63 lm, using ICP-MS (Inductively Coupled Plasma

Mass Spectroscopy) by ‘‘Ultratrace 2’’ procedure. The

procedure was as follows: 0.5 g of sample was dissolved in

aqua regia at 90 �C in a microprocessor controlled micro-

wave digestion unit for 2 h. The solution was diluted and

analyzed using a PerkinElmer SCIEX ELAN 6100 ICP-MS

instrument. The reference materials (USGS GXR-1, GXR-

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

after analysis of each series of samples.

Although this digestion is not total, its use is justified

because the international standard methods for determining

action limits are based on aqua regia leach (Salminen and

Tarvainen 1997). The aqua regia (3:1, v/v, HCl to HNO3)

digestion procedure (ISO standard 11466) is considered

adequate for analyzing total-recoverable heavy metals in

soils of certain regions and is used to estimate the maxi-

mum element availability to plants. Residual elements that

are not released by aqua regia digestion are mostly bound

to silicate minerals and are considered unimportant for

estimating the mobility and behavior of the elements (Chen

and Ma 2001).

Statistical procedure for determination of anomalous

values

Basic statistical parameters and correlation analysis were

performed using STATISTICA 8.0. (StatSoft, Inc. 2007).

Anomalous values of magnetic susceptibility and IRM

were obtained from the experimental data in Table 1 using

the two-dimensional scatter box diagrams (Tukey 1977;

Reimann et al. 2005). The same procedure was used for

assessing anomalous concentrations of toxic elements from

the data in Table 2.

Results

Measurements of magnetic susceptibility

and isothermal remanent magnetization (IRM)

Results of the measurements of mass susceptibility and

isothermal remanent magnetization (IRM) are divided into

three regions/datasets and, for each of them, mean values

for every measured parameter are presented (Table 1). As

expected, the highest values of all parameters are observed

in the Celje industrial region, with mass susceptibility

values ranging from 1.31 9 10-7 to 38.3 9 10-7 m3/kg

and IRM values ranging 0.91–100.42 A/m. Sediments of

the clean karstic and of flysch and alogene rivers showed

extremely low MS values, with mass susceptibility values

ranging from 0.5 9 10-7 to 5.11 9 10-7 m3/kg and IRM

values ranging 0.7–7.88 A/m. Rivers from this clean region

were divided into two groups; those from Slovenian karst

showed a bit higher values than flysch and alogene rivers of

Croatia and Slovenia.

Semiquantitative determination of relations between

grain size and concentration of magnetite was performed

using the Thompson-Oldfield method (1986) (Fig. 5). In

this diagram, magnetic volume susceptibility (abbreviation:

MS, dimensionless in SI units) is plotted versus IRM-

intensity (A/m). The diagram shows that the concentration

of magnetic phases varies largely between rivers. The val-

ues of magnetite concentrations spread approximately from

0.003 to 0.3 %. In Region c, the values are the lowest and in

Region a are the highest. ‘‘Magnetic grain’’ sizes range

between 1 and 16 lm in most samples of regions a and b.

Most samples from Region c have grain sizes above 16 lm.

The use of magnetic susceptibility versus IRM as magnetic

grain size indicator rests on many assumptions; therefore,

the results can be considered only as tentative ones.

Mineral composition of stream sediments

The mineral composition of river sediments (frac-

tion \63 lm) of the Celje industrial region was earlier

1 10 100 1000

SIRM-Intensity (A/m)

1E-005

1E-004

1E-003

1E-002

Susc

eptib

ilty

(SI)

region aregion bregion c

grain size

mag

netit

e-co

ncen

tratio

n

256

µm

16µm

1µm

0.1 %

0.01 %

0.001 %

Fig. 5 Diagram according to Thompson-Oldfield (1986), presenting

semiquantitative determination of relations between grain size and

concentration of magnetite: magnetic volume susceptibility (abbrevi-

ation: MS, dimensionless in SI units) is plotted versus SIRM-intensity

(A/m)

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presented in details (Franciskovic-Bilinski et al. 2006).

Quartz was found as a major mineral in all sediment

samples. Among other major minerals, albite was found in

locations 1 and 3; muscovite in locations 2, 79, and 82;

calcite in locations 4, 5, 6 and 82; dolomite in locations 6

and 81. Depending on locations, there are several minor

minerals and also several trace minerals, some of which

contain Fe-ion in the structure.

In stream sediments from the Slovenian karstic region

quartz, calcite and dolomite are present in different pro-

portions. Quartz predominates in samples 8, 9, 38, 39 and

17; calcite predominates in samples 58 and 10; while

dolomite predominates in sample 11. There are also some

traces of feldspars, muscovite and of chlorite.

In all samples from the Reka River, quartz is a dominant

constituent. Feldspar (presumably albite) is present as the

second abundant mineral in samples 53 and 54 and as a

minor constituent in samples 12, 15, 16 and 56. Calcite is

present in all samples as minor component, except in

sample 12, where it is not present.

In sediments of the Mirna, Rasa, Rizana and Dragonja

rivers, quartz and calcite are the major minerals with

slightly different proportions. Feldspars and muscovite are

present as trace minerals.

Magnetite was not detected by XRD in any sample,

which can be attributed to the generally low concentrations

indicated by MS measurements.

Elemental composition of sediments

Concentrations of 38 elements were determined in sedi-

ments of regions b and c in the present work. From them

only concentrations of 12 potentially toxic elements (Fe,

Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Cd, Ba, Pb and Hg), which

are included in the list of existing sediment criteria issued

by SMSP and FALCONBRIDGE NC SAS (2005), are

shown in Table 2, in addition to macrocomponents (Mg,

Al, Ca, S and K). In the Table 2 for comparison, concen-

trations of elements for Celje region from Franciskovic-

Bilinski et al. (2006) are also shown. Franciskovic-Bilinski

et al. (2006) showed that stream sediments of the Celje

region are still contaminated, although industrial pollution

decreased during the last decades. The most significant

contaminants in the Celje region are Zn and Cd. In two

locations within the town of Celje, several elements have

concentrations above the threshold value that might cause

serious toxic effects. In other locations, elements are

present in concentrations that might cause only minor toxic

effects. Descriptive statistics was used to obtain basic

statistical parameters shown in Table 3 for all three studied

regions. For each element, the values are given for the

arithmetic mean, range and standard deviation. The value

for the arithmetic mean ± standard deviation can be

considered as baseline value for each element studied here.

Comparison of mean concentrations of potentially toxic

elements with sediment quality criteria (SMSP and FAL-

CONBRIDGE NC SAS 2005) is presented in Table 4. In

Region b, mean concentrations of Cu and Zn are below the

level for the lowest toxic effects. Mean concentrations of

Cr, Fe, Ni, As, Cd, Pb and of Hg are above the values that

could cause the lowest toxic effects. Mean concentrations

of Mn and of Ba are above the value capable for causing

significant toxic effects. In Region c, mean concentrations

of Cd and Pb are below the level for the lowest toxic

effects. Mean concentrations of Cr, Mn, Fe, Cu, Zn and of

As are above the values causing the lowest toxic effects.

Mean concentrations of Ni, Ba and of Hg are above the

values causing significant toxic effects. The highest values

of Ni and of Hg are observed in the Reka River. Increased

concentrations of Cu in samples 53, 54 and 56 are similar

to, or even lower than, values recorded in the soils of

nearby Coastal region of Croatia (Halamic and Miko 2009)

with viticulture history. The Reka River area is not a wine

growing area, but copper-based chemicals are also used in

prophylaxis of apples which are cultivated in Brkini area.

There is also a potential influence of chicken farming in the

vicinity of Pivka because copper sulfate could be used in

the diet of broiler chickens for stimulating appetite and

producing increased growth rate. Cu content in two marl

samples taken at outcrops upstream of Ilirska Bistrica is

also in this range, 40 and 65 lg g-1, respectively. There-

fore, natural origin of Cu cannot also be excluded without

additional sampling in spite of the fact that stream sedi-

ments taken closer to analyzed marls contain lower Cu

concentrations.

Concentrations of total Hg are elevated in several

samples: In samples 38, 39 (Region b) and in 13, 15, 53

and 54 of the Reka River, the values are higher than 2 lg

g-1, the value reported as capable of causing significant

toxic effects. The values of Hg concentrations are the

highest in sample 15 (Region c) and in sample 38 (Region

b). These concentrations of total Hg are almost comparable

with Hg concentrations of lower stretch of the Idrijca and

Soca Rivers (Franciskovic-Bilinski et al. 2005).

Anomalies in concentrations of selected elements and of

magnetic susceptibility in sediments of regions a–c were

determined by the boxplot method (Table 5). In other

sediments, which are not included in Table 5, anomalies

were not found.

Comparison of the measured element concentrations

with the available quality criteria for fresh water sediments

(SMSP and FALCONBRIDGE NC SAS 2005) indicates

that some of the investigated sediments contain several

elements in concentrations that could have the lowest (e.g.,

Cr, Fe, Ni) or even significant toxic effects (Ba, Hg), i.e.,

such comparison indicates possible pollution of

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investigated sediments. But careful analysis of such ele-

vated concentrations for several elements shows that they

are most probably the result of natural processes and that

they do not indicate any pollution. A typical example is Ba

in sediments from the flysch region rivers. Sandstones from

this region contain from 50 to 3,600 lg g-1 of Ba, and the

highest values have been observed in the samples from the

Pazin flysch basin (Mikes et al. 2006). These values are in

accordance with the fact that authigenic barite is one of the

most abundant heavy minerals found in marls of the central

Istria flysch (Magdalenic 1972). The fact that sediment

samples with the highest recorded Ba concentrations (99,

100, 107) were taken precisely in the streams which drain

areas in which marls and sandstones contain authigenic

Table 3 Basic statistical parameters (mean, range and standard deviation) for 38 elements analyzed in stream sediments from regions a, b and c

Element Region a Region b Region c

Mean Range SD Mean Range SD Mean Range SD

Li 23.134 29.44 7.557 28.108 36.708 11.483 22.993 36.35 8.58

Be 0.981 0.72 0.207 1.483 1.260 0.490 0.647 0.86 0.22

B 38.651 332.38 86.608 1.404 8.573 3.171 7.694 25.00 6.78

Na % 0.031 0.07 0.016 0.02 0.011 0.005 0.031 0.27 0.05

Mg % 1.295 1.72 0.531 2.305 3.978 1.176 0.566 0.68 0.17

Al % 1.516 1.29 0.345 1.75 1.671 0.578 1.319 1.75 0.44

P % 0.087 0.15 0.041 0.076 0.083 0.032 0.038 0.08 0.02

S % 0.156 0.30 0.081 0.095 0.070 0.021 0.113 0.27 0.05

K % 0.188 0.25 0.070 0.138 0.159 0.048 0.151 0.23 0.06

Ca % 4.820 8.83 2.560 9.548 16.370 5.505 10.809 32.76 7.30

V 37.205 54.29 12.952 62.644 60.539 19.884 32.785 43.95 9.39

Cr 44.603 52.47 12.760 38.544 42.888 14.460 44.897 59.74 16.37

Mn 1,966.180 13,093.03 3,183.640 1,219.86 2,488.361 876.231 968.806 1,711.00 426.33

Fe % 4.063 4.14 1.229 3.352 3.378 1.167 2.658 3.42 0.90

Co 21.727 40.16 9.835 15.393 18.564 6.312 17.912 29.96 8.43

Ni 58.844 54.87 16.400 45.16 64.562 19.700 85.581 111.56 32.37

Cu 56.926 128.16 40.752 20.656 24.369 7.988 28.882 39.71 9.61

Zn 576.509 2,693.95 818.109 82.95 71.573 28.677 70.429 101.84 26.54

Ga 4.515 4.81 1.228 5.212 5.478 1.778 3.385 6.82 1.66

As 20.063 35.14 9.707 14.394 13.821 4.787 6.536 9.37 2.47

Se 1.403 2.78 0.670 1.187 1.798 0.588 0.632 1.60 0.45

Rb 19.710 20.42 5.991 15.404 17.358 5.300 16.907 25.60 6.22

Sr 91.960 110.06 32.248 67.06 54.919 20.333 224.741 471.21 124.21

Y 12.786 10.50 2.865 16.239 12.664 5.030 9.468 6.13 1.68

Zr 1.393 4.77 1.140 2.611 2.769 1.017 1.205 1.10 0.30

Cd 2.271 12.28 3.271 0.844 0.662 0.247 0.262 0.60 0.13

Sn 2.585 8.03 2.447 2.24 3.844 1.492 1.109 6.30 1.25

Sb 1.043 6.65 1.549 0.618 0.822 0.252 0.268 0.76 0.15

Cs 1.399 0.97 0.323 0.684 0.966 0.331 0.975 1.80 0.50

Ba 310.491 945.10 319.103 78.281 59.788 19.852 116.389 247.70 51.96

La 17.657 16.82 4.766 19.72 12.070 4.831 9.705 17.40 3.08

Ce 37.404 31.60 8.812 41.252 24.908 8.717 21.951 33.02 6.19

Tl 0.288 0.80 0.194 0.44 0.812 0.264 0.145 0.33 0.06

Pb 65.834 211.57 51.784 41.262 34.655 13.093 21.176 42.98 12.92

Bi 0.421 0.51 0.128 0.554 1.365 0.440 0.284 1.46 0.25

Th 3.512 7.36 1.715 1.59 1.444 0.595 2.577 3.65 0.90

U 0.925 0.63 0.171 1.086 0.384 0.144 0.493 1.08 0.20

Hg (ng g-1) 645.794 2,289.56 597.002 1,634.801 8,345.519 2,842.725 2,494.577 57,743.92 10,312.46

All mean values are in lg g-1, except for those with indicated percentages or ng g-1

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barite supports the conclusion that Ba is naturally present

in investigated sediments. Similar conclusions could be

reached for Cr whose concentrations are lower in stream

sediments than in flysch sandstones. The highest measured

Cr concentrations are in the Reka river sediments that drain

the Brkini area in which sandstones generally have higher

Cr values. Cr is concentrated in chromium spinel, a key

mineral in ophiolitic detritus which was more abundant in

Brkini flysch sandstones than in sandstones from other NW

External Dinarides flysch basins (Mikes et al. 2006). Ele-

vated concentrations of Ni, another element that indicates

ultramafic–mafic detritus origin, in the Reka river sedi-

ments are also in accordance with that.

The only element which has elevated concentrations

in some sediment samples, which for the moment could

not be explained by natural processes, is mercury. This

can be said in spite of the fact that Idrija, where one of

the biggest Hg mines in the world was located, is

roughly 50 km away from the investigated area. Even

closer, about 30 km, is Trsce where Hg ore occurrences

are known. But both of these occurrences are within

rocks formations which are not present in the analyzed

area and drain to other watersheds. Analyses of two

marls collected upstream of Ilirska Bistrica showed that

their Hg content is very low: 87 and 25 ng g-1,

respectively. Apart from that, there is no available data

on Hg concentration in source rocks, but in the soils

from the surroundings of nearby town Rijeka values

Table 4 Comparison of mean concentrations of potentially toxic

elements in regions a, b and c with sediment quality criteria (SMSP

and FALCONBRIDGE NC SAS 2005); all values except Fe are in

lg g-1

Element Mean

region a

Mean

region b

Mean

region c

The

lowest

toxic

effects

Significant

toxic

effects

Cr 44.60 38.54 44.90 26 110

Mn 1,966.18 1,219.86 968.81 460 1,100

Fe % 4.06 3.35 2.66 2.12 4.38

Ni 58.84 45.16 85.58 35 75

Cu 56.93 20.66 28.88 28 110

Zn 576.51 82.95 70.43 90 200

As 20.06 14.39 6.54 6 33

Cd 2.27 0.84 0.26 0.6 10

Ba 310.49 78.28 116.39 20 60

Pb 65.83 41.26 21.18 31 250

Hg 0.646 1.634 2.495 0.2 2

Table 5 Anomalies in sediments of regions a–c determined by boxplot method

Sample no. Location Anomaly

Extreme Outlier

Region a Celje industrial region

2 Voglajna, Gorica Mn –

3 Voglajna, Vrbno – P, Sn

4 Voglajna, Teharje-Store vmass, Mo, Sb, IRM P, Cr, Cu, Re, Pb, Bi, W

5 Savinja, Temerje Zn, Au Ag

47 Dobrinjski Potok, Hrastje Th Li, Mn, Ga

48 Locnica, Lipovec – V, Mn, Th, Yb

49 Voglajna, Celje B, Na, Co, Zn, Se, Zr, Cd, In, Pb, Tl vmass, Cu, Hg, IRM

79 Hudinja, Celje B Co, Cu, Se, Cd, Sb, Ba, Tl, W

80 Hudinja, Sp. Hudinja – Ba

Region b Slovenian karstic rivers

38 Unec, near Planina Hg –

Region c Flysch and alogene rivers of Croatia and Slovenia

13 Reka, Topolc Hg, IRM vmass, Zn

14 Reka, Ribnica Hg Zn

15 Reka, Gornje Lezece Hg Zn

16 Reka, Vreme Hg –

53 Reka, Donja Bitnja Hg Cu, Zn

54 Reka, Suhorje Cu, Hg Zn

56 Suhorica, near Padez – Cu

112 Rasa, downstream Most Rasa – IRM

All studied locations (samples) which are not included in table do not show any anomaly

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higher than 170 ng g-1 were only rarely observed, and

the median value for Croatian soils is 60 ng g-1 (Ha-

lamic and Miko 2009). Therefore, it can be presumed

that some of the highest measured values (i.e., 57,800 ng

g-1 in sample 15) indicate some pollution especially due

the fact that sediments taken closer to the river sources

(i.e., sample 12) have significantly lower Hg concentra-

tions. Possibly, the elevated concentrations are the result

of agriculture, in which mercury is used among other

ways as a foliar spray against plant diseases. Other

possible explanation is that Hg originates from inade-

quate waste dump of organic acids factory in Ilirska

Bistrica. The factory was closed in 1990 but deposited

waste influenced the environment long after the factory

closure (Soltes 2010). For more reliable conclusions

about the origin of Hg in investigated sediments, more

detailed sampling of stream sediments and source rocks

is needed.

Such conclusions raise a question about usage of the

available quality criteria for freshwater sediments (SMSP

and FALCONBRIDGE NC SAS 2005). In our case,

obviously unpolluted river sediments and even rocks from

which they have been derived have some element con-

centrations that are supposed to have possibility to cause

even significant toxic effect. Use of such criteria which are

based merely on concentrations and not taking in account

the bioavailability of elements should be done with

judiciousness.

Discussion of magnetic properties of sediments

in context of their geochemical and mineral composition

In the current discussion, we refer to our earlier papers

(Franciskovic-Bilinski et al. 2003, 2006, 2007), in which

geochemistry and mineralogy of here studied sediments

was described.

Earlier investigations in the Celje area (Franciskovic-

Bilinski et al. 2006) described in details the contamination of

river sediments with following toxic metals for which are

given their maximal measured values: Zn (1,040 lg g-1),

Cd (7 lg g-1), Cu (138 lg g-1), Ni (82 lg g-1), Pb

(133 lg g-1), Ag (3 lg g-1), Hg (1,086 ng g-1) and As

(30 lg g-1). An extreme MS value is observed in Voglajna

River at Teharje-Store, the point which showed significant

number of anomalies of toxic metals (Mo, Sb, P, Cr, Cu, Re,

Pb, Bi, W). Another outlier MS value was measured in Vo-

glajna River at Celje at the point which showed numerous

anomalies (B, Na, Co, Zn, Sc, Zr, Cd, In, Pb, Tl).

XRD mineralogical analysis showed that sediments of

the Celje area have mostly quartz as major mineral, with

relatively small amount of carbonate minerals, while in

sediments of karstic rivers carbonate minerals prevail.

According to Franciskovic-Bilinski et al. (2007), high

concentration of toxic elements Cd, Sb, Pb and Hg in

sample 18 in upper flow of the Rizana River could be of

concern; therefore, more sampling upstream can be sug-

gested. Magnetic susceptibility of these samples shows

values only slightly above the mean values for the

investigated flysch and alogene rivers. Therefore, low

value of MS does not always mean that there is no con-

tamination with some elements. Rasa, Mirna and Dragonja

represent clean environments according to most of MS

results. But sample 112 in the lower flow of the Rasa

River showed increased value of IRM (6.40 A/m), what

could be due to the influence of nearby Plomin coal power

plant. Coal combustion products which enter river systems

are known to cause increased magnetic susceptibility of

river sediments, what was investigated in details on the

case of Mreznica River, Croatia (Franciskovic-Bilinski

2008a).

The results of correlation analysis between element

concentrations and magnetic parameters vv (SI) and IRM

(A/m) for all three studied regions are presented in Table 6.

In the polluted Celje industrial region (Region a), signifi-

cant correlations of vv (SI) and IRM (A/m) were obtained

with S, Cr, Cu and Pb. Significant correlations were

obtained between vv (SI) and Al, Cr, Mn, Fe, Co, Ni, Cu,

Zn, As, Cd, Ba and Pb in Region b and between vv (SI) and

Mg, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn and Pb in Region c. It

is interesting to notice that in regions b and c, there is no

significant correlation between IRM (A/m) and any ele-

ment. Also, correlation of vv (SI) and Hg was not obtained

in any of studied regions; therefore, the magnetic method is

not applicable to detect all pollution sources, particularly of

mercury, unless there was mercury ore processing, like in

case of sample taken under smelter in town Idrija, Slovenia

(Franciskovic-Bilinski et al. 2005), which shows increased

MS.

Zhang et al. (2011) proved the correlation of elevated

MS and IRM values with heavy metal (Fe, V, Cr, Mo,

Zn, Pb, Cd, Cu) concentrations from industrial activities

(mainly the Fe-smelting plant) in Loudi City, Hunan

Province (China). They demonstrated that magnetic

parameters can be used as proxies for the anthropogenic

contribution of pollutants to the river sediments. But, in

contrast, they observed very weak correlations with Be,

Cs, Rb, Nd, Co, Ni and Ba, what indicate that these

metals stem from soil in the catchment region.

Dlouha et al. (2013) investigated polluted alluvial soils

by magnetic susceptibility methods on the example of the

Litavka River. Their research demonstrates a statistically

significant correlation between magnetic susceptibility and

soil concentration of Cu, Pb and Zn.

Research from the current paper is in accordance with

the research of other authors.

Environ Earth Sci

123

Author's personal copy

Conclusions

Magnetic susceptibility measurements as fast and simple

method for estimation of pollution with numerous toxic

elements in different environmental systems were for the

first time applied on stream sediments from several karstic

and flysch rivers of Croatia and Slovenia. The presented

results led to following conclusions:

– The highest values of all measured parameters are present

in the Celje industrial region with mass susceptibility

values ranging from 1.31 9 10-7 to 38.3 9 10-7 m3/kg

and IRM values ranging 0.91–100.42 A/m;

– Sediments of the clean karstic and flysch rivers showed

extremely low MS values, ranging from 0.5 9 10-7 to

5.11 9 10-7 m3/kg and IRM values ranging

0.7–7.88 A/m. The studied rivers were divided into

two groups, the Slovenian karstic rivers (Region b)

showed slightly higher MS values than flysch and

alogene rivers of Croatia and Slovenia (Region c);

– The results could serve as a database for the pollution

state of sediments with respect to toxic elements,

although not with Hg. No correlation of MS and Hg

was obtained; therefore, magnetic method is not

applicable to detect all pollution sources in the area,

particularly of mercury.

– Significant correlations were obtained between MS and

Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd and Ba in Region b;

between MS and Cr, Fe, Co, Ni and Zn in Region c.

In addition performed investigation gave information on

chemical composition of stream sediments for unpolluted

karst and flysch rivers in Notranjska and Istria regions

which will be available for further environmental studies.

In some sediments, elevated concentrations, in comparison

with available quality criteria for freshwater sediments

(SMSP and FALCONBRIDGE NC SAS 2005) of several

elements, were recorded. Careful analysis of elevated

concentrations for several elements (e.g., Ba, Cr and Ni)

shows that they are most probably the result of natural

processes and that they do not indicate any pollution.

Additional sampling of stream sediments and their

source rocks is necessary for obtaining answers about the

origin of elevated concentrations of other elements (e.g.,

Cu and Hg).

Acknowledgments Field work was organized within the Croatian–

Slovenian bilateral project (2001–2003), principal investigators H.

Bilinski and D. Hanzel. Magnetic measurements were performed at

the Montanuniversitat Leoben and at its Paleomagnetic Laboratory in

Gams. A short stay of S. F–B. in Austria was covered from the

Croatian–Austrian bilateral project (2010-2011), principal investiga-

tors S. Franciskovic-Bilinski and T. Hofmann. Additional expenses

were covered from projects of Croatian Ministry of Science Educa-

tion and Sport No. 098-0982934-2720 (Principal investigator I.

Pizeta) and No. 119-1191155-1156 (Principal investigator D. Balen).Ta

ble

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a,b

and

c

Mg

Al

SK

Ca

Cr

Mn

Fe

Co

Ni

Cu

Zn

As

Cd

Ba

Pb

Hg

Reg

ion

aV

v(S

I)-

0.1

6-

0.2

40

.61

-0

.12

0.0

50

.62

-0

.08

0.3

30

.12

0.2

40

.68

0.1

20

.12

0.2

3-

0.0

70

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0.2

8

Reg

ion

aIR

M(A

/m)

-0

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-0

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0.5

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0.1

40

.02

0.6

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0.0

60

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0.6

60

.11

0.1

20

.22

-0

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50

.29

Reg

ion

bV

v(S

I)2

0.7

60

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0.0

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0.8

90

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0.7

90

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0.8

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0.5

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ion

bIR

M(A

/m)

-0

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Environ Earth Sci

123

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Authors are grateful to R. Koscal for preparing graphics. We also

thank three anonymous reviewers, whose suggestions helped a lot to

improve the overall quality of manuscript.

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