Distribution of Heavy Metals (Cd, Cu, Co, Cr, Hg, Mn, Ni, Pb, Zn, and As) in Overbank Sediments of Tributaries (in )

Božidar V. Đokić (  [email protected] ) Geological Survey of Serbia https://orcid.org/0000-0002-0162-7433 Dragana Vidojević Serbian Environmental Protection Agency Olivera Đokić Highway Institute https://orcid.org/0000-0002-8464-3673

Research Article

Keywords: overbank sediments, geological and pedological composition, factor analysis, Spearman’s rank correlation

Posted Date: August 25th, 2021

DOI: https://doi.org/10.21203/rs.3.rs-821344/v1

License:   This work is licensed under a Creative Commons Attribution 4.0 International License. Read Full License

Page 1/21 Abstract

The Ibar River is an international river whose watercourse passes next to numerous technogenic landflls and chemical-industrial complexes. They can affect the quality of water in the river, as well as the quality of overbank sediments. The river fows into the River near and it represents its largest tributary. The analysis of the overbank sediments of Ibar tributaries showed high concentration of heavy metals at some points. The statistical analysis of the content determined the existence of two synthetic factors around which heavy metals were concentrated. The comparison of the chemical composition of overbank sediment with the composition of geological and pedological substratum on which they were developed showed that the increased concentrations of heavy metals were mostly a product of geological and pedological composition of the river’s substratum and basin, and had no connection with (possible) anthropogenic factors. However, due to the sensitivity and proximity of potential pollutants, the necessity to constantly monitor chemical composition of overbank sediments in the river basin was determined.

Introduction

The Ibar River is an international river. Its river source is located on the Mountain in at an altitude of 2,400 m. It fows through Montenegro and Serbia. In , near Kraljevo, it fows into the West Morava River as its largest tributary. The upper, middle, and lower course can be differentiated. The upper course is located mostly in Montenegro and only partly in Serbia ( and ). The middle and lower course of the river were investigated in this paper. The river often fows through narrow and not easily accessible gorges. A 110 m high dam was built 24 km upstream from Kosovska Mitrovica on the Ibar, and because of this, the artifcial lake Gazivode was created. The total length of Ibar is 276 km, and the river’s basin surface area is 8,059 km2 (Fig. 1). Larger tributaries in Serbia are River, Rudnjačka River, Raška River, River, Jošanica River, River, and River.

The Ibar River fows through areas with specifc geomorphological structure. The infow of wastewater, which originates from mining-industrial complexes, tailings, intensive agriculture, illegal landfll sites, etc., into the river basin is high. Due to orography, the river often overfows. Numerous studies indicate that more than 12% of watercourses that belong to the Ibar River basin are susceptible to fooding (Dragićević et al. 2019). When the water that fooded the area retreats, it leaves pollutants behind. Numerous studies have confrmed this. There are few studies that investigate the direct origin and chemical composition of this material.

The middle course of Ibar has a high infow of industrial wastewater that originates from the wider area of Kosovska Mitrovica, Zvečan, and Leposavić. Waters from the wider area of Kosovska Mitrovica come from several mining-metallurgical-chemical plants and landflls of Trepča Mines. The watercourse passes by the Pb-Zn ore fotation tailings site in Leposavić and further downstream next to the fotation and fotation tailings of Suva Ruda ( and Kukanjica streams). The contouring showed that the

Page 2/21 Rudnica tailings covered the area of 18 hectares 79 acres 8 m2. The granulometric composition of the tailings content showed that it consisted of siltstone / sand. The content of chalcopyrite was three times higher than content of andradite in one part of the tailings site, while other minerals were less present. In other part of the site quartz and gypsum were equally present, and in the third part of the site quartz was predominant. The distribution of heavy metals in the tailings site did not exhibit any patterns. One part of the site had elevated U content compared to the natural background radiation. Kukanjica Stream tailings covers the area of 10 hectares 48 acres 9 m2. The granulometric composition showed the presence of clay/ siltstone. The X-ray analysis determined that quartz was predominant compared to clay, siderite, pyrite, gypsum, and ankerite, and feldspars and calcite occurred locally. Hydro-chemical analysis showed increased contents of Pb, Zn, and Fe compared to standards for class II water, while the concentrations of As and Sb were above the allowed for class IV waters. The soil samples from the area surrounding the tailings site contained the concentrations of Zn and As in the phytotoxic range, and Co, Cr, Sb, Sn, Cu, and Cd had increased content locally (Đokić 2011, Đokić et al. 2013).

The tailings sites are located in (), Jarandol, Pobrdje, , , and Korlaća. Wastewaters from these tailings fow directly into the Ibar. Jarandol and Progorelica tailings were created as a result of the exploitation of coal. The exploitation began at the end of the 19th century. The areas of initial exploitation and tailings were spontaneously recultivated with pioneer plants. The mean U and Th content at this site is higher compared to their mean content in the earth’s crust. The excavated coal at the Piskanje location is refned by separation process. The tailings site for boron minerals is located at Pobrdje. This site was formed after manual sorting of the excavated ore. Hydro- chemical analysis showed increased content of Fe and Pb, and increased contents of Zn, Cu, Cd, Cr, Co, Ni, Sb, As, and Hg were high as well. Bela Stena tailings site was formed after the exploitation of magnesite during the last twenty years of the 20th century. The tailings site at Korlaća was formed after the exploitation and processing of asbestos (Đokić 2011).

The lower course of Ibar receives the infow of industrial and communal waters from Raška and Baljevac (Nikolić et al. 2014). Ibar is polluted by industrial wastewaters that originate from dairy and meat industries, municipal wastewater, etc. The river passes by 47 settlements in its middle and lower course which endanger the quality of the water and its sediments (Nikolić et al. 2014). All in all, the river is polluted by industrial, agricultural, and municipal wastewaters.

The construction of several hydroelectric power plants is planned on the Ibar. Numerous analyses have been performed on how these hydroelectric power plants could affect the quality of water. The conclusion was that the planned accumulations would prevent the formation of the stable thermal stratifcation during the warmer part of the year, which would further impede the full realization of eutrophication potential (Jaćimović et al. 2014).

The quality of the water in river is systematically and continuously controlled by measuring the parameters that infuence it the most, which are the concentrations of Pb, Cu, Ni, Co, Cd, Mn, Zn, Cr, and Hg. These measurements are performed at several locations along the Ibar watercourse (SEPA 2019).

Page 3/21 The suspended material transported by the river during the food, which is frequent, is deposited as the overbank sediment in the soil on the banks of the Ibar. This sediment, most of all, affects the chemical properties of the soil. However, the geological stratum on which the soil is developed has the greatest infuence on the structure and mineral and chemical composition of the soil (Dorfer et al. 2018a, Dorfer et al. 2018b). The climate also has considerable infuence on these properties (Gore 2009).

The overbank sediment is a food sediment formed under the conditions of higher energy of relief from the material transported in the suspension. The overbank sediment is a complex, dynamic system susceptible to changes.

The tributaries of Ibar often have the characteristics of a torrent, which can cause the mixing of materials (overbank sediments) (Veljković et al. 2019, Peh and Miko 2001). Heavy metals found in overbank sediments can be remobilized in different ways (e.g. during new foods) and can again become a source of contamination (Adánez Sanjuán et al. 2018).

These tributaries also fow through numerous settlements and receive their wastewaters. This way they directly or indirectly affect the quality of the water in Ibar and the quality of the sediment as well. The sources of the pollution can be diffuse, point, and combined, and in the case of this river, they are combined. The regularity of the increased presence of heavy metals (Cd, Cu, Co, Cr, Hg, Mn, Ni, Pb, Zn, and As) in the overbank sediments of the tributaries of Ibar was analyzed in this paper.

Materials And Methods

Sampling

The collection of the samples was performed according to the recommendations for the drawing of the Geochemical Map of Serbia 1:500,000, stream, overbank, and foodplain sediments (Đokić 2016). The coordinates for the sampling were determined using a GARMIN-GPSmap60CSx. The depth of sample collection was from 0 to 10 cm. To avoid the infuence of organic matter, samples were collected under the layer of humus. The collection was performed by an Eijkelkamp probe with a nozzle for soil testing and a spade with a stainless steel blade. Each sample consisted of 10 subsamples which were homogenized in the feld. A total of 75 samples (750 subsamples) were collected. The samples collected for the realization of the project Geochemical Map of Serbia 1:500,000, stream, overbank, and foodplain sediments were used in this study (Đokić 2017, Đokić 2018).

Analytical procedures, methods, and concentrations

The samples were dried at room temperature under atmospheric conditions for 60 days, and then they were quartered. The reduced sample was dried in a porcelain dish, in a laboratory dryer at 40° C. The sample weighing 100 g was ground and then sieved to a grain size of ˂100µm. The sample was then chemically analyzed.

Page 4/21 The chemical analyses of the samples were performed in an accredited laboratory for chemical testing at the Institute of Mining and Metallurgy Bor. Cobalt (Co), cadmium (Cd), copper (Cu), lead (Pb), nickel (Ni), mercury (Hg), zinc (Zn), and arsenic (As) were examined by Inductively Coupled Plasma Mass Spectroscopy (ICP-MS), and chromium (Cr) and manganese (Mn) by X-Ray Fluorescence (XRF). The lower limit for determination of Zn and Mn was 0.001%; As <1 mg/l; Pb and Cu <0.5 mg/l; Ni, Hg, Co, and Cr <0.1 mg/l; and Cd <0.05 mg/l (Đokić 2017, Đokić 2018).

Data analysis

The concentrations of heavy metals in overbank sediments were analyzed in this paper. The reference values were obtained from the Serbian standard (Ofcial Gazette of the RS 2012). The reference values represent target values and maximum permissible values. The target value is the limit value of the concentration of the pollutant below which negative effect on the environment can be neglected. The maximum permissible value of pollutant concentration is the value above which negative impacts on the environment are likely (Ofcial Gazette of the RS 2012, Veljković et al. 2019).

Data analysis was performed by multivariate statistical analysis (factor analysis).

The factor analysis consisted of:

Normality test of distribution (10 selected elements from 75 locations connected to the tributaries of Ibar). Due to the number of samples (75), the Shapiro–Wilk test was used. (Based on the obtained level of signifcance, as well as histogram and diagram of normality, the assumption of normality of distribution was determined); Ln transformation of concentrations (variables). (Based on the obtained level of signifcance of Ln transformation values, the assumption of normality of distribution was determined); Determination of Spearman's rank correlation of Ln transformation of data in order to determine the correlation at the standard level of signifcance (possible error up to 5%). The scale for the interpretation of correlation coefcient was from 0 to 0.4 as weak positive correlation, from 0.4 to 0.75 moderate positive correlation, from 0.75 to 0.85 good positive correlation, and higher than 0.85 as excellent positive correlation. The other part of the scale was from 0 to -0.4 as weak negative correlation, from -0.4 to -0.75 moderate negative correlation, from -0.75 to -0.85 good negative correlation, and lower than -0.85 as excellent negative correlation; Determination of the synthetic groups around which the investigated heavy metals were concentrated, their bond; Exploratory factor analysis on Ln transformation of concentrations. Varimax rotation was performed for a more even distribution between the components. Based on the exploratory analysis by the extraction method, the factors around which the elements were grouped were singled out; Filling factor estimation matrix to determine the links between elements and factors; and Confrmatory factor analysis to confrm the percentage of variance grouped into wholes and determine (degree) the signifcance of variables for the factors. Page 5/21 Results

The concentrations of the tested heavy metals were grouped into concentration intervals. The length of the group interval was determined using the Sturge’s rule: k=1+3.332logN.

Based on the number of intervals, the width of the interval was calculated: i=Xmax - Xmin/k where: Xmax and Xmin are the highest and lowest feature values in the series (Mutavdžić and Nikolić-Đorić 2018).

The intervals are shown on the principle of equal numbers.

Geographical, geological, and pedological background

Description of the larger tributaries of the Ibar River in Serbia

The tributaries of Ibar often form smaller basins. The basins of the following rivers were included in this paper: Raška, Brvenica, Jošanica, Gokčanica, Studenica, Rudnjačka River, and Ribnica. Data on the overbank sediments for the Sitnica River basin (Kosovo and Metohija) were not included.

SITNICA RIVER BASIN. The length of the river is 90 km, and it covers the surface area of 2,861 km2 (Veselaj and Morina 2006). It has the characteristics of rivers that fow through valleys (alluvial rivers) (small fall height, shallow winding river bed susceptible to foods). Sitnica is the largest and most polluted river in Kosovo and Metohija. The reason for this is a large number of landflls, primarily those that belong to the Kosovo Energy Corporation. Studies that have analyzed its chemical composition indicated that there was a periodical increase of Pb, Zn, Cd, and Cu contents (Arbneshi et al. 2007). The outfows of mine tailings into Sitnica are frequent occurrence. Thirty-nine collective and nine individual pollutants were found in the region of Mitrovica. The largest pollutant is the Stari Trg Mine, tailings site, and commercial yard of the chemical plant. The water in this basin has the characteristics of high acidity and presence of heavy metals (Veselaj and Morina 2006).

Increased concentrations of phenol (organic pollutant) and other organochlorine compounds have been often recorded in Sitnica. These compounds were found in Ibar near the town of Kraljevo, and in the wells of the Kraljevo waterworks as well. The overbank sediments from the Sitnica River basin were not investigated in this paper.

RAŠKA RIVER BASIN. The source of the river is located on the slopes of Pester plateau. There is a tailings site in the basin of the river formed after the exploitation of andesite in Velika Bisina. A tailings site is also formed in due to the surface and underground exploitation of ultrabasite (specifcally dunite) (Đokić 2011). The city of is supplied with drinking water from the spring of

Page 6/21 Raška (Beta 2019). The length of the river from its source to the mouth of the river near the town of Raska is 60 km, and the total area the basin covers 1,193 km2. The spring of the river was used for the needs of the Ras hydroelectric power plant in 1953, and a 4.5-km-long supply tunnel was built. The quality of the water is signifcantly lower downstream of the collectors in Novi Pazar. It is the most polluted in winter and autumn (Marinović and Rašljanin 2010). In certain parts the quality of the water corresponds to class V – sewage water (Korhner 2013). Smaller watercourses that form this basin are: Ljudska River I, II, III, IV, and V, Raška I, II, III, and IV, Dramićki Stream, Kuzmićka River, Đurićka River, Šaronjska River, Deževska River I and II, Nosoljinska River, Tušimska River, Kosurička River, Rečice, Trnavska River, Sebimiljska River, Jošanica I and II, Brezovačka River, Sebečevska River, Trnavska River I, II, and III, Izbička River, and Jovska River (Fig. 1).

BRVENICA RIVER BASIN. The river Brvenica (also known as ) is formed by merging of Gradačka and Kruševačka rivers on the south side of the mountain Radočela. The tailings site formed by the exploitation of dolomite is located in the area of the village Gradac which is established on the river (Đokić 2011). The quality of water is systematically controlled in several locations (SEPA 2019). The quality of this water belongs to category 1A (Korhner 2013). The length of the river is 25.5 km and it cover the surface area of 133 km2. The smaller watercourses that form this basin are Andrićka River, Vrani Stream, Borovićka River, Jablanovićka River, Lučka River, Kruševićka River, Gradačka River, Klisurski Stream, Brvenica I and II, Zarički Stream (Fig.1).

JOŠANICA RIVER BASIN. The river Jošanica is formed by merging of Kriva and Pločanska rivers. The length of the river is 17 km and it covers the surface area of 257.61 km2 (Vuckovic 2021). The quality of water in Jošanica is continuously determined in several locations by measuring the parameters that have the greatest impact on its quality (SEPA 2019). The construction of 15 small hydro power plants of derivative type is planned, which will greatly change the characteristics of the river. Smaller watercourses that form the basin are Jošanica III, Planska River I, Gobeljska River, Lužnjanski Stream, Veleštica, and Samokovka River (Fig. 1).

GOKČANICA RIVER BASIN. The river Gokčanica is formed by merging Predolska and Kolska rivers. The length of the river is 4.6 km (Lukić et al. 2015). The watercourses that form the basin are Rudnjačka River, Dubovski Stream, Zastupski Stream, and Gokčanica (Fig. 1).

STUDENICA RIVER BASIN. The source of the Studenica River is located on the mountain in the place called Odvraćenica. The length of the river is 57.6 km, and it covers the surface area of 582 km2. Its valley is very narrow and deep. The quality of water in Studenica is systematically controlled (SEPA 2019). The construction of several small hydro power plants of derivative type is planned at different locations. Smaller watercourses that form the basin are Raduše I and II, Brevina, and Studenica River (Fig. 1).

RUDNJAČKA RIVER BASIN. The Rudnjačka River originates on the west side of and it is formed by merging Linska and Barska rivers in a hardly accessible place (Korhner 2013). The length of the river is

Page 7/21 1.5 km (Lukić et al. 2015).. The construction of small hydro power plants of derivative type is planned at several locations (Tomić 2016). Smaller watercourses that form this basin are Rudnjačka and Lisinska rivers (Fig. 1).

RIBNICA RIVER BASIN. The length of this river is 26 km and it covers the surface of 115 km2. Its upper and middle courses are located in the mountain area and they have the characteristics of a torrent in some parts. The lower course is calm with the characteristic of a lake (Fig. 2). The quality of the river water is constantly controlled (SEPA 2019).

Other smaller watercourses whose sediments were tested were Ibar I and II, Jarandolski Stream, Varevski Stream, Kaznovićka River, Gajovska River, Brezanska River, Krivačka River, Popova River, Planska River, Maglašnica, , Pivnica, Vrški Stream, Pavlićka River, and Kneževićki Stream (Fig. 1).

Geological and pedological structure of the investigated area

Geological heterogeneity of the Ibar tributaries environment can have a great effect on the chemical composition of overbank sediments (Fig.2). The physical size of the basins does not have to affect the (increased) presence of the analyzed heavy metals (Cd, Cu, Co, Cr, Hg, Mn, Ni, Pb, Zn, and As) in overbank sediments. Table 1 shows the geological composition of the smaller basins of the tributaries.

The immediate sampling site may affect the chemical composition of overbank sediments. Table 2 shows the local geological structure of the immediate sampling sites for sediments in the investigated watercourses.

Table 3 shows the occurrence of mineral raw materials that were found during geological mapping and drawing of metallogenic maps (Vanđel et al. 1981).

The geological stratum has signifcant infuence on the formation of the soil. Due to the heterogeneous geological structure, overbank sediments were collected from different soil types (Table 4, Fig. 3,) (Tanasijević 2011).

The geological composition of stratum, as well as geological and pedological processes, are the main reasons for the existence of different concentrations of heavy metals in soils formed on different rocks.

The content of cadmium found in the Earth’s crust amounts to 0.1 mg/kg, and in unpolluted soil up to 0.35 mg/kg. The highest content can be found in soil formed on sedimentary rocks (0.3-11 mg/kg). Phytotoxic concentrations of cadmium in soil on the surface amount to 3- 8 mg/kg (Goldschmidt 1954, Mason 1966, Jović and Jovanović 2004). The content of copper in the upper part of the lithosphere measures from 70-128 mg/kg, while in unpolluted soil it amounts to 30 mg/kg. However, in the contaminated soil, the content of this element can be higher than 100 mg/kg. Phytotoxic concentrations of copper in soil on surface can be from 60-125 mg/kg (Goldschmidt 1954, Mason 1966, Jović and Jovanović 2004). The average cobalt content in the earth's crust is 30 mg/kg, and in the soil it can range from 1-100 mg/kg. Phytotoxic concentrations of cobalt in soil on surface can reach 25-50

Page 8/21 mg/kg (Goldschmidt 1954, Mason 1966, Jović and Jovanović 2004). The range of chromium concentrations is 7-1,500 mg/kg, and the mean content is 50 mg/kg. It is mostly found in ultrabasic rocks and serpentinite (1,600-3,400 mg/kg). Phytotoxic concentrations of chromium in soil on the surface amount to 75-100 mg/kg (Goldschmidt 1954, Mason 1966, Jović and Jovanović 2004). Mercury in unpolluted soil can be found in the concentration range from 0.01-0.5 ug/kg, and in the polluted soil it ranges from 0.5-50 ug/kg. The mean content value in clastic rocks is 300 ug/kg, in carbonate rocks 200 ug/kg, and in clay sediments 400 mg/kg (Mason 1966). The sources of the mercury in the environment are industrial plants that use it in the technological process (Jović and Jovanović 2004). The content of manganese found in the Earth’s crust amounts to 950 mg/kg (Mason 1966). It can occur with oxides and hydroxides of iron and clay minerals with which it often forms a bond with microelements by adsorption (Jović and Jovanović 2004). In normal unpolluted soil, nickel concentrations measure 50 mg/kg, in soil developed on serpentinite 0.1-2%, and in mining areas 100-500 mg/kg (Cox 1995). The average lead content in the earth's crust is 14 mg/kg, and in unpolluted soil 2-200 ug/kg. Phytotoxic concentrations of lead in soils on surface are 100-400 mg/kg (Goldschmidt 1954, Mason 1966). The average zinc content in the earth's crust is 75 mg/kg, while in the soil it is 30-1,000 mg/kg. Phytotoxic concentrations of zinc in soils on surface are 70-400 mg/kg (Goldschmidt 1954, Mason 1966, Jović and Jovanović 2004). The average content of arsenic in the earth's crust is 1.5 mg/kg, and the concentrations in unpolluted soil range from 1-10 mg/kg. Phytotoxic total concentrations of arsenic in soils on surface amount to 15-50 mg/kg (Goldschmidt 1954, Mason 1966, Jović and Jovanović 2004).

Results And Discussion

Heavy metals in overbank sediments

CADMIUM. This heavy metal occurs in contents higher than the maximum permissible value allows (6.4 mg / kg, (Ofcial Gazette of the RS 2012) in sediments found in the Rudnjačka river basin (Lisinska River - 7.5 mg / kg). The contents higher than target value allows (0.8 mg/kg, (Ofcial Gazette of the RS 2012)) can be found in sediments from Gajovska and Kaznovićka rivers, in Jošanica river basin (maximum value obtained for Samokovka river), Maglašnica, Planska River II, and in Rudnjačka river basin (Rudnica). Somewhat lower contents, but still higher than the target value, were found in Raška river basin (Dramićki Stream), and in the sediments from Ibar I and II and Pavlićka River. The contents below the detection limit of the used method were found in sediments from the Raška river basin (Ljudska River I, II, and II), Raška (I and II), Đurićka, Šaronjska and Deževska River I and II, and Nosoljinska River. The content of Cd in half of the sediment samples was between 0.29 mg/kg and 0.53 mg/kg (Fig.4).

COPPER. This heavy metal occurs in contents extremely higher than the maximum permissible value allows (110 mg/kg, (Ofcial Gazette of the RS 2012)) in Rudnjačka river basin (Lisinska River – 865.50 mg/kg), Raška river basin (Kosurička River and slightly lower content in Ljudska River V), Jošanica river basin (Samokovka), Brvenica river basin (Andrićka River, Vrani Stream and Borićka River, and slightly lower content in Jablanovićka, Kruševićka, and Gradačka rivers). Content higher than the target value (36 mg/kg, (Ofcial Gazette of the RS 2012)), but lower than maximum permissible value was discovered in

Page 9/21 Raška river basin (Dramićki Stream, Nosoljinska River, Trnavska River, Sebimiljska River, Brezovačka River, Raška III and V, Trnavska River I and III, Izbička River, and Jovska River), Brvenica river basin (Klisurski Stream, Brvenica I, Zarički Stream), Studenica river basin (Raduše I, Brevina), Kaznovićka River, Jošanica river basin (Jošanica III, Planska River I, Gobeljska River, Lužnjanski Stream, Veleštica), Rudnjačka river basin (Rudnica), Gokčanica river basin (Zastupski Stream), Popova River, Planska River II, Maglašnica, Pavlićka River, and Ibar II sediments. The content of Cu in half of the sediment samples was in the range from 28.7 mg / kg to 83.8 mg / kg (Fig. 4).

COBALT. This heavy metal is not included in the regulation that defnes the limit of concentrations in sediments in Serbia (Ofcial Gazette of the RS 2012). However, due to its high toxicity, it was included in this paper. The extremely high concentrations were discovered in the Krivačka and Raška (Rečica) river basins. High concentrations were found in the Brezanska River, the Brvenica river basin (Klisurski Stream), Gokčanica river basin (Rudnjačka River, Zastupski Stream, and Dubovski Stream), Popova River, and Pivnica. The content of cobalt in half of the sediment samples was in the range from18 mg/kg to 56 mg/kg (Fig. 4).

CHROMIUM. This heavy metal was found in extremely high concentrations in sediments from Raška river basin (Rečica) and Krivačka River. Contents higher than the maximum permissible value (240 mg/kg, (Ofcial Gazette of the RS 2012)) was present in sediments from Raška river basin (Nosoljinska River, Tušimska River, Trnavska River I and III, Sebimiljska River, and Jovska River), Brvenica river basin (Jablanovićka River, Andrićka River, Vrani Stream, Borovićka River, Kruševićka River, Gradačka River, Klisurski Stream, Brvenica I and II), Jošanica River basin (Planska River I, Gobeljska River, Veleštica, and Samokovka), Studenica river basin (Brevina and Studenica), Gokčanica river basin (Rudnjačka River, Dubovski Stream, Zastupski Stream, and Gokčanica), and in Kaznovićka, Gajovska, Brezanska, and Popova rivers, Planska River II, Maglašnica, Lopatnica, Pivnica, Ibar I and II, and Ribnica. In concentrations between the target value (100 mg / kg, (Ofcial Gazette of the RS 2012)) and maximum permissible value, chromium occurred in sediments from the Raška river basin (Ljudska River I, III, IV, and V, Dramićki Stream, Đurićka River, Šaronjska River, Deževska River I and II, Raška II and V, Kosurička River, Brezovačka River, Trnavska River I, Izbička River), Brvenica river basin (Lučka River and Zarički Stream), Studenica river basin (Raduša I and II), and Jošanica river basin (Gobeljska River). The content of chromium in half of the sediment samples was higher than the target value and it ranged from 111 mg / kg to 675 mg / kg (Fig. 4).

MERCURY. The maximum concentration for mercury (1.4 mg/kg) was found in the sediments from Maglašnica. In the range above the target value (0.3 mg / kg, (Ofcial Gazette of the RS 2012)) and lower than maximum permissible value (1.6 mg / kg, (Ofcial Gazette of the RS 2012)), it was discovered in the sediments of the Brvenica river basin (Andrićka River, Jablanovićka River, Brvenica I and II, and Zarički Stream), Jarandolski Stream, Gajovska River, Maglašnica, and Kneževićki Stream. The contents below the detection limit of the used method were found in sediments from the Raška river basin (Šaronjska River, Deževska River I and II, Nosoljinska River, Raška II, Kosurička River, Trnavska River, and Izbička River), Brvenica river basin (Klisurski Stream), Studenica river basin (Brevina), Jošanica river basin

Page 10/21 (Lužnjanski Stream and Veleštica), Rudnjačka river basin (Lisinska River), Gokčanica river basin (Dubovski Stream, Zastupski Stream, and Gokčanica), and in the Krivačka and Popova rivers, Planska River II, Lopatnica, Pivnica, Vrški Stream, Pavlićka River, Kneževićki Stream, Ibar I and II, and Ribnica (Fig. 4).

MANGANESE. This heavy metal was not included in the regulation on limit values for pollutants (Ofcial Gazette of the RS 2012). The literature suggested that the content from 1,500 to 3,000 mg/kg can be toxic (Kabata-Pendias and Pendias 1984). It can be mobilized into the soil from the sediment. These high contents were found in the Raška river basin (Dramićki Stream, Tušminska River, and Jovski Stream), Brvenica river basin (Vrani Stream and Borovića River), Studenica river basin (Brevina), Jošanica river basin (Jošanica II and Lužnjaski Stream), Rudnjačka river basin (Lisinska River) and in Kaznovića River, Krivačka River, Planska River I and II, and Maglašnica. The content of this metal in half of the sediment samples was in the range from 929.90 mg / kg to 1,312.40 mg / kg (Fig. 4).

NICKEL. The samples from Raška river Basin (Raška IV) and Vrški Stream had contents of nickel lower than the target value (35 mg/kg, (Ofcial Gazette of the RS 2012)). Samples obtained from Raška river basin (Ljudska River I, II, and III, Raška I, II, and IV, Kuzmićka River, Sebečevska River, and Trnavska River) and Rudnjačka river basin (Lisinska River) had nickel concentrations in the range between the target values and maximum permissible values (44 mg/kg, (Ofcial Gazette of the RS 2012)). Extreme values for nickel were recorded in sediments from the Brvenica river basin (Klisurski Stream), Pivnica, Raška river basin (Rečica), and Gokčanica river basin (Rudnjačka River). The concentrations of the rest of the samples were higher than the maximum permissible value. The content of nickel in half of the sediment samples was signifcantly higher than the maximum permissible value and it was in the range from 63.3 mg/kg to 682.6 mg/kg (Fig. 4).

LEAD. The contents higher than maximum permissible value (310 mg / kg, (Ofcial Gazette of the RS 2012)) was found in sediments from Jošanica river basin (Samokovka), Gokčanica (Zastupski Stream and Gokčanica), and in Gajovska and Kaznovićka Rivers. The contents between the target value and maximum permissible value was discovered in sediments from Raška river basin (Kuzmićka River and Deževska River I), Jošanica river basin (Jošanica III and Veleštica), Rudnjačka river basin (Rudnica), and in Krivačka River, Planska River II, Maglašnica, Vrški Stream, Pavlićka River, and Ibar I and II. The rest of the sediment samples had the lead content lower than the target value. The content of lead in half of the samples was lower than the target value and it was in the range from 36.80 mg/kg to 79.00 mg/kg (fg.4).

ZINC. The contents of zinc higher than maximum permissible value (430 mg/kg, (Ofcial Gazette of the RS 2012)) were found in the sediments from Kaznovićka River, Jošanica river basin (Samokovka), Gajovska River, and Maglašnica. The concentration between the target value (140 mg/kg, (Ofcial Gazette of the RS 2012)) and maximum permissible value was discovered in the sediments from Raška river basin (Dramićki Stream, Kuzmićka River, and Kosurička River), Rudnjačka river basin (Rudnica and Lisinska River), Gokčanica river basin (Zastupski Stream and Gokčanica), Planska River II, Lopatnica,

Page 11/21 Pavlićka River, and Ibar I and II. In other sediment samples the concentrations were lower than the target value. The content of zinc in half of the samples was below the target value and it ranged from 81.5 mg/kg to 127.5 mg/kg (Fig. 4).

ARSENIC. The extremely high concentrations of arsenic were discovered in the sediments from Gajovska River, Rudnjačka river basin (Samokovka), Kaznovićka River, Maglašnica, Pavlićka River, Gokčanica river basin (Dubovski Stream and Zastupski Stream), and Planska River II. The contents of As between target value (29 mg/kg, (Ofcial Gazette of the RS 2012)) and maximum permissible value (42 mg / kg, (Ofcial Gazette of the RS 2012)) was found in sediments from the Raška river basin (Dramićki Stream, Deževska River I, and Jarandolski Stream), Jošanica river basin (Jošanica III and Planska River I), Rudnjačka river basin (Rudnica), and Gokčanica river basin (Zastupski Stream and Gokčanica). In other sediments the content of arsenic was lower than the target value. The content of arsenic in half of the sediment samples ranged from 15.3 mg/kg to 38.4 mg/kg (Fig.4).

Cadmium and mercury were below detection limit of the used method; cadmium in the overbank sediments from Ljudska River I, II, III, and IV, Raška I, Đurićka River, Šaronjska River, Deževska River I and II, Nosoljinska River, and Pivnica; and mercury in the sediments from Ibar and Ribnica, Šaronjska River, Deževska River I and II, Nosoljinska River, Raška River, Kosurička River, Klisurički Stream, Trnovska River, Brevina, Izbička River, Lužnjanski Stream, Veleštica, Lisinska River, Dubovski Stream, Zastupski Stream, Gokčanica, Krivačka River, Popova River, Planska River, Lopatnica, Pivnica, Vrški Stream, and Pavlićka River.

Factor analysis

Based on the obtained level of signifcance and visual review of the histogram for all 10 elements, it was determined that the assumption of normality of distribution could not accepted.

Based on the obtained level of signifcance and visual review of histogram, the Ln variables for transformation values showed that the assumption of the normality of distribution could not be accepted for any of the tested heavy metals.

Table 5 shows the values of Spearman’s rank correlation for the analyzed heavy metals.

EXPLORATORY factor analysis on Ln transformation values by the extraction method determined that the examined heavy metals in overbank sediments were grouped around two synthetic factors and that they defned 63.91% of the variance.

Based on the flling factor estimation matrix, it was determined that Cd, Zn, As, Pb, and Cu were concentrated around the frst synthetic factor, and Ni, Cr, and Co around the second factor.

CONFIRMATORY factor analysis confrmed that 68.96% of the variance could be explained by factor 1, and 95.16% by factor 2.

Page 12/21 FACTOR 1. Table 6 shows the signifcance of correlation between the elements (Cd, Zn, As, Pb, and Cu) concentrated around FACTOR 1.

Moderate positive correlation numerical values of Spearman’s rank correlation coefcient were obtained for Cd/Zn 0.635, Cd/-As 0.607, Cd/Pb 0.566, Zn/As 0.637, Zn/Pb 0.690, and As/Pb 0.655. Weak positive correlations were obtained for Zn/Cu 0.212, As/Cu 0.149, Pb/Cu 0.049, and Cd/Cu 0.093 (Table 5).

Table 7 shows the surface distribution of element concentrations grouped around factor 1.

FACTOR 2. Table 8 shows the signifcance of correlation between the elements (Ni, Cr, and Co) concentrated around FACTOR 2.

The obtained numerical values of Spearman’s rank correlation coefcient were in the excellent correlation range; Ni/Cr 0.952, Ni/Co 0.946, Co/Cr 0.910 (Table 5).

Table 9 shows the surface distribution of element concentrations grouped around factor 2.

The quality of water in the Ibar River has improved from Raška to Kraljevo. Increased concentrations of heavy metals in the sediments of other watercourses have occurred due to the geological and pedological stratum underneath them.

Factor analysis identifed two synthetic factors around which the analyzed heavy metals were grouped and further formed geochemical associations. Factor 1 explained 68.96% of the variance. Cd-Zn-As-Pb-Cu were concentrated around factor 1. The increased content of these elements occurred in northern and northeastern tributaries of Ibar. Extremely high contents were found in watercourses where occurrence and deposits of these heavy metals were already confrmed. The contents of Cd, As, and Cu were extremely high in the Rudnjačka river basin. The contents of Zn and Pb were high in the Jošanica river basin. The Gokčanica river basin had high contents of As and Pb, and Gajovska and Kaznovićka rivers had Zn, As, and Pb. The concentrations of Zn and As were increased in the Maglašnica river basin, and As content was increased in Pavlićka and Planska River II. The increased concentrations of Cu were only found in the Raška and Brvenica river basins.

Factor 2 was substantive and it defned 95.16% of the variance. Ni-Cr-Co were grouped around factor 2. The high concentrations of these elements were present in almost all analyzed sediments, they were only slightly less present in southwestern tributaries of Ibar. This geochemical association was typical for this geological environment, i.e. ophiolites.

The analysis determined that heavy metals were grouped around these two factors based on similar geochemical behavior and that they actually represented geochemical associations. These geochemical associations were directly dependent on the environment lithology in which watercourses (or smaller basins) were formed and, to a lesser extent, on the immediate sampling environment. This was mostly minimized by the anthropogenic factor as a condition for the formation of these geochemical associations.

Page 13/21 Conclusion

The Ibar is an international river. There are numerous objects along its watercourse or the watercourses that make up its basin that can affect the quality of sediments, and therefore the quality of water. The origin of the heavy metals in sediments from watercourses that form Ibar river basin and Ibar River were analyzed in this paper.

The quality of water in Ibar was mostly affected by the overbank sediments from Sitnica (Kosovo and Metohija) and Raška river basins. The anthropogenic factor had the greatest infuence on the quality of sediments from these two basins: the mining-industrial complex in Kosovo and Metohija on Sitnica river basin and municipal solid waste on the Raška river basin. However, due to the specifcity of anthropogenic sediments (numerous tailing sites and mining-chemical compounds) in the Ibar river basin, especially in its upper and middle course, periodic control of the chemical composition of overbank sediments from its tributaries has been necessary.

The area through which the Ibar fows is ideal for the development of tourism. It has a potential for cattle- breeding and fruit growing that could be achieved with the right incentive. The Ibar river basin is covered in forest and has many geothermal water sources whose enormous potential is not fully exploited.

Declarations

Acknowledgment

Authors would like to thank Vladimir Simić, a full professor at the Faculty of Mining and Geology, University of Belgrade, whose useful advice had a signifcant infuence on the quality of this paper. This paper originated from the research that has been conducted since 2016 within the project Geochemical Map of Serbia 1:500,000 (stream, overbank, and foodplain sediments). The project is funded by the Ministry of Mining and Energy Serbia (No 310-02-00208/2021-02).

References

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Tables

Due to technical limitations, table 1-9 is only available as a download in the Supplemental Files section.

Figures

Page 16/21 Figure 1

Geographical position of the river Ibar and locations of overbank sediment testing Legend: 1. Ljudska I, 2. Ljudska reka II (Donje buče), 3. Ljudska reka III (Štitarski potok), 4. Ljudska reka IV (Vučiniće), 5. Raška I, 6. Dramićki potok, 7. Kuzmićka reka, 8. Đurićka reka, 9. Šaronjska reka, 10. Deževska reka I, 11. Deževska reka II (Aluloviće), 12. Nosoljinska reka, 13. Raška II (Panojevice), 14. Tušimska reka, 15. Kosurička reka, 16. Ljudska reka V (Požega), 17. Andrićka reka, 18. Vrani Potok, 19. Borovićka reka, 20.

Page 17/21 Jablanovićka reka, 21. Lučka reka, 22. Kruševićka reka, 23.Gradačka reka, 24. Klisurski potok, 25. Brvenica I, 26. Zarički potok, 27. Brvenica II (Mandići), 28. Rečice, 29. Trnavska reka, 30. Sebimiljska reka, 31. Raduše I, 32. Brevina, 33. Studenica, 34. Raduša II (Grabovita kosa), 35. Jarandolski potok, 36. Jošanica I, 37. Brezovačka reka, 38. Raška III (Bukovik), 39. Sebečevska reka, 40. Raška IV (Bagri), 41. Jošanica II (Šutenovac), 42. Trnavska reka I, 43. Trnavska reka II (Pljevljani), 44. Izbička reka, 45. Jovska reka, 46. Varevski potok, 47. Trnavska reka III (Draganići), 48. Raška V (Nastasićko polje), 49. Kaznovićka reka, 50. Jošanica III (), 51. Planska reka, 52. Gobeljska reka, 53. Lužnjanski potok, 54. Veleštica, 55. Rudnica, 56. Lisinska reka, 57. Samokovka, 58. Rudnjačka reka, 59. Dubovski potok, 60. Zastupski potok, 61. Gokčanica, 62. Gajovska reka, 63. Brezanska reka, 64. Krivačka reka, 65. Popova reka, 66. Planska reka II (Vlas), 67. Maglašnica, 68. Lopatnica, 69. Pivnica, 70. Vrški potok, 71. Pavlićka reka, 72. Kneževićki potok, 73. Ibar I, 74. Ibar II (), 75. Ribnica

Figure 2

Page 18/21 Geological material of the wider area of the river Ibar. Legend: Black crosses are sampling locations

Figure 3

Pedological material of the wider area around the river Ibar Legend: Black crosses are sampling locations

Page 19/21 Figure 4

Box-plot dijagrams (Cd, Cu, Co, Cr, Hg, Mn, Ni, Pb, Zn i As)

Supplementary Files

This is a list of supplementary fles associated with this preprint. Click to download.

Page 20/21 Tables.pdf

Page 21/21