12. Hydrology and water resources
CHEMICAL ASSESSMENT OF HEAVY METALS IN THE RIVER WATER OF MIRUSHA (KOSOVO) – A STATISTICAL APPROACH
Dr. Fatbardh Gashi1, Dr. Stanislav Frančišković-Bilinski2, Dr. Halka Bilinski2, Dr. Naser Troni1 and Dr. Hazir Çadraku3
1Department of Chemistry, Faculty of Natural Sciences, University of Prishtina, Kosovo
2Ruđer Bošković Institute, Division for Marine and Environmental Research, Croatia
3Faculty of Civil Engin. and Infrastructure, Univ. for Business and Technol., Prishtina, Kosovo
ABSTRACT
Generally, waters of Kosovo are enriched in dissolved solids, as the consequence of aquifer lithology and residence time of ground water. The main objective of this study was to perform assessment of heavy metals (Zn, Cu, Fe, Cd, Cr, Ni, Pb and Mn) content and water pollution of River Mirusha (Kosovo) using atomic absorption spectroscopy (AAS) method. Multivariate-statistical analysis approaches were used to determine the anthropogenic and natural contribution of heavy metals. The obtained results show that values of some heavy metals in studied river water samples were significantly high, with following maximal concentrations: Zn (0.053 mgL-1), Cu (0.012 mgL-1), Fe (0.062 mgL-1), Cd (0.029 mgL-1), Cr (0.109 mgL-1), Pb (0.034 mgL-1) and Mn (0.093 mgL-1). Cadmium and Lead were found to be the most significant contaminants. According to WHO recommended values for drinking water, on all locations values were within the limits for Zn, Cu, Fe and Mn, while for Cd, Cr, Ni and Pb values exceed recommended values on some sampling stations. The results for Pearson’s correlation factors show very high positive relationship (correlation) between variables Cu and Fe, Cd, Cr and Mn. Fe showed high significant positive relationship with Cd, Cr and Mn. Cd showed high significant positive relationship with Cr, Pb and Mn. Those high values of some heavy metals could be caused by geological composition of rocks and by soil influence, also partly from different influences of anthropogenic nature.
Keywords:Mirusha River (Kosovo), pollution, heavy metals, atomic absorption spectroscopy (AAS), multivariate-statistical assessment
12. Hydrology and water resources
INTRODUCTION
More than a billion people do not have access to safe water supplies and well over 2 billion people live without adequate sanitation. At any given time, more than half of the developing world’s population is suffering from one or more of the main diseases associated with unsafe water and poor sanitation. Therefore, problems of drinking water and its quality are of extreme importance in any part of the world. The sources of physico-chemical contamination are numerous and include the land disposal of sewage effluents, sludge and solid waste, septic tank effluent, urban runoff and agricultural, mining and industrial practices.Heavy metals are significant environmental pollutants, and their toxicity is a problem of increasing significance for ecological, evolutionary, nutritional and environmental reasons [1]. They have largest availability in soil and aquatic ecosystems and to a relatively smaller proportion in atmosphere as particulate or vapours. Mining activities are one of the most important and abundant source of metal contamination of ecosystems. These activities can affect small areas, but could have a significant impact on the environment, and they are considered to have the potential for causing heavy metal pollution and associated diseases [2].
Potable and safe water gradually became scarce commodity, due to mixing up of huge contaminants through natural process like soil and rock weathering and anthropogenic activities such as industrial effluents, domestic sewage, garbage, over mining activity, explosive population etc. [3]. Metallic elements are environmentally stable. They can enter in living system through an aquatic medium and accumulate up to prolong period, resulting in acute adverse effects on human being, animals and plants. They have significant role to increase the degradation of water quality via thermal power plants, extraction of metals, transpiration, over application of fertilizers, pesticides and insecticides, even some of them as Cu, Fe, Mn, Ni and Zn are compulsory as micro nutrients for flora – fauna and microbes. Traces of metals in natural waters allocate between dissolved species and species bound to particular (colloid) particles. Interaction of dissolved traces of metals with sediment and biota depends on physico-chemical characteristics and of their chemical speciation. For better understanding of processes which control cycling of trace metals between certain components in water it is necessary to know their distribution and concentration of their particular species [4].
This study is a continuation of earlier studies [5 - 8] of our research group on quality of the surface and ground waters in Kosovo, which investigated in details four main rivers of Kosovo - Drini i Bardhë, Morava e Binçës, Lepenc and Sitnica.
STUDY AREA AND SAMPLING
The Mirusha is a river in Kosovo, that tributary to the Drini i bardhë River. The river has carved a 10 km canyon and created 13 lakes with waterfalls between them. The waterfalls are one of the most visited attractions of the area and people often swim there. The walls around the waterfalls are white in colour, whereas the water from the Mirusha River is a dirty brown. The waterfall's caves are also popular with visitors. The highest waterfall, between the sixth and seventh lake, is 22. The composite valley of the river is densely populated, with several villages (Bajë, Malishevë, Turjakë, Panorcë and Volljakë),
Sampling of river water was performed at 19 may 2016. The sampling network was established in order to cover the river spatially, taking into account anthropogenic pressures, the different habitats and the hydromorphological conditions of the river. Portable instruments were used to measure water temperature, electrical conductivity (EC), pH and total dissolved solids (TDS). At each sampling location, water samples were collected in polyethylene bottles. Before taking water samples, the bottles were rinsed three times with lake’s water to be collected. Water samples were collected for analysis according to usual procedures, near the river bank at a depth of 15 cm, put into 1dm3 bottles and stored at 4° C. Preparation of the samples was as following: from each sample a quantity was extracted and filtrated using filter paper “selecta no. 589”, for measuring of turbidity, total alkalinity, total hardness, temporary hardness, etc. Rest of water samples was preserved according to standard procedures [9]. The selected heavy metals (Zn, Cu, Fe, Cd, Cr, Ni Pb and Mn) were analysed. Geographic coordinates were measured by GPS device Extras, “GARMIN, 12 channel” and locations were well described. The study area with 8 sampling locations is shown in Figure 1 and the details about all sampling sites are presented in Table 1.
Figure 1. Map showing the study area and positions of sampling stations
Table 1. Sampling stations with detailed locality description
Sample / Locality / Coordinates / Altitude/m a.s.l. / Possible pollution sources
S1 / Bajë / 34T0481739
4704134 / 547 / Settlement
S2 / Bajë / 34T0479966
4702378 / 537 / Iron waste
S3 / Malishevë / 34T0478195
4703619 / 532 / Settlement
S4 / Mirushë / 34T0477213
4704708 / 517 / Settlement and traffic
S5 / Turjak / 34T0475272
4704581 / 505 / Settlement and traffic
S6 / Panorc / 34T0471535
4707975 / 491 / Settlement, agriculture land
S7 / Ujvara / 34T0465641
4708010 / 457 / Restaurant and traffic
S8 / Volljak / 34T0464009
4708051 / 370 / Traffic
MATERIALS AND METHODS
Double distilled water was used in all experiments. All instruments were calibrated according to manufacturer’s recommendations. Temperature of water was measured immediately after sampling. TDS and pH measurements were performed using pH/ion-meter of Hanna Instruments. Electrical conductivity was measured by „InoLab WTW“ conductometer. Concentrations ofNO3-(in 500 nm) and NH4+ (in 655 nm) were determined using UV-VIS spectrometry method, using „SECOMAM Prim light” SECOMAM pastel UV and „Hach 2800 Spectrophotometer“. Metals in water were analyzed using atomic absorption spectrometer model Perkin Elmer, AAS Analyst 400, HGA 900’. Accuracy of determination was ±10 %, and limits of detection (LOD) were as follows: Zn (0.0015 mgL-1), Cu (0.0015 mgL-1), Fe (0.005 mgL-1), Cd (0.002 mgL-1), Cr (0.003 mgL-1), Ni (0.006 mgL-1), Pb (0.05 mgL-1) and Mn (0.0015 mgL-1).
Program Statistica 6.0 [10] was used for the statistical calculations in this work, such as: descriptive statistics, two dimensional Scatter box plot diagrams for determination of anomalies (extremes and outliers) for solution data.
RESULTS
The physico-chemical parameters of 8 water samples, i.e. water temperature, EC, pH, TDS, NH4+, NO3-are presented in Table 2. In Table 3 are presented concentrations of 8 heavy metals (mgL-1) in water of Mirusha River in comparison with WHO standards for drinking waters. The Descriptive statistics summary of the selected variables of water samples are presented in Table 4. For each variable, the values are given as arithmetic mean, geometric mean, median, variance and standard deviation. Using experimental data from Table 3, obtained by AAS method and box plot approach [11], anomalous values (extremes and outliers) of 14 parameters were determined. No positive anomalies were detected and therefore scatterplot figures will not be presented. From that could be concluded that no “hot spots” exist, e.g. that concentrations of all studied heavy metals are uniformly distributed along the whole studied river course.
Table 2. Values of some physico-chemical parameters determined in river water
Parameter / S1 / S2 / S3 / S4 / S5 / S6 / S7 / S8 / WHO standardW. T.
/°C / 23.4 / 18.4 / 18.9 / 17.5 / 16.4 / 14.8 / 14.5 / 14.1 / 8-12
EC
/µScm-1 / 729 / 719 / 699 / 683 / 649 / 666 / 633 / 668 / 1000
pH / 7.03 / 6.29 / 8.34 / 8.14 / 8.06 / 7.98 / 8.62 / 8.01 / 6.5-8.5
TDS
/mgL-1 / 366 / 360 / 350 / 342 / 324 / 333 / 317 / 334 / 1500
NO3-
/mgL-1 / 6.5 / 6.9 / 7.5 / 5.4 / 6.4 / 6.9 / 7.1 / 7 / 50
NH4+ /mgL-1 / 0.18 / 0.35 / 0.37 / 0.57 / 0.28 / 0.13 / - / - / 0.5
Table 3. Concentrations of 8 metals determined in river water
Heavy metals/mgL-1 / Sample
S1 / S2 / S3 / S4 / S5 / S6 / S7 / S8 / WHO standard
Zn / 0.031 / 0.034 / 0.029 / 0.022 / 0.052 / 0.053 / 0.038 / 0.031 / 5
Cu / 0.001 / 0.008 / 0.003 / 0.004 / 0.004 / 0.001 / 0.002 / 0.012 / 2
Fe / 0.047 / 0.013 / 0.025 / 0.062 / 0.051 / 0.031 / 0.006 / 0.03 / 0.3
Cd / 0.017 / 0.015 / 0.016 / 0.029 / 0.021 / 0.008 / 0.006 / 0.005 / 0.005
Cr / 0.109 / 0.044 / 0.064 / 0.062 / 0.041 / 0.019 / 0.021 / 0.018 / 0.05
Ni / nd / nd / 0.002 / 0.001 / 0.011 / 0.027 / 0.019 / 0.01 / 0.07
Pb / 0.018 / 0.017 / 0.021 / 0.033 / 0.017 / 0.022 / 0.033 / 0.034 / 0.01
Mn / 0.013 / 0.043 / 0.044 / 0.093 / 0.057 / 0.035 / 0.024 / 0.016 / 0.1
Table 4. Descriptive statistics of the 8 variables in 8 cases
Variable / Descriptive statisticsMean / Geometric / Median / Min. / Max. / Variance / Std.Dev.
Zn/mgL-1 / 0.0362 / 0.0349 / 0.0325 / 0.0220 / 0.0530 / 0.000 / 0.01100
Cu/mgL-1 / 0.0044 / 0.0031 / 0.0035 / 0.0010 / 0.0120 / 0.000 / 0.00381
Fe/mgL-1 / 0.0331 / 0.0268 / 0.0305 / 0.0060 / 0.0620 / 0.000 / 0.01915
Cd/mgL-1 / 0.0146 / 0.0125 / 0.0155 / 0.0050 / 0.0290 / 0.000 / 0.00816
Cr/mgL-1 / 0.0473 / 0.0392 / 0.0425 / 0.0180 / 0.1090 / 0.001 / 0.03095
Ni/mgL-1 / 0.0117 / 0.0070 / 0.0105 / 0.0010 / 0.0270 / 0.000 / 0.00999
Pb/mgL-1 / 0.0244 / 0.0234 / 0.0215 / 0.0170 / 0.0340 / 0.000 / 0.00763
Mn/mgL-1 / 0.0406 / 0.0339 / 0.0390 / 0.0130 / 0.0930 / 0.001 / 0.02593
DISCUSSION
In the present study, the temperature of 8 of water samples varied from 14.1-23.4° C. High value of water temperature was recorded at sample station S1, as a possible sign of influence ofthermal water.The electrical conductivity (EC) of water samples varied from 633-729 µScm-1 as sign of natural pollution, and were higher than values measured value of Izbitac karstic spring on the slopes of Biokovo Mt. in Croatia (362.5 µScm-1), which is known to be under the significant anthropogenic influence [12]. pH values varied from 6.29-8.62 and samples S2 and S7 exceed recommended WHO norms for drinking waters [13]. It could be from composition of rocks in that area. TDS values in all water samples were 317-366 mgL-1 and not exceed recommended WHO norms for drinking waters. Concentrations of nitrites and ammonia, (except the sample S4) were found to be under recommended WHO standards for drinking water.
The obtained results show that values of some heavy metals in studied river water samples are significantly high, with following maximal concentrations: Zn (0.053 mgL-1), Cu (0.012 mgL-1), Fe (0.062 mgL-1), Cd (0.029 mgL-1), Cr (0.109 mgL-1), Pb (0.034 mgL-1) and Mn (0.093 mgL-1). Cadmium and Lead were found to be the most significant contaminants. In comparison with waters around abandoned Gyöngyösoroszi Pb-Zn mine in Hungary [14], Cd concentrations in the Mirusha River are significantly higher, while Pb concentrations in the Mirusha River are almost 20 times higher. Contrary to that, Zn concentrations in Mirusha River are lower than those measured in the Gyöngyösoroszi abandoned Pb-Zn mine.
According to WHO recommended values for drinking water, on all locations values were within the limits for Zn, Cu, Fe and Mn, while for Cd, Cr, Ni and Pb values exceed recommended values on some sampling stations. The results for Pearson’s correlation factors, presented in Table 5, show very high positive relationship (correlation) between variables Cu and Fe, Cd, Cr and Mn. Fe showed high significant positive relationship with Cd, Cr and Mn. Cd showed high significant positive relationship with Cr, Pb and Mn. Those high values of some heavy metalscould be caused by geological composition of rocks and soil influence, also partly from different influences of anthropogenic nature.
Table 5. Pearson’s correlation factors for 8 variables in 8 cases
Marked correlations are significant at p < 0.050Zn / Cu / Fe / Cd / Cr / Ni / Pb / Mn
Zn / 1.0
Cu / -0.5 / 1.00
Fe / -0.8 / 0.94 / 1.00
Cd / -0.8 / 0.93 / 1.00 / 1.0
Cr / -0.9 / 0.87 / 0.99 / 1.0 / 1.00
Ni / 0.8 / -0.92 / -1.00 / -1.0 / -0.99 / 1.0
Pb / -0.9 / 0.21 / 0.54 / 0.6 / 0.66 / -0.6 / 1.0
Mn / -0.9 / 0.79 / 0.95 / 1.0 / 0.99 / -1.0 / 0.8 / 1.00
CONCLUSION
In this study, the distribution of 6 physico-chemical parameters and 8 heavy metals in water of Mirusha River were investigated. Generally, ground waters of Kosovo are enriched in dissolved solids, as the consequence of aquifer lithology and residence time of ground water. High values of some parameters showed a possible sign for significant contamination of river water. According to WHO recommended values for drinking water, River water of Mirusha was on all locations within those limits for Zn, Cu, Fe, Ni and Mn. For following metals it exceeds recommended WHO values: Cd in all locations, Cr on locations S1, S3 and S4, and Pb in all locations.
When compared with waters around abandoned Gyöngyösoroszi Pb-Zn mine in Hungary, Cd concentrations in the Mirusha River are significantly higher, while Pb concentrations in the Mirusha River are almost 20 times higher. Contrary to that, Zn concentrations in Mirusha River are lower than those measured in the Gyöngyösoroszi abandoned Pb-Zn mine.
Using experimental data obtained by ASS method and box plot approach, anomalous values (extremes and outliers) of 8 heavy metals were not detected. From that could be concluded that no “hot spots” exist, e.g. that concentrations of all studied heavy metals are uniformly distributed along the whole studied river course.
The results for Pearson’s correlation factors show very high positive relationship (correlation) between variables Cu and Fe, Cd, Cr and Mn. Fe showed high significant positive relationship with Cd, Cr and Mn. Cd showed high significant positive relationship with Cr, Pb and Mn. Those high values of some heavy could be a possible sign of geological compound of rocks and earth influence, also partly from different transfers of anthropogenic nature.
Finally it could be concluded that despite of rather high concentrations of some heavy metals, especially of Cd and Pb, significant anthropogenic influence in Mirusha River does not exist. Best proof for this statement is that concentrations of all studied heavy metals are rather uniform along the whole studied river course, also that no “hot spots” exist, what is in favor of naturally elevated concentrations, caused mostly by geologic composition of surrounding rocks and soil influence.
ACKNOWLEDGEMENTS
This paper is a part of MSc thesis of Habibe Paçarizi, defended at the University of Prishtina, in March 2016 (supervisor Dr. Fatbardh Gashi). The study was financially supported by University of Prishtina. Measurements were performed at laboratory of Chemistry Department, Faculty of Science in Prishtina and Hydrometeorological Institute, in Prishtina. Colleagues from the Department of Chemistry, University of Prishtina are thanked for their assistance.
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