0ACTA VET. BRNO 2012, 81: 063-068; doi:10.2754/avb201281010063
Assessment of mercury contamination in the Bilina River (Czech Republic)
using indicator fish
Department of Veterinary Public Health and Toxicology, Faculty of Veterinary Hygiene and Ecology, University of Veterinary and Pharmaceutical Sciences Brno, Czech Republic
The aim of the study was to determine mercury content in the muscle of indicator fish and to assess mercury pollution along the Bilina River, which is one of the most important tributaries of the Elbe River. A total of eight sites were chosen on the Bilina River for sampling. Indicator fish chub (Leuciscus cephalus L), roach (Rutilus rutilus L.) and brown trout (Salmo trutta m. fario L.) in the total numbers of 24, 26 and 27, respectively, were sampled at four locations, since at the remaining sites fish were absent. Mercury concentrations in the muscle of sampled indicator fish were measured using cold vapour atomic absorption spectrometry on an AMA 254 analyser. The highest mercury content (0.12 ± 0.027 mg-kg-1) was found in the muscle of roach at the Usti nad Labem site and the lowest mercury content (0.04 ± 0.008 mg-kg-1) in the muscle of brown trout from the Brezenec (the first upstream site) site. A significant difference (P < 0.05) between the analyzed fish species was found only between chub (0.08 mg-kg-1) and brown trout (0.04 mg-kg-1) at the Brezenec site. The priority of this study was to assess the mercury contamination of the Bilina River because this river flows through a heavy industrial activity in the region (especially production of petrochemicals, agrochemicals, sorbents, plasticizers and textile auxiliaries). Despite the fact that the Bilina is an extensively polluted river, the obtained mercury results were very low and did not exceed the limit of 0.5 mg-kg-1 set by Commission Regulation No. 1881/2006.
Brown trout, roach, chub, river pollution
The aquatic environment is polluted by many different forms of industrial and agricultural waste. Waste water includes many chemicals, pharmaceuticals and metals. Most xenobiotic substances have the capacity to accumulate in living organisms and can be harmful to humans. One of them is mercury, a global pollutant with high toxicity even at very low concentrations. Its organic form, methylmercury, is easily taken up by biota and accumulates in the food chain, especially in fish.
In this study, the concentration of mercury was tested in fish from the Bilina River in the Czech Republic. The Bilina River springs on the slopes of the Ore Mountains in the Czech Republic, flows between the Czech Central Mountains and the Ore Mountains to the northeast, and joins the Elbe River at Usti nad Labem. The catchment area of the river covers 1,071 km2. This river is extensively polluted due to heavy industrial activity in the region. Additionally, the largest open coal mine with the highest production of brown coal in the Czech Republic is located in this monitored area. In the past, a substantial portion of the flow was extracted for use in chemical plants in Zaluzi near Litvinov. The river flowed out as lifeless chemical waste water, heavily polluted with phenols and other chemicals. The situation much improved in the 1990s, when most of the industrial activity declined, especially the mining; however, the Bilina is still one of the most polluted rivers in the Czech Republic and contains high concentrations of inorganic and organic pollutants. The Bilina River basin is the location of large chemical plants, especially Unipetrol RPA, Litvinov-Zaluzi (a refinery and producer of petrochemical products, agrochemicals, sorbents, and composites), Enaspol Teplice (surfactants, plasticizers, textile auxiliaries),
Kamila Kruzikova, Zdenka Svobodova
Received November 8, 2011 Accepted February 14, 2012
Abstract
Address for correspondence:
Kamila Novotna Kruzikova, Ing. Ph.D.
Department of Veterinary Public Health and Toxicology
Faculty of Veterinary Hygiene and Ecology
University of Veterinary and Pharmaceutical Sciences Brno
Palackeho 1-3, 612 42 Brno, Czech Republic
Phone: +420 541 562 783 E-mail: novotnak@vfu.cz http://www.vfu.cz/acta-vet/actavet.htm
Spolchemie Usti nad Labem (basic and special inorganic compounds, synthetic resins), and Ceska Rafinerska, Litvinov-Zaluzi (petroleum products).
The aim of the study was to determine the mercury content in the muscle of indicator fish and to evaluate the concentration of mercury pollution along the flow of the Bilina River which could affect the Elbe River.
The study was done on the Bilina River in the Czech Republic at the following eight sites: Brezenec (the first site upstream), Jirkov, Jiretin, Litvinov-Zaluzi, Zelenice, Bilina, Rtyne nad Bilinou, and Usti nad Labem (Fig. 1). Study sites upstream were limited by natural (shallow riffles, boulder ramp) or artificial (weir) transversal barriers. The indicator fish species were chub (Leuciscus cephalus L.), roach (Rutilus rutilus L.) and brown trout (Salmo trutta m. fario L.) in the total numbers of 24, 26 and 27, respectively, collected from four localities on the Bilina River (Brezenec, Jirkov, Jiretin and Usti nad Labem) by electrofishing in 2010; no fish were caught at the other four locations because of absence of fish in these parts of the river. The fish were weighed and their scales collected for age determination. The main characteristics of fish are summarized in Table 1.
Fig. 1. Map of sampling sites on the Bilina River in the Czech Republic
Sampling sites: 1 - Brezenec (the first upstream site) (river km 71), 2 - Jirkov (river km 68), 3 - Jiretin (river km 58), 4 - Litvinov-Zaluzi (river km 54), 5 - Zelenice (river km 42.5), 6 - Bilina (river km 34), 7 - Rtyne nad Bilinou (river km 16), and 8 - Usti nad Labem (river km 0.2)
For mercury analysis, samples of muscle tissue were taken from the cranial parts of fish under the lateral line, and were placed into polyethylene bags, marked, and stored in a freezer at -18 °C. The amount of mercury in muscle was determined by cold vapour atomic absorption spectrometry on an AMA 254 analyser (Altec Ltd., Dvur Kralove n. L., Czech Republic). The accuracy of the method was confirmed using certified reference material BCR 464 (certified value 5.24 ± 0.1 mg-kg"1).
Statistical analyses were done using Statistica 8.0. for Windows software. Individual differences between the means were tested successively using the Kruskal-Wallis test at the level of the significance 0.05.
Mercury concentration was measured in the muscle of indicator fish. The contents of mercury in analyzed fish from individual sites are summarized in Figs 2-4. The highest
Materials and Methods
Results
Table 1. The main characteristics of indicator fish from the sampling sites of the Bilina River.
Indicator fish Site n Age (mean ± SD) Body weight (mean ± SD)
Brown trout Brezenec 17 2.5 ± 0.51 80 ± 28.4
Jirkov 9 3.7 ± 0.71 231 ± 154.8
Jiretin 0 - -
Usti nad Labem 1 3.0 ± 0.00 148 ± 0.0
Roach Brezenec 2 3.0 ± 0.00 46 ± 1.4
Jirkov 8 4.3 ± 0.52 158 ± 59.7
Jiretin 9 3.0 ± 0.00 75 ± 11.9
Usti nad Labem 7 3.7 ± 0.76 102 ± 36.9
Chub Brezenec 6 4.2 ± 1.17 391 ± 225.1
Jirkov 8 4.1 ± 0.64 290 ± 106.9
Jiretin 0 - -
Usti nad Labem 10 4.3 ± 0.95 325 ± 160.3
average mercury content (0.12 ± 0.027 mg-kg-1) was found in the muscle of roach at the Usti nad Labem site and the lowest (0.04 ± 0.008 mg-kg-1) in the muscle of brown trout from the Brezenec site (the first site upstream).
Fish species were analysed separately and the following significant differences were found: in brown trout, a significantly higher (P < 0.05) mercury content was found at the Jirkov site in comparison with the Brezenec site. For roach, a significantly lower (P < 0.05) mercury content was found at the Jiretin site in comparison with the Usti nad Labem site. Significant differences (P > 0.05) were not confirmed with respect to the mercury content in chub.
Discussion
This study was focused on mercury pollution along the stream of the Bilina River. Eight sites were chosen for fish sampling, but indicator fish were sampled only at four sites; no fish were found at the other four sites. Jurajda et al. (2010) performed a survey
Jirkov
Fig. 2. Mercury content in the muscle of brown trout from the sampling sites of the Bilina River. ,b different alphabetic letters differ significantly (P < 0.05)
Jirkov Jifetiri Usti riad Labem
Fig. 3. Mercury content in the muscle of roach from the sampling sites of the Bilina River. ab different alphabetic letters differ significantly (P < 0.05)
0.16 0.14 0.12 0.1
^ 0.08
0.06 0.04 0.02 0
Brezenec Jirkov Usti nad Labem
Fig. 4. Mercury content in the muscle of chub from the sampling sites of the Bilina River. ,b different alphabetic letters differ significantly (P < 0.05)
of fish and macroinvertebrates in the same river. They did not find fish at five sites from a total of 18 sites and only minimal occurrence of fish at the other sites. The river was very poor in species richness. The water in the river was heavily organically polluted and malodorous due to the outlets and waste water from the industry, and its conditions were not conducive to life. Adamek and Jurajda (2001) stated that in addition to waste outlets, the river is affected by the existence of extremely poor physical river habitat, which has also contributed to a sudden decline in macroinvertebrate and fish assemblage quality, or nearly absence of fish.
In our study, the lowest mercury content was found at the Brezenec site (the first site upstream), except for roach. Mercury in the muscle of roach was lowest at the Jiretin site, which was the site upstream of the city of Most. The highest values for roach and chub were found at Usti nad Labem, which was the last site on the Bilina River monitored in this
study and the last before its confluence with the Elbe River. Increased mercury value could be caused by the burden of waste water from Spolchemie Company in Usti nad Labem which, however, eliminated mercury from the area of the chemical plant in late 1990s (Zlabek et al. 2005).
Although mercury concentrations were the highest at Usti nad Labem in the muscle of roach and chub, they did not exceed the safety limit of 0.5 mg-kg-1 in the muscle of fish and fish products set by Commission Regulation No. 1881/2006. Svobodova et al. (1993) studied fish from the Bilina River in a complex study focused on foreign compounds including mercury. They found a similar amount of mercury in the muscle of roach (0.059 ± 0.004 mg-kg"1) from the Jiretin site. A slightly lower content than that found in our study (0.021 ± 0.0007 mg-kg"1) was found in the muscle of brown trout at the Brezenec site. The mercury concentrations correspond with non-mercury polluted rivers in the Czech Republic. Analogous amount of mercury was found in chub from the Luznice, Otava, Sazava, and Berounka Rivers (0.07-0.13 mg-kg"1) and from the Svitava and Svratka rivers (0.08-0.12 mg-kg-1) by Kruzikova et al. (2008a, 2009). Kruzikova et al. (2008b) studied tributaries of the Elbe River and investigated male chub from the Bilina River. Mercury concentrations in these fish were slightly higher (about 0.15 mg-kg"1) than in our study. Water quality at the Usti nad Labem site could be affected by the activities of the Spolchemie chemical company. This site is also located before the Bilina River's confluence with the Elbe, without natural or manmade transversal barriers; thus, fish from the Elbe River can occur here.
The Bilina River is suspected to be the most polluted river in the Czech Republic. There are several main sources of pollution: waste water from industry, municipal waste water, agricultural procedures, and mining activities (Kohusova et al. 2011). Because the Bilina River is an important tributary of the Elbe River, it affects the aquatic ecosystem of this river with respect to water quality and consequently remains a potential pollution risk to the North Sea (Stachel et al. 2003). Kohusova et al. (2011) indicated in a long-term study that the middle and lower portions of the Bilina River were heavily polluted by metals and organic pollutants. They identified the main sources of these contaminants to be oil, coal, the chemical industry, and municipal waste water. The Bilina River was also studied by B lahova et al. (2011), who detected polycyclic aromatic hydrocarbons (PAHs) using passive samples and 1-OHP in fish bile. Their study indicates that the highest level of PAH pollution is in the middle stretches of the river flow, especially at Litvinov-Zaluzi. This site is affected by waste water from the town of Litvinov and the refinery operated by Unipetrol RPA. The lowest PAHs were found at the Brezenec site. In the case of 1-OHP, the highest value was determined at Usti nad Labem and the lowest also at Brezenec.
Despite the fact that the Bilina River is still one of the most polluted rivers in the Czech Republic and contains high concentrations of inorganic and organic pollutants, there are no known mercury sources upstream of Usti nad Labem and in terms of mercury, it is polluted only to a very small degree.
Acknowledgments
This study was supported by the grant "Veterinary aspects of food safety and quality" MSM 6215712402. The authors would like to thank colleagues from the Faculty of Fisheries and Protection of Waters (University of South Bohemia in Ceske Budejovice) for fish sampling, and Matthew Nicholls for English revision.
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