Changes in the Content of Heavy Metals in Bílina River during 2012–2017: Effects of Flood and Industrial Inputs

This article presents the development of selected heavy metals contained in river sediments at selected sites along the Bílina River. It describes the situation before the large flood in 2013, the situation just after that flood, the situation approximately 1 year after the flood, and 4 years after the flood. The contents of selected heavy metals from industrial pollution originating from transport and industry located along the river flow were monitored. Since the situation in the river before the flood was also known, it was possible to assess the impact of the 2013 flood on the distribution of heavy metals in the settled sediments. The results obtained show that the heavy metal content has changed significantly. During the flood in 2013 there was an increase in the concentration of almost all the monitored elements compared to the situation before the flood and one year after the flood. This could be caused by the churning of sediments as a result of the flood. The only exception was Cd, the concentration of which did not change significantly. However, Cd is present in the sediment samples at a low concentration at the limit of quantification (LOQ), so the change may not be noticeable. In 2017, four years after the flood, an increase in the concentration of all the monitored elements was found. The highest increase in the content of the monitored elements was observed at the sites with the highest industrial pollution. Following the flood in 2014, there was a situation where no significant differences were observed in the content of metals at the individual sampling points in contrast to the values obtained in 2012, 2013, and 2017. As a result of sediment churning and re-settlement during and after the flood, the sediment became homogenized along the entire river flow. After a longer period of time that was not accompanied by floods, a significant increase in the heavy metal concentration was observed due to anthropogenic pollution. The results show that the effect of flooding is only temporal and that anthropogenic pollution is more important than the impact of floods.

The response of macroinvertebrate community taxa and functional groups to pollution along a heavily impacted river in Central Europe (Bílina River, Czech Republic)

Macroinvertebrate communities were investigated along a gradient of heavy industrial and municipal pollution in the highland Bílina River (Czech Republic). Physico-chemical determinants and ions were monitored and community analysis performed focusing on taxonomic composition, ecological functioning (feeder and dweller guilds) and water quality metrics, including saprobity index, BMWP and diversity. Impacted sites differed significantly from reference and from recovered stretches. Chemical data revealed two main pollution factors, (1) a “salinity determinant”, described best by conductivity and SO42−, and (2) an “organic pollution determinant”, represented best by O2 concentrations and NO2−, all varying locally and temporally. Some metrics and taxa showed significant correlations to abiotic parameters. Functional communities showed a stronger relationship to the “organic pollution determinant”, suggesting that elevated organic pollution had a dominating influence on functional community metrics; though other variables may also have an influence in this multistress environment. On the other hand, there were indications that the taxonomic community was more influenced by ion concentrations (“salinity determinant”). The gradient from reference sites to polluted sites was weaker in the final sampling campaign. The results presented here can be used as a reference for assessing future changes in environmental impact from pollution, being finer and more detailed than assessment according to the EU’s WFD.

Assessment of mercury contamination in the Bílina River (Czech Republic) using indicator fish

The aim of the study was to determine mercury content in the muscle of indicator fish and to assess mercury pollution along the Bílina River, which is one of the most important tributaries of the Elbe River. A total of eight sites were chosen on the Bílina 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 Ústí nad Labem site and the lowest mercury content (0.04 ± 0.008 mg·kg-1) in the muscle of brown trout from the Březenec (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 Březenec site. The priority of this study was to assess the mercury contamination of the Bílina 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 Bílina 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.

Assessment of polycyclic aromatic hydrocarbon contamination of the Bílina River (Czech Republic) using passive water samplers and fish biliary metabolites

The aim of the study was to assess polycyclic aromatic hydrocarbon (PAH) contamination on the Bílina River (the Czech Republic) by measurement of three PAH biliary metabolites in fish and 16 PAHs in passive samplers. A total of sixty-one fish were collected; the indicator species were chub (Leuciscus cephalus L.; n = 25), roach (Rutilus rutilus L.; n = 17) and brown trout (Salmo trutta m. fario L.; n = 19). Three biliary PAH metabolites were measured: 1-hydroxypyrene (1-OHP), 2-naphtol, and 1-hydroxyphenanthrene, but only 1-OHP was detected in all fish. The highest median value of 32.3 ng·mg-1of 1-OHP was found at Ústí nad Labem, while the lowest median value of 27.6 ng·mg-1was found in the control site, Březenec. No significant differences (P < 0.05) among the sites were found. The highest concentration of PAH was detected in Litvínov-Záluží (172.0 ng·l-1) and the lowest concentration (7.9 ng·l-1) was detected in Březenec. A positive, but non-significant correlation (rs = 0.8) was confirmed between biliary 1-OHP and total PAH in passive samplers. These results indicate the highest pollution in the middle stretches of the Bílina River, especially at Litvínov-Záluží. We confirmed 1-OHP as the most prevalent PAH biliary metabolite in fish that could be used as a biomarker for assessment of PAH pollution of the aquatic ecosystem. The main importance of the present study is in the combination of biochemical and chemical monitoring that provides complex evaluation of aquatic environment contamination. It was the first study on the Bílina River, in which the assessment of PAH contamination in the aquatic ecosystem was realized using combination of biotic and abiotic monitoring.