The aim of study was to integrate chemical analyses and toxicity bioassays in order to assess the environmental risk connected with the presence of trace elements in the sediments. This study examined the ecological significance of trace elements in bottom sediments by applying a set of complementary sediment quality assessment methods sediment quality guidelines (SQGs) (mean probable effect concentration quotient (PECQ)), potential ecological risk index (PERI), contamination degree (C d ) and two bioassays: the bacterial luminescence inhibition test with Vibrio fischeri on sediment elutriates and the direct contact test with the ostracod crustacean Heterocypris incongruens. The samples were collected from 50 stations of Rybnik reservoir. The reservoir is a region with enormous concentration of industry, mainly hard coal mining, electric power industry, and transportation. Despite the high diversity in metal concentration in the sediments, the spatial distribution of trace elements in the sediments was very similar. Moreover, the strong positive correlations between individual pairs of trace elements indicate that they may derive from a similar source and move together. According to mean PECQs, 68 % of the samples were potentially non-toxic and 32 % of the samples were potentially toxic. PERI values suggested that 70 % of the sediment sampling sites exhibited low ecological risk from metal pollution while 24 % of the samples had severe and serious risk. Based on our combined evaluation, we believe that Cd and Cu in the sediment samples frequently caused adverse biological effects. Higher toxic responses were observed in the Microtox test than in the Ostracodtoxkit test. All the sediment samples were found toxic to V. fischeri, and 96 % of the samples had effect percentages >50 %. For H. incongruens, 12 % of the sediments were not toxic and 44 % had effect percentages >50 %. In order to perform a complex assessment of the environmental impact of metal pollution, both chemical and ecotoxicological analysis should be carried out.

Knowledge on the fraction of trace elements in the bottom sediments is a key to understand their mobility and ecotoxicological impact. The purpose of this study was to assess the influence of the content of organic matter fractions on the mobility and ecotoxicity of trace elements in sediments from the Rybnik reservoir. The most refractory fraction of organic matter—Cnh (non-hydrolysing carbon)—dominated in the sediments. The content of organic matter fractions are arranged in the following order: Cnh (non-hydrolysing carbon) > Cfa (fulvic acid) > Cha (humic acid) > DOC (dissolved organic carbon). On the other hand, the highest value of correlation coefficients was found for different fractions of trace elements and DOC content in the bottom sediments. A higher content of TOC in the sediments significantly increased the share of elements in the potential mobile fraction and, at the same time, decreased the binding of elements in the mobile fractions. Moreover, in sediments that contain more than 100 g/kg d.m. TOC, no and medium risk of trace element release from sediments was observed. The Cu, Cd and Ni were potentially the most toxic elements for biota in the Rybnik reservoir. However, the correlation between the content of trace elements and the response of bacteria was insignificant. These results suggested that the complexation of trace elements with organic matter makes them less toxic for Vibrio fischeri. The transformation and sources of organic matter play an important role in the behaviour of trace elements in the bottom sediments of the Rybnik reservoir.

The aims of the study were to investigate the concentration of trace elements, nutrients, and ecotoxicity in bottom sediment cores collected from the silted part of the Rożnów reservoir (Southern Poland). Significant differences in the content of nutrients, trace elements, and ecotoxicity between five sediment cores were found. However, in the vertical distribution, there was no high variability of the above parameters, which means that the intensely suspended matter transported by the Dunajec river is and, at various times, has been homogeneous. Significant correlations between nutrients and trace elements (r = 0.33–0.91, at p ≤ 0.05) point to the same sources of the above-mentioned substances and similar levels of contamination in the sediment cores. However, the PCA results showed that cadmium and phosphorus in the sediment cores had different behaviors than other elements and can be associated mainly with anthropogenic sources. According to the degree of contamination factor, sediment cores fall under the category of considerable contamination of metals. Geochemical factors indicated that nickel, chromium, and cadmium (only sediment core C1) were found to be the cause of significant pollution in the sediment cores. Toxicity assessment found that most of the bottom sediment samples were classified as non-toxic or slightly toxic, only 10% of the sediment samples were toxic for Vibrio fischeri, and 6% of the samples were toxic for Sinapis alba. The two test organisms showed a different sensitivity, and higher toxic responses were recorded for V. fischeri than for S. alba. Cadmium and phosphorus were associated with toxicity for S. alba (r = 0.29–0.58, at p ≤ 0.05), whereas TOC, N, and S, and Ca for stimulation of growth this plants. Trace elements (r = 0.32–0.51, at p ≤ 0.05) and nutrients (S, K, Mg, Na, r = 0.44–0.58, at p ≤ 0.05) were positively correlated with inhibition of luminescence of V. fischeri. The studies of concentration and relation between trace elements, nutrients, and ecotoxicity are important in the ecological risk assessment and describing the quality of sediments with multiple sources contamination.

The aim of the study was to assess the properties of bottom sediments from the inlet zone of the Rożnów Reservoir (South Poland) and to analyse the potential possibilities to use them for environmental purposes. The inlet zone of the reservoir is particularly intensely shallowed by means of the silts of the Dunajec River. A total of 20 samples were collected from the designated cross-sections. In air-dry samples of the sediments, granulometric composition, pH electrolytic conductivity (EC), sorption properties, organic carbon carbonates and macroelements content were determined. Bottom sediments from the Rożnów Reservoir indicate a great potential possibility to use them for environmental purposes (agriculture, reclamation). However, in order to fully evaluate the possibility of bottom sediment management, it is necessary to carry out an analysis of the ecological risk related to the content of heavy metals, PAHs, PCBs and to evaluate their eco-toxicity. Moreover, the main barriers to the environmental application of bottom sediments are a lack of appropriate legislation.

Abstract:The aim of the study was to assess the effect of bottom sediments on the selected properties of light soil as well as the content of trace elements in tested plants. The bottom sediments collected from the Besko reservoir were added to the soil in an amount of 5%, 10%, 30% and 50% of air-dried sediment, in relation to dry soil mass. The pot experiment was conducted on a light soil, with weak loamy sand grain size composition and slightly acid reaction, which was enriched with a supplement of bottom sediment. The test plant was a maize, Bora c.v. An applied bottom deposit revealed in its composition a considerable content of clay fractions, alkaline reaction and low total heavy metal content. Therefore, it may be applied as an admixture to light soils to improve their productivity. The addition of sediment to light soil resulted in the improvement of acidification in soil indicators: increased soil pH and reduced value of hydrolytic acidity, as well as improved sorption properties. A non-uniform effect of bottom sediment admixture on the content of trace elements in maize was determined. The sediment added to the soil increased the content of copper, nickel, chromium and, decreased the contents of zinc and cadmium in shoots. We did not find any excess of the permissible content of metals in plants used as animals forage in the maize biomass.