No abstract

In this pilot study, we evaluated the usefulness of the alkaline comet assay as a biomonitoring tool at the level of plankton communities affected by varying water quality. Zooplankton was collected in autumn 2007 and spring 2008 in two shallow lakes, one being predominantly polluted with aluminium compounds as result of water treatment process (Lake Njivice; 45°10′ N, 14°30′ E) and the other unpolluted (Lake Ponikve; 45°05′ N, 14°30′ E) used as control. Water and sediment chemistry parameters were assessed at both lake sampling sites. The results indicated that the main pollutant in both matrices was aluminium, whose concentrations exceeded the value of 0.15 mg/L −1 legally accepted for drinking water by Croatian water quality regulations. Plankton composition of the investigated lakes showed that only a few species are dominant and appear at both sites. Cladocerans are represented by Daphnia magna Straus 1820, and copepods by the calanoid Eudiaptomus padanus etruscus (Losito 1901), the cyclopoid Cyclops sp. and dipterans by larvae of Chaoborus flavicans (Meigen 1830). Other species were determined only occasionally and with low abundance. As observed, the comet assay had adequate sensitivity to detect the differences in levels of DNA damage among the dominant zooplankton taxa. Zooplanktons collected in Lake Njivice show a lower degree of DNA integrity compared with animals from the reference lake (Lake Ponikve). Inter-species variability in DNA damage was observed, indicating different genome susceptibility to the same genotoxic pollutants present in the aquatic environment. Furthermore, in the polluted Lake Njivice, seasonal differences in the levels of DNA damage within particular species of zooplankton were also noted. Calanoida, Daphnia and Chaoborus mainly had higher values of all three comet parameters in autumn 2007 than in spring 2008. Feeding modes strongly influenced the level of DNA damage in zooplankton species studied. We assume that the mechanisms of DNA damage and genotoxicity, as Water Air Soil Pollut (

Two gypsum karst lakes and one nongypsum karst lake were studied for copepod and cladoceran species composition in relation to specific habitat characteristics. The investigation was conducted from March to June 2007. Four copepod and six cladoceran species were recorded. Gypsum karst lakes are characterized as sulphate lakes and they show significant differences from non-gypsum karst lakes in conductivity, TDS, alkalinity, calcium and sulphates. Data on environmental variables and zooplankton were analyzed using redundancy analysis (RDA). The model explained 65.73% of the variance of the crustacean zooplankton and environmental data by the first two axes. The analysis confirmed that the major environmental variables influencing zooplankton in gypsum karst lakes are conductivity, TDS, calcium and sulphates. In the non-gypsum karst lake, on the contrary, the major variables were oxygen concentration and alkalinity. Specific habitat characteristics of gypsum karst lakes influence the zooplankton community by reducing the number of species and leading to the dominance of one of them.

Several adsorbents, such as natural zeolite clinoptilolite, modified zeolite, grape and olive wastes have been investigated for removal of chromium (VI) ions from aqueous solutions by performing batch kinetic sorption experiments. Natural zeolite, modified zeolite, grape and olive wastes have removed 5 %, 13 %, 73 % and 62 %, respectively, of Cr(VI) ions from aqueous solution. Equilibrium experimental results were fitted to Langmuir and Freundlich isotherms to obtain the characteristic parameters of each model. According to an evaluation using Langmuir equation, the maximum Cr(VI) adsorption capacity of grape waste was 108.12 mg g -1 and of olive waste 100.47 mg g -1 at pH 2. The equilibrium kinetic data were analyzed using pseudo-first-order and pseudo-second-order models, and parameters were estimated by using non-linear regression analysis. Langmuir model and pseudo-second-order model describes better the obtained results than Freundlich model and the pseudo-first-order model. The adsorption of Cr(VI) ions increased with temperature and the negative values of ∆G° for investigated adsorbents confirmed the feasibility and spontaneous nature of the adsorption process.

Coke is a high-calorie carbon mass obtained by dry distillation of coal, and used in various processes, the most significant of which is production of iron and steel. Coke production is present worldwide, especially in recent years when due to economic growth the global demand for steel is growing, which consequently increases demand for coke. During coke production, enormous amounts of toxic wastewater of extremely complex composition are generated. Priority pollutants that coking wastewater contains are phenols, cyanides, and thiocyanates. For successful treatment of such wastewater and achieving safety discharge standards, the application of a single process is insufficient. Accordingly, a combination of different physicochemical and biological treatment procedures, of which biological treatment is the most important, should be applied. In this article, a literature review of coking wastewater characteristics and treatment technologies is presented. In addition, this review addresses the complexity and limitations associated with coking wastewater treatment, with special emphasis on biological treatment methods. The aim of this review was to summarise the current knowledge on coking wastewater treatment technologies, which could eventually help optimisation of existing solutions.