Acute toxicity of heavy metals towards freshwater ciliated protists.
ABSTRACT The acute toxicity of five heavy metals to four species of freshwater ciliates (Colpidium colpoda, Dexiotricha granulosa, Euplotes aediculatus, and Halteria grandinella) was examined in laboratory tests. After exposing the ciliates to soluble compound of cadmium, copper, chromium, lead, and nickel at several selected concentrations, the mortality rate was registered and the LC50 values (with 95% confidence intervals) were calculated. Large differences appeared in sensitivities of the four species to the metals. H. grandinella showed the highest sensitivity for cadmium (0.07 mg l(-1), LC50) and lead (0.12 mg l(-1), LC50), whilst E. aediculatus showed the highest sensitivity for nickel (0.03 mg l(-1), LC50). The comparison with data obtained with other species indicate that Halteria grandinella and Euplotes aediculatus are excellent and convenient bioindicator for evaluating the toxicity of waters and wastewaters polluted by heavy metals. The short time (24 h) and simplicity of the test procedure enable this test to be used in laboratory studies.
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ABSTRACT: Several experiments were performed in the laboratory condition using an SBR bioreactor modelling the expected conditions, created by malfunction of certain bioreactor elements, thus the different oxygen condition. In the course of the experiments, the concentrations of ammonia nitrogen, nitrates(III), nitrates(V), TOC, and TC were systematically measured. Besides physico-chemical parameters, the structure of activated sludge community was analyzed. In the samples, the number and species composition of protozoa (ciliates) were determined. Each of the three measuring series conducted for various types of process conditions was repeated three times. The activated sludge used for inoculation of the bioreactor was sampled at Hajdow WWTP in Lublin. The results obtained are the average of three repetitions of every experimental series. On this ground, we may conclude that the number of ciliates shows a high correlation with the O2 concentration, pH and TOC. Zmiany w Strukturze Zbiorowiska Pierwotniaków Osadu Czynnego w Zróżnicowanych Warunkach Tlenowych W pracy przedstawiono wyniki badań prowadzonych w laboratoryjnym bioreaktorze SBR, symulującym warunki występujące w przypadku awarii urządzeń stanowiących wyposażenie bioreaktora (systemu mieszania i systemu napowietrzania). Analizowano skład chemiczny ścieków, w tym stężenia związków azotu (azot amonowy, azotany(III) i azotany(V)), a także stężenia związków organicznych wyrażanych jako ogólny węgiel organiczny (OWO) i węgiel całkowity. Oprócz wskaźników chemicznych analizowany był również zespół organizmów osadu czynnego. W pobieranych próbkach określano ilość pierwotniaków (orzęski) w wymienionej grupie. Każdą z trzech serii pomiarowych prowadzonych dla różnych warunków procesowych powtarzano trzykrotnie. W eksperymencie wykorzystano osad czynny pobierany z oczyszczalni ścieków Hajdów w Lublinie. Na podstawie uzyskanych wyników badań można stwierdzić, że liczebności analizowanych zbiorowisk orzęsków wykazują związek ze stężeniem tlenu, pH oraz wartością OWO.Chemistry-Didactics-Ecology-Metrology. 12/2014; 19(1-2):87-95.
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ABSTRACT: Polar coastal seawaters are saturated by high oxygen concentrations, which impose very effective adaptive strategies to strive against a continuous environmental oxidative stress. We studied these strategies in Euplotes nobilii (Ciliophora: Spirotrichea), a ciliate species dwelling in Antarctic and Arctic coastal seawaters, in comparison with Euplotes raikovi, a sister species living in temperate seawaters. Cell samples of the two species were exposed to hydrogen peroxide (H2O2)-induced oxidative stress and analyzed for their survival rates and levels of expression of the genes encoding the enzyme methionine-sulfoxide reductase (Msr) A, which restores oxidized methionines (in their S form) of damaged proteins to the status of functional methionines. While 6 h of exposure to a 750-µM concentration of H2O2 did not affect E. nobilii viability, these conditions were lethal to E. raikovi. In correlation with this inter-specific difference in the cell survival to oxidative stress, the MsrA-coding genes of the two species showed different mechanisms of expression: constitutive in E. nobilii, elicited by induction in E. raikovi.Italian Journal of Zoology 07/2014; 81(3). · 0.87 Impact Factor
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ABSTRACT: We have developed a novel microrespirometric method to characterize the inhibitory effects due to heavy metals on activated sludge treatment. This method was based on pulse dynamic respirometry and involved the injection of several pulses of substrate and inhibitors, of increasing concentration. Furthermore, we evaluated the inhibitory effects of heavy metals (copper and zinc), substrate and biomass concentrations, and pH on activated sludge activity. While higher biomass concentrations counteracted the inhibitory effects of both copper and zinc, higher substrate concentrations predominantly augmented the inhibitory effect of copper but no significant change in inhibition by zinc was observed. pH had a clear but relatively small effect on inhibition, partially explained by thermodynamic speciation. We determined the key kinetic parameters; namely, the half saturation constant (K S ) and the maximum oxygen uptake rate (OUR max ). The results showed that higher heavy metal concentrations substantially decreased K S and OUR max suggesting that the inhibition was uncompetitive.Biodegradation 08/2014; · 2.49 Impact Factor