Gyula Lakatos

Application of constructed wetlands for wastewater treatment in Hungary

This paper presents a brief survey of the Hungarian constructed wetland types that have been established for wastewater treatment in the last thirty years, and gives an analysis of the design and performance of those reed ponds that have been constructed for the polishing of petrochemical wastewaters. Natural treatment processes are in great demand because they are protective of the environment and have low operation costs and satisfactory purification efficiency. Three major types of treatment wetlands are utilized in Hungary: free water surface system, subsurface flow system, and artificial floating meadow system. Since the 1970s, the petrochemical industry has utilized sewage treatment systems consisting of ponds of emergent and/or submerged macrophyte vegetation that operate as free water surface systems. In the wastewater treatment system of Nyirbogdany, the average COD removal efficiency is around 60%, while the reed-submerged weeds pond has an efficiency of 25%. In the reed pond of the TIFO post-treatment pond system, the total phosphorus removal averaged 40% for several years, while the nitrogen removal efficiency has not exceeded 35%. For both constructed wetlands, the nutrient stabilising and heavy metal accumulating role of the aquatic plant-periphyton complex has been quantified, and the biological water quality has been found to be typical of any other natural water bodies.

Effect of chromium on photosystem 2 in the unicellular green alga, Chlorella pyrenoidosa

We investigated the effect of chromium (20–40 g m−3, 8–72 h) on the photosystem 2 (PS2) activities of Chlorella pyrenoidosa cells. By using chlorophyll fluorescence transients, thermoluminescence, oxygen polarography, and Western blot analysis for D1 protein we found that inhibition of PS2 can be accounted for by the enhanced photodestruction of the reaction centres in the cells cultivated in the presence of Cr(VI) at 25 °C in “white light” (18 W m−2). Hence photodestruction of D1 is caused by an enhanced oxidative stress and lipid peroxidation, as indicated by the appearance of a high-temperature thermoluminescence band.

Heavy metal content of common reed (Phragmites australis/Cav./Trin, ex Steudel) and its periphyton in Hungarian shallow standing waters

In order to reveal the actual effects of common reed (Phragmites australis (Cav) Trin. ex Steudel) and its periphyton complex on the water quality, studies on the heavy metal contents of common reed and its periphyton are important. This paper discusses the results of studies on heavy metal contents of the host plant-periphyton complex carried out in Lake Balaton, Lake Velence, Lake Fertö and Kis-Balaton Reservoir. A second goal was to study the effects of reed stands in different condition (healthy, transitional, die-back) on the structure of its periphyton and their role in water quality indication. Simultaneously with the reed and periphyton sampling, water samples were taken for investigation. We determined the wet mass of periphyton and after drying at 105 °C; the dry mass was measured and ash contents of reed and its periphyton samples were also determined. The concentration of 27 (Na, Mg, Ca, K, Zn, Cu, Cd, Cr, Pb, Mo, etc.) cations was determined from the reed, periphyton and water samples by ICP-AES method. The heavy metal content of reed and periphyton was especially high at places impacted by high anthropogenic loadings. On the basis of our results, the biofilter role of periphyton-reed complex can be confirmed. Since the main reasons of reed decline have not been revealed, future research has to focus on involving reed-periphyton studies also, which may provide good basis to find the most appropriate ways to protect and restore the reed communities of shallow standing waters.

Littoral macrophyte-periphyton complexes in two Hungarian shallow waters

Periphyton developing on the surfaces of emergent and submerged aquatic plants has a significant influence on water quality. The periphyton types that form on various plant species can be characterized by their mass values, the proportion of the present organic and inorganic fractions, as well as their chlorophyll-a contents. Studies on periphyton complexes constituting integrated biomonitoring systems are useful to gain essential long-term information about the performance of shallow water bodies. The filtering and settling effect of Phragmites and other aquatic plants, as well as their periphyton was examined and clearly observable in the water areas and non-flooded aquatic habitats belonging to the second phase of Kis-Balaton Protection System, as it was indicated by the mass values and ash contents. The periphyton forming on the aquatic vegetation that annually develops in Kisköre Reservoir and yields a considerable biomass has a critical part in influencing water quality. The only difference (p<0.05) was found in the ash content of the periphyton, being lower in Kis-Balaton (48.64 ± 2.29 S.E., %) and higher in Kisköre Reservoir (57.42 ± 2.54 S.E., %). This paper presents the dry mass of the periphyton, as well as its ash and chlorophyll-a content, and the results obtained on the composition of the alga species of the periphyton.

Accumulative heavy metal patterns in the sediment and biotic compartments of the Tisza watershed

The paper presents data on toxic heavy metals in sediments measured after two large chemical spills on the Tisza watershed area. On the basis of the results, it is concluded that significant volume, high concentration heavy metals reached the Upper Tisza and Szamos River sections. Based on the longitudinal distribution of the heavy metals in sediments, the primary sedimentation zones and concentration increase compared with reference site was determined. Results verified arrival of fresh spills of mining origin and superimposed pollution. Regarding to chronic ecotoxicological effects, degradation and bioaccumulation rates of heavy metals priority problems are associated with arsenic, lead, mercury and cadmium in the sediments of the Tisza and Szamos Rivers after the spills of Romanian origin in 2000. Results indicate that the biological availability of the various heavy metals significantly differ along the river, particularly upstream and downstream of the Tisza Lake. The recent investigation did not identify one single sample in which muscular metal concentration of pike (Esox lucius L.) exceeded the present Hungarian consumer guidelines. The investigated pike population on the Tisza River could be divided into characteristic subgroups based on muscular tissue metal concentrations (Cd, Hg, Pb, Cu and As), depending on the bioavailability of the metalloids at the different river sections. On the basis of the data evaluation, it is concluded that the present state of pollution on Tisza River indicates the potential for deterioration and need for further biomonitoring.

Biomass of planktonic crustaceans and the food of young cyprinids in the littoral zone of Lake Balaton

The littoral zone of Lake Balaton and its periphyton-zooplankton-fish communities have been investigated intensively in recent years. Total average number of crustacean plankton varied from 36 to 126 ind l−1, their biomass from 0.49 to 1.86 mg ww l−1 month−1 at different areas of the littoral zone. In general, these values for the above parameters were higher in hypertrophic areas. 23 fish species occurred in the littoral zone with cyprinids dominating. The seasonal food spectra of Y-O-Y roach (Rutilus rutilus), white bream (Blicca bjoerkna) and bream (Abramis brema) were based mainly on planktonic crustaceans and benthic/periphytic invertebrates. According to the frequency of occurrence of crustaceans and other invertebrates, the food composition of young cyprinids differed significantly in the NE and SW-basins of the lake.

Ecotoxicological studies and risk assessment on the cyanide contamination in Tisza river

As a result of the dam failure of January 30, 2000 in Rumania, water and a huge amount of sediment contaminated with cyanide and later heavy metals entered the Tisza river system. In order to determine the chronic consequences of the contamination, periphyton and sediment samples were collected from River Tisza and her tributaries over the next 2 years. After flooding periods, the sediment deposited in the foreshore was also sampled. Applying the ICP-AES analysis method, the amounts of major heavy metals in the periphyton and sediment samples were measured, and the related concentration factors were calculated. Attempts were also made to find a correlation with the toxicity data. Ecotoxicological analyses were performed on the sediment using the following test techniques: Daphnia test, static fish test, alga test (chlorophyll content measurements), seedling test (Sinapis) and Lemna test (increase in mass and measurements on the chlorophyll concentration). Examinations on the chronic effects of heavy metals deposited in the periphyton and sediment can be regarded as an important factor in assessing ecological-conservational disasters and in carrying out biomonitoring activities in the future.

Application of Lemna species in ecotoxicological studies of heavy metals and organic biocides

Abstract Owing to their small size and easy manipulation under aseptic conditions, duckweeds (Lemnaceae) provide good material for studying the effects of toxicants and organic biocides. Applying static acute ecotoxicological tests the responses of three duckweed species to different chemicals were compared. In each species the IC 50 values of copper and Bonion biocide reached 10 mg/1 and 15 mg/1, respectively. Comparing the two Lemna species L. minor proved to be more sensitive than L. gibba . Simultaneously with the measurement of the productivity the changes in the CO 2 and O 2 exchange were also determined during the static acute tests of biocide (methylene bisthiocyanate) by means of a gas analyser (Quadrupole MS) in special growth chambers. There were no correlations between the respiration of duckweds and the concentration of biocide. Differences were found in the intensity of the photosynthesis as a function of the biocide treatment.

Short-term chromium(VI) stress induces different photosynthetic responses in two duckweed species, Lemna gibba L. and Lemna minor L.

Physiological responses of two duckweed species, Lemna gibba and Lemna minor, to hexavalent chromium [Cr(VI)] were studied in axenic cultures using short-term (48 h) treatments by K2Cr2O7 (0–200 μM). Chlorophyll (Chl) fluorescence parameters and photosynthetic pigment composition of plants were screened to determine the effects of Cr(VI) exposures. The two duckweed species exhibited different sensitivity in the applied Cr(VI) concentration range. Chl fluorescence parameters of dark-adapted and light-adapted plants and electron transport inducibility were more sensitive to Cr(VI) in L. minor than in L. gibba. We also found fundamental differences in quantum yield of regulated, Y(NPQ), and nonregulated, Y(NO), non-photochemical quenching between the two species. As Cr(VI) concentration increased in the growth medium, L. minor responded with considerable increase of Y(NPQ) with a parallel significant increase of Y(NO). By contrast, in L. gibba only 200 μM Cr(VI) in the growth medium resulted in elevation of Y(NPQ) while Y(NO) remained more or less constant within the regarding Cr(VI) concentration range during 48 h. Photosynthetic pigment content did not change considerably during the short-term Cr(VI) treatment but decrease of Chl a/b and increase of Car/Chl ratios were observed in good accordance with the changes in Chl fluorescence parameters. The data suggest that various duckweed species respond with different sensitivity to the same ambient concentrations of Cr(VI) in the growth medium, and presumably to other environmental stresses too, which may have an influence on their competitive relations when heavy metal pollution occurs in aquatic ecosystem.

Carotenoid composition and photochemical activity of four sandy grassland species

The photosynthetic pigments and photochemical efficiency of photosystem 2 (PS2) were studied in four constitutive species (Achillea millefolium L., Festuca pseudovina Hack. ex Wiesb., Potentilla arenaria Borkh., and Thymus degenianus Lyka) of a semiarid grassland in South-eastern Hungary. Every species displayed typical sun-adapted traits and substantial plasticity in the composition and functioning of the photosynthetic apparatus. The contents of chlorophylls (Chls) and carotenoids (Cars) on a dry matter basis declined from May to July, however, the amount of total Cars on a Chl basis increased. This increase was the largest in Potentilla (48 %) and the smallest in Achillea (14 %). The pool of xanthophylls (VAZ) was between 25 % and 45 % of the total Car content and was larger in July than in May. The content of β-carotene increased by July, but lutein content did not change significantly. The Chl fluorescence ratio Fv/Fm was reduced by 3–10 % at noon, reflecting the down-regulation of PS2 in the period of high irradiance and high temperature. The occurrence of minimal values of ΔF/Fm’ showed close correlation to the de-epoxidation rate of violaxanthin. Hence in natural habitats these species developed a considerable capacity to dissipate excess excitation energy in the summer period in their photosynthetic apparatus through the xanthophyll cycle pool and a related photoprotective mechanism, when the photochemical utilization of photon energy was down-regulated.