Environmental Protection

Debrecen, Hungary

Environmental Protection

Debrecen, Hungary
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Bolla B.,Hungarian Danube Research Station of Ecological and Botanical Institute of HAS | Borics G.,Environmental Protection | Kiss K.T.,Hungarian Danube Research Station of Ecological and Botanical Institute of HAS | Reskone N.M.,Environmental Protection | And 2 more authors.
Vie et Milieu | Year: 2010

Diatom communities of Lake Balaton, the largest shallow lake of Central Europe, were studied between 2006 and 2008, with the purpose of establishing an initial database for a monitoring system for the lake in accordance with the EU Water Framework Directives. Four basins of the lake were investigated at several sampling sites; diatoms were sampled from four different substrates (reed, stone, sediment, and artificial substrates) in summer and in autumn. The goals of the investigation were to choose sampling sites, to select the most suitable substrate, and to identify an adequate index for monitoring studies of Lake Balaton in the future. 101 samples were collected and 289 diatom species were identified. The most abundant species were Achnanthidium minutissimum, Amphora pediculus, Cymbella exigua, Encyonopsis minuta, Staurosira grigorszkyi, Navicula cryptotenella and Nitzschia dissipata. Data sets were analyzed with multivariate statistical methods. Cluster analysis, Principal Component Analysis (PCA) and Self Organizing Map method indicated a clear separation between the northern and southern shore of the lake. Taking diatom samples at several sites from each shore of the lake is suggested in the future. It was shown that reed is the most suitable substrate for studying diatoms of Lake Balaton. Our results have indicated that artificial substrate is an adequate alternative, since its epiphytic diatom biota is quite similar to reed. The water quality of the lake was generally good. The Keszthely basin is the most impacted area of the lake (caused by the nutrient load of River ZaIa), where diatoms indicate a moderate water quality. Using IBD along with TDIL seems to be the best method of assessing the water quality of Lake Balaton.

Vasas G.,Debrecen University | M-Hamvas M.,Debrecen University | Borics G.,Balaton Limnological Research Institute | Gonda S.,Debrecen University | And 3 more authors.
Harmful Algae | Year: 2012

The unicellular alga Prymnesium parvum has been responsible for toxic incidents with severe ecological impacts in many parts of the world, and causes massive fish kills worldwide. Recently the haptophyte microalgae have caused water-bloom (4.3×10 4cellsml -1) in 6 fish ponds with high conductivity in Hungary, and caused fish mortality with typical symptoms. Toxicity of P. parvum from water samples was quantified by the assay of the influence of its cell-free filtrates on haemolysis (346±42.2) and in fish and daphnia toxicity tests. High amount of proteases in P. parvum containing waterbloom samples were detected with the help of activity gel electrophoresis. The proteases of investigated P. parvum samples (125-18kDa) showed high gelatinolytic activity and some of them showed sensitivity to EDTA (inhibitors of metalloproteases) and to PMSF (inhibitors of serine proteases). © 2012 Elsevier B.V.

Bacsi I.,Debrecen University | Torok T.,Debrecen University | B-Beres V.,Environmental Protection | Torok P.,Debrecen University | And 3 more authors.
Hydrobiologia | Year: 2013

In the last few years, halogenated hydrocarbons have been detected in the soil, in the aquatic environment, in organisms, and even in drinking water. The toxic effects of three chlorinated aliphatic hydrocarbons (trichloroethylene, tetrachloroethylene and tetrachloroethane) were studied in laboratory experiments (using the cyanobacterium Synecococcus elongatus PCC 6301 as test organism) and in field-like circumstances (natural phytoplankton assemblages enclosed in microcosms). The results of the laboratory experiments showed that all of the tested compounds significantly inhibited the growth of the cultures within the first 4 h. Enzymatic changes of the treated cultures suggested that oxidative stress occured-all of the three compounds caused an increase in the activity of peroxidases and superoxide dismutase, and also increased the levels of lipid peroxidation. Observed changes in microcosms were comparable with the results of the laboratory experiments: the number of individuals and chlorophyll contents decreased in the treated assemblages. The elevated levels of peroxidation on the second day in the assemblages treated with tetrachloroethane and tetrachloroetylene suggest that oxidative stress could occur in field conditions. One of the most important findings is the decrease in species number. Our results showed that cryptomonads, some green algae species and the cyanobacterium Limnothrix gradually disappeared from the treated beakers during the experiment. © 2012 Springer Science+Business Media Dordrecht.

B-Beres V.,Environmental Protection | B-Beres V.,Debrecen University | Grigorszky I.,Debrecen University | Vasas G.,Debrecen University | And 6 more authors.
Hydrobiologia | Year: 2012

The inhibitory effects of cyanobacterial compounds as possible explanation of the lack of stable Cyanobacteria-Cryptophyta coexistence in steady-state phytoplankton assemblages were studied. The possible interactions between two phytoplankton species, a toxic Microcystis aeruginosa (cyanobacteria) and a non-toxic Cryptomonas ovata (Cryptophyta) were investigated (i) in mixed cultures (containing C. ovata and M. aeruginosa cells); (ii) in M. aeruginosa crude extract-treated C. ovata cultures and (iii) in purified microcystin-LR (MC-LR) treated C. ovata cultures. The results of experiments proved that the presence of living M. aeruginosa cells have more inhibitory effects on C. ovata cultures than the crude extract of the M. aeruginosa cells; or the presence of the purified MC-LR. These results suggest that MCs does not play as important role in cyanobacteria-Cryptophyta interaction as it was presumed; hence more complex effects (allelopathy among them) can be significant in shallow lakes ecosystems. © 2012 Springer Science+Business Media B.V.

Lyu X.,Hong Kong Polytechnic University | Guo H.,Hong Kong Polytechnic University | Simpson I.J.,University of California at Irvine | Meinardi S.,University of California at Irvine | And 7 more authors.
Atmospheric Chemistry and Physics | Year: 2016

Many taxis and public buses are powered by liquefied petroleum gas (LPG) in Hong Kong. With more vehicles using LPG, they have become the major contributor to ambient volatile organic compounds (VOCs) in Hong Kong. An intervention program which aimed to reduce the emissions of VOCs and nitrogen oxides (NOx) from LPGfueled vehicles was implemented by the Hong Kong government in September 2013. Long-term real-time measurements indicated that the program was remarkably effective in reducing LPG-related VOCs, NOx and nitric oxide (NO) in the atmosphere. Receptor modeling results further revealed that propane, propene, i-butane, n-butane and NO in LPGfueled vehicle exhaust emissions decreased by 40.8±0.1, 45.7±0.2, 35.7±0.1, 47.8±0.1 and 88.6±0.7 %, respectively, during the implementation of the program. In contrast, despite the reduction of VOCs and NOx, O3 following the program increased by 0.40±0.03 ppbv (∼5.6 %). The LPGfueled vehicle exhaust was generally destructive to OH and HO2. However, the destruction effect weakened for OH and it even turned to positive contribution to HO2 during the program. These changes led to the increases of OH, HO2 and HO2 =OH ratio, which might explain the positive O3 increment. Analysis of O3-VOCs-NOx sensitivity in ambient air indicated VOC-limited regimes in the O3 formation before and during the program. Moreover, a maximum reduction percentage of NOx (i.e., 69 %) and the lowest reduction ratio of VOCs =NOx (i.e., 1.1) in LPG-fueled vehicle exhaust were determined to give a zero O3 increment. The findings are of great help to future formulation and implementation of control strategies on vehicle emissions in Hong Kong, and could be extended to other regions in China and around the world. © 2016 Author(s).

Borics G.,Center for Ecological Research | Nagy L.,Romanian Water Authority | Miron S.,Romanian Water Authority | Grigorszky I.,Debrecen University | And 4 more authors.
Hydrobiologia | Year: 2013

The restoration and management of shallow, pond-like systems are hindered by limitations in the applicability of the well-known models describing the relationship between nutrients and lake phytoplankton biomass in higher ranges of nutrient concentration. Trophic models for naturally eutrophic small, shallow, endorheic lakes have not yet been developed, even though these are the most frequent standing waters in continental lowlands. The aim of this study was to identify variables that can be considered as main drivers of phytoplankton biomass and to build a predictive model. The influence of potential drivers of phytoplankton biomass (nutrients, other chemical variables, land use, lake use and lake depth) from 24 shallow eutrophic lakes was tested using data in the Pannonian ecoregion (Hungary and Romania). By incorporating lake depth, TP, TN and lake use as independent and Chl-a as dependent variables into different models (multiple regression model, GLM and multilayer perception model) predictive models were built. These models explained >50% of the variance. Although phytoplankton biomass in small, shallow, enriched lakes is strongly influenced by stochastic effects, our results suggest that phytoplankton biomass can be predicted by applying a multiple stressor approach, and that the model results can be used for management purposes. © 2013 Springer Science+Business Media Dordrecht.

Borics G.,Center for Ecological Research | Gorgenyi J.,Center for Ecological Research | Grigorszky I.,Debrecen University | Laszlo-Nagy Z.,Environmental Protection | And 3 more authors.
Ecological Indicators | Year: 2014

Ecological water quality problems are frequently connected to increment of phytoplankton productivity and overdominance of some phytoplankton species. Metrics that show monotonously increasing or decreasing tendencies along stressor gradients is recommended for ecological state assessment. Diversity metrics are influenced by various physical disturbances and show high within-year variability; thus, there is no agreement on the usefulness of these metrics as state indicators. To test the usefulness of phytoplankton diversity in ecological state assessment we investigated the productivity-diversity relationships for lakes and rivers in the Carpathian Basin (Hungary). We demonstrated that the shape of productivity-diversity relationship depends on the investigated water body type. Regarding lakes, hump-shaped relationship was found for all computed metrics. Parallel with the increase in phytoplankton productivity values, diversity metrics showed monotonously increasing tendencies in rhithral and decreasing tendencies in large potamal rivers. We found no systematic relationship in the case of small lowland rivers. Changes of diversity metrics calculated for species and functional groups showed similar tendencies within the types, only the slopes of regression lines differ each other. The use of diversity metrics as ecological state indicators should be restricted to water body types where diversity decreases or increases monotonously with phytoplankton biomass. Regarding the lakes the use of diversity metrics is not recommended for ecological state assessment. In rhithral and large potamal river assessment, application of diversity metrics should be strongly considered. We demonstrated that diversity metrics can be useful components of multimetric indices proposed to use by the Water Framework Directive. © 2014 Elsevier Ltd.

Shang W.,Hohai University | Sun S.H.,Hohai University | Bai Q.,Environmental Protection
Journal of Environmental Protection and Ecology | Year: 2011

The scope of this paper is to develop a modified two-part wedge analysis method, introducing the effects of matric suction on the translational failure of landfills. Using this method, a more truly safety factor can be calculated, and simply ignoring the matric suction will lead to serious underestimation of the safety factor. As the matric suction increases, the safety factor increases, and vice versa. A 25% shear resistance proportion provided by matric suction obtained when the safety factor arrived 1.3. The exceed safety margin can be converted to vertical expansion. Given the safety factor and φb of 1.3 and 5°, respectively, the height of landfill can enlarge 7.7% as the matric suction increases from 0 to 20. This enables a landfill serving for a longer time to benefit the economics and society.

Krasznai E.,Environmental Protection | Krasznai E.,Debrecen University | Borics G.,Environmental Protection | Varbiro G.,Environmental Protection | And 4 more authors.
Hydrobiologia | Year: 2010

Numerous oxbows of different sizes, depths and ages accompany alluvial rivers in the Carpathian basin. These water bodies provide various habitats for macroscopic and microscopic assemblages. Phytoplankton of 13 oxbows in the Tisza valley was studied between 2005 and 2008. In this article, we focussed on the following questions (i) do the oxbows have unique microflora? (ii) does the macrophyte coverage have a large effect on the composition and biomass of the algal assemblages? and (iii) does the higher plants dominated state result in clear-water conditions in the oxbows? The studied oxbows were in different stages of the ageing process. We classified the sampled oxbows according to their macrophyte vegetation into five types. A total of 646 species of algae were recorded in the oxbows over the study period. The microflora was dominated by cyanophytes, chlorococcalean green algae, euglenophytes and diatom species. Phytoplankton species were allocated into 32 coda. For the determination of typical algal assemblages, we used Kohonen's Self Organizing Map (SOM) statistical analysis combined with K-means clustering, which has resulted five different types of phytoplankton associations. These types were dominated by coda Y, LO, W1, WS and J. Chlorophyll a data of the sparsely and densely vegetated oxbows did not differ, since a wide range of values characterised both types of the lakes. In this study, the composition of the microflora is similar to that of other eutrophic lakes, but some rarely occurring taxa such as Peridinium gatunense Nygaard and Peridiniopsis elpatiewskyi (Ostenf.) Bourelly might play a key role in the phytoplankton succession of the oxbows. The effect of the macrophyte coverage was decisive in the composition of the algal assemblages, and our investigations indicated that, in the case of the oxbows, the macrophytedominated state does not necessarily result in a clearwater state. © Springer Science+Business Media B.V. 2009.

Borics G.,Balaton Limnological Research Institute | Abonyi A.,University of Pannonia | Krasznai E.,Environmental Protection | Vabirbro G.,Balaton Limnological Research Institute | And 4 more authors.
Journal of Plankton Research | Year: 2011

Horizontal sampling within a lentic oxbow demonstrated the uneven distribution of algae at both large and small scales. An index of heterogeneity is proposed to characterize the fine-scale horizontal patchiness, which is defined as the ratio of the coefficient of variation among samples and the error in counting the algae. Applying a vertical grid sampling strategy, a distinct patchy distribution of several algal species was observed. Most of the patches were formed by those species that have good buoyancy-regulating mechanisms (bluegreen algae, dinoflagellates). Atelomixis caused by surface cooling may be the explanation of the heterogeneity. We have shown that the anisotropic horizontal distribution of the phytoplankton could cause high uncertainty in lake quality assessment. Therefore, to improve accuracy composite sampling is needed. © 2011 The Author.

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