Andrea Farsang

Construction of bioluminescent cyanobacterial reporter strains for detection of nickel, cobalt and zinc

Two whole-cell bioluminescent reporters were constructed by fusing the reporter genes luxAB with the Co(2+) and Zn(2+) inducible coaT promoter or the Ni(2+)-inducible nrsBACD promoter, respectively, in the genome of Synechocystis sp. PCC 6803. The obtained reporters, designated coaLux and nrsLux, respectively, responded quantitatively to metal ions. After 3 h incubation at 40 micromol m(-2) s(-1) visible light, the detection range of coaLux was 0.3-6 microM for Co(2+) and 1-3 microM for Zn(2+). Incubation in darkness increased the detection range by about four times. The nrsLux reporter was specific to Ni(2+), with a detection range of 0.2-6 microM. However, its activity was inhibited by Zn(2+) with a half maximal inhibitory concentration c. 6 microM, and totally inhibited by darkness. This is the first whole-cell Ni(2+)-specific reporter with a clear dose-signal relationship. In a soil-like mixture of different chemical and oil industry wastes, the coaLux reporter strain detected about 90% of the zinc content of the sample. This study demonstrates the potential for development of a rapid, simple and economical field assay for nickel, cobalt and zinc detection using the coaLux and nrsLux reporters.

Evaluation of Metal Mobility and Bioaccessibility in Soils of Urban Vegetable Gardens Using Sequential Extraction

Urban soils are recipients of a variety of pollutants, including the toxic heavy metals, which can accumulate in these soils. The consumption of vegetables and fruits grown in urban gardens with elevated heavy metal content may pose a health risk to residents, because the plants can absorb the heavy metals to different degrees depending on a number of factors (soil properties, forms of metals, plant specific factors, etc.). Total metal content and heavy metal fractions were determined using a sequential extraction procedure in the soils of urban vegetable gardens in order to assess both mobile and potentially mobile amounts of heavy metals in these soils. The heavy metal content of different vegetable types grown in these gardens and those soil properties relevant to controlling metal mobility were also investigated. Soil properties of the studied vegetable gardens influenced metal retention positively, but these soils were not heavily contaminated with metals. The high content of total Pb, Cu, Zn and Cd in the mobile and potentially mobile fractions did, however, indicate a possible anthropogenic enrichment of these metals. The vegetables grown in these gardens accumulated no toxic metal content but the concentration of Cu in the studied vegetables was generally higher than the mean Cu content of different plant foodstuffs, clearly indicating an anthropogenic impact on the Cu status of these soils. Based on the calculated bioaccumulation indices and in accordance with the result of the sequential extraction, Zn and Cd were the most mobile elements in the present soil–plant system.

Weather Extremities and Soil Processes: Impact of Excess Water on Soil Structure in the Southern Great Hungarian Plain

With global climate change, the frequency of extreme weather events, which also affect soil properties, has increased. Hungarian agriculture was stricken with drought in the 1990s, whereas inland excess water has caused damages in 2000, 2006 and again in 2010. According to multivariable correlation tests, in addition to hydrometeorological, geological and topographical factors, soil properties also influence the formation of excess water, which can, in turn, modify soils (bring about hydromorphic characteristics or physical degradation). The aim of the present study is to reveal the interactions between inland excess water and soil properties illustrated by a case study carried out on a fertile chernozem soil after the extensive excess water coverage of 2010. Three excess water patches were identified for analysis from multitemporal Landsat images in the study area and were connected in a southwest-west–northeast-east aligned, 700-m-long, catena. In July 2011, topsoil samples were collected along this catena at 50-m intervals from three depths, to compare the particle-size distribution and agronomical structure of soils of temporary excess water with those not affected by it. In order to create a multilayer map from soil compaction data, penetration resistance and relative soil moisture were measured at a depth of 60 cm at 117 points in the 45-ha study field using a 3 T System hand penetrometer. The results call attention both to the physical soil degradation caused by excess water and to the risk of erosion due to inadequate tillage or cultivation practices.

Estimation of Soil Material Transportation by Wind Based on in Situ Wind Tunnel Experiments

Abstract 25% and 40% of territory of Hungary is moderate to highly vulnerable to deflation. However, precise estimates about the soil loss and related losses of organic matter and nutrients due to wind erosion are missing in most cases. In order to determine magnitudes of nutrient masses removed at wind velocities that frequently occur in SE Hungary, in-situ experiments using a portable wind tunnel have been conducted on small test plots with an erosional length of 5.6 m and a width of 0.65 m. The wind tunnel experiments have been carried through on a Chernozem which is typical for this region. In order to compare the effects of soil coverage on the masses of blown soil sediment and adsorbed nutrients, two soil surface types have been tested under similar soil moisture und atmospheric conditions: (1) bare soil (dead fallow) and (2) bare soil surface interrupted by a row of maize plants directed downwind along the center line of the test plots. The results of our experiments clearly show that a constant wind velocity of 15 m s-1 (at a height of 0.3 m) lasting over a short time period of 10 minutes can already cause noticeable changes in the composition and size of soil aggregates at the top of the soil surface. Due to the grain size selectivity of the erosive forces the relative share of soil aggregates comprising diameters > 1 mm increased by 5-10% compared with the unaffected soil. Moreover it has shown that short time wind erosion events as simulated in this study can result in erosion rates between 100 and 120 g m-2, where the erosion rates measured for bare soils are only slightly, but not significantly higher than those of the loosely vegetated ones. Soil samples taken from sediment traps mounted in different heights close to the outlet of the wind tunnel point to an enrichment of organic matter (OM) of about 0.6 to 1 % by mass referred to the control samples. From these findings has been calculated that the relocation of organic matter within short term wind erosion events can amount to 4.5 to 5.0 g OM m-2. With the help of portable field wind tunnel experiments we can conclude that our valuable, high quality chernozems are struck by wind erosion mainly in drought periods.

Spatial modelling of contamination in a catchment area impacted by mining: a case study of the Recsk copper mine, Hungary

The metals and metal compounds that have been exposed by mining or have been discarded in mine wastes tend to become chemically more available, generating acid mine drainage as well as releasing toxic metals into soils, surface waters and groundwater in the affected catchment area. Here we present a case study of the spatial assessment of contamination in a catchment area impacted by mining. A detailed statistical analysis was performed in order to identify geochemically homogeneous areas, including those contaminated by mining. A distributed model is also presented. This assesses the mean annual export of heavy metals from a catchment area, taking into account the spatial pattern of metal concentration and the topological relationships between sediment sources and sinks. Results show that the spatial pattern of background geology, mineralization and mines is important for understanding and assessing the geochemistry of contamination in the affected catchment. Moreover, certain spatial configurations of land use can minimize the total amount of sediment exported and the volume of polluted waste and sediments that is exported.

Testing a sequential stochastic simulation method based on regression kriging in a catchment area in Southern Hungary

Modelling spatial variability and uncertainty is a highly challenging subject in soil- and geosciences. Regression kriging (RK) has several advantages; nevertheless it is not able to model the spatial uncertainty of the target variable. The main aim of this study is to present and test a sequential stochastic simulation approach based on regression kriging (SSSRK), which can be used to generate alternative and equally probable realizations in order to model and assess the spatial variability and uncertainty of the target variable, meanwhile the advantages of the RK technique are retained. The SSSRK method was tested in a catchment area, in Southern Hungary for the modelling of spatial variability and uncertainty of soil organic matter (SOM) content. In the first step, the auxiliary information was derived according to the soil forming factors; then the RK system was built up, which provides the base of SSSRK. 100 realizations were generated, which reproduced the model statistics and honored the input dataset. These realizations provide 100 simulated values for each grid node, which number is appropriate to calculate the cumulative distributions. Using these distributions the following maps were derived: map of expected values, the corresponding 95% confidence interval’s width, furthermore the probability of the event of {SOM < 1.5%}, since this threshold value is highly informative in soil protection and management planning. The resulted maps showed that, SSSRK is a valuable technique to model and assess the spatial variability and uncertainty of the target variable. Furthermore, the comparison of RK and SSSRK showed that, the SSSRK’s E-type estimation and the RK estimation gave almost the same results due to the fairly high R 2 value of the regression model (R 2 =0.809), which decreased the smoothing effect.

Influence of human impacts on trace metal accumulation in soils of two Hungarian cities

Despite the advanced activity of urban soil research, comparison of available trace metal contents in the soil of settlements has not yet been well investigated. First aim of research was the comparison of human impacts on urban soils in two Hungarian cities with different structure and development. To detect the sources of contamination, Szombathely and Sopron cities were separated into urban, suburban and peri-urban areas. Altogether 192 topsoil samples were collected at 0-20 cm in order to measure the physicochemical properties of the soil. Instead of total element contents, plant-available trace metal concentrations - Cd, Co, Cu, Ni, Pb, Zn - were determined using ICP-OES method. Due to different geological conditions, urban soils of the investigated settlements had similar properties in the case of pH, CaCO3 and texture. In the case of plant available trace metals, limit excesses were found in urban and peri-urban areas mostly, but high values were recorded in the suburb. The amount of Cdavailable, Coavailable and Niavailable were negligible. Downtown area was the most contaminated in both cities, but extremes appeared in suburban areas. In Szombathely, Cuavailable values were <40 mg Cu/kg, but extremely high Cuavailable results were found in the peri-urban viticulture areas of Sopron (>90 mg Cu/kg). The samples taken alongside busy roads near the city centre were Pbavailable-contaminated due to traffic. The Pbavailable concentration decreased slightly towards the suburban areas of the cities. The Znavailable level exceeded 40 mg Zn/kg in soils taken from the watercourses of Szombathely. The highest trace metal pollution levels were recorded in soils of public parks of Sopron. Urban soils of Szombathely were more homogenized than urban soils of Sopron. Based on statistical analyses and comparison of the relations of urban, suburban, and peri-urban areas of Sopron to Szombathely, Szombathelys urban soils show more homogeneity.

Integrated evaluation of urban groundwater hydrogeochemistry in context of fractal behaviour of groundwater level fluctuations

ABSTRACT The present study was carried out as part of a complex survey of urban groundwater quality and quantity in Szeged, southeast Hungary. The concentrations of 12 inorganic contaminants in 28 shallow groundwater monitoring wells were determined over a 2-year period (2010–2012). The evaluation of concentrations indicates remarkable contamination all over the city. Discriminant analysis (DA) was used to evaluate the spatial changes of groundwater quality. The groundwater levels were measured over a 14-year period (2000–2013). The fractal properties of water level fluctuations time series characterizing the groundwater system and Tisza River were investigated using rescaled range (R/S) analysis. The resulting Hurst exponents clearly showed the persistency and thus long memory effects of both the groundwater and the river flow. Comparison of the results of DA with the results of R/S analysis thus implies that the geological conditions and the changing groundwater quantities are not related to groundwater quality. EDITOR A. Castellarin ASSOCIATE EDITOR A. Fiori

Modellezett vízelöntés talajszerkezetre gyakorolt hatásának komputertomográfiás vizsgálata

Kutatasunk soran a belviz talajszerkezetre gyakorolt hatasat modelleztuk haromszor ismetelt nedvesitesi–szaradasi ciklussal (WDC) negy darab, kozel 10 ezer cm3 terfogatu, bolygatatlan talajmintan. A talajszerkezet valtozasat vizsgaltuk komputertomograffal (CT), annak erdekeben, hogy 1) a mintak belso szerkezeti viszonyait lathatova tegyuk, 2) a mintavetelezessel jaro, zavaro falhatast kikuszobolhessuk es 3) a nedvesitesi–szaradasi ciklusok utan osszehasonlito elemzest vegezhessunk. A harom nedvesedesi-szaradasi ciklusbol allo kiserlet soran az eredendően talajhibatol mentes, jo vizgazdalkodasu, jo minosegű talajmintakat 880 × 880 µm2 pixel felbontasban felveteleztuk komputertomograffal. Meghataroztuk a vizsgalat szempontjabol reprezentativ elemi terfogatot, majd a talajoszlopokat e terfogati elemekre osztva elemeztuk tovabb. A CT-vel mert, sűrűseget jelző Hounsfield-egysegeket atszamoltuk szaraz terfogattomeg ertekekre. A kiserlet eredmenyekent a bolygatatlan mintak kismertekű terfogattomeg novekedeset, v...

Nehézfémek eredetének elkülönítése városi kerti talajokban, Szeged példáján

A varosi kertek talajai, a tipikus varosi szennyező forrasokon (legkori ulepedes, kozlekedes femterhelő hatasa, haztartasok fűtese stb.) tul, művelesukből kifolyolag is szennyeződhetnek a toxikus es potencialisan toxikus nehezfemekkel, igy nagy kihivast jelent az ezekben a talajokban merhető femtartalom eredetenek (litogen, pedogen, antropogen) meghatarozasa, egyreszt a lehetseges szennyező-forrasok sokfelesege, masreszt az e talajokat erő antropogen hatasok miatt. Kutatasunk soran a varosi kornyezetterheles es a kertműveles kumulativ nehezfem-szennyező hatasat vizsgaltuk Szeged peldajan. A kulvarosi kerti talajok nehezfem-terheltsegenek felmerese mellett fő celunk volt, hogy kulonboző modszereket egyuttesen alkalmazva elkulonitsuk a kerti talajokban antropogen forrasbol feldusulo femek koret. Jelen tanulmanyban azt mutatjuk be, hogy az altalunk alkalmazott feldusulasi faktorok, a femkoncentraciok vertikalis eloszlasanak vizsgalataval kiegeszitve mikent segitik az egyes elemek eredetenek (litogen, pedogen...