Monitoring of ozone effects on the vitality and increment of Norway spruce and European beech in the Central European forests

The ozone effect on Norway spruce (Picea abies (L) Karst.) and European beech (Fagus sylvatica L.) was studied on 48 monitoring plots in 2005-2008. These plots represent two major forest tree species stands of different ages in eight regions of the Czech Republic. The forest conditions were represented by defoliation and the annual radial increment of individual trees. The ozone exposure was assessed by using modeled values of mean annual O(3) concentration and the AOT40 index. The malondialdehyde (MDA) content of the foliage was analysed and used as an indicator of oxidative stress. The correlation analysis showed a significant relation of Norway spruce defoliation to the AOT40 exposure index, and European beech defoliation to the MDA level. The radial increment response to ozone was significant only for the European beech: (a) the correlation analysis showed its decrease with increasing AOT40; (b) the regression model showed its decrease with increasing mean annual ozone concentration only at lower altitudes (<700 m a.s.l.).     

The impact of ambient ozone on mountain spruce forests in the Czech Republic as indicated by malondialdehyde

Malondialdehyde (MDA), a product of lipid peroxidation and biomarker of oxidative stress, is measured over the long term in spruce Picea abies needles under real conditions in three Czech mountain border areas. The trends presented collate the MDA content in spruce needles with ambient ozone, temperature and precipitation as casual, and defoliation as a subsequent factor for the period 1994-2006. We have found the overall decreasing trends in MDA and defoliation. The highest MDA and defoliation are recorded in the Jizerske, the lowest in the Krusne hory Mts. Out of the examined variables the MDA is predicted best by mean temperature in vegetation season, median of O₃ concentrations and AOT40; these three variables account for 34% of MDA1 and 36% of MDA2 variability. Our hypothesis that higher ambient O₃ exposure results in higher MDA contents in P. abies needles under real conditions has not been approved.     

Zero-valent iron nanoparticles in treatment of acid mine water from in situ uranium leaching

Acid mine water from in situ chemical leaching of uranium (Straz pod Ralskem, Czech Republic) was treated in laboratory scale experiments by zero-valent iron nanoparticles (nZVI). For the first time, nZVI were applied for the treatment of the real acid water system containing the miscellaneous mixture of pollutants, where the various removal mechanisms occur simultaneously. Toxicity of the treated saline acid water is caused by major contaminants represented by aluminum and sulphates in a high concentration, as well as by microcontaminants like As, Be, Cd, Cr, Cu, Ni, U, V, and Zn. Laboratory batch experiments proved a significant decrease in concentrations of all the monitored pollutants due to an increase in pH and a decrease in oxidation-reduction potential related to an application of nZVI. The assumed mechanisms of contaminants removal include precipitation of cations in a lower oxidation state, precipitation caused by a simple pH increase and co-precipitation with the formed iron oxyhydroxides. The possibility to control the reaction kinetics through the nature of the surface stabilizing shell (polymer vs. FeO nanolayer) is discussed as an important practical aspect.     

New approach to common removal of dioxins and NOx as a contribution to environmental protection

Meeting environmental limits represents the most important issue in the field of waste processing. Our primary effort consists either in eliminating hazardous emissions or in prevention of their production. However, this is not feasible in most cases therefore the so called secondary methods have to be applied. Technologies based on adsorption of hazardous compounds using activated carbon, deNOx/deDiox technologies as well as technology of catalytic filtration using a special material REMEDIA^® proved itself to be very efficient. The latter technology consists in using a baghouse with bags manufactured from a special material (two layers – membrane from ePTFE and felt with bound in catalyst) called REMEDIA^® which has successfully been used for removal of PCDD/F during recent period. However, it has been found that this technology can partially remove NOx as well. Based on our experience from operation industrial incineration plants it has been proved that even after more than three years' operation the activity of filtration material was not decreased and efficiency of dioxins removal from flue gas ranges from 97 to 99% (Pa?ízek et al., 2008).Based on industrial experience and new findings it has been decided to focus continuing research and development on deNOx experiments by applying SCR using the above mentioned efficient filtration material. This type of material is primarily designed for reduction of PMs and PCDD/F. Experiments with this filtration material should test possibilities for simultaneous reduction of PMs, PCDD/F and NOx. Tests are performed in MSW incineration plant utilizing new experimental unit and under standard conditions. Waste processing capacity of the incineration plant amounts to 15 t/h. Tests result in evaluation of overall reduction efficiency and negative factors that might influence the efficiency. Catalytic filtration is further compared to other types of deNOx methods.Thus we have obtained qualitatively new knowledge about this method the value of which is emphasized by full scale industrial testing.     

Vertical distribution of heavy metals in grain size fractions in sedimentary rocks: Mosina–Krajkowo water well field, Poland

The paper presents the results of heavy metals determination in samples of sedimentary rocks from the Mosina-Krajkowo water well field (Poland). The concentration of heavy metals was analysed by type of rock (sand, gravel, warp, silt, till, and clay). Variation of heavy metal concentrations with depth was studied taking into account the age series of the rocks (fluvial sediments of the modern Warta River valley, sediments of the Baltic Glaciation, tills of the Middle-Polish Glaciation, sediments of the Masovian Interglacial (Holstein), tills of the Poznań series) and granulometric fractions. The grain sizes considered included: >2.0, 2.0-1.0, 1.0-0.5, 0.5-0.25, 0.25-0.1, 0.1-0.063, and <0.063 mm. The concentrations of the heavy metals studied were found to change with the type of rock, age series, and granulometric fraction. The levels of the metals were determined by the technique of atomic absorption spectrometry with flame atomisation (F-AAS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES).     

Characterization of humic substances of different origin by means of mass spectrometry and neural networks

Mass spectrometry fingerprinting of humic acids extracted from different soils has been carried out using laser desorption/ionization mass spectrometry (LDI-TOF MS). LDI-TOF MS provides characteristic mass spectra fingerprints for the humic acids of different origin. The information given in the fingerprints was evaluated for natural grouping trends in the samples by neural networks computing tools, such as self-organizing feature map (SOFM). This approach is efficient for recognizing patterns in the humic acids samples independently of their characteristic variability; variability characterizing natural products such as humic substances. The use of multi-layer perceptron artificial neural networks gave a successful classification of the samples.     

Investigating the coagulation of non-proteinaceous algal organic matter: Optimizing coagulation performance and identification of removal mechanisms

The removal of algal organic matter(AOM) is a growing concern for the water treatment industry worldwide. The current study investigates coagulation of non-proteinaceous AOM(AOM after protein separation), which has been minimally explored compared with proteinaceous fractions. Jar tests with either aluminum sulphate(alum) or polyaluminium chloride(PACl) were performed at doses of 0.2–3.0 mg Al per 1 mg of dissolved organic carbon in the p H range 3.0–10.5. Additionally, non-proteinaceous matter was characterized in terms of charge, molecular weight and carbohydrate content to assess the treatability of its different fractions. Results showed that only up to 25% of non-proteinaceous AOM can be removed by coagulation under optimized conditions. The optimal coagulation p H(6.6–8.0 for alum and 7.5–9.0 for PACl) and low surface charge of the removed fraction indicated that the prevailing coagulation mechanism was adsorption of non-proteinaceous matter onto aluminum hydroxide precipitates. The lowest residual Al concentrations were achieved in very narrow p H ranges, especially in the case of PACl. High-molecular weight saccharidelike organics were amenable to coagulation compared to low-molecular weight( 3 k Da)substances. Their high content in non-proteinaceous matter(about 67%) was the reason for its low removal. Comparison with our previous studies implies that proteinaceous and nonproteinaceous matter is coagulated under different conditions due to the employment of diverse coagulation mechanisms. The study suggests that further research should focus on the removal of low-molecular weight AOM, reluctant to coagulate, with other treatment processes to minimize its detrimental effect on water safety.     

High-valent iron-based oxidants to treat perfluorooctanesulfonate and perfluorooctanoic acid in water

Perfluoroalkyl and polyfluoroalkyl substances are occurring in consumer and industrial products. They have been found globally in the aquatic environment including drinking water sources and treated wastewater effluents, which has raised concern of potential human health effects because these substances may be bioaccumulative and extremely persistent. The saturated carbon–fluorine bonds of the substances make them resistant to degradation by physical, chemical, and biological processes. There is therefore a need for advanced remediation methods. Iron-based methods involving high-valent compounds are appealing to degrade these substances due to their high oxidation potentials and capability to generate environmentally friendly by-products. This article presents for the first time the oxidation ability of tetraoxy anions of iron(V) (Fe^VO₄ ^3?, Fe(V)), and iron(IV) (Fe^IVO₄ ^4?, Fe(IV)), commonly called ferrates, in neutral and alkaline solutions. Solid compounds of Fe(V) (K₃FeO₄) and Fe(IV) (Na₄FeO₄) were added directly into buffered solution containing perfluorooctansulfonate and perfluorooctanoic acid at pH 7.0 and 9.0, and mixed solutions were subjected to analysis for remaining fluoro compounds after 5 days. The analysis was performed by liquid chromatography–mass spectrometry/mass spectrometry technique. Fe(IV) showed the highest ability to oxidize the studied contaminants; the maximum removals were 34 % for perfluorooctansulfonate and 23 % for perfluorooctanoic acid. Both Fe(V) and Fe(IV) had slightly higher tendency to oxidize contaminants at alkaline pH than at neutral pH. Results were described by invoking reactions involved in oxidation of perfluorooctansulfonate and perfluorooctanoic acid by ferrates in aqueous solution. The results demonstrated potentials of Fe(V) and Fe(IV) to degrade perfluoroalkyl substances in contaminated water.     

Combined biocidal action of silver nanoparticles and ions against Chlorococcales (S<Emphasis Type="Italic">cenedesmus quadricauda</Emphasis>, <Emphasis Type="Italic">Chlorella vulgaris)</Emphasis> and filamentous algae (<Emphasis Type="Italic">Klebsormidium sp.</Emphasis>)

Despite the extensive research, the mechanism of the antimicrobial and biocidal performance of silver nanoparticles has not been unequivocally elucidated yet. Our study was aimed at the investigation of the ability of silver nanoparticles to suppress the growth of three types of algae colonizing the wetted surfaces or submerged objects and the mechanism of their action. Silver nanoparticles exhibited a substantial toxicity towards Chlorococcales Scenedesmus quadricauda, Chlorella vulgaris, and filamentous algae Klebsormidium sp., which correlated with their particle size. The particles had very good stability against agglomeration even in the presence of multivalent cations. The concentration of silver ions in equilibrium with nanoparticles markedly depended on the particle size, achieving about 6 % and as low as about 0.1 % or even less for the particles 5 nm in size and for larger ones (40–70 nm), respectively. Even very limited proportion of small particles together with larger ones could substantially increase concentration of Ag ions in solution. The highest toxicity was found for the 5-nm-sized particles, being the smallest ones in this study. Their toxicity was even higher than that of silver ions at the same silver concentration. When compared as a function of the Ag⁺ concentration in equilibrium with 5-nm particles, the toxicity of ions was at least 17 times higher than that obtained by dissolving silver nitrite (if not taking into account the effect of nanoparticles themselves). The mechanism of the toxicity of silver nanoparticles was found complex with an important role played by the adsorption of silver nanoparticles and the ions released from the particles on the cell surface. This mechanism could be described as some sort of synergy between nanoparticles and ions. While our study clearly showed the presence of this synergy, its detailed explanation is experimentally highly demanding, requiring a close cooperation between materials scientists, physical chemists, and biologists.