Ernst Bäucker

Silica uptake from nanoparticles and silica condensation state in different tissues of Phragmites australis

Silicon is described as beneficial for grasses by enhancing yield and fitness via a considerable contribution to pathogen, drought, and pest resistance. Silicic acid is the predominant form for uptake and transport within the plant and will precipitate in leaves. But it is unknown whether polymeric nanosilicon compounds in its synthetic form, with an increasing concentration in aquatic environments, can be suitable for plant nutrition. Therefore, we investigated the uptake, transport, and deposition of silicic acid/silica within plants using synthetic nanosilica. Our results show a significant difference in silicon (Si) content within the different tissues of Phragmites australis. The nanosilica had been dissolved prior to the uptake by plants. The chemical form of Si during uptake was not traceable. A significant enhancement in the condensation state of the silica was found from root to leaves especially from culm to leaf tips visible by the increasing content of Q(4)-groups in the NMR spectra. We conclude that synthetic nanosilica has the same quality as source for the beneficial element Si like natural silica. Since the condensation state is described to control silica solubility, we suggest that different condensation states within the plant may result in different remobilization of silicon during decomposition of the plant material.

Radial Growth Dynamics of Spruce (Picea Abies) Measured by Micro-Cores

Using medical cannulas of 0.5 mm inside diameter, micro-cores were taken at three circurnferential heights from five spruce trees [Picea abies (L.) Karst.] in the Ore Mountains (Germany). The micro-cores were taken every second week during the growing seasons of 1996 and 1997 and light-microscopy studies were made on the micro-cores. The number of xylem and phloem cells, and total cell count in the cambial zone, were tabulated for each sampIe. Determination of the intra-annual cellular growth rate of conifers is simplified and will be possible also in long-term experiments. Preliminary evaluations of the wound response indicate that this micro-coring technique causes minimal injury.

Indicative properties of fly-ash affected forest soils in Northeastern Germany

Many forest ecosystems in Germany are strongly influenced by emissions of pollutants like SO2 and alkaline dusts. To quantify and evaluate the consequences of long-term fly ash deposition on forest soils, a study was conducted in pine stands (Pinus sylvestris) in the Dubener Heide in Northeastern Germany. This forest area has been influenced mainly by emissions from coal-fired power plants and the chemical industry of the industrial region Bitterfeld-Wolfen-Zschornewitz since the early 1900. The study sites are located along a fly ash deposition gradient of 8, 16, 14, 18, and 25 km away from the main emission source in Bitterfeld (sites 1, 2, 3, 4, and 5, respectively). Samples of the organic horizons (Oi, Oe, and Oa) and mineral topsoil (0—10 cm) were taken in fall 1998 and analyzed for their ferromagnetic susceptibility and total ash content. Scanning electron microscopy (SEM) and energy dispersive X-ray microanalysis (EDX) were performed on selected samples to differentiate between the pedogenic and atmospheric origin of the mineral components in the organic horizons. As a result of the long-term deposition, ferromagnetic fly ash components are mainly accumulated in the Oe and Oa horizons of the forest soils studied. Ferromagnetic susceptibility was significantly higher (p ≤ 0.05) in the Oe horizon of sites 1 and 2 compared to sites 3, 4, and 5. Unusually high total ash contents for organic horizons of > 74 % were determined in the Oa at all sites. SEM revealed 3 distinct features of persistent fly ash deposits from coal-fired power plants within the organic horizons that can be defined as ”stable glasses” with magnetic properties, aluminum-silicate-minerals, and slag fragments. SEM and EDX indicated that a great portion of the mineral particles found in the organic horizons of forests soils influenced by fly ash are from atmospheric sources. For detection of atmospheric lignite-derived deposition into forest soils, the Oe and Oa horizons have to be considered as specific diagnostic horizons because they show indicative properties for such soils. Indikatoreigenschaften von flugaschebeeinflussten Waldboden in Nordostdeutschland Viele Waldokosysteme in Deutschland sind durch Emissionen von SO2 und alkalischen Stauben stark beeinflusst. Zur Erfassung und Bewertung der Folgen der langfristigen Flugaschedepositionen auf Waldboden wurden Untersuchungen auf Kiefernstandorten (Pinus sylvestris) der Dubener Heide, Nordostdeutschland, durchgefuhrt. Dieses Waldgebiet wurde seit Anfang 1900 hauptsachlich durch Emissionen von Braunkohlekraftwerken und der chemischen Industrie der Industrieregion Bitterfeld-Wolfen-Zschornewitz beeinflusst. Die Untersuchungen erfolgten entlang eines Flugaschedepositionsgradienten in Entfernung von 8, 16, 14, 18 und 25 km vom Hauptemittenten Bitterfeld (Standorte 1, 2, 3, 4 bzw. 5). Im Herbst 1998 wurden Proben der organischen Auflagehorizonte (L, Of und Oh) und des Mineralbodens (0—10 cm) entnommen und auf die ferromagnetische Suszeptibilitat und die Gesamtaschegehalte untersucht. Zur Differenzierung zwischen pedogener und atmospharischer Herkunft der mineralischen Partikel in den untersuchten organischen Auflagen wurden an ausgewahlten Proben rasterelektronenmikroskopische Aufnahmen (REM) und energiedispersive Rontgenmikroanalysen (EDX) durchgefuhrt. Als Ergebnis jahrzehntelanger Eintrage sind die Flugaschebestandteile hauptsachlich in den Of- und Oh-Horizonten der untersuchten Waldstandorte akkumuliert. Die ferromagnetische Suszeptibilitat war in den Of-Lagen der Standorte 1 und 2 signifikant hoher (P ≤ 0,05) als in jenen der Standorte 3, 4 und 5. Die Oh-Horizonte aller untersuchten Flachen wiesen hohe Gesamtaschegehalte von > 74 % auf. Mittels REM-Analyse konnten 3 typische Erscheinungsformen von persistenten Flugaschebestandteilen aus Braunkohlenkraftwerken innerhalb der organischen Auflagen bestimmt werden, welche als „stabile Glaser“ mit magnetischen Eigenschaften, Aluminium-Silikat-Mineralpartikel und Schlackefragmente definiert wurden. REM- und EDX-Analysen zeigten, dass ein groser Teil der Mineralpartikel, welche in den Humusauflagen von flugaschebeeinflussten Waldstandorten gefunden wurden, atmospharischen Quellen entstammen. Zum Nachweis von atmospharischen Eintragen aus Braunkohlekraftwerken sollten Of und Oh als diagnostische Horizonte berucksichtigt werden, da sie Indikatoreigenschaften fur derartig beeinflusste Standorte aufweisen.

Stratigraphic Distribution of Lignite-Derived Atmospheric Deposits in Forest Soils of the Upper Lusatian Region, East Germany

Atmospheric fly ash emissions from lignite-fired power plantsin the Upper Lusatian and Turówan mining districts stronglyaffected large forest areas along the German-Polish border. Afield study was conducted in old spruce stands (Piceaabies (L.) Karst.) to assess the stratigraphic distributionof fly ash in the forest floor and mineral topsoil in the St. Marienthal forest area in the eastern part of Saxony,Germany. This forest area is subjected to long-termatmospheric depositions by two German and one Polish powerplants since the early 1900s. The three study sites arelocated along a fly ash deposition gradient of 3, 6 and 15 kmfrom the power plant in Turów (Sites Ia, II and III,respectively). An additional site (Site Ib) at a distance of 3 km from Turów was chosen to study the influence of vegetationtype on fly ash deposition intensity in forest soils. Samplesof the humic layer (Oi (L), Oe (F) and Oa (H) horizons) andmineral soil (0–10 cm) were taken in Spring and Fall 1999 andanalysed for their ferromagnetic susceptibility and total ashcontent. Particle size distribution, magnetic susceptibilityof individual size fractions, scanning electron microscopy(SEM), and energy dispersive X-ray microanalysis (EDX) wereperformed on selected samples to evaluate the origin ofmineral particles found in the forest floor. High magneticsusceptibility of the Oa and Oe horizons is a result of thelong-term accumulation of lignite-derived atmospheric depositsin the forest floors of the studied area. Pure conifer stands(year-round filtration of airborne pollutants) resulted inhigher inputs of ferromagnetic fly ash particles in forestsoils. Unusually high total ash contents for humic horizons(up to 77%) were determined in the Oa and Oe horizons atSites Ia and IIb, indicating the need for a new classificationsystems for the organic layer in forest soils near coal-firedpower plants. SEM revealed 4 typical phases of persistent flyash deposits formed by combustion of Lusatian lignite: (1) iron-containing `stable glasses’, (2) aluminium-iron-silicate-minerals,(3) slag fragments and (4) lignite-derived fossilcarbon. Particle size analysis, magnetic susceptibilitymeasurements and SEM-EDX techniques indicated that a greatportion of the mineral particles found in the humic horizonsof forests soils are from atmospheric sources. Fly ashaccumulation consisting of ferromagnetic minerals contributesmainly to the 125–63 and <63 μm fractions in soils. EDXanalysis revealed that atmospheric input of lignite-derivedfly ash increases the contents of the following ecologicalrelevant elements in soils: carbon, iron, aluminium, calcium,potassium, sulphur, titanium and sodium.

Silicon Availability Affects the Stoichiometry and Content of Calcium and Micro Nutrients in the Leaves of Common Reed

PurposeAlthough silicon is not an essential element in sensu stricto for plant growth, it affects plant stress resistance and may affect the composition of cell wall compounds, especially of grasses. Where silicon availability alters the stoichiometry of macro nutrients in grasses, data on the interaction with calcium and micro nutrients are rare and hence are focussed on in this study.MethodsThe effect of silicon availability on calcium and micro nutrient content of the leaf blades of common reed, Phragmites australis, were assessed in a pot experiment with three levels of silicon supply.ResultsCalcium and micro nutrient concentrations and stoichiometry in leaf blades is altered by changing silicon availability during plant growth. In addition, Scanning Electron Microscopy (SEM) reveals that elevated silicon supply promotes silica deposition and changes the element content of micro and macro nutrients in the near epidermis tissue of P. australis leaves.ConclusionSilicon availability has a major impact on calcium and micro nutrient content and stoichiometry in grasses. This in turn may considerably affect the nutrient cycling in grass dominated ecosystems.

UV-screening of grasses by plant silica layer?

UV-screening by terrestrial plants is a crucial trait since colonization of terrestrial environments has started. In general, it is enabled by phenolic substances. Especially for grasses it remains unclear why plants grown under the absence of UV-B-radiation exhibit nonetheless a high UV-B-screening potential. But this may be explained by the UV-screening effect of the silicon double layer. It was shown for seedlings of soybeans (Glycine max L.) and wheat (Triticum aestivum L.) that enhanced silicon supply reduces stress induced by UV-radiation. Even more important is a direct correlation between silicon content in the epidermis near area (intercellular spaces) and the absorption of UV-radiation in this area shown in other papers. The silicon double layer may act like a glass layer and decreases the transmission of UV-radiation at the epidermis near area. In summary, the absorbance/reflection of ultraviolet radiation is dependent on the characteristics of the epidermis near area of leaves, particularly the occurrence (qualitatively and quantitatively) of phenolic substances and/or a silicon double layer in this area. Consequently, UV-screening by plant silicon double layer should get more attention in future research with emphasis on effects of UV-radiation on plant physiology.

Silica decouples fungal growth and litter decomposition without changing responses to climate warming and N enrichment

Ongoing global changes, such as climate warming and increasing supply of reactive nitrogen (N), are expected to affect essential ecosystem processes such as the decomposition of plant litter. Determining the influence of environmental heterogeneity on the magnitude of these effects remains an important task, with silicon (Si) availability being a notable component of this heterogeneity, especially for grasses. We conducted an outdoor enclosure experiment to test if increased Si supply to a widespread foundation species (Phragmites australis) alters the effect of climate warming and excess N supply on litter decomposition by curbing fungal decomposers. Consistent with expectations, Si supply during plant growth reduced fungal biomass in decomposing leaf blades by 50%, an effect that was doubled by excess external N supply. These strong impacts, however, did not directly translate to reduced litter decomposition or associated changes in nutrient dynamics. Instead, plant tissue-specific effects determined th...

Solid-state spectroscopic characterization of α-chitins deacetylated in homogeneous solutions.

Synthesis and spectroscopic characterization of α-chitins exhibiting degrees of acetylation (DA) between 0.5 and 1 were reported. Crab shell α-chitin consisting of microfibrils with a width of less than 1 μm was regenerated from or alkaline deacetylated in 30% aqueous NaOH solution. After the deacetylation in homogeneous solution, the DA of α-chitins decreased steadily with prolonged deacetylation times from 1 to 0.54. The native microfibrils of starting α-chitin were destroyed, while aggregates or sheets were formed depending on the DA of chitins. According to WAXD measurements, deacetylated chitins with DA lower than 0.76 have different crystalline structures than starting α-chitin. Furthermore, FT Raman spectroscopy demonstrated a novel rapid method to determine the DA of chitin with correlation coefficients greater than 0.99. On the basis of the FT Raman signals ascribed to the amide groups, the amount of hydrogen bonds linked to C═O groups decreased strongly with lower DA and the relationship between them was presented.

Nutrition-physiological responses of spruce to different levels of sulfur dioxide stress in the Erzgebirge Mountains and the Thüringian Forest.

ZusammenfassungIn einer Freilandstudie wurden 11 mittelalte Fichtenbestände (Picea abies (L.) Karst) auf vergleichbaren Bodenformen des Thüringer Waldes und Erzgebirges bei unterschiedlichen SO2-Depositionen untersucht. In den Nadeln wurden Gesamtelementgehalte und wasserlösliche Elementgehalte gemessen. Energiedispersive Röntgenmikroanalyse (EDR) in Verbindung mit Kryo-Rasterelektronenmikroskopie (REM) ermöglichte die direkte Bestimmung der Elementgehalte in Mesophyll- und Endodermisvakuolen an gefrorenen Proben.Die chemische Analyse der Elementgehalte der Nadeln ergab, dass der Gehalt an Sulfatschwefel, an organischem Schwefel und an Kalium von der SO2-Belastung der Luft abhängt. Die Bodenparameter hatten keinen signifikanten Einfluss auf den Ernährungsstatus der Fichten.Die EDR-Analysen bestätigen, dass an den SO2-belasteten Standorten des Erzgebirges vor allem Kaliumionen dem Ladungsausgleich der Sulfationen dienen. In geringerem Ausmaß sind Magnesium und bei hohen Gehalten im Boden Mangan an der Neutralisation der bei der oxidativen Entgiftung gebildeten Schwefelsäure beteiligt.SummaryEleven middled-aged Norway spruces (Picea abies (L.) Karst) growing in stands in the two highlands Erzgebirge Mountains and Thuringian Forest which have been subject to different SO2 deposition were investigated in a field study. Measurements were made of total element contents and the water-soluble proportions of the element contents. Low-temperature scanning-electron microscopy (LTSEM) techniques were used for structural observations. Energy dispersive microanalyses (EDX) on bulk-frozen hydrated samples led to the direct determination of element contents in the vacuoles of both the mesophyll and endodermis.Chemicals analysis of the element contents of needles revealed a significant dependency of sulphate sulphur, organic sulphur, and potassium on the SO2 pollution of the air. However, a significant influence of soil parameters on the nutrient status of the spruce growing on the different plots could not be verified.The EDX-analyses proved that potassium is the chief ion for neutralisation of the sulphate ions at the SO2 loaded sites of Erzgebirge Mountains. To a lower extent, magnesium and, at sites rich in manganese, also manganese are involved in sulphuric acid neutralisation.Eleven middled-aged Norway spruces (Picea abies (L.) Karst) growing in stands in the two highlands Erzgebirge Mountains and Thuringian Forest which have been subject to different SO₂ deposition were investigated in a field study. Measurements were made of total element contents and the water-soluble proportions of the element contents. Low-temperature scanning-electron microscopy (LTSEM) techniques were used for structural observations. Energy dispersive microanalyses (EDX) on bulk-frozen hydrated samples led to the direct determination of element contents in the vacuoles of both the mesophyll and endodermis.Chemicals analysis of the element contents of needles revealed a significant dependency of sulphate sulphur, organic sulphur, and potassium on the SO₂ pollution of the air. However, a significant influence of soil parameters on the nutrient status of the spruce growing on the different plots could not be verified.The EDX-analyses proved that potassium is the chief ion for neutralisation of the sulphate ions at the SO₂ loaded sites of Erzgebirge Mountains. To a lower extent, magnesium and, at sites rich in manganese, also manganese are involved in sulphuric acid neutralisation.

Ernährungsphysiologische Reaktionen der Fichte auf unterschiedliche Schwefeldioxidbelastung im Erzgebirge und im Thüringer Wald

ZusammenfassungIn einer Freilandstudie wurden 11 mittelalte Fichtenbestände (Picea abies (L.) Karst) auf vergleichbaren Bodenformen des Thüringer Waldes und Erzgebirges bei unterschiedlichen SO2-Depositionen untersucht. In den Nadeln wurden Gesamtelementgehalte und wasserlösliche Elementgehalte gemessen. Energiedispersive Röntgenmikroanalyse (EDR) in Verbindung mit Kryo-Rasterelektronenmikroskopie (REM) ermöglichte die direkte Bestimmung der Elementgehalte in Mesophyll- und Endodermisvakuolen an gefrorenen Proben.Die chemische Analyse der Elementgehalte der Nadeln ergab, dass der Gehalt an Sulfatschwefel, an organischem Schwefel und an Kalium von der SO2-Belastung der Luft abhängt. Die Bodenparameter hatten keinen signifikanten Einfluss auf den Ernährungsstatus der Fichten.Die EDR-Analysen bestätigen, dass an den SO2-belasteten Standorten des Erzgebirges vor allem Kaliumionen dem Ladungsausgleich der Sulfationen dienen. In geringerem Ausmaß sind Magnesium und bei hohen Gehalten im Boden Mangan an der Neutralisation der bei der oxidativen Entgiftung gebildeten Schwefelsäure beteiligt.SummaryEleven middled-aged Norway spruces (Picea abies (L.) Karst) growing in stands in the two highlands Erzgebirge Mountains and Thuringian Forest which have been subject to different SO2 deposition were investigated in a field study. Measurements were made of total element contents and the water-soluble proportions of the element contents. Low-temperature scanning-electron microscopy (LTSEM) techniques were used for structural observations. Energy dispersive microanalyses (EDX) on bulk-frozen hydrated samples led to the direct determination of element contents in the vacuoles of both the mesophyll and endodermis.Chemicals analysis of the element contents of needles revealed a significant dependency of sulphate sulphur, organic sulphur, and potassium on the SO2 pollution of the air. However, a significant influence of soil parameters on the nutrient status of the spruce growing on the different plots could not be verified.The EDX-analyses proved that potassium is the chief ion for neutralisation of the sulphate ions at the SO2 loaded sites of Erzgebirge Mountains. To a lower extent, magnesium and, at sites rich in manganese, also manganese are involved in sulphuric acid neutralisation.Eleven middled-aged Norway spruces (Picea abies (L.) Karst) growing in stands in the two highlands Erzgebirge Mountains and Thuringian Forest which have been subject to different SO₂ deposition were investigated in a field study. Measurements were made of total element contents and the water-soluble proportions of the element contents. Low-temperature scanning-electron microscopy (LTSEM) techniques were used for structural observations. Energy dispersive microanalyses (EDX) on bulk-frozen hydrated samples led to the direct determination of element contents in the vacuoles of both the mesophyll and endodermis.Chemicals analysis of the element contents of needles revealed a significant dependency of sulphate sulphur, organic sulphur, and potassium on the SO₂ pollution of the air. However, a significant influence of soil parameters on the nutrient status of the spruce growing on the different plots could not be verified.The EDX-analyses proved that potassium is the chief ion for neutralisation of the sulphate ions at the SO₂ loaded sites of Erzgebirge Mountains. To a lower extent, magnesium and, at sites rich in manganese, also manganese are involved in sulphuric acid neutralisation.