bluuebunny/crossref_metadata_2025_split huggingface dataset:
What predicts nitrous oxide emissions and denitrification N‐loss from European soils?
Authors: Kaiser E.‐A. , Eiland F. , Germon J. C. , Gispert M. A. , Heinemeyer O. , Henault C. , Lind A. M. , Maag M. , Saguer E. , Van Cleemput O. , Vermoesen A. , Webster C. 
Published: December 2011

AbstractN20 emissions and denitrification N‐losses. precipitation, air temperature, soil moisture, bulk density and content of mineral N were monitored in 9 different agricultural soils in 6 European countries throughout the vegetation period (April to September) 1992 and 1993. N2O emissions and denitrification N‐losses were log‐normal distributed, reflecting high temporal changes.While small flux rates (< 2 g N ha−1 d−1) were detectable every day, high rates (> 10 g N ha−1 d−1) were measured after fertilization.An attempt to relate the emission variables to climate and soil variables was made through the use of correlation analysis. The mean N20 emissions from soil were significantly correlated with the soil properties clay, organic C and mineral N content and the amount of applied mineral N fertilizer. The best prediction of the N2O emission rates (r2 = 0.734) was achieved by multiple linear regression using the soil parameter clay and mineral N. Only 50% of the observed variation could be explained by the factors Corg and mineral N, which describe the substrate availability for microbial processes. No successful statistical model was found for the prediction of denitrification N‐losses.
Influence of nitrogen concentration and form in the nutrient solution N20 and N2 emissions from a soilless culture system
Authors: Daum Diemo , Schenk Manfred K. 
Published: December 2011

AbstractThe influence of nitrogen concentration and form in the nutrient solution on the N2O and N2 emissions from a closed rockwool system with cucumber crops was investigated. At optimum, nitrate‐accented nitrogen supply of plants (120 mg N l−1) on average 0.59 kg N per hectare greenhouse area and day was released. Comparable emission rates occurred with moderate sub‐ and supraoptimum nitrogen fertilization. Thus, in this range the N supply was non‐limiting for the gaseous nitrogen losses. Only in the case of severe suboptimum N supply (40 mg N l−1) the N2O N2 emissions were clearly lower, probably as a result of diminished plant growth and therefore reduced root respiration and exudation of organic carbon sources for microorganisms. The proportion of nitrous oxide in the gaseous nitrogen losses increased on average from 5 to 13% with increasing N supply, possibly because of an impaired N2O reduction in denitrification due to high nitrate concentrations.Short‐term shifting with optimum nitrogen supply from nitrate‐ accented composition to pure nitrate did not affect the gaseous nitrogen emissions, whereas an exclusive ammonium supply resulted in a considerable decrease. The results indicated that the N2O emission and the total nitrogen losses from the soilless culture system were predominantly caused by denitrification.
Schadstoffpotential technogener Substrate in Böden urban‐industrieller Verdichtungsräume
Authors: Meuser Helmut 
Published: December 2011

AbstractIn urban‐industriellen Verdichtungsräumen liegen häufig anthropogene Auftragsböden aus Gemengen natürlicher und technogener Substrate vor. Mit der Beimengung technogener Substrate kann eine Akkumulation von Schadstoffen im Boden verbunden sein. Anhand umfangreicher Untersuchungen im zentralen Ruhrgebiet, ergänzt durch Angaben aus der Literatur, wird dargestellt, mit welchen Schadstoffgehalten (As, Cd, Cr. Cu, Hg, Ni, Pb, Zn, Benzo(a)pyren, Σ PCB) bei den unterschiedlichen technogenen Substraten zu rechnen ist. Die Datenmenge erlaubt, dem Belastungsgrad der einzelnen technogenen Substrate Bewertungsklassen in einer fünfstufigen Skala (sehr gering, gering, mittel, hoch, sehr hoch) zuzuordnen.
Hydraulische Eigenschaften von Basaltsaproliten
Authors: Häfele Stephan , Wiechman Horst 
Published: December 2011

AbstractIn Erosionslagen sind Saprolite häufig in beträchtlichem Maße Wurzelraum. Da bisher kaum Untersuchungen zum Wasserhaushalt und den hydraulischen Eigenschaften vorliegen, wurden Basaltsaprolite und zum Vergleich ein ferratlitisches Bodensediment in Stechzylindern und vor allem in größeren Monolithen untersucht. Bestimmt wurde die Porengrößenverleilung sowie die ungesättigte Leitfähigkeit in Abhängigkeit von der Wasserspannung. Klüftung bedingt eine sehr hohe gesättigte Wasserleitfähigkeit. Im Bereich pF 1.8 nimmt die ungesättigte Wasserleitfähigkeit bereits stark ab. Trotz hoher Porenvolumina und einem beträchtlichen Anteil mäßig fest gebundenen Wassers (pF 2.5–4.2), ist dieses für die Pflanzen, in Abhängigkeit von dem Grad der Durchwurzelung, nur zum Teil verfügbar. Die Durchlässigkeit von Saproliten für Sickerwasser wird leicht unter‐ und der Beitrag zur Wasserversorgung der Vegetation leicht überschätzt.
The dynamics of root production and loss in Betula papyrifera seedlings in response to elevated CO2 and an aluminium pulse
Authors: Li Alison , Berntson Glenn M. , Godbold Douglas L. , Bazzaz Fakhri A. 
Published: December 2011

AbstractSeedlings of Betula papyrifera were grown in sand/nutrient solution cultures in rhizotrone growth containers under elevated (700 ppm) or ambient (375 ppm) atmospheric CO2 concentrations for approximately 10 weeks. Thirty seven days after the begin of the experiment the plants were exposed to a 10 day pulse of 400 or 1200 μM Al. Elevated atmospheric CO2 increased both root production and loss. Exposure to Al reduced root production and slightly reduced root loss. The reduced root production due to Al was amplified after the pulse had receded, resulting in a significantly lower net and gross root production at the end of the experiment. There were no clear CO2 × Al interactions.
Effects of fallow system and cropping frequency upon quantity and composition of earthworm casts
Authors: Hauser Stefan , Asawalam Damian O. 
Published: December 2011

AbstractThe quantities of earthworm surface casts were monitored in traditional bush fallow regrowth (BFR), Pueraria phaseoloides live mulch (PLM), Leucaena leucocephala alley cropping (LAC) and undisturbed forest. The fallow systems were planted to maize/cassava intercrop either permanently or for one year after three years of fallow i.e. at 100 and 25% cropping frequencies. Earthworm casting activity was lower in fields cropped after clearing three year old fallow than in the respective permanently cropped fallow management system. The reduction in casting was related both to the degree of biomass removed through burning and to re‐establishment of cover crops. Higher exchangeable cation concentration in the soil did not cause increased casting activity.Concentrations of organic C, total N and exchangeable Ca and Mg in casts were significantly higher than in the 0–15 cm topsoil. Exchangeable Ca and Mg in casts did not significantly differ between treatments, with the exception of significantly higher Mg in casts after three years of P. phaseoloides fallow. Topsoil (0–15 cm) exchangeable Ca and Mg were not correlated with cast exchangeable Ca and Mg, but concentrations of organic C and total N in casts were significantly correlated with organic C and total N in the topsoil. Coefficients of variability of organic C, total N and exchangeable Ca and Mg were about twice as high in the soil than in casts. Significant negative correlations between the cast to soil ratio (cast enrichment factor) of organic C, total N and exchangeable Ca and Mg and the respective concentrations in the soil show that earthworms are increasingly selective in organic carbon and nutrient uptake as these parameters of soil fertility are declining.
The occurrence of terrestrial algae on two beech sites on a Cambisol
Authors: Wöhler Ingo , Klaß Stefan , Derakshani Manigee , Stellmacher Gerold , Winter Jörg‐Ulrich , Reißer Werner 
Published: December 2011

AbstractThe occurrence of terrestrial algae on two beech sites was determined qualitatively and quantitatively in the litter, organic and mineral layer. Both sites are beech stands of different age and the soil type is a Cambisol. On the site with young beech the maximal value determined was 1.0 · 108 algae g−1 dw in the litter layer. With increasing soil depth the number of algae decreased on both sites, and at the young beech stand site no algae were found in the mineral soil. Chlorophyceae were the dominant algae group and at the young beech stand Bacillariophyceae were present.
PAK‐Abnahmen in Bodenproben verschiedener Altlaststandorte bei Aktivierung der autochthonen Mikroflora
Authors: Thiele Sören , Brümmer Gerhard W. 
Published: December 2011

AbstractIm Rahmen von 74‐ bzw. 168wöchigen Freiland‐Gefäßversuchen wurde die PAK‐Abnahme in zehn verschiedenen Altlastbodenproben unterschiedlicher Belastung untersucht. Bestimmt wurden 15 der 16 PAK nach US EPA (ohne Acenaphthylen). Den Bodenproben wurden in verschiedenen Varianten leicht abbaubare organische Substanzen, Mineraldünger sowie synthetische Tenside und z.T. Kalk zugegeben.In Abhängigkeit von Art und Menge der Zugaben konnte die biologische Aktivität und damit die (co‐)metabolische Abbauleistung der Bodenmikroorganismen erheblich gesteigert werden. In den unterschiedlichen Bodenproben wurde binnen 74 Wochen eine Abnahme der PAK‐Ausgangsgehalte um 12–90% erzielt. Auch von 74–168 Wochen war zum Teil eine deutliche weitere Abnahme der PAK‐Gehalte festzustellen.Die Abnahmen der Gehalte an extrahierbaren PAK mit zunehmender Versuchsdauer sind v.a. auf mikrobiellen Ab‐, Um‐ und Einbau zurückzuführen und lassen sich durch zwei gekoppelte Exponentialfunktionen für eine anfänglich schnelle und anschließende langsame PAK‐Abnahme beschreiben. Zwei unterschiedliche Prozesse (I, II) bestimmen demnach die PAK‐Abnahme. In der ersten Versuchswoche betragen die Abnahmeraten für Prozeß I 4.2–88.3 und für Prozeß II 0.06–5.3 mg PAK ṁ kg−1 Boden Woche−1; in der 168. Woche sind sie für Prozeß I nicht mehr bestimmbar und betragen für Prozeß II 0.05–2.3 mg ṁ kg−1 ṁ Woche−1. Höhere PAK Ausgangsgehalte bedingen meist größere relative PAK‐Abnahmen. führen jedoch zu höheren absoluten Restgehalten. Die Persistenz der PAK wird v.a. durch ihre Bioverfügbarkeit bestimmt.Der PAK‐Abbau wird durch die vorgenommenen Bodenbehandlungen erhöht. Dabei steigert die Zugabe von 30 g ṁ kg−1 (w/w) leicht abbaubarer organischer Substanz (C/N‐Verhältnis < 20) in Kombination mit einer erhöhten Nilraigabe und Tensidzusatz die PAK‐Abnahme am effektivsten. Der abbaufördernde Effekt durch Anhebung des pH einer sehr stark sauren Bodenprobe war bei einem pH‐Wert um 6 maximal.
Cyanides in a soil of a former coking plant site
Authors: Mansfeldt Tim , Gehrt Sandra B. , Friedl Josef 
Published: December 2011

AbstractSoils of former coking plant sites are frequently contaminated with cyanide, which mainly occurs as the pigment Berlin blue, FeIII4 [FeIICN)6]3, and soluble iron cyanide complexes, Fe(CN)63‐/4−. Berlin blue is only slightly soluble under acidic conditions.The cyanide mobility in a strongly acid soil (pH about 3) of such a site was studied by assessing the distribution of cyanides in the soil and sediment and by conducting batch experiments at different pH levels.The soil is based on a disposal layer (0–32 cm) overlying sandy loess (32–145 cm) overlying glaciofluvial sand (145–250 cm) overlying marlstone (250–500 cm). Highest cyanide concentrations were found in the disposal layer (62–2865 mg CN− kg−1), medium concentrations in the sandy loess (16–29 mg CN− kg−1), concentrations of about 100 mg CN− kg−1 in the glaciofluvial sand and lowest concentrations in the marlstone (0.22–0.49 mg CN−1 kg−1). The surfaces of macropores, which occur in the sandy loess and finish in the glaciofluvial sand, are dark‐blue dyed and have much higher cyanide concentrations than the surrounding bulk soil. Thus, the accumulation of cyanides in the sand layer may partly be the result of macropore flow.Batch experiments show a strong pH dependence of the solubility of cyanide in the soil as well as of Berlin blue which was found by Mössbauer spectroscopy to be the dominating or sole iron cyanide.The time necessary to transport the cyanides solely as hexacyanoferrate into the undisturbed horizons is estimated to 1000 yr. However, because Berlin blue is known to form colloids, we discuss the possibility of cyanide transport as colloid not requiring dissolution and reprecipitation. We postulate that colloidal Berlin blue transported by macropore flow is responsible for the high mobility of cyanides in this acid soil.
Characterisation of a humus profile under beech forest by using wet‐chemistry and CPMAS 13C NMR‐spectroscopy in consideration of spatial heterogeneity
Authors: Wachendorf Christine 
Published: December 2011

AbstractThree of ten macromorphologically similar humus profiles of a Dystric Cambisol under a beech forest were randomly chosen and the litter and humus layers were characterized by wet‐chemistry and CPMAS 13C NMR‐spectroscopy. The spatial heterogeneity of the litter and humus layers was high for the bulk density and for the sugar and starch fraction; lowest coefficients of variation were obtained for the chemical shift range of O‐Alkyl‐C. The spatial heterogeneity of the layers did not differ by means of all chemical methods. Changes in the chemical composition at the beginning of humification were high from the fresh fallen litter (Ln‐layer) to the morphologically only slightly altered litter in the L‐layer, whereas the changes in the litter and humus layers from the L to the Ohf‐layer were minor. However, the organic matter of the first mineral horizon was characterized by a decrease in lignin and cellulose. With wet‐chemistry and 13C NMR‐spectroscopy similar results were obtained for polysaccharides whereas results which can be attributed to changes in lignin deduced by the methoxyl content differed from each other.
The influence of surfactants applied by sewage sludge on the behaviour of Atrazine and PAHs in semiarid soils
Authors: Litz Norbert , Müller‐Wegener Ulrich 
Published: December 2011

AbstractThe effect of two surfactants applied via sewage sludge: LAS (linear Alkylbenzenesulfonate) and Nonylphenol as a metabolite of Nonylphenol ethoxylate, on PAHs and Atrazine mobility was investigated under semiarid soil conditions in a Vertisol and a Gypsisol treated with sewage sludge. In both cases the surfactants promoted the leachability of Atrazine only moderately compared to the untreated plot. PAHs were leached from the surface layer (0–20 cm) into 20–50 cm layer during the three month test period. Relatively higher leaching was observed in the sandy Gypsisol. Atrazine was leached only in the clayrich Vertisol where the surfactants were present longer than in the plot with sandy Gypsisol.
The fate of freshly added phosphorus in representative agricultural soils
Authors: Assimakopoulos J. , Bovis C. , Kosmas C. , Nychas A. 
Published: December 2011

AbstractSurface and subsurface samples from 26 representative agricultural soils (13 Entisols, 9 Alfisols and 4 Vertisols) from Central and South Western Greece were equilibrated for a week with P solutions ranging from zero to 800 mg P kg−1 soil. The Freundlich and in the cases of high fine carbonate content (> 6%) the linear equations described the sorption isotherms in a satisfactory way.Sequential fractionation indicated that a 0.1 M NaOH plus 1 M NaCl + 0.3 M Na‐citrate + 1 M NaHCO3 (buffer) solution extracted more than 60% of the P retained by Entisols containing low to medium fine carbonates and by Vertisols, and less than 60% by Entisols with a high fine carbonate content. In all Entisols, this percentage decreased significantly at P additions higher than 150 mg kg−1. The opposite was observed in Vertisols, in which this fraction was the most important part of the retained P up to the maximum P addition. In contrast, in Alfisols this fraction reached 100%, but in the case of high Bray‐P (> 50 ppm) it was more than 100% of the retained P. The second fraction extracted with the 0.3 M Na‐citrate + 1 M NaHCO3 buffer plus Na‐dithionite was found to be much smaller than the first fraction, increasing with P additions in absolute amounts but remaining constant as a percentage of the retained P, ranging from 15–35% among the studied samples. The third fraction obtained with 1 M HCl solution showed a peculiar behaviour. It was close to zero of the retained P in samples containing carbonates (Entisols and Vertisols) at P additions up to 300 mg kg−1 soil, but increased significantly at higher P additions and almost doubled in Entisols. Finally, the P fraction obtained after seven successive extractions with 0.01 M CaCl2, correlated well by a polynomial of 2nd degree equation with NaOH+CB‐P and linearly with Olsen‐P and Bray‐P.
Measuring interlayer potassium release rates from soil materials. II. A percolation procedure to study the influence of the variable ‘solute K’ in the < 1…10 μM range
Authors: Springob Günther , Richter Jörg 
Published: December 2011

AbstractRelease rates of nonexchangeable K from Ap material of a Luvisol (‘Eckerde’ loess, 15% clay) are determined using a percolation procedure which avoids the common artifacts due to shaking or stirring soil suspensions and thus provides less biased kinetic data. CaCl2 solution (10 mMc. 20 °C. pH 5.8) is percolated through packages of soil aggregates (0.5–1 mm grain size, 0.5 g samples) with 0.02 to 25 ml h−1. Solute K (CK) was varied between < 1 and > 10 μM and is shown to have a dominant influence on the rates of interlayer K release. These increase exponentially below 3.5 μM (no steady state but steady decrease of release rates in each sample). The difference between the related CK between moderate and high release rates is as small as 1 μM K. The average rates, of a 10‐day‐interval, starting after 1.3 times the exchangeable K had been removed, are 40 μmol K kg−1 soil d−1 at 4 μM CK and 240 μmol kg−1 d−1 at 3 μM CK, respectively. It is concluded that larger quantities of interlayer K become plant available in the studied soil if the of soil solutions gets below 3.5 μM (for 10 mMc Ca, 20 °C, pH 5.8), probably because the dominant dioctahedral illites start to join the release process below this critical limit. The higher K concentration range was accounted for by K‐Ca exchange isotherms which, by alteration of shape, indicate that Knex release becomes measurable below 10 to 20 μM K. It is further argued that existing diffusion or reaction kinetics approaches towards K release are incomplete because the influence of solute K is not considered.
The regulation of apoplastic calcium in relation to intracellular signalling in stomatal guard cells
Authors: Lionel D. , De Silva R. , Hetherington Alistair M. , Mansfield Terry A. 
Published: December 2011

AbstractIt is now well established that calcium has a substantive role in intracellular signalling in stomatal guard cells. Much less attention has, however, been paid to the importance of maintaining an apoplastic calcium concentration which permits this mechanism to operate. Data are presented for the calcicole Leontodon hispidus, in which the xylem sap may contain over 16 mM free calcium, showing that the concentration of calcium in the guard cell apoplast may be as low as 0.10 mM. This appears to be achieved by the deposition of considerable amounts of calcium oxalate in the mesophyll, particularly in the palisade tissue. Of the calcium delivered directly into the epidermis by the transpiration stream, a large proportion is diverted into the trichomes.It seems unlikely that stomatal regulation over long distances (e.g. from root to shoot) is accomplished via apoplastic calcium, but over shorter distances (the span of a few cells in the epidermis) signalling via calcium in the apoplast is entirely feasible and it is worthy of further investigation.
Parameterization and regionalization of Cd sorption characteristics of sandy soils. I. Freundlich type parameters
Authors: Springob Günther , Böttcher Jürgen 
Published: December 2011

AbstractCd sorption isotherms (n = 24) were established for arable, sandy soils of the ‘Fuhrberger Feld’ catchment area northeast of Hannover (Germany) using 0.01 Mc Ca(NO3)2 solution with Cd additions ranging from 0 to 44 μMc Cd. Alternative fractions of initially (prior to analysis) sorbed Cd (S0) were added to the amount sorbed during the experiments. The Freundlich equation was fitted to the resulting isotherms. The obtained retention parameters k and M varied with respect to the different S0 fractions. Isotherms corrected with CdEDTA as S0 fraction were nonlinear in their log‐form. The highest degree of log‐linearity is obtained if S0 is characterized by 40% of the agua regia extractable Cd. The corresponding k values ranged from 36 to 1275 g1‐M LM kg−1 (mean 338 g1‐M LM kg−1, cv = 92%). The Freundlich exponent M showed less variation (0.7 to 1.1, cv = 12%) with a mean of 0.88. Functions based on these parameters predicted Cd concentrations in Ca(NO3)2−soil suspensions well (r2 = 0.96) but were hardly related to Cd concentrations of ‘fresh’ soil solutions (r2 = 0.20).
Quasi‐convexly dense and suitable sets in the arc component of a compact group
Authors: Dikranjan Dikran , Shakhmatov Dmitri 
Published: December 2011

AbstractLet G be an abelian topological group. The symbol \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\widehat{G}$\end{document} denotes the group of all continuous characters \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\chi :G\rightarrow {\mathbb T}$\end{document} endowed with the compact open topology. A subset E of G is said to be qc‐dense in G provided that χ(E)⊆φ([− 1/4, 1/4]) holds only for the trivial character \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\chi \in \widehat{G}$\end{document}, where \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\varphi : {\mathbb R}\rightarrow {\mathbb T}={\mathbb R}/{\mathbb Z}$\end{document} is the canonical homomorphism. A super‐sequence is a non‐empty compact Hausdorff space S with at most one non‐isolated point (to which S converges). We prove that an infinite compact abelian group G is connected if and only if its arc component Ga contains a super‐sequence converging to 0 that is qc‐dense in G. This gives as a corollary a recent theorem of Außenhofer: For a connected locally compact abelian group G, the restriction homomorphism \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$r:\widehat{G}\rightarrow \widehat{G}_a$\end{document} defined by \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$r(\chi )=\chi \upharpoonright _{G_a}$\end{document} for \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\chi \in \widehat{G}$\end{document}, is a topological isomorphism. We show that an infinite compact group G is connected if and only if its arc component Ga contains a super‐sequence converging to the identity that is qc‐dense in G and generates a dense subgroup of G. We also offer a short alternative proof of the result of Hofmann and Morris on the existence of suitable sets of minimal size in the arc component of a compact connected group.
On the gradient flow for the anisotropic area functional
Authors: Pozzi Paola 
Published: December 2011

AbstractWe consider the anisotropic mean curvature flow for parametrized hypersurfaces and provide a new definition of gradient flow that takes into account the anisotropic nature of space. With this new approach we succeed in identifying the natural candidate for the anisotropic mean curvature vector using a variational method. Under the obtained flow Wulff shapes shrink self similarly. The new definition of gradient flow relies on understanding which Banach structure plays a fundamental role and performing a consistent choice of function spaces. The geometric setting we introduce also allows us to provide and justify a natural formulation for the anisotropic Willmore functional. Its first variation is computed.