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Mechanism of molybdenum sorption to iron oxides using pressure‐jump relaxation

It is widely accepted that the fixation of oxyanions is due to diffusion of the ions into the pores and interdomains of iron oxides. Most studies have used batch techniques, which do not allow to clearly differentiate chemisorption from mass transport phenomena. Thus, it is not yet clear, whether strengthening of chemical Mo bonding occurs along with residence time, in addition to diffusion processes. In this study we used pressure jump relaxation (p‐jump), a very fast kinetic technique, to (1) elucidate the Mo/goethite interaction and to (2) analyze the effects of aging the Mo/goethite complex on Mo chemisorption. A synthetic goethite was incubated with Mo solution (1 mM Mo) for 12, 24, and 72 hours at pH 4. At the end of the incubations p‐jump experiments were performed on the suspensions at temperatures ranging from 283 to 303 K. Relaxation kinetics were modelled using a combination of two first order terms. In addition, the amount of Mo sorbed to the goethite after different incubation times was determined by graphite furnace atomic absorption spectroscopy. The MoO₄/goethite systems revealed a fast relaxation time (= reciprocal of rate constant, about 4 ms), that decreased with increasing temperature and a slow one (about 60 ms) that did not depend on temperature. Activation energy of the fast process was 76 kJ mol^—1. We did not observe any effects of incubation time on the fast process. However, the amount of Mo sorbed to the iron oxide increased with increasing incubation time. We conclude that the fast relaxation represents Mo chemisorption to the goethite. Slow relaxation seems to be due to Mo transport within the suspension. The pressure jump results indicate, that the dominant surface species of Mo sorbed to goethite do not change along with residence time.     

Iodine and bromine contents of some Austrian soils and relations to soil characteristics

Inductively coupled plasma mass spectrometry (ICP-MS) analysis was used to determine iodine and bromine concentrations in several Austrian agricultural soils. The determined iodine concentrations in topsoils vary between 1.1 and 5.6 mg kg^—1, the arithmetic mean amounted to 3.1 mg kg^—1, bromine contents are always higher than the corresponding iodine values, varying between 2.4 and 11.9 mg kg^—1 with an arithmetic mean of 5.7 mg kg^—1. Due to their different geological origin lime-free soils on average contained significantly less iodine and bromine than calcareous soils. In general the observed values are supported by literature values from other countries far from the sea. A correlation analysis of results with several soil parameters resulted in positive correlations with clay content and a negative relation to sand content. In the group of calcareous soils I and Br correlated positively with organic carbon contents and exchangeable calcium.     

Analysis of systematic and genetic effects on the prevalence of primary cataract, persistent pupillary membrane and distichiasis in the two color variants of English Cocker Spaniels in Germany

Genetic parameters were estimated for prevalences of primary cataract (CAT), persistent pupillary membrane (PPM) and distichiasis (DIST) in 615 single-colored and 617 multi-colored English Cocker Spaniels (ECS) bred in the German kennel club for Spaniels (Jagdspaniel-Klub e.V.). CAT or CAT diagnosed in dogs up to three and a half years of age (early-onset cataract, CAT-early) and CAT diagnosed in dogs over three and a half years of age (late-onset cataract, CAT-late), PPM and DIST were included as binary traits in multivariate genetic analyses. Heritabilities on the underlying liability scale were 0.15 for CAT, 0.34 for CAT-early, 0.13 for CAT-late, 0.46 for PPM, and 0.62 for DIST in single-colored ECS and 0.06 for CAT, 0.13 for CAT-early, 0.14 for CAT-late, 0.10 for PPM, and 0.61 for DIST in multi-colored ECS. There were indications for a different genetic basis of CAT-early and CAT-late in single-colored ECS as genetic correlations were close to zero. In multi-colored ECS, a similar tendency for CAT-early and CAT-late could be observed.     

Bodenfauna als Ökologischer Dienstleister – Collembolen und Nematoden fördern den Abbau von Deoxynivalenol in Fusarium-infiziertem Weizenstroh

A minicontainer-study under laboratory conditions was conducted with the following fungivorous members of soil fauna: Aphelenchoides saprophilus, Nematoda and Folsomia candida, Collembola. The objective was to investigate, if the introduced soil fauna is able to reduce the concentration of Fusarium-biomass and the mycotoxin deoxynivalenol (DON) in wheat straw. Furthermore, the study aimed wether the degradation efficiency is affected by different soil texture (sandy loam, silt loam, clay loam). Therefore, minicontainer were filled with soil and wheat straw. Soil fauna was introduced in different combination into the minicontainer (single collembolan, single nematode, faunal interaction and a non-faunal treatment). The minicontainer were divided into 2 sets: one set received artificially Fusarium-infected and DON-contaminated wheat straw, the second set received non-infected straw. After 2 and 4 weeks, soil and straw were sampled for analysing Fusarium-biomass and DON content by using ELISA-technique. After 4 weeks Fusarium-biomass was reduced notably and DON-concentration was degraded significantly throughout all treatments. The highest reduction of DON-concentration was found in the faunal interaction treatment. The DON-concentration in the sandy- and silt loam treatments were reduced more efficiently compared to the clay loam treatment. We conclude that nematodes and collembolans contribute to the degradation of Fusarium-biomass and the mycotoxin DON in wheat straw as ecosystem services.     

Breaking of <Emphasis Type="Italic">Beet necrotic yellow vein virus</Emphasis> resistance in sugar beet is independent of virus and vector inoculum densities

Beet necrotic yellow vein virus (BNYVV) is transmitted by Polymyxa betae to sugar beet, causing rhizomania disease. Resistance-breaking strains of BNYVV, overcoming single (Rz1) or double (e.g. Rz1  +  Rz2) major resistance genes in sugar beet have been observed in France and recently in the USA and Spain. To demonstrate if resistance-breaking is dependent on inoculum density, the inoculum concentration of BNYVV and P. betae in soil samples where resistance-breaking had been observed was estimated using the most probable number (MPN) method. The MPN-values obtained displayed highly significant differences with respect to the virus concentration in various soils and did not correlate with the ability to overcome resistance. Virus quantification in susceptible plants demonstrated that soils containing resistance-breaking isolates of BNYVV did not produce higher virus concentrations. The MPN assay was repeated with Rz1  +  Rz2 partially-resistant sugar beets to see if the resistance-breaking is concentration-dependent. There was no correlation between soil dilution and increased virus concentration in Rz1  +  Rz2 plants produced by BNYVV resistance-breaking strains. Determination of the absolute P. betae concentration by ELISA demonstrated that all resistance-breaking soil samples contained elevated concentrations. However, the calculation of the proportion of viruliferous P. betae did not show a positive correlation with the resistance-breaking ability. Finally resistance-breaking was studied with susceptible, Rz1 and Rz1  + Rz2 genotypes and standardised rhizomania inoculum added to sterilised soil. Results from these experiments supported the conclusion that resistance-breaking did not correlate with virus concentration or level of viruliferous P. betae in the soil.