Fumigant distribution in forest nursery soils under water seal and plastic film after application of dazomet, metam-sodium and chloropicrin

Adequate concentration, exposure time and distribution uniformity of activated fumigant gases are prerequisites for successful soil fumigation. Field experiments were conducted to evaluate gas phase distributions of methyl isothiocyanate (MITC) and chloropicrin (CP) in two forest-tree nurseries. Concentrations of MITC and CP in soil air were measured from replicated microplots that received dazomet, metam-sodium and CP. Half of the plots were covered with high-density polyethylene tarp immediately after fumigation; the other half were not covered but received daily sprinkler irrigation for 1 week to create and maintain a water seal. The magnitude of MITC concentrations was similar between nurseries for metam-sodium in both tarp and water seal treatments and for dazomet in the tarp treatment. Consistently greater MITC and CP concentrations were found in the upper 30 cm of soil in the tarped plots compared with the water-sealed plots. Despite potential environmental and economic benefits with the water seal method, tarp covers were more reliable for achieving and maintaining higher MITC and CP concentrations and less prone to variations due to irrigation/rain, soil bulk density and other environmental conditions.     

Sorption-desorption of flucarbazone and propoxycarbazone and their benzenesulfonamide and triazolinone metabolites in two soils

Sorption-desorption interactions of pesticides with soil determine the availability of pesticides in soil for transport, plant uptake and microbial degradation. These interactions are affected by the physical and chemical properties of the pesticide and soil and, for some pesticides, their residence time in the soil. While sorption-desorption of many herbicides has been characterised, very little work in this area has been done on herbicide metabolites. The objective of this study was to characterise sorption-desorption of two sulfonylaminocarbonyltriazolinone herbicides, flucarbazone and propoxycarbazone, and their benzenesulfonamide and triazolinone metabolites in two soils with different physical and chemical properties. K(f) values for all four chemicals were greater in clay loam soil, which had higher organic carbon and clay contents than loamy sand. K(f-oc) ranged from 29 to 119 for the herbicides and from 42 to 84 for the metabolites. Desorption was hysteretic in every case. Lower desorption in the more sorptive system might indicate that hysteresis can be attributed to irreversible binding of the molecules to soil surfaces. These data show the importance of characterisation of both sorption and desorption of herbicide residues in soil, particularly in the case of prediction of herbicide residue transport. In this case, potential transport of sulfonylaminocarbonyltriazolinone herbicide metabolites would be overpredicted if parent chemical soil sorption values were used to predict transport.     

A Survey of Horse Owner's Compliance with the Finnish Vaccination Program

Finnish Trotting and Breeding Association's electronic database (IT register) in Finland does not include vaccination entries of all horses. Especially, vaccination status of horses outside sport arenas is unclear. Objectives were to investigate vaccination practices of horse owners in Finland, to look for reasons associated with nonvaccination, and to evaluate the accuracy of the other statistics in Finland. The questionnaire study was executed. Horse owners (n = 1,198) told their vaccination practices, vaccinations used, and reasons for nonvaccination. Horses were mainly (85%–95%) vaccinated depending on the number of horses per horse owner. Equine influenza vaccine was mainly favored (94%). One reason for nonvaccination is that the horse is inactive in equine sport arenas (43%). Other reasons (53%) were age, horse does not take part in competitions but stay at home, and the owner decides that the horse does not need vaccination. Differences between age groups (young and old), competition types, and regions were not found by one-variable analysis, but vaccination status of horses outside equine sport arenas differed from horses active in competitions. By logistic regression analysis, it was indicated that purpose of use had influence on vaccination status. Reasons for nonvaccination surveyed in UK were confirmed. The control of the competition rules and possible sanctions exercised in competition venue are better explanatory factors than age, type of competition, and geographic home area. However, the risk to meet a nonvaccinated horse increases when going to the northern part of Finland.     

Plasma acceleration above martian magnetic anomalies

Auroras are caused by accelerated charged particles precipitating along magnetic field lines into a planetary atmosphere, the auroral brightness being roughly proportional to the precipitating particle energy flux. The Analyzer of Space Plasma and Energetic Atoms experiment on the Mars Express spacecraft has made a detailed study of acceleration processes on the nightside of Mars. We observed accelerated electrons and ions in the deep nightside high-altitude region of Mars that map geographically to interface/cleft regions associated with martian crustal magnetization regions. By integrating electron and ion acceleration energy down to the upper atmosphere, we saw energy fluxes in the range of 1 to 50 milliwatts per square meter per second. These conditions are similar to those producing bright discrete auroras above Earth. Discrete auroras at Mars are therefore expected to be associated with plasma acceleration in diverging magnetic flux tubes above crustal magnetization regions, the auroras being distributed geographically in a complex pattern by the many multipole magnetic field lines extending into space.     

Influence of Cry1Ac toxin on mineralization and bioavailability of glyphosate in soil

The impact of transgenic plants containing Bacillus thuringiensis (Bt) toxin on soil processes has received recent attention. In these studies, we examined the influence of the lepidopterean Bt Cry1Ac toxin on mineralization and bioavailability of the herbicide glyphosate in two different soils. The addition of 0.25-1.0 microg g(-1) soil of purified Cry1Ac toxin did not significantly affect glyphosate mineralization and sorption in either a sandy loam or a sandy soil. In contrast, extractable glyphosate decreased over the 28 day incubation period in both soils. Our findings suggest that the reduction in the bioavailability of glyphosate was not influenced by the presence of Cry1Ac toxin but rather the results of aging or sorption processes. Results from this investigation suggest that the presence of moderate concentrations of Bt-derived Cry1Ac toxin would have no appreciable impact on processes controlling the fate of glyphosate in soils.     

Solvent extraction characterization of bioavailability of atrazine residues in soils

Characterization of pesticide bioavailability, particularly in aged soils, is of continued interest because this information is necessary for environmental risk assessment. The objective of this study was to correlate atrazine residue bioavailability in aged soils, as determined by solvent extraction methods, to atrazine mineralization by an atrazine-degrading bacterium. Webster clay loam and Zimmerman fine sand soils were treated with UL-ring-labeled [14C]atrazine and incubated for up to 8 weeks. At the end of each incubation period, soils were either not extracted, extracted with 0.01 M CaCl2, or extracted with 0.01 M CaCl2/aqueous methanol. Soils were then inoculated with the bacterium Pseudomonas sp. strain ADP, which is capable of rapidly mineralizing the atrazine ring. This allowed for the evaluation of the bioavailability of aged atrazine residues without the contribution of atrazine desorption from soil. Results of these studies indicated that the amounts of atrazine residues in aged soils extracted by 0.01 M CaCl2 and aqueous methanol were correlated to amounts of atrazine mineralized by Pseudomonas sp. strain ADP. Consequently, 0.01 M CaCl2/methanol extractable atrazine in aged soils may be used to estimate bioavailable residues, and this technique may be useful to determine the bioavailability of other compounds in soils, especially other triazine herbicides.     

Effect of soil properties on the degradation of isoxaflutole and the sorption-desorption of isoxaflutole and its diketonitrile degradate

The transformation of isoxaflutole (ISOX) to its herbicidally active diketonitrile degradate (DKN) was significantly enhanced in the presence of soil and occurred more rapidly in systems containing soil with a greater soil pH. Sorption-desorption of ISOX and DKN in five soils collected within a field revealed both ISOX and DKN were more readily sorbed to soils with greater organic matter, clay content, and lower soil pH. Sorption of ISOX residues occurred within 2 h, and extracts contained similar concentrations of ISOX and DKN at 24 h, suggesting the 24-h sorption coefficients for ISOX-treated systems were actually for mixed ISOX residues. Freundlich sorption coefficients were 3 and 4 times greater for ISOX than for DKN. On the basis of the Freundlich organic carbon sorption constants, ISOX and DKN can be categorized in the very high and high mobility classes, suggesting their potential to leach in the soils needs to be evaluated.     

Solar wind-induced atmospheric erosion at Mars: first results from ASPERA-3 on Mars Express

The Analyzer of Space Plasma and Energetic Atoms (ASPERA) on board the Mars Express spacecraft found that solar wind plasma and accelerated ionospheric ions may be observed all the way down to the Mars Express pericenter of 270 kilometers above the dayside planetary surface. This is very deep in the ionosphere, implying direct exposure of the martian topside atmosphere to solar wind plasma forcing. The low-altitude penetration of solar wind plasma and the energization of ionospheric plasma may be due to solar wind irregularities or perturbations, to magnetic anomalies at Mars, or both.