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31.
Veterinary Research Communications - Industrial chemical solutions are widely used as a method to disinfection of aquaculture water and environments. The aim of the present study was to evaluate...  相似文献   
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An important goal of the European Commission-funded ECOGEN project is to develop a computer-based decision support system (DSS) for the assessment of economic and ecological impacts of using genetically modified crops. In ecological impact assessment, special emphasis is put on soil biology and estimating soil quality from the observed biological parameters. Methodologically, we have addressed this goal using model-based DSS, taking the approach of qualitative multi-attribute modelling. The approach is based on developing various hierarchical multi-attribute models that consist of qualitative attributes and utility (aggregation) functions, represented by decision rules. The model presented in this paper assesses the impact of cropping systems on soil quality and can subsequently be used to assess crop management options. It was developed as a collaboration between ECOGEN soil experts and decision analysts, and consists of 34 attributes, hierarchically structured into eight levels. There are 21 input attributes, most of which measure the richness and biomass of representative soil organisms. The assessment of soil quality is based on two main indicators: (1) soil diversity (assessed through microfauna, mesofauna and macrofauna richness) and (2) soil functioning (in terms of leaching, comminution, mineralisation and plant growth). In the paper, we address the methodological aspects of the model and its development, and describe the components of the model (attributes, value scales, decision rules and weights). We present initial results of its application to the assessment of crop management on soil quality in the case of using conventional and Bacillus thuringiensis (Bt)-maize at three field sites in France and Denmark. Our finding was that soil quality was unaffected even though several input attributes had changed. We also analyse the sensitivity of the model and discuss its current and potential contribution to soil quality management. The model is operational (available through a web page) and can be used for the assessment, comparison and analysis of realistic management scenarios. Furthermore, it provides an effective means of synthesising a lot of data, encoding knowledge about soil-quality factors, supporting communication among experts, answering ‘what-if’ and ‘so-what’ questions, and supporting the evaluation of new agricultural practices.  相似文献   
34.
This study integrated physical, chemical, and molecular techniques to assess relationships between soil bacterial community structures and the quantity and quality of soil organic carbon (SOC) at the soil microenvironment scale (e.g., within different aggregate size-fractions). To accomplish this goal, soil samples (0–5 cm) were collected from the Texas High Plains region under a variety of dryland and irrigated cropping systems. The soil was separated into macroaggregates, microaggregates, and silt + clay fractions that were analyzed for (1) bacterial diversity via pyrosequencing of the 16s rRNA gene and (2) SOC quantity and quality using a combustion method and mid-infrared diffuse reflectance spectroscopy (mid-IR), respectively. Results from pyrosequencing showed that each soil microenvironment supported a distinct bacterial community. Similarly, mid-IR data revealed distinct spectral features indicating that these fractions were also distinguished by organic and mineral composition. Macroaggregates showed relatively high abundance of Actinobacteria (excluding order Rubrobacteriales) and α-Proteobacteria and contained the most SOC. Microaggregates showed high relative abundance of Rubrobacteriales and the least amount of SOC. Predominance within the soil microenvironment and correlations along the mid-IR spectra were different between members of the order Rubrobacteriales compared with all other members of the Actinobacteria phyla, suggesting they have different ecological niches. Mid-IR results revealed microaggregates had greater absorbance in the 1370–1450 cm?1 region for phenolic and alkyl groups (possibly recalcitrant C). Silt + clay fractions were distinguished by Gemmatimonadetes and OP10 phyla, which positively correlated with spectral absorption in the1250–1150 cm?1 range (indicating both degradable and recalcitrant C forms). In contrast to general diversity index measurements, distributions of the more rare bacterial phyla (phyla representing <6% of the identified population) were more important for differentiating between communities in soil microenvironments. To our knowledge, this is the first study to investigate soil bacterial communities among soil aggregates using pyrosequenging and to associate these communities to specific soil C chemistries as indicated by mid-IR absorbance.  相似文献   
35.
Secondary xylem of Norway spruce was studied by X-ray microanalysis. Average dimensions of cellulose crystallites, fraction of oriented cellulose, mean microfibril angle, and nutrient element concentrations of K, Ca, Mn, and Zn were simultaneously determined using microfocused synchrotron radiation and a combination of X-ray diffraction and X-ray fluorescence spectroscopy techniques. The variation of these quantities in the microscopic size scale was noticeable, and similar between samples taken from the same annual ring. The mean microfibril angle and the nutrient concentrations of Ca, Mn, and Zn showed a correlation. The mean values of the structural parameters and their variation as a function of the annual ring were similar as reported in previous studies on Norway spruce.  相似文献   
36.
The greenhouse trials were conducted to determine the efficacy of environmentally safe insecticides/fungicides with physical mode of action [Agri-50E (propylene glycol alginate, hydrated) and SB Plant Invigorator] against Trialeurodes vaporariorum (Westwood). The efficacy of Agri-50E on adults and nymphs (first, second, third, and fourth instars) was compared to the commercially available standard Boxer 200 SL (imidacloprid) and an untreated control on greenhouse-grown poinsettia. Insecticides were applied by foliar spraying, Agri-50E (2 or 3 ml/l) two times and Boxer 200 SL (1 ml/l) once. Three and 7 days after first application (DAFA), imidacloprid was more effective than both concentrations of Agri-50E in controlling T. vaporariorum adults, whereas 10 DAFA there were no differences between insecticides. Twelve DAFA, imidacloprid was more effective than Agri-50E in controlling first, second and third instars and after 19 days in controlling second, third, and fourth instars. The results obtained from the poinsettia study, indicated that Agri-50E (2 or 3 ml/l) is successful in controlling T. vaporariorum adults and moderately effective against T. vaporariorum immature stages. In the second experiment, the efficacy of Agri-50E on adults was compared to SB Plant Invigorator (SBPI), the standard treatment Calypso 480 SC (thiacloprid), and an untreated control on greenhouse-grown tomato. Agri-50E (3 ml/l) and SBPI (2 ml/l) were applied four times while Calypso 480 SC (0.4 ml/l) was applied twice. The results obtained from tomato study showed that SBPI was the most effective insecticide against T. vaporariorum adults, followed by Agri-50E and Calypso 480 EC. Beside the ecological benefits, the alternative insecticides Agri-50E and SBPI might have an important role to play in future pest management programs.  相似文献   
37.
Environmental concern due to plant accumulation of natural radionuclides is a major concern in uranium mining areas. To evaluate the risk associated with the transfer of radionuclides to edible plants, the uptake of 238U, 226Ra, and 210Pb by Chinese cabbage (Brassica rapa L. subsp. pekinensis (Lour.) Hanelt) grown in soils contaminated with uranium-mill tailings (UMT) was investigated. Test plants were grown under controlled conditions in substrate composed of soil and UMT in different ratios. Activity concentrations of 238U, 226Ra, and 210Pb in substrate, leaves, and roots were measured and the concentration ratios determined. Soil characteristics were determined, since they directly affect bioavailability of radionuclides. Concentration ratios of 238U, 226Ra, and 210Pb in leaves varied from 0.001 to 0.006, 0.024 to 0.172, and 0.004 to 0.011, respectively, and in roots from 0.020 to 0.126, 0.015 to 0.241, and 0.033 to 1.460, respectively. Concentrations of 238U, 226Ra, and 210Pb in leaves and roots were found to correlate with the amount of 238U, 226Ra, and 210Pb in the substrate. A higher amount of 226Ra accumulated in aboveground parts (57–877 Bq kg?1 d. m. for leaves) compared to 238U (0.6–4.7 Bq kg?1 d. m. for leaves) and 210Pb (8–53 Bq kg?1 d. m. for leaves), which were mainly stored in the roots. The relationships between the amount of radionuclides in plants and soil characteristics and their role in radionuclide uptake are discussed and critically evaluated.  相似文献   
38.
Although Prune dwarf virus (PDV) is one of the most common viruses infecting stone fruits (Prunus spp.), most of the molecular diversity studies have so far focused on the capsid protein (CP) gene. An alternative diagnostic primer pair targeting the movement protein (MP) gene was used in the present work, increasing then polyvalence of PDV detection in cherry samples from Slovakia as compared to the previously published primers amplifying 5′MP-intergenic region-CP-3′UTR fragment. The nearly complete sequence of the RNA3 from 24 Slovak PDV isolates was determined, together with 19 partial sequences of the MP gene for other isolates. Even though the isolates originated from a geographically limited region, analyses showed a high degree of nucleotide sequence diversity between isolates. No clear-cut phylogenetic grouping based on host or geographical origin could be observed. The topology of the MP and CP trees were incongruent for some isolates. Highly supported recombination signals were detected in five PDV isolates, with breakpoints located at different positions in the central part of RNA3, within or close to the intergenic region. Taken together these results extend our understanding of the variability of PDV and for the first time highlight the contribution of recombination to the evolutionary history of this virus.  相似文献   
39.

Purpose

Because the stability of soil aggregates is affected by many factors, we studied aggregates formed in forest and agricultural soils in different soil types (Cambisols, Luvisols, Chernozems). We evaluated: (1) the differences in water-stable aggregates (WSA) as related to soil type and land management and (2) the relationships between quantitative and qualitative parameters of soil organic matter (SOM), particle-size distribution and individual size classes of WSA.

Materials and methods

Soil samples were taken from three localities (Sobě?ice, Báb, Vieska nad ?itavou). Each study locality included both a forest and an agricultural soil-sampling area.

Results and discussion

We found that in forest soils, the proportion of water-stable macroaggregates (WSAma) relative to water-stable microaggregates (WSAmi) was greater than in agricultural soils. When all soils were assessed together, positive statistically significant correlations were observed between the size classes WSAma > 1 mm and organic carbon (Corg) content; however, the WSAmi content was negatively correlated with Corg content. Favorable humus quality positively influenced the stabilization of WSAma > 5 mm; however, we found it had a negative statistically significant effect on stabilization of WSAma 1–0.25 mm. In agricultural soils, the stabilization of WSAma was associated with humified, i.e., stable SOM. The WSAma content was highly positively influenced mainly by fulvic acids bound with clay and sesquioxides; therefore, we consider this humus fraction to be a key to macroaggregate stability in the studied agricultural soils. On the other side, all fractions of humic and fulvic acids participated on the formation of WSAma in forest soil, which is a major difference in organic stabilization agents of macroaggregates between studied forest and agricultural soils. Another considerable difference is that WSAmi in agricultural soils were stabilized primarily with humic acids and in forest soils by fulvic acids. Moreover, in forest soils, a higher content of labile carbon in WSA had a positive effect on formation of WSAmi.

Conclusions

The observed changes in individual size classes of WSA and interactions between SOM, particle-size distribution, and WSA have a negative impact on soil fertility and thereby endanger agricultural sustainability.
  相似文献   
40.
This study discusses a novel approach for fabrication of floating photocatalyst which can be efficiently exploited for photodegradation of dyes in aqueous solutions. A fabrication of the floating photocatalyst consisted of two steps: transformation of the poly(ε-caprolactone) beads (PCLb) into poly(ε-caprolactone) foam (PCLf) with porous structure in supercritical carbon-dioxide and subsequent loading of PCLf with TiO2 nanoparticles (NPs). Morphological characterization of the PCLf before and after TiO2 NPs loading was carried out by FESEM. The presence of titanium on the surface and inside the PCLf was detected by EDX. Photocatalytical activity of the floating photocatalyst was investigated in aqueous solution of textile dyes C.I. Acid Orange 7 (AO7) and C.I. Basic Yellow 28 (BY28) which were exposed to lamp that simulates the sun light. In addition to sustainable floatability for a long period of time, developed floating photocatalyst exhibited high rate of photodegradation since the complete discoloration of AO7 and BY28 solutions and photocatalysts alone occurred after 300 and 180 min of illumination, respectively. Its photocatalytic activity was preserved after three repeated photodegradation cycles with unchanged chemical structure that was confirmed by FTIR analysis.  相似文献   
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