Dynamics of surface sealing,runoff formation and interrill soil loss as related to rainfall intensity,microrelief and slope     

Christian H. Roth  Katharina Helming 《植物养料与土壤学杂志》1992,155(3):209-216

The aim of this study was to determine what effect rainfall intensity, microrelief roughness and slope have on the interactions between sealing, runoff formation, rainsplash detachment and interill soil loss by wash from air dry soil surfaces. Soil material from the plough horizon of a loess-derived Haplic Luvisol was subjected to simulated rainfall to measure these effects. Irrespective of the above three treatments studied, rates of runoff, splash, and interill soil loss were found to follow three distinct stages, confirming earlier work. Splash rates as a function of rainfall energy indicated a distinct maximum before leveling off, while both runoff and soil loss displayed asymptotic curves, the respective rise of rates coinciding with the maximum splash rates. Rainfall intensity had the greatest effects on the studied parameters, high intensities increasing final infiltration rates at the expense of overproportionally higher soil loss rates. Rough soil surfaces diminished both splash and soil loss, while slope only affected soil loss. In an additional treatment with a pre-crusted soil surface, dispersion of the crust due to air slaking was believed to be the cause of increased runoff rates and a decrease in equilibrium splash and soil loss rates. Seal erosion by runoff, dissipation of rainfall energy due to puddling, increased cohesion of the soil surface as a result of sealing are some of the factors involved in the interactions studied, and the extent to which these single processes counteract or compensate each other depends on the type of force acting and the flow conditions at the soil surface.  相似文献   

Influence of Atmospheric Oxygen on Heavy Metal Mobility in Sediment and Soil (7 pp)     

Katharina?ZehlEmail author  Jürgen?EinaxEmail author 《Journal of Soils and Sediments》2005,5(3):164-170

Background  

Aims. Pollution of sediment and soil by heavy metals is still an environmental problem. In order to assess the actual environmental risk, the mobile and biologically available content of heavy metals needs to be determined rather than the total content. This requires an analytical strategy preserving the actual binding forms of the heavy metals. Sampling and sample preparation are usually carried out in the presence of oxygen. As a consequence, oxidation of the metal and/or its binding partners is possible under these conditions, changing the original binding character. Therefore, sampling and sample preparation must be performed under inert conditions. The influence of atmospheric oxygen on the heavy metal mobility in sediment and soil for Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn is shown for samples of different origin. By means of a case study, an alternative for the extensive inert sampling and sample preparation is given; also, a mobility correction factor for the heavy metals mentioned is determined.  相似文献   

Comparative morphometric study of the mimic facial muscles of brachycephalic and dolichocephalic dogs     

Katharina Zoë Schatz  Elisabeth Engelke  Christiane Pfarrer 《Anatomia, histologia, embryologia》2021,50(6):863-875

Excessive breeding of dogs has led to a disadvantageous morphology in some breeds, for example extreme brachycephaly, which is responsible for many health issues. We hypothesize that alterations of the mimic muscular system are present in brachycephalic dogs and could contribute to behavioural problems due to a restricted mimic display. Therefore, the purpose of this paper was to compare the mimic muscular systems of brachycephalic with dolichocephalic dogs. Mimic muscles were measured and set in ratio to measurements of the head and calculated indices. When bringing the length of the muscles m(x) in proportion to the length of the head, highly significant differences (p < .0001) and significant difference (p < .05) were found in all but two of the examined muscles. Calculations of the m(x) divided by the cranial index and the square index showed significant differences for all muscles. For example, the musculus (m.) levator nasolabialis was morphologically different from the one of dolichocephalic dogs. Muscle fibres of the m. levator nasolabialis were localized in the fold over the nasal bridge of brachycephalic dogs. The raphe of the m. orbicularis oris was not always apparent in brachycephalic dogs. The proportions of the muscle lengths and the length of the eye slots to the size of the skull have shifted considerably in brachycephalic dogs. We conclude that many alterations contribute to the strong shift in the proportions of the head of brachycephalic dogs versus that of dolichocephalic dogs. Our findings suggest that brachycephalic dogs have reduced mimic skills that can lead to ambiguous communication.  相似文献   

Epidemiology, control and management of an EBHS outbreak in captive hares     

Drews B  Szentiks CA  Roellig K  Fickel J  Schroeder K  Duff JP  Lavazza A  Hildebrandt TB  Goeritz F 《Veterinary microbiology》2011,154(1-2):37-48

Here we describe an outbreak of European brown hare syndrome (EBHS) in a captive hare population. The EBHS outbreak occurred in March 2009, at the beginning of the breeding season. Overall mortality was 53% out of an original population of 61 animals. Animals between five and eleven months showed a significantly higher mortality rate than other age classes. Pregnant females either aborted their foetuses and survived or died pregnant. All foetuses (n=10) of the pregnant hares were PCR positive for EBHSV. Only one offspring born during the outbreak survived. Shortly after the outbreak, the surviving hares developed a specific anti-EBHSV titre between 1:80 and 1:2560, which dropped to 1:10-1:160 nine months later. Hares between one and three years of age developed a significantly higher titre than hares younger than one year or older than four years. Offspring born after the outbreak showed a lower titre of 1:10, indicating passive antibody transfer via placenta and milk. After two months, the titre was not detectable any longer. In December 2009, the captive population was vaccinated against EBHS virus with inactivated virus prepared from the organs of infected hares. The titres after the first vaccination ranged from 1:10 to 1:640, and after the second vaccination from 1:10 to 1:320. To estimate the effect of EBHS on reproduction, we compared the breeding seasons 2008 and 2009. Several possible sources of infection of the colony are discussed, but the definite cause could not be determined.  相似文献   

Networks in plant epidemiology: from genes to landscapes, countries, and continents   总被引：1，自引：0，他引：1  

Moslonka-Lefebvre M  Finley A  Dorigatti I  Dehnen-Schmutz K  Harwood T  Jeger MJ  Xu X  Holdenrieder O  Pautasso M 《Phytopathology》2011,101(4):392-403

There is increasing use of networks in ecology and epidemiology, but still relatively little application in phytopathology. Networks are sets of elements (nodes) connected in various ways by links (edges). Network analysis aims to understand system dynamics and outcomes in relation to network characteristics. Many existing natural, social, and technological networks have been shown to have small-world (local connectivity with short-cuts) and scale-free (presence of super-connected nodes) properties. In this review, we discuss how network concepts can be applied in plant pathology from the molecular to the landscape and global level. Wherever disease spread occurs not just because of passive/natural dispersion but also due to artificial movements, it makes sense to superimpose realistic models of the trade in plants on spatially explicit models of epidemic development. We provide an example of an emerging pathosystem (Phytophthora ramorum) where a theoretical network approach has proven particularly fruitful in analyzing the spread of disease in the UK plant trade. These studies can help in assessing the future threat posed by similar emerging pathogens. Networks have much potential in plant epidemiology and should become part of the standard curriculum.  相似文献   

Optimization, in-house validation, and application of a liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based method for the quantification of selected polyphenolic compounds in leaves of grapevine (Vitis vinifera L.)     

Schoedl K  Forneck A  Sulyok M  Schuhmacher R 《Journal of agricultural and food chemistry》2011,59(20):10787-10794

Polyphenols in grapevine can be constitutive or induced, depending upon cultivar, plant organ, and environmental influences. The aim of the presented work was to develop and optimize a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to study the pattern and amount of selected polyphenols in leaves of Vitis vinifera L. The method is simple and does not require any sample cleanup. It covers representative metabolites of the structure classes cinnamic acids, flavonoids, and stilbenes and enables the simultaneous separation and quantification of 13 polyphenols within 9 min at concentration levels between 0.1 and 3 μg/g. We present the method performance characteristics and its application to the quantification of polyphenols in grapevine leaves of the cultivars Riesling and Pinot noir. A total of 7 of 13 target polyphenols were detected at concentrations above the limits of quantification. Interestingly, instead of the expected trans-resveratrol, the investigated leaf samples of both cultivars contained cis-resveratrol-3-O-glucoside. The measurements also showed that Riesling leaves tended to contain higher concentrations of the selected polyphenols than Pinot noir. In view of its intended future use, the developed method has been shown to be a powerful and fast tool to study polyphenols in grapevine leaves subjected to environmental stress conditions.  相似文献   

Development of a stable isotope dilution assay for tenuazonic acid     

Asam S  Liu Y  Konitzer K  Rychlik M 《Journal of agricultural and food chemistry》2011,59(7):2980-2987

A stable isotope dilution assay (SIDA) for the Alternaria mycotoxin tenuazonic acid was developed. Therefore, [(13)C(6),(15)N]-tenuazonic acid was synthesized from [(13)C(6),(15)N]-isoleucine by Dieckmann intramolecular cyclization after acetoacetylation with diketene. The synthesized [(13)C(6),(15)N]-tenuazonic acid was used as the internal standard for determination of tenuazonic acid in tomato products by liquid chromatography tandem mass spectrometry after derivatization with 2,4-dinitrophenylhydrazine. Method validation revealed a limit of detection of 0.1 μg/kg and a limit of quantitation of 0.3 μg/kg. Recovery was close to 100% in the range of 3-300 μg/kg. Determination of tenuazonic acid in two samples of different tomato ketchups (naturally contaminated) was achieved with a coefficient of variation of 2.3% and 4.7%. Different tomato products (n = 16) were analyzed for their content of tenuazonic acid using the developed SIDA. Values were between 15 and 195 μg/kg (tomato ketchup, n = 9), 363 and 909 μg/kg (tomato paste, n = 2), and 8 and 247 μg/kg (pureed tomatoes and comparable products, n = 5).  相似文献   

Antiradical properties of red wine portisins     

Pirker KF  Oliveira J  de Freitas V  Goodman BA  Mateus N 《Journal of agricultural and food chemistry》2011,59(21):11833-11837

The free radical chemistry of two polyphenolic pigments from red wine, belonging to the family of portisins, has been investigated after reaction with O(2)(?-) radicals using electron paramagnetic resonance (EPR) spectroscopy. Two portisins derived from malvidin-3-glucoside and cyanidin-3-glucoside were used for this study. Stable free radicals were detected with both portisins and correspond to unpaired electrons localized on the B as well as F rings of the portisins. Interpretations were confirmed by comparison with the spectra of free radicals formed by oxidation of the model compounds cyanidin-3-glucoside, malvidin-3-glucoside, and catechin. These results concur with previous work reporting the higher antiradical properties of these pigments compared to their anthocyanin precursors.  相似文献   

Structural basis for specific substrate recognition by the chloroplast signal recognition particle protein cpSRP43     

Stengel KF  Holdermann I  Cain P  Robinson C  Wild K  Sinning I 《Science (New York, N.Y.)》2008,321(5886):253-256

Secretory and membrane proteins carry amino-terminal signal sequences that, in cotranslational targeting, are recognized by the signal recognition particle protein SRP54 without sequence specificity. The most abundant membrane proteins on Earth are the light-harvesting chlorophyll a/b binding proteins (LHCPs). They are synthesized in the cytoplasm, imported into the chloroplast, and posttranslationally targeted to the thylakoid membrane by cpSRP, a heterodimer formed by cpSRP54 and cpSRP43. We present the 1.5 angstrom crystal structure of cpSRP43 characterized by a unique arrangement of chromodomains and ankyrin repeats. The overall shape and charge distribution of cpSRP43 resembles the SRP RNA, which is absent in chloroplasts. The complex with the internal signal sequence of LHCPs reveals that cpSRP43 specifically recognizes a DPLG peptide motif. We describe how cpSPR43 adapts the universally conserved SRP system to posttranslational targeting and insertion of the LHCP family of membrane proteins.  相似文献   

Enols are common intermediates in hydrocarbon oxidation   总被引：1，自引：0，他引：1  

Taatjes CA  Hansen N  McIlroy A  Miller JA  Senosiain JP  Klippenstein SJ  Qi F  Sheng L  Zhang Y  Cool TA  Wang J  Westmoreland PR  Law ME  Kasper T  Kohse-Höinghaus K 《Science (New York, N.Y.)》2005,308(5730):1887-1889

Models for chemical mechanisms of hydrocarbon oxidation rely on spectrometric identification of molecular structures in flames. Carbonyl (keto) compounds are well-established combustion intermediates. However, their less-stable enol tautomers, bearing OH groups adjacent to carbon-carbon double bonds, are not included in standard models. We observed substantial quantities of two-, three-, and four-carbon enols by photoionization mass spectrometry of flames burning representative compounds from modern fuel blends. Concentration profiles demonstrate that enol flame chemistry cannot be accounted for purely by keto-enol tautomerization. Currently accepted hydrocarbon oxidation mechanisms will likely require revision to explain the formation and reactivity of these unexpected compounds.  相似文献