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71.
72.
A study of the downward movement of 137Cs in an undisturbed forest soil is presented. Seasonal variations and depth profiles of 137Cs activities were measured in seepage water, which is the transport medium for the downward movement of anthropogenic substances in soils. Furthermore the correlation of 137Cs mobilization and production of dissolved organic carbon (DOC) was investigated. Seasonal variations of both 137Cs and DOC fluxes in the seepage water in a depth of 5 cm depth were observed, where the maximum fluxes in the summer months were about one order of magnitude higher than the minimum fluxes in the winter months. 137Cs fluxes are found to be correlated with DOC fluxes with a correlation coefficient of r = 0.63, and both are highly correlated with soil temperature. This indicates that cesium is bound to soil organic material. The production of DOC is controlled by microbial decomposition of soil organic matter and we assume that this holds true for the 137Cs release as well. The actual transport velocity (0.2 ± 0.14 mm/a) of 137Cs (calculated by the weighed mean of 137Cs concentration in the seepage water and the total 137Cs content of the soil) is about one order of magnitude less than the mean transport velocity (1.2 ± 0.3 mm/a) over the past 25 years (calculated from the 137Cs depth profile). It is possible that the transport velocity of 137Cs in undisturbed soils decreases with time as it binds to aged organic material which is less easily decomposable than fresh organic material. 相似文献
73.
Mehrländer K Dietrich H Sembries S Dongowski G Will F 《Journal of agricultural and food chemistry》2002,50(5):1230-1236
Eight apple pomace liquefaction juices were produced to characterize soluble cell wall material released by the action of pectolytic and cellulolytic enzyme preparations. Very high colloid values from 9.7 to 19.6 g/L were recovered from the juices by ethanol precipitation. The crude polysaccharides consisted mainly of galacturonic acid (49-64 mol %), arabinose (14-23 mol %), galactose (6-15 mol %), and minor amounts of rhamnose, xylose, and glucose. Separation of the polysaccharides by anion-exchange chromatography yielded one neutral, one slightly acidic, and one acidic polymer accounting for 60% of total colloids. Preparative size exclusion chromatography of the acidic fractions resulted in four polymers of different molecular weights and different sugar compositions. Among them, high molecular weight arabinans and rhamnogalacturonans as well as oligomeric fractions consisting of only galacturonic acid could be found. Linkage studies were performed on neutral fractions from anion-exchange chromatography and size exclusion chromatography. They revealed highly branched arabinans, xyloglucans, and mainly type I arabinogalactans. 相似文献
74.
S. K. Hassler R. M. Lark A. E. Milne H. Elsenbeer 《European Journal of Soil Science》2011,62(6):891-901
Saturated hydraulic conductivity (Ks) of the soil is a key variable in the water cycle. For the humid tropics, information about spatial scales of Ks and their relation to soil types deduced from soil map units is of interest, as soil maps are often the only available data source for modelling. We examined the influence of soil map units on the mean and variation in Ks along a transect in a tropical rainforest using undisturbed soil cores at 0–6 and 6–12 cm depth. The Ks means were estimated with a linear mixed model fitted by residual maximum likelihood (REML), and the spatial variation in Ks was investigated with the maximum overlap discrete wavelet packet transform (MODWPT). The mean values of Ks did not differ between soil map units. The best wavelet packet basis for Ks at 0–6 cm showed stationarity at high frequencies, suggesting uniform small‐scale influences such as bioturbation. There were substantial contributions to wavelet packet variance over the range of spatial frequencies and a pronounced low frequency peak corresponding approximately to the scale of soil map units. However, in the relevant frequency intervals no significant changes in wavelet packet variance were detected. We conclude that near‐surface Ks is not dominated by static, soil‐inherent properties for the examined range of soils. Several indicators from the wavelet packet analysis hint at the more dominant dynamic influence of biotic processes, which should be kept in mind when modelling soil hydraulic properties on the basis of soil maps. 相似文献
75.
Brunnberg MM Engelke E Gielen IM van Bree HJ Hoffmann JE Brunnberg L Waibl HR 《American journal of veterinary research》2011,72(10):1318-1324
76.
Deep intrauterine insemination in pigs allows sperm deposition only into one uterine horn, but bilateral fertilization of oocytes occurs. How the sperm reach the contralateral oviduct remains disputable. The aim of this experiment was to study possible transperitoneal and/or transuterine sperm migration ways. Follicle growth and ovulation were induced in 24 peripubertal gilts with eCG and hCG 72 h after eCG. Endoscopic intrauterine insemination (IUI) was performed 32 h after hCG with 20 ml of extended semen (60 × 10(6) spermatozoa) as follows: Group CONTROL (n=8) received IUI into the right horn, and the left horn served as non-treated control; Group LIGATURE (n=8) received IUI into the right horn, and the left horn was closed by endoscopic double ligature close to the bifurcation; Group INTRAPERITONEAL (IPI; n=8) received IUI into the right uterine horn, the left horn was closed by double ligature and semen was deposited intraperitoneally at the surface of the left ovary. Genital tracts were removed 65-66 h after hCG, the oviducts were flushed and ova (n=299) were analyzed for fertilization and cleavage. Furthermore, the accessory spermatozoa count/oocyte was graded as 0, without spermatozoa, 1, <5 spermatozoa, 2, 5-50 spermatozoa, 3, 50-100 spermatozoa and 4, >100 spermatozoa. The results indicate that low dose IUI into one horn provides a lower grade of accessory spermatozoa in the contra-lateral side (1.6 vs. 2.8). No spermatozoa were found in ova flushed from oviducts of the ligated uterine horn, even after intraperitoneal insemination (P<0.05), and no fertilization occurred, respectively. Our results clearly indicate that after low dose IUI into one uterine horn, spermatozoa reach the contralateral oviduct via transuterine migration. 相似文献
77.
Helmut Rauleder 《Erwerbs-Obstbau》2011,53(2):51-58
Antagonists of the white scale (Pseudaulacaspis pentagona, Targioni-Tozzetti, 1886) were determined from peaches and sweet cherries as host plant at the orchards of the Centre for Agriculture and Technology Augustenberg (LTZ) in 2009 and 2010 as well as from four other commercial red and black currant orchards in Baden-Wuerttemberg in 2010. The study focused mainly on the parasitoid species of P. pentagona as well as the rate of parasitism of white scale caused by these parasitoids using emergence traps with invested branch samples of the different host plants in the laboratory. Beside the parasitoids, possible predators of the white scale were observed in the field in 2010 at the orchard of the LTZ. The two parasitic wasp species Aphytis diaspidis and Encarsia berlesei (Howard, 1881 and 1906) were determined as parasitoids of the white scale, whereas A. diaspidis was dominant at most sites. Rate of parasitism caused by both species ranged from 1.9 to 23.0%. The Kidney-Spot Ladybird Beetle (Chilocorus renipustulatus, Scriba, 1790) could be observed as a predator of the white scale in the field. 相似文献
78.
Soil properties of coal, iron and steel industrial sites in Essen The physical and chemical soil properties of some Urbic Anthrosols derived from technogenic substrata in the study area Essen (Northrhine-Westfalia, Germany) were analyzed with special consideration of toxic elements. The sites are characterized by high contents of coarse fragments (> 2 mm) of different species and size whereby this fragments are partly porous. Bulk densities and particle densities are low due to the high contents of carbon. The sites show high pH-values with the exception of sulphur containing mining substrata, which are characterized by low pH-values in consequence of pyrite oxidation. Partly the technogenic substrata have a high content of carbon, especially of coal, before depositing. There are high contents of anorganic and organic toxic elements in some horizons due to the deposit species, e.g. high Cr-values in horizons with steel industrial slags and high PAH-values in horizons with coal tar containing material. 相似文献
79.
Cu deficiency — a potential factor in BSE? Recent data indicate that ”︁normal prions” contain copper as an antioxydative cofactor. In ”︁infective prions” Cu seems to be replaced by other trace metals. Cu deficiency symptoms of ruminants as described in the older literature are compared with the symptoms of bovine spongiform encephalopathy (BSE). 相似文献
80.