MODELLING LEACHING OF INORGANIC Hg(II) IN A SCANDINAVIAN IRON-HUMUS PODZOL - VALIDATION AND LONG-TERM LEACHING UNDER VARIOUS DEPOSITION RATES     

SCHLÜTER  K.  GÄTH  S. 《Water, air, and soil pollution》1997,96(1-4):301-320

Increasing mercury contents are reported from freshwater systems and fish in northern Europe and North America. Mercury input from soils is a major source with the leaching being affected by increased atmospheric mercury deposition compared to pre-industrial times and by other environmental conditions such as acid rain. The results of a mathematical model-calculation of vertical inorganic Hg(II) leaching in a Scandinavian iron-humus podzol under different atmospheric input rates of mercury are presented. Leaching under background rain conditions was calculated to be considerably stronger than under acid rain conditions. Increasing fractions of deposited soluble or solute atmospheric mercury were leached from the O _f(h)-horizon with decreasing soil content of soluble mercury under acid rain conditions; this effect was less pronounced under background rain conditions. The steady state concentrations of soluble mercury of the upper soil horizons were calculated and compared with the actual concentrations of total (= soluble + insoluble mercury) and extractable (= estimate of soluble) mercury measured in these horizons. The results indicate that even if the deposition of airborne mercury to soil is strongly reduced, the total mercury content of the soil decreases only slowly. It may take decades or even centuries before a new steady state concentration of total mercury is established in the soil. The decrease of the mercury concentration in the O _f(h)-horizon is probably largely dependent on the turnover of organic matter, binding most of the deposited airborne mercury in an insoluble form. Hence, present day mercury leaching is likely to be dominated by mercury deposited during former times and temporarily retained in an insoluble form in the organic matter.  相似文献   

Pharmacokinetics of carprofen and firocoxib for medication control in racing greyhounds     

TH Morris  SW Paine  PW Zahra  EC Li  SA Colgan  SL Karamatic 《Australian veterinary journal》2020,98(12):578-585

Animals used in sport should be treated as required to ensure animal welfare but any such use of medication should also be controlled to ensure integrity. Pharmacokinetic studies on groups of six greyhounds were performed to measure plasma and urine levels of carprofen and firocoxib to inform medication control advice. Using the standard methodology for medication control the Irrelevant Plasma Concentration was determined as 20 and 2 ng/mL for carprofen and firocoxib, respectively. The Irrelevant Urine Concentration was also determined as 0.3 and 2 ng/mL for carprofen and firocoxib, respectively. These Irrelevant Plasma and Urine Concentrations will allow laboratory Screening Limits, Detection Times and Withdrawal Time advice to be determined and publicised by regulators of greyhound racing. The Screening Limits will also inform Recommended Limits of Detection if meat-containing residues of these medications are fed to greyhounds.  相似文献   

Lymphosarcoma in a wild grayling, Thymallus thymallus L.: a case report     

R. W. HOFFMANN  TH. FISCHER-SCHERL  C. PFEIL-PUTZIEN 《Journal of fish diseases》1988,11(3):267-270

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Successful sterlet, Acipenser ruthenus L., propagation with synthetic LH-RH hormone     

L. HORVÁTH  A. PÉTERI  J. KOURIL 《Aquaculture Research》1986,17(2):113-116

Abstract. The synthetic LH-RH (luliberine) has proved to be successful in inducing the ovulation of sterlet, Acipenser ruthenus L. Three dosages of LH-RH 50, along with carp pituitary, and 100 and 300 μg/kg of body weight were administered, and 100 and 300 μg of LH-RH/kg body weight were found to be successful in ovulation. Spawners were kept at low temperature (9–12°C). Forty-two hours after treatment the eggs entered ovulation in the ovary and became suitable for stripping. The ripening ratio for spawners varied between 75 and 83%. The eggs that could be obtained by opening the abdominal wall were fertilized with milt diluted with pond water to avoid polyspermism. The fertility of the stripped eggs was 89–90%. Despite a reduced number of subjects (12 treated, 2 control females), as a result of the favourable fertilization percentage, approximately 55 000 fingerlings were reared in tanks to approximately 5–7cm in size.  相似文献   

Weed vegetation of poppy (Papaver somniferum) fields in Hungary: effects of management and environmental factors on species composition     

G PINKE  R W PÁL  K TÓTH  P KARÁCSONY  B CZÚCZ  Z BOTTA‐DUKÁT 《Weed Research》2011,51(6):621-630

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Carbon and Nitrogen Amendments Lead to Differential Growth of Bacterial and Fungal Communities in a High-pH Soil     

Pramod N. KAMBLE  Erland B&#;&#;TH 《土壤圈》2018,28(2):255-260

Microbial growth in soil is mostly limited by lack of carbon (C). However, adding fresh, C-rich litter can induce nitrogen (N) limitation. We studied the effect of alleviating C and N limitation in high-pH (> 8) soils, soils expected to favor bacterial over fungal growth. Nitrogen limitation was induced by incubating soils amended with C-rich substrate (starch or straw) for 4 weeks. Limiting nutrients and the effects of alleviating limitation were then studied by adding C (as glucose) or N (as NH₄NO₃) and measuring microbial growth and respiration after 4 d. In non-amended, C-limited soils, adding C but not N increased both microbial respiration and bacterial growth. In N-limited, substrate-amended soils, adding C increased respiration, whereas adding N increased both microbial respiration and growth. Inducing N limitation by amending with straw was most easily detected in increased fungal growth after the addition of N, whereas with starch, only bacterial growth responded to alleviating N limitation. Compared to earlier results using a low-pH soil, the effect of substrate used to induce N limitation was more important than pH for inducing bacterial or fungal growth after alleviating N limitation. Furthermore, we found no evidence that alleviating N limitation resulted in decreased respiration concomitant with increased microbial growth in soil, suggesting no drastic changes in C use efficiency.  相似文献   

Effect of Different Combinations of Cryoprotectants on In Vitro Maturation of Immature Buffalo (Bubalus bubalis) Oocytes Vitrified by Straw and Open‐Pulled Straw Methods     

KGhM Mahmoud  TH Scholkamy  YF Ahmed  GE Seidel Jr  MF Nawito 《Reproduction in domestic animals》2010,45(4):565-571

This study was designed to evaluate effects of different combinations of cryoprotectants on the ability of vitrified immature buffalo oocytes to undergo in vitro maturation. Straw and open‐pulled straw (OPS) methods for vitrification of oocytes at the germinal vesicle stage also were compared. The immature oocytes were harvested from ovaries of slaughtered animals and were divided into three groups: (i) untreated (control); (ii) exposed to cryoprotectant agents (CPAs); or (iii) cryopreserved by straw and OPS vitrification methods. The vitrification solution (VS) consisted of 6 m ethylene glycol (EG) as the standard, control vitrification treatment, and this was compared with 3 m EG + 3 m dimethyl sulfoxide (DMSO), 3 m EG + 3 m glycerol, and 3 m DMSO + 3 m glycerol. Cryoprotectants were added in two steps, with the first step concentration half that of the second (and final) step concentration. After warming, oocyte samples were matured by standard methods and then fixed and stained for nuclear evaluation. Rates of MII oocytes exposed to CPAs without vitrification were lower (54.3 ± 1.9% in EG, 47.5 ± 3.4% in EG + DMSO, 36.8 ± 1.2% in EG + glycerol and 29.9 ± 1.0% in DMSO + glycerol; p < 0.05) than for the control group (79.8 ± 1.3%). For all treatments in each vitrification experiment, results were nearly identical for straws and OPS, so all results presented are the average of these two containers. The percentages of oocytes reaching telophase‐I or metaphase‐II stages were lower in oocytes cryopreserved using all treatments when compared with control. However, among the vitrified oocytes, the highest maturation rate was seen in oocytes vitrified in EG + DMSO (41.5 ± 0.6%). Oocytes cryopreserved in all groups with glycerol had an overall low maturation rate 19.0 ± 0.6% for EG + glycerol and 17.0 ± 1.1% for DMSO + glycerol. We conclude that the function of oocytes was severely affected by both vitrification and exposure to cryoprotectants without vitrification; the best combination of cryoprotectants was EG + DMSO for vitrification of immature buffalo oocytes using either straw or OPS methods.  相似文献   

A tunable kondo effect in quantum dots   总被引：1，自引：0，他引：1  

SM Cronenwett  TH Oosterkamp  LP Kouwenhoven 《Science (New York, N.Y.)》1998,281(5376):540-544

A tunable Kondo effect has been realized in small quantum dots. A dot can be switched from a Kondo system to a non-Kondo system as the number of electrons on the dot is changed from odd to even. The Kondo temperature can be tuned by means of a gate voltage as a single-particle energy state nears the Fermi energy. Measurements of the temperature and magnetic field dependence of a Coulomb-blockaded dot show good agreement with predictions of both equilibrium and nonequilibrium Kondo effects.  相似文献   

Size distribution approaches for monitoring and conservation of coastal Cymodocea habitats     

S. Orfanidis  V. Papathanasiou  S. Gounaris  TH. Theodosiou 《水产资源保护:海洋与淡水生态系统》2010,20(2):177-188

• 1. Cymodocea nodosa's leaf length distribution was studied as an easily measurable indicator to monitor and conserve Macedonian, North Aegean, Greek coastal habitats.
• 2. Three Cymodocea meadows off the eastern Kavala Gulf coast (Nea Karvali, Erateino, Agiasma), with that of Nea Karvali close to an industrial area being the most degraded, were sampled during the seagrass main growing season in July 2004. Two further meadows, one pristine to less degraded (Brasidas, Gulf of Kavala) and one degraded (Biamyl, Inner Thessaloniki Gulf), were sampled as benchmarks in July 2005. The results were evaluated using Gaussian fit curves, and non‐parametric and nested parametric ANOVA on a hierarchy of spatial scales: area (tens of metres), site (hundreds of metres) and meadow (kilometres).
• 3. Frequency (%) distribution of leaf length values and CymoSkew index variation were best associated with anthropogenic stress. Frequency (%) distribution of adult and intermediate photosynthetic leaf length values revealed a unimodal distribution possible to be fitted, at least at pristine to less degraded meadows, by normal distribution (R²>0.5).
• 4. Statistically significant variation was estimated for CymoSkew index, a quantitative expression of leaf length asymmetry, on the meadow scale (P<0.001). Biamyl (3.82) and Nea Karvali (3.64) were indicated as heavily degraded meadows, Erateino (2.93) as a degraded meadow, Agiasma (2.18) as a meadow with the first signs of degradation, and Brasidas (1.68) as a pristine to less degraded meadow. These results in combination with other meadow specific biotic parameters were used to suggest a preliminary angiosperm ‘Ecological Status Classes’ classification scheme useful for the implementation of WFD in the north Aegean Sea.
• 5. The CymoSkew index seems to respond to lower levels of stress than is needed for other more conservative plant modules and therefore, could be regarded as an early warning indicator of Cymodocea habitat degradation. Copyright © 2009 John Wiley & Sons, Ltd.

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Immunofluorescent detection of transmissible gastroenteritis virus in the intestines of piglets     

Z Pospísil  E Mesáros  J St?pánek 《Zentralblatt für Veterin?rmedizin. Reihe B. Journal of veterinary medicine. Series B》1969,16(9):840-846

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