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  • 1990-1994  (2)
  • Aluminum  (1)
  • Ozone uptake  (1)
  • General Chemistry
  • 1
    ISSN: 1432-2285
    Keywords: Ozone uptake ; Stomatal conductance ; Spruce
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The uptake of air pollutants depends both on pollutant concentration and on stomatal conductance. This paper deals with the uptake of ozone (O3) from the air into the needles of Norway spruce [Picea abies (L.) Karst.] under ambient climatic conditions. Regulation of O3 uptake by the stomata is shown and also the difference between the “physiologically active O3 concentration” and the O3 concentration of the ambient air. Data from the sun and shade crown of spruce trees at 1000 m a.s.l. are presented. Analysis of data from three vegetation periods has shown that at low ambient O3 concentrations the O3 uptake is largely regulated by stomatal conductance. Water vapour pressure deficit (VPD) of the atmosphere is the climatic factor which showed the highest positive correlation with O3 concentration. However, a high leaf-air VDP led to stomatal closure, thus reducing the O3 uptake in the needles despite high O3 concentrations in the ambient air. The potential O3 stress caused by high O3 concentrations can be strongly mitigated by this natural closing of the stomata and the simultaneous occurrence of moderate drought stress.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archives of toxicology 66 (1992), S. 700-705 
    ISSN: 1432-0738
    Keywords: Aluminum ; Toxicokinetics ; Rat ; Parenterals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The toxicokinetics of aluminum (Al) in male Wistar rats was studied after single intragastric (IG) doses of 1000 and 12000 μg Al/kg and intravenous (IV) doses of 10, 100, 1000, and 12000 μg Al/kg. Serial blood samples, daily samples of urine and feces as well as brain, liver, kidney, spleen, quadriceps muscle, and femur samples were collected. Al was measured by atomic absorption spectrometry. Al blood profiles after IV doses were adequately described by a two-compartment open model. Al toxicokinetics was dose dependent and appeared to plateau at 12000 μg/kg. At IV doses between 10 and 1000 μg/kg the terminal half-life of elimination from whole blood (t1/2β) increased from 29.9±7.8 to 209.3±32.6 min, and the total body clearance (CL) decreased from 2.45±0.64 to 0.28±0.03 ml min−1 kg−1. Following an IV bolus of 10 and 100 μg/kg the administered Al was recovered completely from urine (94.4%±9.9% and 98.5%±3.2%). Twenty-nine days after the IV dose of 1000 μg/kg daily renal excretion decreased to baseline values while only 55.1%±8.0% of the dose was excreted. Nineteen days after the single IV dose of 1000 μg/kg Al accumulated in liver (28.1±7.7 versus 1.7±0.5 μg/g of control rats) and spleen (72.5±21.1 versus 〈0.4 μg/g). After the single 1000 μg/kg IG dose no absorption of Al was detectable. The IG dose of 12000 μg/kg resulted in a maximum blood Al level of 47.9±12.4 μg/l after 50 min. The blood concentration time curve fitted a one-compartment open model with a half-life of absorption of 28.2±3.6 min and a t1/2β of 81.2±20.2 min. Cumulative renal Al excretion was 0.18%±0.10% of the dose and oral bioavailability was 0.02%. Seventeen days after the 12000 μg/kg IG dose the Al content in femur samples was increased (2.7±1.3 versus 0.6±0.4 μg/g). In no case was fecal elimination of incorporated Al observed.
    Type of Medium: Electronic Resource
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