Uptake factor

Bioavailability from Environmental Media. The absorption and distribution of americium as a result of inhalation and ingestion exposures have been discussed in Sections 3.3.1 and 3.3.2. EPA lists identical uptake factors for inhaled and ingested americium (and all the other transuranics other than plutonium) regardless of compound solubility, indicating that the knowledge base for americium is not sufficiently developed to quantify the differences that are recognized for most other elements. 

National Radiological Protection Board. 1982. Gut uptake factors for plutonium, americium and curium. Hartwell, England National Radiological Protection Board. DE83702055. 

The fractional value can be calculated because we know the relative changes in DIG and/ g at chemical equilibrium for a given Ac b./co. temperature, and pressure. Pilson (1998) referred to this value as the uptake factor, UF ... 

The change in the uptake factor (L/f) and Revelle factor (R) as a function of the fco, in equilibrium with a seawater solution containing a total alkalinity of 2300 peq kg . ... 

We have so far assumed that the atmosphere and ocean are in equilibrium. This of course cannot be the case, as the CO2 content of the atmosphere is rising rapidly, so there must be a gradient in /co across the air-water interface to drive the flux into the ocean. The concepts of the Revelle and uptake factors are also useful in determining the response time of the upper ocean to perturbations of gas and isotope changes in the atmosphere. As discussed in Chapter 2, the residence time of a substance is equal to its reservoir size divided by the flux in or out. For an inert gas, C, in the upper ocean the time for (1-1/e) of the gas to be exchanged by flux across the air-water... 

Alternatively, plants and the bees that visit them can provide a means of detecting and monitoring radionuchde pollution over large areas. Depending on the honey bee pasture types and the plant uptake factors mentioned previously, Cs appears in measurable levels in various types of honey [19-21], Heather plants, Calluna vulgaris especially, are species well-known as indicators of cesium pollution [22,23],... 

However, it is now recognized as representing a range of possible release fractions and uptake factors and it is convenient to consider intake factors in terms of these two parameters independently. 

Extrapolation of the models employed to evaluate the atmospheric dilution factors used here to shorter downwind distances is unreliable, but reducing the exposure distance by an order of magnitude to 10 m would increase the above uptake factors by about a factor of 30. This indicates that as the downwind distance approaches a few metres the uptake factors would approach the 10 -10 range used within the Q system. However, under these circumstances other factors which would tend to reduce the activity uptake come into effect and may even become dominant. The additional turbulence to be expected in the presence of a fire has been mentioned earlier. Similar reductions in airborne concentrations can be anticipated as a result of turbulence originating from the flow of air around any vehicle involved in an accident or from the effects of nearby buildings. 

The importance of the water uptake of the samples is not so expressed constant of water-uptake factor was 22.69. The interaction coefficient of the water uptake and the wetting contact angle of film samples of 1.24 indicates the existence of a sUght relation between them. The surface tension decreasing effect of surfactant aqueous solutions does not influence significantly the drug release rate the constant of this factor was -1.24. 

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