Measurements of thorium–B () in the outdoor environment and evaluation of equivalent dose

Observations and modelling of thoron and its progeny in the soil–atmosphere–plant system

“…Reineking et al (1992) reported unattached fractions of 212 Pb between 0.010 and 0.112 with mean 0.057 at an urban area. Since these data agree with results given elsewhere Mohammed et al, 2000), the value 0.057 was adopted for our simulations. For the dry deposition velocities, the average values of 3.1 Â 10 À4 m s À1 ðv a d Þ and 3.2 Â 10 À2 m s À1 ðv u d Þ given by Porstendörfer (1994) for deposition on grass vegetation are used.…”

“…The fraction of the atmospheric 212 Pb attached to aerosols depends on concentrations of the aerosol (Porstendörfer, 1994;Mohammed et al, 2000;Vecchi et al, 2005) which are much higher in urban than in rural areas. Reineking et al (1992) reported unattached fractions of 212 Pb between 0.010 and 0.112 with mean 0.057 at an urban area.…”

“…It has been stressed (Mohammed et al, 2000;Marcazzan et al, 2003;Ho and Measday, 2005) that despite of its potential radiological and scientific significance, data on outdoor 212 Pb are limited.…”

Assessment of the influence of in situ210Bi in the calculation of in situ210Po in air aerosols: Implications on residence time calculations using210Po/210Pb activity ratios

“…On the other hand, it is interesting to note that besides 210 Pb and its decay products, 212 Pb ( t 1/2 = 10.64 h) and its decay products can be also retained in the filters [ Mohammed et al , 2000; Marcazzan et al , 2003]. This radionuclide, which is a thoron ( 220 Rn) daughter, decays to 212 Bi (60.55 min).…”

A simple model for describing the concentration of 212Pb in the atmosphere

“…220 Rn) is somewhat different; it is short-lived (T 1/2 =55.6 s), so it diffuses out from only the top layer of the soil (w1 cm), and does not get far off the ground before decaying. It has one key product, 212 Pb (ThB), which has a reasonably long half-life of 10.64 h, so it can linger in the atmosphere, attached to aerosols which have an AMD (Activity Mean Diameter) of about 0.4 mm (see Mohammed et al, 2000;Porstendo¨rfer et al, 2000;Winkler et al, 1998). Further details of the properties of radon in the environment can be found in many references, for example the standard reference books of Eisenbud (1997) and Wilkening (1990), or the excellent review by Porstendo¨rfer (1994).…”