Inventories of fallout 210Pb and 137Cs radionuclides in moorland and woodland soils around Edinburgh urban area (UK)

Abstract

Inventories of fallout 210Pb and 137Cs have been measured in moorland and woodland soils around the Edinburgh urban area, using a high purity germanium detector. The 210Pb inventories in moorland soils were relatively uniform, with a mean value of 2520 ± 270 Bq m−2. The mean 137Cs inventory in moorland soils varied greatly from 1310 to 2100 Bq m−2, with a mean value of 1580 ± 310 Bq m−2. The variability was ascribed mainly to the non-uniform distribution of fallout Chernobyl 137Cs. The mean 210Pb and 137Cs inventories in woodland canopy soils were found to be 3630 ± 380 Bq m−2 and 2510 ± 510 Bq m−2, respectively. At sites for which both moorland and woodland data were available, the mean inventories provided fairly similar average enhancements of (47 ± 7)% and (46 ± 18)% of 210Pb and 137Cs under woodland canopy soils relative to open grassland soils, respectively. The enhancement factors are broadly in line with other independent findings in literature. Enhancement of both 210Pb and 137Cs in woodland soils relative to moorland soils is, in part, due to deposition by impaction during air turbulence, wash-off, gravitational settling and deposition during leaf senescence. Results of this study suggest that these processes affect both 210Pb and 137Cs carrier aerosols in a similar way.