An evaluation of the natural radionuclides, beryllium-7, lead-210, polonium-210, and bismuth-210, as tracers of atmospheric aerosols

The natural radionuclides (7Be, 210Pb, 210Bi, 210Po) in fine aerosols are useful tracers to understand their tropospheric transport and removal. Aerosol samples were collected at UALR and The University of Chicago. The concentrations and ratios of 7Be and 210Pb in atmospheric aerosols vary seasonally consistent with their sources. The 7Be shows stronger correlation with black carbon than the 210Pb. In contrast, the 210Pb shows stronger correlation with the rain levels than the 7Be. The distribution coefficient (Kd) was used to evaluate the binding strength between the natural radionuclides and atmospheric aerosols in water to mimic atmospheric washout. The K d values tend to increase with increasing pH. This study suggests that the binding between the natural radionuclides and atmospheric aerosols is strong. The results are discussed in terms of sources for 7Be and 210Pb and their attachment to aerosols, particularly carbonaceous aerosols that have low water affinities.