Open AccessThe 214 Bi to 214 Pb ratio in lower boundary layer aerosols and aerosol residence times at New Haven, Connecticut
Author(s) -
Turekian Vaughan C.,
Graustein William C.,
Turekian Karl K.
Publication year - 1999
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/1999jd900031
Subject(s) - aerosol , residence time (fluid dynamics) , atmospheric sciences , environmental science , boundary layer , atmosphere (unit) , altitude (triangle) , sampling (signal processing) , box model , residence , meteorology , analytical chemistry (journal) , chemistry , physics , environmental chemistry , mathematics , geology , thermodynamics , geometry , demography , geotechnical engineering , sociology , detector , optics
The activities of 214 Pb (half‐life 26.8 min) and 214 Bi (half‐life 19.7 min), decay products of 222 Rn, are nearly equal in 187 aerosol samples collected over 1 year at an altitude of 12 m in New Haven, Connecticut. These observations do not agree with the large variations in ( 214 Bi)/( 214 Pb) reported by others for southern California. We derive a “reference ratio” as a technique for relating the measured activities of 214 Bi and 214 Pb accumulated on filters over sampling times that are longer than their half‐lives to the ( 214 Bi)/( 214 Pb) in the atmosphere and derive simple models relating the reference ratio to aerosol residence time. The observed ( 214 Bi)/( 214 Pb) ratios imply a mean residence time of 16 hours (with the 2 standard error limits of +72 and −7 of this mean) in a steady state box model and mean age of 2.8 hours (with the 2 standard error limits of +0.9 and −0.4 of this mean) in an isolated parcel model. The variance of the data indicates that the conditions of sampling are closer to the assumptions of the box model than the isolated parcel model.