Hv. Kazemi et al., MEASUREMENT OF BROMIDE ION USED AS A SOLUTE-TRANSPORT MONITOR VIA EPITHERMAL NEUTRON-ACTIVATION ANALYSIS, Journal of radioanalytical and nuclear chemistry, 235(1-2), 1998, pp. 249-254
In soil science (ca. 1970), bromide ion (Br-) in various forms (e.g.,
KBr, NaBr, SrBr2) was introduced as a non-reactive stable tracer in so
lute transport studies normally moving freely with the flux of water w
ithout substantial chemical or physical interactions with the soil; Ty
pically, Br is extracted from soil and quantified using either a bromi
de selective electrode (sensitivity is similar to 10 mu g/ml) or by hi
gh-performance liquid chromatography (sensitivity is similar to 0.010
mu g/ml). Where the sensitivity is adequate, the selective conductivit
y method, which is simple, affordable and fast, is preferred. More rec
ently (ca. 1990), workers have reported that 20% of Br tracers, at low
groundwater pH, may be adsorbed by iron oxides and kaolinite when pre
sent in the alluvial aquifer. We investigated the use of Epithermal Ne
utron Activation Analysis (ENAA) as a means of measuring Br directly i
n soil samples without an extraction. ENAA was chosen because of its h
igh theoretical advantage factor over aluminum (i.e. similar to 20), t
he principal interfering soil constituent calculated for the Br-79(n,g
amma)Br-80 reaction compared to Al-27(n,gamma)Al-28. Br- was measured
(sensitivity is similar to 0.050 mu g/g) in one gram soil samples from
a 5 s irradiation (phi(epi) = 2.5.10(12) n.cm(-2).s(-1)) using a BN c
apsule.