title: Optimized low-level liquid scintillation spectroscopy of 35S for atmospheric and biogeochemical chemistry applications.
abstract: Anthropogenic activities, dominated by emissions of sulfur dioxide (SO(2)), have perturbed the global sulfur (S) cycle. Uncertainties in timescales of S transport and chemistry in the atmosphere lead to uncertainties in the predicted impact of S emissions. Measurements of cosmogenic (35)S may potentially be used to resolve existing uncertainties in the photochemical and chemical transformation of S in the environment. The lack of a simple, effective, and highly sensitive technique to measure (35)S activity in samples with low activities may explain the scarcity of published measurements. We present a set of new sample handling and measurement procedures optimized for the measurement of (35)S in natural samples with activities as low as 0.20 dpm above background (2sigma, integration time = 2 hr). We also report simultaneous measurements of aerosol (35SO4 ) and gas phase (35SO2) collected at inland and coastal locations; the range of observed activities corresponds to SO(2) residence lifetimes of 0.2 +/- 0.04 (coastal) - 22.3 d +/- 0.04 (inland). These optimized techniques offer the potential for resolving atmospheric processes that occur on 6-12-hour timescales as well as resolving transport phenomena such as stratospheric mixing into the troposphere.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, San Diego, CA 92093-0356, USA.
authors.forename: Lauren A
authors.initials: LA
authors.lastname: Brothers
authors.forename: Gerardo
authors.initials: G
authors.lastname: Dominguez
authors.forename: Anna
authors.initials: A
authors.lastname: Abramian
authors.forename: Antoinette
authors.initials: A
authors.lastname: Corbin
authors.forename: Ben
authors.initials: B
authors.lastname: Bluen
authors.forename: Mark H
authors.initials: MH
authors.lastname: Thiemens