title: Feasibility of Applying a Stable Isotopic Tracer for Direct Determination of Dry Particulate Deposition to Soybean Plants.
abstract: A stable rare-earth isotopic tracer was used to measure the deposition of KNO3particles on soybean leaves by direct measurement of the tracer on the plant surfaces by thermal-ionization mass spectrometry. Submicrometer particles, made from a solution containing 3 |mg mL-1neodymium isotope (148Nd, 87.9%) and 1,000 mg mL-1KNO3, were dispersed with a two-fluid nozzle and released upwind of a soybean field. Total suspended- and size-fractionated-aerosol particles were collected on an open-face filter and in a micro-orifice impactor, respectively, at a distance of 40 m from the release point. Soybean leaves exposed to the plume were collected at distances ranging from 25 to 100 m. As little as 5.5 pg of the tracer (i.e., excess148Nd) was detected in soybean leaves at signal-to-noise ratios ranging from 7,500 to 240,000, in the presence of 200 to 2,700 pg of naturally occurring Nd. The dry-particle deposition velocity, determined from the ratio of the aerial concentration and directly deposited aerosol (geometric mass mean diameter, 0.20 mm) flux, and its corresponding analytical uncertainty were 0.30 cm sec-1and 2.5%, respectively.
authors.affiliation: a Department of Chemistry and Biochemistry , University of Maryland , College Park , Maryland , USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Hoff
authors.affiliation: a Department of Chemistry and Biochemistry , University of Maryland , College Park , Maryland , USA.
authors.forename: P V
authors.initials: PV
authors.lastname: Borgoul
authors.affiliation: a Department of Chemistry and Biochemistry , University of Maryland , College Park , Maryland , USA.
authors.forename: G
authors.initials: G
authors.lastname: Tuncel
authors.affiliation: a Department of Chemistry and Biochemistry , University of Maryland , College Park , Maryland , USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Ondov
authors.affiliation: b Analytical Chemistry Division , National Institute for Standards and Technology , Gaithersburg , Maryland , USA.
authors.forename: W R
authors.initials: WR
authors.lastname: Kelly
authors.affiliation: b Analytical Chemistry Division , National Institute for Standards and Technology , Gaithersburg , Maryland , USA.
authors.forename: L T
authors.initials: LT
authors.lastname: Chen