Determination of Size-Dependent Dry Particle Deposition Velocities with Multiple Intrinsic Elemental Tracers
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- 作者：Peter F. Caffrey ; John M. Ondov ; Maria J. Zufall ; and Cliff I. Davidson
- 刊名：Environmental Science & Technology
- 出版年：1998
- 出版时间：June 1, 1998
- 年：1998
- 卷：32
- 期：11
- 页码：1615 - 1622
- 全文大小：177K
- 年卷期：v.32,no.11(June 1, 1998)
- ISSN：1520-5851
文摘
Dry deposition flux and aerosol size distribution measurements were made concurrently aboard the RV LakeGuardian 19 km east of the Chicago shoreline duringsummer1994 to assess atmospheric inputs of minor and traceelements to southern Lake Michigan. Size-segregatedaerosolmeasurements were made over consecutive 12-h periodswith Micro-Orifice and Noll Rotary impactors (MOI andNRI), and depositing-particulate collections toaerodynamicallysmooth airfoils were made over periods of 3-4 days.Thecombination of the MOI and NRI provided size-segregatedparticulate samples in 12 discrete intervals between 0.059and, nominally, 100 
m. The samples were analyzed forAs,Ca, Mg, Se, Sb, V, and Zn by instrumental neutronactivationanalysis and for S by X-ray fluorescence. Aerosol anddeposition data for individual elemental constituents werefit with a chemical mass balance deposition (CMBD)model in which a set of particle-size-specific depositionvelocities (Vd), best reconciling the depositiondata, weredetermined by iterative (constrained) solution of a seriesof six linear equations using the Levenberg-Marquardtmethod. Under stable conditions and mean wind speedof4.0 m s-1, minimum Vdvalues for particles with physicaldiameters between 0.09 and 0.53 m averaged 0.006 ±0.005 cm s-1, wherein uncertainties weredetermined byMonte Carlo analysis. This agrees favorably withvaluesdetermined by microscopy for which uncertainties weremuch larger and with those predicted by the Williamsmodel for the same period. The results suggest thatphysicallysignificant Vd values are obtainable from aconstrainedCMBD model.
m. The samples were analyzed forAs,Ca, Mg, Se, Sb, V, and Zn by instrumental neutronactivationanalysis and for S by X-ray fluorescence. Aerosol anddeposition data for individual elemental constituents werefit with a chemical mass balance deposition (CMBD)model in which a set of particle-size-specific depositionvelocities (Vd), best reconciling the depositiondata, weredetermined by iterative (constrained) solution of a seriesof six linear equations using the Levenberg-Marquardtmethod. Under stable conditions and mean wind speedof4.0 m s-1, minimum Vdvalues for particles with physicaldiameters between 0.09 and 0.53 m averaged 0.006 ±0.005 cm s-1, wherein uncertainties weredetermined byMonte Carlo analysis. This agrees favorably withvaluesdetermined by microscopy for which uncertainties weremuch larger and with those predicted by the Williamsmodel for the same period. The results suggest thatphysicallysignificant Vd values are obtainable from aconstrainedCMBD model.