@article {668, title = {A Critical Evaluation of Interlaboratory Data on Total, Elemental, and Isotopic Carbon in the Carbonaceous Particle Reference Material, NIST SRM 1649a}, journal = {J Res Natl Inst Stand Technol}, volume = {107}, year = {2002}, note = {Currie, L ABenner, B A JrKessler, J DKlinedinst, D BKlouda, G AMarolf, J VSlater, J FWise, S ACachier, HCary, RChow, J CWatson, JDruffel, E R MMasiello, C AEglinton, T IPearson, AReddy, C MGustafsson, OQuinn, J GHartmann, P CHedges, J IPrentice, K MKirchstetter, T WNovakow, TPuxbaum, HSchmid, Heng2002/01/01 00:00J Res Natl Inst Stand Technol. 2002 Jun 1;107(3):279-98. doi: 10.6028/jres.107.022. Print 2002 May-Jun.}, month = {May-Jun}, pages = {279-98}, abstract = {Because of increased interest in the marine and atmospheric sciences in elemental carbon (EC), or black carbon (BC) or soot carbon (SC), and because of the difficulties in analyzing or even defining this pervasive component of particulate carbon, it has become quite important to have appropriate reference materials for intercomparison and quality control. The NIST "urban dust" Standard Reference Material((R)) SRM 1649a is useful in this respect, in part because it comprises a considerable array of inorganic and organic species, and because it exhibits a large degree of ((14)C) isotopic heterogeneity, with biomass carbon source contributions ranging from about 2 \% (essentially fossil aliphatic fraction) to about 32 \% (polar fraction). A primary purpose of this report is to provide documentation for the new isotopic and chemical particulate carbon data for the most recent (31 Jan. 2001) SRM 1649a Certificate of Analysis. Supporting this is a critical review of underlying international intercomparison data and methodologies, provided by 18 teams of analytical experts from 11 institutions. Key results of the intercomparison are: (1) a new, Certified Value for total carbon (TC) in SRM 1649a; (2) (14)C Reference Values for total carbon and a number of organic species, including for the first time 8 individual PAHs; and (3) elemental carbon (EC) Information Values derived from 13 analytical methods applied to this component. Results for elemental carbon, which comprised a special focus of the intercomparison, were quite diverse, reflecting the confounding of methodological-matrix artifacts, and methods that tended to probe more or less refractory regions of this universal, but ill-defined product of incomplete combustion. Availability of both chemical and (14)C speciation data for SRM 1649a holds great promise for improved analytical insight through comparative analysis (e.g., fossil/biomass partition in EC compared to PAH), and through application of the principle of isotopic mass balance.}, issn = {1044-677X (Linking)}, doi = {10.6028/jres.107.022}, author = {Currie, L. A. and Benner, B. A., Jr. and Kessler, J. D. and Klinedinst, D. B. and Klouda, G. A. and Marolf, J. V. and Slater, J. F. and Wise, S. A. and Cachier, H. and Cary, R. and Chow, J. C. and Watson, J. and Druffel, E. R. and Masiello, C. A. and Eglinton, T. I. and Pearson, A. and Reddy, C. M. and Gustafsson, O. and Quinn, J. G. and Hartmann, P. C. and Hedges, J. I. and Prentice, K. M. and Kirchstetter, T. W. and Novakow, T. and Puxbaum, H. and Schmid, H.} } @article {637, title = {Radiocarbon as a tool to apportion the sources of polycyclic aromatic hydrocarbons and black carbon in environmental samples}, journal = {Environmental Science \& Technology}, volume = {36}, year = {2002}, note = {541gfTimes Cited:133Cited References Count:59}, month = {Apr 15}, pages = {1774-1782}, abstract = {To determine the relative inputs of polycyclic aromatic hydrocarbons (PAHs) and black carbon (BC) in environmental samples from the combustion of fossil fuels and biomass we have developed two independent analytical methods for determining the C-14 abundance of PAHs and BC. The 5730 yr half-life of C-14 makes it an ideal tracer for identifying combustion products derived from fossil fuels (C-14-free) versus those stemming from modern biomass (contemporary C-14). The C-14 abundance of PAHs in several environmental Standard Reference Materials was measured by accelerator mass spectrometry after extraction and then purification by high-performance liquid chromatography and preparative capillary gas chromatography. This method yields pure compounds that allow for a high degree of confidence in the C-14 results. The PAHs data were then used to compare and evaluate results from an operationally defined thermal oxidation method used to isolate a BC fraction. The C-14 compositions of PAHs and BC were very similar and suggest that the thermal oxidation method employed for isolating BC is robust and free from interferences by non-BC components. In addition, these data indicate that both the PAHs and the BC species derive mostly from fossil fuels and/or their combustion products.}, issn = {0013-936x}, doi = {10.1021/es011343f}, author = {Reddy, C. M. and Pearson, A. and Xu, L. and McNichol, A. P. and Benner, B. A. and Wise, S. A. and Klouda, G. A. and Currie, L. A. and Eglinton, T. I.} } @article {798, title = {Isotopic and molecular fractionation in combustion; three routes to molecular marker validation, including direct molecular {\textquoteright}dating{\textquoteright} (GC/AMS)}, journal = {Atmospheric Environment}, volume = {33}, year = {1999}, note = {208duTimes Cited:38Cited References Count:31}, month = {Aug}, pages = {2789-2806}, abstract = {The identification of unique isotopic, elemental, and molecular markers for sources of combustion aerosol has growing practical importance because of the potential effects of fine particle aerosol on health, visibility and global climate. It is urgent, therefore, that substantial efforts be directed toward the validation of assumptions involving the use of such tracers for source apportionment. We describe here three independent routes toward carbonaceous aerosol molecular marker identification and validation: (1) tracer regression and multivariate statistical techniques applied to field measurements of mixed source, carbonaceous aerosols; (2) a new development in aerosol (14)C metrology: direct, pure compound accelerator mass spectrometry (AMS) by off-line GC/AMS ({\textquoteright}molecular dating{\textquoteright}); and (3) direct observation of isotopic and molecular source emissions during controlled laboratory combustion of specific fuels. Findings from the combined studies include. independent support for benzo(ghi)perylene as a motor vehicle tracer from the first (statistical) and second (direct {\textquoteright}dating{\textquoteright}) studies; a new indication, from the third (controlled combustion) study, of a relation between (13)C isotopic fractionation and PAH molecular fractionation, also linked with fuel and stage of combustion; and quantitative data showing the influence of both fuel type and combustion conditions on the yields of such species as elemental carbon and PAH, reinforcing the importance of exercising caution when applying presumed conservative elemental or organic tracers to fossil or biomass burning field data as in the first study. Published by Elsevier Science Ltd.}, issn = {1352-2310}, doi = {10.1016/S1352-2310(98)00325-2}, author = {Currie, L. A. and Klouda, G. A. and Benner, B. A. and Garrity, K. and Eglinton, T. I.} } @article {795, title = {Radiocarbon measurements of atmospheric volatile organic compounds: Quantifying the biogenic contribution}, journal = {Environmental Science \& Technology}, volume = {30}, year = {1996}, note = {Uc413Times Cited:26Cited References Count:25}, month = {Apr}, pages = {1098-1105}, abstract = {The radiocarbon (C-14) abundance of atmospheric volatile organic compounds (VOC) gives a quantitative estimate of contributions from biomass and fossil-mass sources, important information for effective regulation of ozone precursors. We report here details of a methodology to perform such measurements and the first exploratory C-14 results on VOC fractions separated from two composited urban tropospheric air samples, collected during the summer (1992) in Atlanta, GA. The upper limit of the percentage of VOC originating from biomass sources during the morning and evening hours in Atlanta were 9 and 17\%, respectively, measurements reported at the 95\% confidence level. However, due to the level of the process blank and its uncertainty, in both cases the percentage can be as low as zero. The results of these experiments, designed to (i) evaluate the entire [C-14]VOC measurement process and (ii) obtain reliable estimates of biogenic contributions to atmospheric VOC, emphasize how important controls are throughout this multi-step chemical process to ensure quality data.}, issn = {0013-936x}, doi = {10.1021/es9501981}, author = {Klouda, G. A. and Lewis, C. W. and Rasmussen, R. A. and Rhoderick, G. C. and Sams, R. L. and Stevens, R. K. and Currie, L. A. and Donahue, D. J. and Jull, A. J. T. and Seila, R. L.} } @article {845, title = {Comparative-Study of Fe-C Bead and Graphite Target Performance with the National-Ocean-Science-Ams (Nosams) Facility Recombinator Ion-Source}, journal = {Nuclear Instruments \& Methods in Physics Research Section B-Beam Interactions with Materials and Atoms}, volume = {92}, year = {1994}, note = {Nv547Times Cited:23Cited References Count:13}, month = {Jun}, pages = {166-171}, abstract = {An accelerator mass spectrometry (AMS) experiment was designed to investigate C-14 target performance for two target types over a range of isotopic concentrations and sample sizes, with a special focus on the ability to measure C-14 in environmental samples having only microgram amounts of carbon. The findings were positive, showing that precision, accuracy, and stability were adequate to determine C-14 to 1\% or better in samples containing as little as 25 mug carbon. Satisfactory Poisson uncertainty and target stability were demonstrated down to a level of 7 mug carbon, but experimental data showed that accurate measurements at that level require detailed knowledge of blank variability and mass dependence of the modern carbon calibration factor.}, issn = {0168-583x}, doi = {10.1016/0168-583x(94)95999-4}, author = {Klinedinst, D. B. and McNichol, A. P. and Currie, L. A. and Schneider, R. J. and Klouda, G. A. and vonReden, K. F. and Verkouteren, R. M. and Jones, G. A.} } @article {797, title = {Sources of Urban Contemporary Carbon Aerosol}, journal = {Environmental Science \& Technology}, volume = {28}, year = {1994}, note = {Pe258Times Cited:111Cited References Count:45}, month = {Sep}, pages = {1565-1576}, abstract = {Emissions from the major sources of fine carbonaceous aerosol in the Los Angeles basin atmosphere have been analyzed to determine the amounts of the C-12 and C-14 isotopes present. From these measurements, an inventory of the fossil carbon and contemporary carbon particle emissions to the Los Angeles atmosphere has been created. In the winter, more than half of the fine primary carbonaceous aerosol emissions are from sources containing contemporary carbon, including fireplaces, charbroilers, paved road dust, cigarette smoke, and brake lining dust, while in the summer at least one-third of the carbonaceous particle emissions are contemporary. Using a mathematical model for atmospheric transport, predictions are made of the atmospheric fine particulate fossil carbon and contemporary carbon concentrations expected due to primary source emissions. Model predictions are in reasonable agreement with the measured radiocarbon content of the fine ambient aerosol samples. It is concluded that the high fraction of contemporary carbon measured historically in Los Angeles is not due to local emission sources of biogenic material; rather, it is due to a combination of local anthropogenic pollution sources and background marine aerosol advected into the city.}, issn = {0013-936x}, doi = {10.1021/es00058a006}, author = {Hildemann, L. M. and Klinedinst, D. B. and Klouda, G. A. and Currie, L. A. and Cass, G. R.} } @conference {1591, title = {Comparative study of Fe-C Bead vs. graphite target performance with the NOSAMS Facility recombinator ion source}, booktitle = {6th International Conference on Accelerator Mass Spectrometry}, year = {1993}, note = {id: 931}, month = {1993}, pages = {71}, address = {Canberra, Australia}, author = {Kleindinst, D. B. and McNichol, A. P. and Currie, L. A. and Jones, G. A. and Verkouteren, R. M. and von Reden, K. F. and Klouda, G. A. and Schneider, R. J.} }