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List of Abstracts 34expression, [EC]sed = K[EC], where K is a constant. In the absence of necessary information for severalvariables K can not be calculated from first principles. We have measured monthly [EC]atm at WhitefaceMountain, NY, from July 1978 to December 2005. Furthermore, we collected sediment cores from twonearby lakes, sectioned cores in thin slices, freeze dried, and determined the time of deposition or ages ofvarious sections by 210Pb dating technique. This technique provides the ages and sedimentation ratesaccurately for about 150 years. Assuming a constant sedimentation rate we extended the ages to around 1100AD. The value of K was determined from the [EC]atm and [EC]sed measurements for the 1978 -2005period. This K was used to determine the [EC]atm from [EC]sed. The data for the ~1900 to 2005 period wascompared with the model calculations of Novakov et al [2003] {GRL 30, doi 10.1029/2002GLO16345}.From around 1100 to 1850 the [EC]atm showed small variations. This data can be used to deduceinformation on forest fires. Data for the 1850 to 2005 is generally consistent with the industrialization.P-Sources.48 ID:4442 15:35Intercomparison of measurement methods for elemental carbon in atmospheric aerosol samples at anurban site in Havana CubaImran Shahid 1 , Heidi Bauer 1 , Pire Rivas 2 , Regina Hitzenberger 3 , Hans Puxbaum 11 Institute of chemical technologies and analytics, Vienna university of technology, vienna Austria2 Polytechnic Institute José Antonio Echeverría, Havana Cuba3 Institute of Experimental Physics, University of Vienna, Boltzmangasse 5, 1090, Vienna AustriaContact: e0826894@student.tuwien.ac.atThere is no generally accepted standard method for the measurement of black carbon (BC) or Elementalcarbon (EC). The EC and BC concentrations are method specific and can differ widely (Schmid et al., 2001,ten Brink et al., 2004). In this study measurement methods (both thermal and optical) for EC (BC) inatmospheric aerosol were compared at an urban site in the city of Havana Cuba. Filter samples werecollected on quartz microfiber filters and were analyzed for elementac carbon by thermal methods: amodified Cachier method (Cachier et al., 1989), a thermal-optical method (Schmid et al., 2001), for BC withan optical method; integrating sphere method (Hitzenberger et al., 1996) and total carbon (TC) with acombustion method (Puxbaum and Rendl et al., 1983). There is no big difference in the EC concentrationmeasured by Sunset and Cachier method; however TOT gives relatively 20-60 % higher values than sunsetand Cachier methods. The brown carbon (measured by Integrating sphere method) is also a major reason invariation of EC values.Key words: Elemental carbon, brown carbon, atmospheric aerosol measurementP-Sources.49 ID:4281 15:35Decreases in elemental carbon and fine particle mass in the United StatesDaniel Murphy 1 , Judy Chow 2 , William Malm 3 , Charles McDade 4 , Marc Pitchford 5 , Bret Schichtel 6 , JohnWatson 2 , Warren White 41 NOAA ESRL Chemical Sciences Division2 Desert Research Institute3 CIRA Colorado State University4 UC Davis Crocker Nuclear Laboratory5 NOAA Air Resources Laboratory6 National Park ServiceContact: daniel.m.murphy@noaa.goviCACGP-IGAC 2010 12 July, 2010