Processos de remoção de material particulado atmosférico: uma modelagem numérica de estudo de casos

Below cloud scavenging processes have been investigated considering a numerical simulation, local atmospheric conditions and particulate matter (PM) concentrations, at different sites in Germany. The below cloud scavenging model has been coupled with bulk particulate matter counter TSI (Trust Portacounter dataset, consisting of the variability prediction of the particulate air concentrations during chosen rain events. The TSI samples and meteorological parameters were obtained during three winter Campaigns: at Deuselbach, March 1994, consisting in three different events; Sylt, April 1994 and; Freiburg, March 1995. The results show a good agreement between modeled and observed air concentrations, emphasizing the quality of the conceptual model used in the below cloud scavenging numerical modeling. The results between modeled and observed data have also presented high square Pearson coefficient correlations over 0.7 and significant, except the Freiburg Campaign event. The differences between numerical simulations and observed dataset are explained by the wind direction changes and, perhaps, the absence of advection mass terms inside the modeling. These results validate previous works based on the same conceptual model.Os processos de remoção atmosféricos foram investigados em simulação numérica, levando-se em conta as condições atmosféricas locais e a concentração de matéria particulada (MP) em diferentes lugares na Alemanha. Um modelo de remoção foi desenvolvido com intuito de predizer a variabilidade da concentração no ar da matéria particulada observada por um contador de partículas totais TSI, durante eventos de precipitação. As amostras de TSI, bem como os dados meteorológicos, foram coletadas em três Campanhas em Deuselbach, em três diferentes eventos; Sylt e Freiburg, respectivamente durante os meses de março de 1994, abril de 1994 e março de 1995. Os resultados mostram boa concordância entre os dados modelados e observados, com altos coeficientes de correlação quadráticos acima de 0.70, dentro da significância, exceto na Campanha de Freiburg. As diferenças apresentadas são devidas a alterações significativas da direção do vento e, talvez, devido à ausência de advecção de massa dentro do modelo. Estes resultados auxiliam a validação de trabalhos prévios baseados no mesmo modelo conceitual

Full Paper Total re¯ection X-ray¯uorescence analysis of laser-deposited solid sample material

Laser ablation (LA) was applied as a sampling technique for the analysis of solids by total re¯ection X-raȳ uorescence (TXRF). The sample material ablated by a pulsed Nd : YAG laser was collected directly on a quartz glass or Plexiglas1 disc commonly used as a sample carrier for TXRF. The analytical capabilities of the combined method were investigated using an improved arrangement of solid sample and TXRF carrier. The technique was applied to the analysis of metallic samples, i.e. Fe±Cr binaries and high-alloy steel, and non-metallic samples, i.e. Al±Ti ceramics, native mineral rocks and gallstones. The nanogram amounts of material deposited on the carrier were always suf®cient for TXRF analysis. Quanti®cation was performed by addition of an internal standard. Absolute detection limits for Fe and Cr in binary samples were 50±60 pg, corresponding to a mass fraction of 5±6 mg g 21 assuming a 10 ng deposit. Sampling from preselected spots of mineral rocks made possible the identi®cation of different components in granite by means of their major and minor constituents. The combined method of LA and TXRF can be used for the rapid characterization of solids on the 10 mm scale without laborious steps of sample preparation