02006naa a2200301 a 450000100080000000500110000800800410001910000200006024501010008026000090018130000100019050000130020052011340021365000190134765000110136665300140137765300140139165300090140565300090141465300090142370000190143270000170145170000210146870000190148970000160150870000140152477301660153810266442010-03-02       1991    bl ---       0--  u    #d1 aCRUVINEL, P. E.  aStudying the influence of the aggregate sizes on the trace elements of an ione oxisol with PIXE.  c1991  ap.62.  aRef.018.  aThe retention of certain trace elements through a saturated aggregated oxisol was studied under different aggregate sizes using the proton induced X-ray emission (PIXE) technique. This analytical technique is based on the ionization of the soil sample atoms by the incidence of a proton beam, and the subsequent emission of X-rays characteristic of the elements present in the sample. The number of X-rays photons of a given element provides information on the amount of this element, up to one part in 10E9. The results obtained show that an increase in aggregate size from &lt 0,5mm to 1,0 -4,7mm affected significatively the relative amounts of Cl,K, and Ca. The presence of Cl and Ca was greatest in the small aggregate fractions. The presence of K was greatest in the large aggregate fractions. These results, in particular for Cl and Ca, are indeed applicable and related to those obtained by Nkedi-Kizza. His miscible displacement techniques revealed that the transport and retention of Cl and Ca through a saturated aggregate oxisol were influenced by the size of the aggregates within the particular soil column studied.  atrace elements  aOxisol  aAggregate  aInfluence  aIone  aPIXE  aSize1 aNIELSEN, D. R.1 aCRESTANA, S.1 aFLOCCHINI, R. G.1 aMORALES, J. R.1 aMIRANDA, J.1 aKUSKO, B.  tIn: CONGRESSO BRASILEIRO DE CIENCIA DO SOLO, 23., jul. 1991, Porto Alegre, RS. Programa e resumos... Porto Alegre: Sociedade Brasileira de Ciencia do Solo, 1991.