Data/hora: 20/09/2024 16:49:29

Biblioteca(s): 	Embrapa Semiárido.	
Data corrente: 	12/03/1998	
Data da última atualização: 	30/01/2023	
Autoria: 	MAGALHAES, A. F.	
Título: 	Charge characteristics sof soils from the coastal region of Pernambuco (Brazil).	
Ano de publicação: 	1979	
Fonte/Imprenta: 	Riverside: University of California, 1979.	
Páginas: 	90 p.	
Idioma: 	Inglês	
Notas: 	Ph.D. Thesis	
Conteúdo: 	The objectives of this research were to evaluate the available methods to measure the charge characteristics of tropical soilis from the coastal region of Pernambuco State in Brazil, and to determine the relationships between measured charges and mineralogical properties of the soils. the feasibililty of utilizing an equilibrium ton exchange technique in conjunction with ion-selective electrodes to measure charge characteristics of tropical soils was also evaluated. Samples from A and B horizons of three red yellow Latosols, three red yellow Podzolics, two "Terra roxas " and one reddish Brunizen were collected. They were c?haracterized through chemical and X-ray difractometry ananysis. The surface change properties of these soils were detrmined by the potentiometric titration and ion adsorption (Schofield) methods. An equilibrium-adsorption method to measure charge based on the adsorption of NH4+ and Cl- b the soils from a dilute NH4Cl solution was developed and tested. Mineralogical studies revealed that kaolinite was the dominant mineral in the clay fraction of most soils. Quartz was the predominant mineral in the silt and sand fractions of the Latosol and Podzolic soils. With the exception of the reddish Bruniozen, when the charge characteristics of the soils were measured by potentiometric titration and the ion adsorption technique (Schofield method) all soilsl behaved as variable charge types. It appears that the surface change of  these soils lmay be described by the constant potential surface model. The ZPC values determined by potentiometric titration ranged from 2.2 to 4.6. The ZPC values measured by the Schofield method ranged from 0.5 to 4.5. Only f?ive soil samples were observed t o behave as variably charged adsorption method. No agreement was found among the ZPC values determined by the three methods used. The ighest values were measured by the potent ionametric method and the lowest b?ly the eqauilibrium-adsorption method. The surface charge measurements by experimental techniques were found to be highly dependente on the method employed inn their determination.	
Palavras-Chave: 	chemicophysical properties; Pernambuco; Soils.	
Thesagro: 	Litoral; Propriedade Físico-Química; Solo.	
Thesaurus Nal: 	Brazil.	
Categoria do assunto: 	P Recursos Naturais, Ciências Ambientais e da Terra	
Registro original: 	Embrapa Semiárido (CPATSA)	
Exemplares: 	CPATSA - (24604-1) - ADD - TS - PP - 65/1979 -  - 1979.00065 - DIS