Data/hora: 21/06/2024 10:32:12

Biblioteca(s): 	Embrapa Arroz e Feijão; Embrapa Semiárido; Embrapa Solos.	
Data corrente: 	05/01/2007	
Data da última atualização: 	16/09/2021	
Autoria: 	NOVOTNY, E. H.; AZEVEDO, E. R. de; BONAGAMBA, T. J.; CUNHA, T. J. F.; MADARI, B. E.; BENITES, V. de M.; HAYES, M. H. B.	
Afiliação: 	ETELVINO HENRIQUE NOVOTNY, CNPS; TONY JARBAS FERREIRA CUNHA, CPATSA; BEATA EMOKE MADARI, CNPAF; VINICIUS DE MELO BENITES, CNPS.	
Título: 	Studies of the compositions of humic acids from Amazonian Dark Earth soils.	
Ano de publicação: 	2007	
Fonte/Imprenta: 	Environmental Science & Technology, v. 41, n. 2, p. 400-405, jan. 2007.	
Idioma: 	Inglês	
Conteúdo: 	The compositions of humic acids (HAs) isolated from cultivated and forested "Terra Preta de Índio" or Amazonian Dark Earth soils (anthropogenic soils) were compared with those from adjacent non-anthropogenic soils (control soils) using elemental and thermogravimetric analyses, and a variety of solid-state nuclear magnetic resonance techniques. The thermogravimetric index, which indicates the molecular thermal resistance, was greater for the anthropogenic soils than for the control soils suggesting polycyclic aromatic components in the former. The cultivated anthropogenic soils were more enriched in C and depleted in H than the anthropogenic soils under forest, as the result of the selective degradation of aliphatic structures and the possible enrichment of H-deficient condensed aromatic structures. The combination of variable amplitude cross-polarization (VACP) and chemical shift anisotropy with total suppression of spinning sidebands experiments with composite pi pulses could be used to quantify the aromaticity of the HAs from the anthropogenic soils. From principal component analysis, using the VACP spectra, it was possible to separate the different constituents of the HAs, such as the carboxylated aromatic structures, from the anthropogenic soils and plant derived compounds. The data show that the HAs from anthropogenic soils have high contents of aryl and ionisable oxygenated functional groups, and the major functionalities from adjacent control soils are oxygenated functional groups from labile structures (carbohydrates, peptides, and with evidence for lignin structures). The anthropogenic soils HAs can be considered to be more recalcitrant, and with more stable reactive functional groups which may, in part, explain their more sustainable fertility due to the organic matter contribution to the soil cation exchange capacity.	
Palavras-Chave: 	Ácido húmico; Composição; Terra Preta de Índio.	
Thesagro: 	Solo; Solo Ácido; Solo Florestal.	
Thesaurus Nal: 	Amazonia; Anthropogenic soil types; Humic acids; Soil.	
Categoria do assunto: 	P Recursos Naturais, Ciências Ambientais e da Terra	
URL: 	http://ainfo.cnptia.embrapa.br/digital/bitstream/item/177112/1/Separata-00453.pdf	
Registro original: 	Embrapa Semiárido (CPATSA)	
Exemplares: 	CPATSA - (34539-1) - UPC - AP - PP - 00453 -  - 00453 - DIS
CNPAF - (24802-1) - UPC - AP - DD - 2007 -  - 2007 - DIS
CNPS - (12739-1) - UPC - AP - DD -  -  - 2008.00002 - DIS