Pyrolysis-Gas Chromatography/Mass Spectrometry Characterization of Humic Acids in Coastal Spodosols from Southeastern Brazil

Autor(es)

Gonzalez-Perez, Martha ^[1] ; Buurman, P. ^[2] ; Vidal-Torrado, P. ^[3] ; Martin-Neto, L. ^[4]

Afiliação do(s) autor(es)

^[1] IPT, BR-05508901 Sao Paulo - Brazil

^[2] Wageningen Univ, Dep Environm Sci, Earth Syst Sci & Climate Change Grp, NL-6700 AA Wageningen - Netherlands

^[3] ESALQ USP, Dep Ciencia Solo, BR-13418900 Piracicaba, SP - Brazil

^[4] Embrapa Instrumentacao Agr, BR-13560970 Sao Carlos, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Soil Science Society of America Journal; v. 76, n. 3, p. 961-971, MAY-JUN 2012.
• Citações Web of Science: 6

Resumo

This study on humic acids (HAs) of podzol horizons from the southeastern region of Brazil investigated the accumulation and degradation of soil organic matter (SOM) in warm-climate podzols. Humic acids from sandy coastal Spodosols (Histic Alaquod and Arenic Alorthod) from Cardoso Island in Sao Paulo State were characterized by pyrolysis in combination with gas chromatography and mass spectrometry (Py-GC/MS). The soils developed on quartzitic, sandy, nutrient-poor parent materials under restinga forest in a coastal area. The Py-GC/MS results show that the chemical composition of HAs in B horizons in one out of three profiles was influenced by both dissolved organic C (DOC) and C from in situ decaying roots. Carbon derived from DOC dominated in the deepest part of the B horizons. In the Arenic Alorthod (H9) profile, SOM from the B horizon seemed to be largely derived from roots. The DOC-derived SOM was characterized by large contributions of phenol, methylphenols, and degraded polysaccharide products, while root contributions were mainly characterized by lignin products. Aliphatics were most abundant in A horizons (E and EB horizons were not analyzed). Both DOC-derived and lignin-derived SOM showed distinct degradation patterns. The Py-GC/MS results corroborate those obtained by C-13 variable amplitude cross polarization magic angle spinning nuclear magnetic resonance spectroscopy and Fourier-transform infrared spectroscopy. Molecular chemistry showed that podzol B horizons are variable in composition, and local influences, such as drainage and vertical or lateral water transport, and SOM decomposition play an important role in podzolization processes in warm climates. (AU)

• Processo FAPESP: 04/03477-3 - Materia organica de solos de ambientes costeiros do estado de sao paulo: restinga e manguezal.
• Beneficiário: Pablo Vidal Torrado
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 06/52408-0 - Caracterização da matéria orgânica em espodossolos ferrocárbicos sob vegetação de restinga na Ilha do Cardoso (SP)
• Beneficiário: Martha González Pérez
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado