Metais pesados do solo após aplicação de biossólido: I - Fracionamento
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Data
2004-06-01
Autores
Borges, M. R.
Coutinho, Edson Luiz Mendes [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira de Ciência do Solo
Resumo
Foi realizado experimento em casa de vegetação da FCAV-UNESP, Campus de Jaboticabal, com o objetivo de estudar o efeito do pH e da aplicação de biossólido sobre a distribuição de Cu, Mn, Ni, Pb e Zn nas frações: trocável, orgânica, de óxidos de Fe e Al não-cristalinos, óxidos de Fe e Al cristalinos e residual de dois solos (Neossolo Quartzarênico órtico típico - RQ e Latossolo Vermelho eutroférrico argiloso - LV), coletados da camada arável do terreno, e relacionar esses teores dos metais nas frações com aqueles extraídos pelas soluções de DTPA, HCl 0,1 mol L-1, Mehlich-1 e Mehlich-3 e acumuladas na parte aérea de plantas de milho (Zea mays L.). O delineamento experimental utilizado foi inteiramente casualizado, com três repetições, segundo o esquema fatorial 2 × 2 × 5 (dois solos, presença ou ausência de corretivos e cinco doses de biossólido). Nos tratamentos com calagem, foram adicionados materiais corretivos para elevar o pH(CaCl2) do solo a 5,3. As doses de biossólido utilizadas foram de 0; 13; 26; 52 e 78 g vaso-1 (equivalentes a 0; 10; 20; 40 e 60 t ha-1), com base no material seco. O estudo de fracionamento dos metais mostrou que a maior parte dos metais encontrava-se nas frações com ligações mais estáveis (ligados a óxidos e residual), tendo as frações (trocável e orgânica) apresentado menor representatividade, em relação ao total encontrado. No solo arenoso (RQ), maiores proporções dos metais foram encontradas nas frações mais fitodisponíveis (trocável e orgânica), quando comparado ao solo argiloso (LV). A elevação do pH do solo provocou a redistribuição dos metais da forma trocável para a orgânica e, ou, de óxidos. Por meio de ajustes de regressões múltiplas, verificou-se que as frações, trocável e orgânica, foram as maiores responsáveis pelos teores dos metais extraídos do solo pelas soluções de DTPA, HCl 0,1 mol L-1, Mehlich-1 e Mehlich-3 e pelo acumulado na parte aérea do milho.
The effects of pH changes and sewage sludge application on the distribution of Cu, Mn, Ni, Pb, and Zn among exchangeable, organic, amorphous Fe and Al oxides, crystalline Fe and Al oxides, and residual fractions of two soils (and Eutrustox and a Ultipsamment) were studied in a greenhouse experiment carried out at the FCAV-UNESP, in Jaboticabal (SP), Brazil. The heavy metal contents in these fractions were related to those extracted with DTPA, HCl 0.1 mol L-1, Mehlich-1, and Mehlich-3 extractants and the metal contents of corn shoot (Zea mays L.) as well. A complete randomized design with three replications of treatments in a 2 × 2 × 5 factorial arrangement (two soils, presence or absence of lime, and five sewage sludge rates) was used. In the limed treatments the soils were amended with agricultural lime to raise the soil pH (CaCl2) to 5.3. The sewage sludge rates (dry weight basis) were equivalent to 0, 10, 20, 40, and 60 t ha-1. The soil fractionation showed that most metals were strongly associated to oxides and residual fractions. In the sandy soil a greater proportion of metals were found in more bioavailable fractions (exchangeable and organic matter-bound) in comparison to the fine-textured soil. An increase in soil pH caused a redistribution of the metals from the exchangeable fraction to those bound to organic matter or oxides. Multiple regression analysis showed that the metals extracted by DTPA, HCl 0.1 mol L-1, Mehlich-1, and Mehlich-3, and the metals in the corn shoot were mainly associated to soil exchangeable and organic fractions.
The effects of pH changes and sewage sludge application on the distribution of Cu, Mn, Ni, Pb, and Zn among exchangeable, organic, amorphous Fe and Al oxides, crystalline Fe and Al oxides, and residual fractions of two soils (and Eutrustox and a Ultipsamment) were studied in a greenhouse experiment carried out at the FCAV-UNESP, in Jaboticabal (SP), Brazil. The heavy metal contents in these fractions were related to those extracted with DTPA, HCl 0.1 mol L-1, Mehlich-1, and Mehlich-3 extractants and the metal contents of corn shoot (Zea mays L.) as well. A complete randomized design with three replications of treatments in a 2 × 2 × 5 factorial arrangement (two soils, presence or absence of lime, and five sewage sludge rates) was used. In the limed treatments the soils were amended with agricultural lime to raise the soil pH (CaCl2) to 5.3. The sewage sludge rates (dry weight basis) were equivalent to 0, 10, 20, 40, and 60 t ha-1. The soil fractionation showed that most metals were strongly associated to oxides and residual fractions. In the sandy soil a greater proportion of metals were found in more bioavailable fractions (exchangeable and organic matter-bound) in comparison to the fine-textured soil. An increase in soil pH caused a redistribution of the metals from the exchangeable fraction to those bound to organic matter or oxides. Multiple regression analysis showed that the metals extracted by DTPA, HCl 0.1 mol L-1, Mehlich-1, and Mehlich-3, and the metals in the corn shoot were mainly associated to soil exchangeable and organic fractions.
Descrição
Palavras-chave
extração seqüencial, lodo de esgoto, disponibilidade de metais, micronutrientes, sequential extraction, sewage sludge, metal availability, micronutrients
Como citar
Revista Brasileira de Ciência do Solo. Sociedade Brasileira de Ciência do Solo, v. 28, n. 3, p. 543-555, 2004.