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Urasa, I. T.; Macha, Stephen F.

doi:10.1023/a:1005093600196

Cited by 13 publications

(2 citation statements)

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“…12 The composted sludge was also found having a high affinity for metals and this metal uptake property appears to be particularly pronounced for lead. 13 From the previous discussion it can be seen that although many different sequential extraction methods have been proposed and applied to the evaluation of the composts and its impacts on soil and plants, the lack of uniformity in the procedure has not allow the results to be compared world-wide nor the methods to be validated by certified reference materials. The European Commission's Standards, Measurement and Testing Programme have a programme to harmonize single and sequential extraction schemes for the determination of extractable trace metals in soil and sediment.…”

Section: Introductionmentioning

confidence: 99%

Heavy metal speciation in the composting process

Greenway

Song

2002

J. Environ. Monitor.

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Composting is one of the more efficient and environment friendly methods of solid waste disposal and has many advantages when compared with landfill disposal on which the UK and Ireland are currently heavily dependent. Composting is a very complicated process involving intensive microbial activity and the detailed mechanisms of the process have yet to be fully understood. Metal speciation information can provide an insight into the metal-microbial interaction and would help in the evaluation of the quality of compost. This would facilitate the exploitation of composts in remediation of heavy metal contaminated land. In this work a systematic approach to metal speciation in compost has been taken by applying the three-step method for operationally defined metal speciation of soils and sediments, developed by the European Commission's Standards, Measurement and Testing Programme to monitor the change in metal speciation with time (up to 106 days) for four different waste composting processes. The results have shown that in general metals become less available for the first extraction step as the composting process proceeds. This implies that composting tends to redistribute the metals from more labile forms to more fixed forms which may explain why the application of composts could be useful for with heavy metal contaminated land. There are exceptions to this trend and in some cases, certain metals appear to behave differently depending on the source of the compost.

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Section: Introductionmentioning

confidence: 99%

Heavy metal speciation in the composting process

Greenway

Song

2002

J. Environ. Monitor.

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“…Vários autores tem demonstrado, no entanto, a preferência do cobre em se ligar a fração orgânica 11,15,25,26 . Outros, no entanto, tem encontrado concentrações muito elevadas na fração residual, e valores muito baixos para as outras frações e, em alguns casos, abaixo do limite de detecção para as fases trocáveis, carbonatos e matéria orgânica 27 .…”

Section: Figura 1 Fluxograma Das Etapas Das Extrações Seqüenciais Daunclassified

Determinação de cobre, alumínio e ferro em solos derivados do basalto através de extrações seqüenciais

Costa¹,

Almeida²,

Lenzi³

et al. 2002

Quím. Nova

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Recebido em 24/4/01; aceito em 14/11/01 DETERMINATION OF COPPER, ALUMINUM, AND IRON IN BASALTIC SOILS BY SEQUENTIAL EXTRACTIONS. Copper, aluminum and iron concentrations were determined in four geochemical fractions of three different basaltic soils from the northwest region of the Parana State, Brazil. The fractions examined were the reducible manganese dioxide and amorphous iron oxide, crystaline iron oxide, organic and residual. Metal concentrations were determined in the extracts by flame atomic absorption spectrophotometry. High Fe concentrations were extracted from the crystalline iron oxide (>20%), as well as the amorphous iron oxide (>12%). Copper was extracted from the amorphous and crystalline iron oxides in the range 5 to 12%, but low concentrations were bound to organic matter. Low concentrations of aluminum were extracted (<8%) from the amorphous and crystaline iron oxides, and organic matter. High concentrations of aluminum were found in the residual fraction.Keywords: sequential extractions; basaltic soils; atomic absorption spectrophotometry. INTRODUÇÃOOs minerais da fração argila no solo são os responsáveis pela retenção e distribuição da água, nutrientes, calor e gases. Em solos tropicais, a mineralogia é relativamente simples, sendo constituídos principalmente de caulinita, óxidos de ferro (hematita, goetita e maghemita), óxidos de alumínio (gibbsita) e menores proporções de minerais do tipo 2:1 (vermiculita). Nos óxidos de ferro, alumínio e manganês e, nas periferias das argilas silicatadas, as adsorções de íons metálicos podem ocorrer por meio da formação de ligações covalentes ou eletrostáticas com os grupos funcionais da superfície dos óxidos 1 . Nos argilominerais expansivos, os grupos funcionais estão presentes nos espaços octaédricos das estruturas cristalinas e, nestes sítios, supõem-se que alguns metais sejam fortemente adsorvidos como complexos de esfera interna 2, 3 .Os óxidos de Fe possuem grande poder de pigmentação, determinando assim a coloração de muitos solos. A capacidade de adsorção de metais por esses óxidos é proporcional aos valores de pH. A goetita e hematita adsorvem preferencialmente os metais na seguinte ordem: Cu>Pb>Zn>Cd>Co>Ni>Mn, com a troca de posições do Cu e Pb na hematita 1 . Em geral, os fatores mais importantes que influenciam a adsorção seletiva dos cátions em soluções são o pH, valência, raio iônico e o ponto de carga zero (PCZ) do sólido 4 .O cobre, em virtude de suas propriedades de condutividade, maleabilidade e ductibilidade, pode ser encontrado na composição de vários pigmentos, pesticidas e corantes, entre outros. É indispensável para o desenvolvimento de plantas superiores, sendo classificado como micronutriente e atua praticamente em todas as suas vias metabólicas. Em concentrações elevadas na fase trocável do solo, observam-se efeitos tóxicos nos tecidos vegetais das plantas 5 . A dinâmica do cobre em solos é complexa, sendo afetada por inúmeros fatores entre os quais a composição química, física, mineralógica, a quantidade de matéria orgânica e pH...

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