Retention of Metals by Several Soils of the Southeastern United States

King, Larry D.

doi:10.2134/jeq1988.00472425001700020013x

Cited by 93 publications

(51 citation statements)

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“…Relatively few studies have been undertaken on this aspect with tropical soils but similar findings have been reported. For example, in a study of trace metals added as aqueous solutions to 21 soils (A, B and C horizons) from the southeastern United States (including ultisols, alfisols and entisols), King (1988) found that, for all horizons, most of the variation in exchangeable Cd, Co, Cu, Ni and Zn was explained by pH. Exchangeable Cr, Pb and Sb were related more to soil texture.…”

Section: Phmentioning

confidence: 99%

The mobility and bioavailability of trace metals in tropical soils: a review

Rieuwerts

2007

Chemical Speciation & Bioavailability

135

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In recent years, initiatives on critical loads of metals have resulted in the development of models to predict critical, i.e. mobile or bioavailable, concentrations of potentially toxic elements in soils. These models have been based on data from temperate soils and, considering the fundamentally different soil chemistry of the major tropical soil types, it is unlikely that such models could be applied successfully in the tropics. In particular, the major tropical soil types, particularly oxisols and ultisols, are distinguished from most temperate soils by low activity clays, low organic matter contents, low pH values and high levels of Fe oxides. The aim of this review paper is to collate existing information on the behaviour of trace metals in tropical soils, particularly in relation to metal mobility and bioavailability, and note differences, where these exist, with temperate soils. The main findings are as follows. The acidic nature of many tropical soils may not, of itself, lead to greater metal solubility. The relatively low organic matter content of tropical soils suggests that it cannot be relied upon to retain metals. However, when it is present, it appears to be important in the retention of copper, lead and zinc. The clay fractions of many tropical soils are dominated by kaolinite which is less able than 2 : 1 layer silicate clays to adsorb metals. However, oxisols and ultisols in particular have relatively high Fe oxides contents and these may be effective in metal sorption. Overall though, soils such as oxisols and ultisols appear to sorb relatively low amounts of added metals, most likely explained by the low activity clay minerals they contain and the rapid decomposition of organic matter incorporated into them. Dominant retention mechanisms, where they occur, are inner and outer sphere adsorption but not precipitation. Cadmium, Cu, Zn and Ni appear to be mobile in tropical soils. Chromium may be mobile in the A horizon but retained in the B horizon. The evidence for Pb points to surface retention, as is often observed for this metal in temperate soils. Metals in contaminated tropical soils appear to be rather bioavailable, judging by the few studies on plant uptake. It should be noted that the above statements are based on a relatively small number of studies. Further work is required if we are to gain an improved understanding of the mobility and bioavailability of trace metals in tropical soils.

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Section: Phmentioning

confidence: 99%

The mobility and bioavailability of trace metals in tropical soils: a review

Rieuwerts

2007

Chemical Speciation & Bioavailability

135

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“…Several studies have demonstrated that pH is one of the most important factors in the control of the concentration of these metals in the soil solution (King, 1988). Elliott et al (1986) proposed that under acidic conditions the phenomenon of adsorption is more important in the control of metal bioavailability, while precipitation reactions and complexation have greater influence under neutral and alkaline conditions.…”

Section: Natural and Anthropogenic Factors Affecting The Bioavail-abimentioning

confidence: 99%

Tolerance and prospection of phytoremediator woody species of Cd, Pb, Cu and Cr

Almeida

Valle

Mielke

et al. 2007

Braz. J. Plant Physiol.

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High concentrations of Cd, Pb, Cu and Cr can cause harmful effects to the environment. These highly toxic pollutants constitute a risk for aquatic and terrestrial life. They are associated with diverse bioavailable geochemical fractions, like the water-soluble fraction and the exchangeable fraction, and non-available fractions like those associated with the crystalline net of clays and silica minerals. Depending upon their chemical and physical properties we can distinguish different mechanisms of metal toxicity in plants, such as production of reactive oxygen species from auto-oxidation, blocking and/or displacement of essential functional groups or metallic ions of biomolecules, changes in the permeability of cellular membranes, reactions of sulphydryl groups with cations, affinity for reactions with phosphate groups and active groups of ADP or ATP, substitution of essential ions, induction of chromosomal anomalies and decrease of the cellular division rate. However, some plant species have developed tolerance or resistance to these metals naturally. Such evolution of ecotypes is a classic example of local adaptation and microevolution, restricted to species with appropriate genetic variability. Phytoremediator woody species, with (i) high biomass production, (ii) a deep root system, (iii) high growth rate, (iv) high capacity to grow in impoverished soils, and (v) high capacity to allocate metals in the trunk, can be an alternative for the recovery of degraded soils due to excess of metallic elements. Phytoremediation using woody species presents advantageous characteristics as an economic and ecologically viable system, making it an appropriate, practical and successful technology. Key-words: decontamination, heavy metals, hyperaccumulation, phytodegradation, phytostabilization, phytotoxicity Tolerância e prospecção de espécies lenhosas fitorremediadoras de Cd, Pb, Cu e Cr: Altas concentrações de Cd, Pb, Cu e Cr podem provocar efeitos danosos ao ambiente. Esses poluentes altamente tóxicos constituem um risco para a vida aquática e terrestre. Encontram-se associados às diversas frações geoquímicas biodisponíveis, a exemplo da fração solúvel em água e da fração trocável, e as não disponíveis como a fração associada à rede cristalina de argilas e de minerais silicatados. Conforme as suas propriedades químicas e físicas podem-se distinguir mecanismos diferentes de toxicidade de metais em plantas, tais como produção de espécies reativas de oxigênio pela auto-oxidação, bloqueio e, ou, deslocamento de grupos funcionais ou de íons metálicos essenciais de biomoléculas, mudanças na permeabilidade de membranas celulares, reações de grupos sulfidrílicos com cátions, afinidade para reações com grupos fosfatos e grupos ativos de ADP ou ATP, substituição de íons essenciais, indução de anomalias cromossomais e decréscimo da taxa de divisão celular. Várias espécies vegetais desenvolveram, naturalmente, tolerância ou resistência a esses metais. Essa evolução de ecótipos é exemplo clássico de adaptação local e de microevolução,...

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“…Os maiores valores de pH e V% e de teores de K e P nas amostras do solo 5 em relação ao solo 6 (Tabela 4) foram decisivas para a formação de dois grupos distintos; esses parâmetros foram posicionados em região similar em relação às amostras do solo 5. Mesmo que os valores de pH acima da neutralidade, observados nas amostras do solo 5, reduz a mobilidade de metais pesados no solo e a contaminação ambiental (HARTER, 1983;KING, 1988;COOK;HENDERSHOT, 1996;AZIZIAN;NELSON, 1998), essa condição pode ser desfavorável ao crescimento de plantas por tornar alguns micronutrientes (principalmente Fe e Mn) menos disponíveis (WALLACE, 1989;PAULETTI et al, 200). Figura 5.…”

Section: Propriedades Físicas E Químicasunclassified