A model of phosphate solubilization by organic anion excretion from plant roots

Kirk, G. J. D.

doi:10.1046/j.1365-2389.1999.00239.x

Cited by 91 publications

(84 citation statements)

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“…Multivalent OA are much more efficient than monovalent OA at competing with P i and complexing dissolution end products due to their increased number of ligand binding sites. The ability of multivalent OA to shift dissolution equilibria (through the complexing of end products) is very important in marine systems compared to terrestrial systems, as in terrestrial systems the leaching of soils results in the removal of dissolution end products such as Ca 2+ (Kirk 1999;Delgado and Torrent 2000;Jones et al 2003). In marine sediments where the main hydrodynamic is molecular diffusion, there is little exchange of pore water (compared to terrestrial leaching), and the complexing of dissolution end products by multivalent OA may have large implications in allowing for increased rates of dissolution through the removal of dissolution end products.…”

Section: Discussionmentioning

confidence: 99%

“…First, the organic anion may displace P i on adsorption sites on minerals and organic matter or decrease the total amount of adsorption sites available (Jones 1998;Ryan et al 2001;Strom et al 2001). Second, the organic anion may chelate metal and carbonate dissolution end products, such as Ca 2+ ions, that would otherwise immobilize P i (Knight et al 1992;Kirk 1999;Strom et al 2001). Third, if the excretion of the organic anion is accompanied by the excretion of protons (H + ) or if it is released as an acid, a localized decrease in pH will be observed around the root surface and the dissolution of carbonate minerals will release P i (Bolan et al 1997;Kirk 1999;Jones et al 2003).…”

mentioning

confidence: 99%

“…Second, the organic anion may chelate metal and carbonate dissolution end products, such as Ca 2+ ions, that would otherwise immobilize P i (Knight et al 1992;Kirk 1999;Strom et al 2001). Third, if the excretion of the organic anion is accompanied by the excretion of protons (H + ) or if it is released as an acid, a localized decrease in pH will be observed around the root surface and the dissolution of carbonate minerals will release P i (Bolan et al 1997;Kirk 1999;Jones et al 2003). The consumption of OA by microbes also likely contributes to carbonate sediment dissolution through the production of aqueous CO 2 and H + .…”

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confidence: 99%

“…In terrestrial sediments, the reaction of organic anions with carbonate minerals has been shown to increase P i concentrations and sediment dissolution, even though the anions do not directly increase acidity (Kirk 1999;Ryan et al 2001). This is due to multivalent OA, which have the most significant effect on P i availability because they compete with P i for binding sites and shift the dissolution equilibria by complexing its end products.…”

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confidence: 99%

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The role of organic acid exudates in liberating phosphorus from seagrass‐vegetated carbonate sediments

Long

McGlathery

Zieman

et al. 2008

Limnology & Oceanography

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Sediment-bound phosphorus (P) is a potential nutrient source for P-limited seagrasses inhabiting carbonate sediments. We explored the role of organic acid (OA) exudation by seagrasses in liberating mineral P from carbonate sediments. Organic acids can act to increase available P by dissolving carbonate sediment, competing with P for binding sites and complexing dissolution end products, and also by fueling microbial processes that change pore-water pH. We used dialysis tubing placed around individual roots in situ to quantify dissolved species immediately adjacent to roots (root zone) and compared these to bulk pore-water concentrations in vegetated and nonvegetated sediments. Total OA concentrations were highest in the root zone (29.8 6 1.8 mmol L 21 ) compared to bulk measures of 15.5 6 1.9 and 7.5 6 0.6 mmol L 21 in vegetated and nonvegetated sediments, respectively. Phosphate concentrations were also highest in the root zone and were linearly related to OA concentrations (R 2 5 0.63). Organic acid concentrations increased along a seagrass productivity gradient, and ratios of OA concentrations to productivity showed a significant response to a gradient in P-limitation of seagrasses. Organic acid concentrations found in and around roots, compared to those found in bulk sediment measures, indicate that seagrasses are a significant source of OA. Sampling at small spatial scales (mm) immediately adjacent to the roots is critical, because bulk sediment pore-water measures did not capture the observed fluctuations caused by the rapid reaction and consumption of OA in the sediment. Root-zone processes can liberate considerable quantities of P, and OA exudates likely contribute significantly to the success of T. testudinum in P-limited environments.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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The role of organic acid exudates in liberating phosphorus from seagrass‐vegetated carbonate sediments

Long

McGlathery

Zieman

et al. 2008

Limnology & Oceanography

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“…A capacidade dos ácidos orgânicos em competir com P vai depender das suas concentrações e formas (macromoléculas ou polimerizadas), pH, força iônica da solução e, principalmente, da sua persistência no solo (Ghosh & Schnitzer 1980;Haynes, 1984;Stevenson, 1986;Sposito, 1989;Kirk, 1999;Rauen et al, 2002).…”

Section: Introductionunclassified

Adsorção de fósforo em frações argila na presença de ácido fúlvico

Cessa

Vitorino

Celi

et al. 2010

Rev. Bras. Ciênc. Solo

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RESUMOOs ácidos orgânicos podem ser adsorvidos aos coloides do solo, favorecendo maior disponibilidade de P às plantas. Por meio de isotermas, avaliou-se a influência de ácido fúlvico (AF) sobre a adsorção de P na fração argila de dois Latossolos Vermelhos (LVdf e LVd), caulinita natural pouco cristalizada (KGa 2 ), goethita (Gt) e hematita (Hm) sintéticas. As isotermas de adsorção de P ajustadas pelo modelo de Langmuir na presença de AF foram adequadas somente para a região de baixa concentração de P. De maneira geral, a presença de AF incubado nas frações argila estudadas foi capaz de reduzir a adsorção de P. Na fração argila do LVdf, a adsorção de P em baixas e altas concentrações desse nutriente teve pequena influência da sequência de incubação de P com AF, enquanto para a fração argila do LVd as sequências de incubação com P e AF influenciaram a adsorção de P. A redução da adsorção de P sobre a fração argila da KGa 2 em baixas concentrações de P nas isotermas não dependeu da sequência de incubação de P e AF, e sim da presença do AF. Na região de altas concentrações de P, a sequência de incubação de P e AF influenciou a adsorção desse elemento. A adsorção de P sobre Gt foi dependente da sequência de incubação com AF, e a incubação prévia do AF promoveu redução da adsorção de P. A sequência de incubação do P e AF na Hm influenciou a adsorção de P quando em baixas e altas concentrações nas isotermas. Os menores valores de adsorção de P ocorreram com a incubação de P juntamente ao AF ou incubação de AF precedida da do P.Temos de indexação: isoterma, fosfato, Langmuir.

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The Rhizosphere

2006

Plant Roots

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A model of phosphate solubilization by organic anion excretion from plant roots

Cited by 91 publications

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The role of organic acid exudates in liberating phosphorus from seagrass‐vegetated carbonate sediments

The role of organic acid exudates in liberating phosphorus from seagrass‐vegetated carbonate sediments

Adsorção de fósforo em frações argila na presença de ácido fúlvico

The Rhizosphere

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