Metal Speciation Dynamics and Bioavailability:  Bulk Depletion Effects

Pinheiro, José Paulo; Galceran, Josep; Leeuwen, Herman P. van

doi:10.1021/es034579n

Cited by 45 publications

(124 citation statements)

References 36 publications

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“…[71] Indeed, as mentioned earlier, AgCl complexes were shown to contribute to biouptake for C. reinhardtii [14] and the authors concluded that the increased bioaccumulation was due to the lability of AgCl n (nÀ1)À complexes, rather than to passive diffusion of the uncharged metal species through the biological membrane. This interpretation was supported by subsequent reanalysis of the data by Pinheiro et al [72] Under conditions of a diffusion limitation, both the ligand properties and the size of the organisms will influence metal bioavailability through their influence on mass transport. Thus, for a given stability constant, a metal that is bound to a small ligand will be more bioavailable than the same metal bound by a macromolecule.…”

Section: (4) Dissociation Of Labile Metal Complexesmentioning

confidence: 73%

When are metal complexes bioavailable?

Zhao¹,

Campbell²,

Wilkinson³

2016

Environ. Chem.

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Environmental context. The concentration of a free metal cation has proved to be a useful predictor of metal bioaccumulation and toxicity, as represented by the free ion activity and biotic ligand models. However, under certain circumstances, metal complexes have been shown to contribute to metal bioavailability. In the current mini-review, we summarise the studies where the classic models fail and organise them into categories based on the different uptake pathways and kinetic processes. Our goal is to define the limits within which currently used models such as the biotic ligand model (BLM) can be applied with confidence, and to identify how these models might be expanded.Abstract. Numerous data from studies over the past 30 years have shown that metal uptake and toxicity are often best predicted by the concentrations of free metal cations, which has led to the development of the largely successful free-ion activity model (FIAM) and biotic ligand model (BLM). Nonetheless, some exceptions to these classical models, showing enhanced metal bioavailability in the presence of metal complexes, have also been documented, although it is not yet fully understood to what extent these exceptions can or should be generalised. Only a few studies have specifically measured the bioaccumulation or toxicity of metal complexes while carefully measuring or controlling metal speciation. Fewer still have verified the fundamental assumptions of the classical models, especially when dealing with metal complexes. In the current paper, we have summarised the exceptions to classical models and categorised them into five groups based on the fundamental uptake pathways and kinetic processes. Our aim is to summarise the mechanisms involved in the interaction of metal complexes with organisms and to improve the predictive capability of the classic models when dealing with complexes.

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Section: (4) Dissociation Of Labile Metal Complexesmentioning

confidence: 73%

When are metal complexes bioavailable?

Zhao¹,

Campbell²,

Wilkinson³

2016

Environ. Chem.

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“…[52,53] Other disadvantages of the Michaelis-Menten approach include the large number of assumptions, similar to those given above, [46] including the assumption of overall steady-state conditions (cf. refs [54,55]). …”

Section: Metal Internalization Fluxesmentioning

confidence: 99%

Predicting the Bioavailability of Metals and Metal Complexes: Critical Review of the Biotic Ligand Model

Slaveykova¹,

Wilkinson²

2005

Environ. Chem.

294

273

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Abstract. The biotic ligand model is a useful construct both for predicting the effects of metals to aquatic biota and for increasing our mechanistic understanding of their interactions with biological surfaces. Since biological effects due to metals are always initiated by metal bioaccumulation, the fundamental processes underlying bio-uptake are examined in this review. The model assumes that the metal of interest, its complexes, and metal bound to sensitive sites on the biological surface are in chemical equilibrium. Therefore, many of the equilibrium constants required for the model have been compiled and their methods of determination evaluated. The underlying equilibrium assumption of the BLM is also examined critically. In an attempt to identify which conditions are appropriate for its application, several documented examples of failures of the BLM are discussed. Finally, the review is concluded by identifying some important future research directions.

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“…Such analytical approaches could be successfully implemented provided that a good knowledge of the key players involved in TM speciation is achieved. Furthermore, development of analytical tools allowing to reach the TM speciation dynamics as defined by Pinheiro et al [34] under conditions of bulk depletion is needed. In such particular conditions [19], the speciation and bioavailability of TM must be considered at two different time scales: (i) the time scale of the bio-uptake flux, as determined by diffusion of the bioactive free metal, dissociation of the bioinactive complex species, and the internalization rate; and (ii) the time scale of depletion of the bulk medium.…”

Section: Trace Metals Speciation Fractioning and Bioavailabilitymentioning

confidence: 99%

Fate of Trace Metals in Anaerobic Digestion

Fermoso

Hullebusch²,

Guibaud

et al. 2015

Biogas Science and Technology

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A challenging, and largely uncharted, area of research in the field of anaerobic digestion science and technology is in understanding the roles of trace metals in enabling biogas production. This is a major knowledge gap and a multifaceted problem involving metal chemistry; physical interactions of metal and solids; microbiology; and technology optimization. Moreover, the fate of trace metals, and the chemical speciation and transport of trace metals in environmentsoften agricultural lands receiving discharge waters from anaerobic digestion processes -is completely unknown but simultaneously represents challenges for environmental protection and opportunities to close process loops in anaerobic biotechnologies. Affiliation 1.

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Metal Speciation Dynamics and Bioavailability: Bulk Depletion Effects

Cited by 45 publications

References 36 publications

When are metal complexes bioavailable?

When are metal complexes bioavailable?

Predicting the Bioavailability of Metals and Metal Complexes: Critical Review of the Biotic Ligand Model

Fate of Trace Metals in Anaerobic Digestion

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