The role of complexation and competition in the biouptake of europium by a unicellular alga

Yang, Guang; Tan, Qiao-Guo; Zhu, Lin; Wilkinson, Kevin J.

doi:10.1002/etc.2722

Cited by 35 publications

(34 citation statements)

References 44 publications

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“…While this observation has been validated on numerous occasions, several exceptions, where bioaccumulation or toxicity is significantly greater than can be predicted on the basis of the free ion alone, have also been noted in the literature. [13][14][15][16]27,41,42 For example, Slaveykova et al showed that Pb complexes with dissolved organic matter could contribute to the bioavailability of Pb to C. kesslerii. 41 In earlier work, we ascribed a greater than predicted toxicity of Al to Atlantic salmon to the formation of ternary complexes with Al−OH (K = 10 14.5 M −1 ) and Al−F (K = 10 13.5 M −1 ) at the fish gill surface (cf.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Biotic Ligand Model Does Not Predict the Bioavailability of Rare Earth Elements in the Presence of Organic Ligands

Zhao

Wilkinson

2015

Environ. Sci. Technol.

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Due to their distinct physicochemical properties, rare earth elements (REEs) are critical to high-tech and clean-energy industries; however, their bioavailability is still largely unexplored. In this paper, the bioavailability of several REEs has been carefully examined for the freshwater alga, Chlamydomonas reinhardtii. In the presence of organic ligands (L), the biouptake of REEs was much higher than that predicted by the biotic ligand model (BLM). Enhancement of the biouptake flux was observed for six ligands (metal = thulium) and six REEs (ligand = citric acid), indicating that this could be a common feature for these metals. In order to explore the mechanism for the enhanced uptake, Tm internalization was carefully evaluated. The Tm internalization flux (Jint) followed first-order (Michaelis-Menten) kinetics with a calculated maximum internalization flux (Jmax) of (1.1 ± 0.08) × 10(-14) mol · cm(-2) · s(-1) and an affinity constant for the reaction of the metal with the transport sites (KTm-R) of 10(7.1) M(-1). In the presence of citric acid, malic acid, or NTA, the Jint for Tm was more than 1 order of magnitude higher than that predicted by the BLM when algae were exposed to a constant 10(-9) M Tm(3+). The bioavailability of the metal complexes could not be explained by a piggyback internalization (through an anion channel) or the contribution of labile complexes. The enhanced biouptake was attributed to the formation of a ternary Tm complex {L-Tm-R} at the metal transport site. In the natural environment where organic ligands are ubiquitous, classic models are unlikely to predict the bioavailability of REEs to aquatic organisms.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Biotic Ligand Model Does Not Predict the Bioavailability of Rare Earth Elements in the Presence of Organic Ligands

Zhao

Wilkinson

2015

Environ. Sci. Technol.

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“…When algae were exposed to similar demonstrated that the bioavailability of Ag was largely or completely reduced when algae were exposed to AgNO3 in a wastewater medium. The possible causes for reduced bioavailability in a wastewater medium include i) the complexation of Ag + ions by organic/inorganic ligands that render them non-bioavailable and ii) the presence of numerous ions in a wastewater medium that compete for Ag biouptake (competition) [42][43][44]. In contrast with the majority of previous studies where bioaccumulation experiments were conducted in simple growth media [18][19][20], Ag + bioavailability in the wastewater was greatly reduced due to the complex nature of the medium.…”

Section: Ag Bioavailability In the Wastewatermentioning

confidence: 99%

“…or a dissolution/precipitation mechanism (below 0.8 µM of sulfide), depending on the available sulfide concentrations [43]. …”

Section: Transformation Of Silver Nanoparticles In Wastewatersmentioning

confidence: 99%

Transformations of silver nanoparticles in wastewater effluents: links to Ag bioavailability

Azimzada

Tufenkji

Wilkinson

2017

Environ. Sci.: Nano

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As a result of the burgeoning nanotechnology industry, the number of uses of engineered silver nanoparticles (Ag NPs) in consumer products has risen significantly in recent years.Despite their utility as anti-bacterial agents, the 'nano-scale' properties of these materials may lead to eco-toxicological problems when they end up in the environment. Wastewater effluents represent one of the main routes through which Ag NPs can reach an aquatic environment, where they may potentially interact with aquatic life. However, in wastewaters, Ag NPs may undergo different chemical and physical transformations, which may alter the potential toxicity of these NPs towards aquatic organisms. The main objectives of this study are to characterize the Ag NPs in wastewater effluents and then to assess their interactions with a model organism, the green alga Chlamydomonas reinhardtii.Experiments were conducted to distinguish the effect(s) of the wastewater matrix on the dissolution of Ag NPs and to determine whether the transformed NPs or the dissolved Ag species would be most bioavailable to C. reinhardtii. It was shown that in environmental matrices such as wastewater, the bioavailability of Ag + could be significantly or completely reduced-a Nous avons étudié l'effet de la matrice des eaux usées sur la dissolution des Ag NPs et la biodisponibilité des différentes formes (particulaire et dissoute) des Ag NPs pour C. reinhardtii.Dans les matrices environnementales telles que les eaux usées la biodisponibilité de Ag + serait réduite de façon significative, si ce n'est complète; une conclusion qui va à l'encontre les résultats des études similaires faites dans des matrices biologiques simples. Cette réduction

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“…Experiments using radiolabelled ligands can also show when ligands are not taken up by the organism. [45,47] In such cases, either an equilibrium or a kinetic explanation can be put forward to account for enhanced uptake. For example, for cases where metal adsorption-desorption kinetics are rate-limiting, the formation of the mixed-ligand complex at the cell surface (especially for inorganic ligands, such as hydroxide and chloride) can accelerate the water loss rate of the metal, thus increasing the rate of biouptake (mechanism 5 below).…”

Section: Introductionmentioning

confidence: 99%

“…The formation of ternary complexes has been postulated to occur for both divalent metals, including Pb [43,49,50] and Zn, [44,51] and trivalent metals such as Al, [42,52] Sc, [53] Eu [47] and Tm. [45] Indeed, Aristilde et al [44] suggested that the formation of ternary complexes may be universal, irrespective of the specificity of the metal or ligand.…”

Section: Introductionmentioning

confidence: 99%

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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The role of complexation and competition in the biouptake of europium by a unicellular alga

Cited by 35 publications

References 44 publications

Biotic Ligand Model Does Not Predict the Bioavailability of Rare Earth Elements in the Presence of Organic Ligands

Biotic Ligand Model Does Not Predict the Bioavailability of Rare Earth Elements in the Presence of Organic Ligands

Transformations of silver nanoparticles in wastewater effluents: links to Ag bioavailability

When are metal complexes bioavailable?

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