Biology subjects

Viers, J.

Publications and source records attributed to Viers, J..

3 recordsLinked to original sources

bioRxiv2026

Zinc isotope fractionation in native and cloned mosses: implications for standardized pollution biomonitoring

Mosses are widely used as biomonitors of atmospheric trace-metal deposition, but metal retention by the moss itself may modify source-related isotope signatures. Here, controlled Zn adsorption experiments, stable Zn isotope measurements, surface acid-base characterization, and Zn K-edge X-ray absorption spectroscopy (XAS) were combined to investigate Zn2+ retention and isotope fractionation in four native moss taxa and in vitro-cultivated Sphagnum palustre clones. Zn2+ adsorption was strongly pH-dependent, consistent with progressive deprotonation of reactive surface sites. Moss-associated Zn2+ was slightly enriched in heavy isotopes relative to the coexisting solution, with {Delta}66Znmoss-solution generally ranging from +0.001 to +0.009 per cent, but no systematic relationship was observed between isotopic fractionation and the fraction of Zn2+ adsorbed. Linear-combination fitting of X-ray Absorption Near-Edge Structure (XANES) indicated predominantly cellulose-like, O-rich coordination environments, with variable phosphate and minor acetate contributions and only small nominal Zn-S fractions. Extended X-ray Absorption Fine Structure (EXAFS) showed first-shell Zn-O distances of approximately 1.96 - 2.05 Angstrom and coordination numbers of about 3.6 - 7.6, confirming substantial structural heterogeneity among samples. Importantly, {Delta}66Znmoss-solution was not correlated with either Zn-O distance or coordination number, indicating that the net isotope effect cannot be described by a single bulk structural parameter. Native and cultivated Sphagnum showed comparable isotopic offsets within analytical uncertainty despite differences in surface properties and adsorption capacity. These results indicate that Zn isotope fractionation in mosses reflects the integrated response of multiple binding environments and support the use of standardized Sphagnum clones in isotope-based biomonitoring.

plant biology↗

bioRxiv2020

Stable Zn isotopes reveal the uptake and toxicity of zinc oxide engineered nanomaterials in Phragmites australis

The uptake, transport, and toxicity mechanisms of zinc oxide (ZnO) engineered nanomaterials (ZnO-ENMs) in aquatic plants remain obscure. We investigated ZnO-ENM uptake and phytotoxicity in Phragmites australis by combining Zn stable isotopes and microanalysis. Plants were exposed to four ZnO materials: micron-size ZnO, nanoparticles (NPs) of <100 nm or <50 nm, and nanowires of 50 nm diameter at concentrations of 0-1000 mg l-1. All ZnO materials reduced growth, chlorophyll content, photosynthetic efficiency, and transpiration and led to Zn precipitation outside the plasma membranes of root cells. Nanoparticles <50 nm released more Zn2+ and were more toxic, thus causing greater Zn precipitation and accumulation in the roots and reducing Zn isotopic fractionation during Zn uptake. However, fractionation by the shoots was similar for all treatments and was consistent with Zn2+ being the main form transported to the shoots. Stable Zn isotopes are useful to trace ZnO-ENM uptake and toxicity in plants. Environmental Significance StatementOur understanding of zinc oxide nanomaterials interaction with wetland plants is hampered by the lack of scientific consensus about their uptake and toxicity mechanisms in these species. This is a serious concern given the alarming global increase in the discharge of these nanomaterials into the environment and the key ecological roles of wetland plants. The Zn isotopic signature of plant tissue integrates all the Zn metabolic pathway throughout the plants life, giving insight about the form of Zn taken up, even if this later transforms into another Zn species. Thus, our findings clarify the exposure routes and the mechanisms of action of zinc oxide engineered nanomaterials in wetland plants while advancing the toolbox for plant physiology and environmental studies. Table of contents O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY The Zn stable isotope composition of plants demonstrates that ZnO engineered nanomaterials dissolve before their uptake and accumulation by the roots (brightest inclusions in root cortex above).

plant biology↗

bioRxiv2017

Soil community assembly varies across body sizes in a tropical forest

The relative influence of deterministic niche-based (i.e. abiotic conditions, biotic interactions) and stochastic-distance dependent neutral processes (i.e. demography, dispersal) in shaping communities has been extensively studied for various organisms, but is far less explored jointly across the tree of life, in particular in soil environments. Here, using a thorough DNA-based census of the whole soil biota in a large tropical forest plot, we show that soil aluminium, topography, and plant species identity are all important drivers of soil richness and community composition. Body size emerges as an important feature of the comparative ecology of the different taxa at the studied spatial scale, with microorganisms being more importantly controlled by environmental factors, while soil mesofauna rather display random spatial distribution. We infer that niche-based processes contribute differently to community assembly across trophic levels due to spatial scaling. Body size could hence help better quantifying important properties of multitrophic assemblages.

ecology↗