Metal oxide nanoparticles (NPs) are reported to impact plant growth in hydroponic systems This study describes the impact of commercial CuO (<50 nm) and ZnO (<100 nm) NPs on wheat (Triticum aestivum) grown in a solid matrix, sand The NPs contained both metallic and non-metallic impurities to different extents Dynamic light scattering and atomic force microscopy (AFM) assessments confirmed aggregation of the NPs to submicron sizes AFM showed transformation of ZnO NPs from initial rhomboid shapes in water to elongated rods in the aqueous phase of the sand matrix Solubilization of metals occurred in the sand at similar rates from CuO or ZnO NPs as their bulk equivalents Amendment of the sand with 500 mg Cu and Zn/kg sand from the NPs significantly (p = 005) reduced root growth, but only CuO NPs impaired shoot growth; growth reductions were less with the bulk amendments Dissolved Cu from CuO NPs contributed to their phytotoxicity but Zn release did not account for the changes in plant growth Bioaccumulation of Cu, mainly as CuO and Cu(I)–sulfur complexes, and Zn as Zn-phosphate was detected in the shoots of NP-challenged plants Total Cu and Zn levels in shoot were similar whether NP or bulk materials were used Oxidative stress in the NP-treated plants was evidenced by increased lipid peroxidation and oxidized glutathione in roots and decreased chlorophyll content in shoots; higher peroxidase and catalase activities were present in roots These findings correlate with the NPs causing increased production of reactive oxygen species The accumulation of Cu and Zn from NPs into edible plants has relevance to the food chain

CuO and ZnO nanoparticles: phytotoxicity, metal speciation, and induction of oxidative stress in sand-grown wheat

Metal oxide nanoparticles (NPs) are reported to impact plant growth in hydroponic systems. This study describes the impact of commercial CuO (\50 nm) and ZnO (\100 nm) NPs on wheat (Triticum aestivum) grown in a solid matrix, sand. The NPs contained both metallic and non-metallic impurities to different extents. Dynamic light scattering and atomic force microscopy (AFM) assessments confirmed aggre- gation of the NPs to submicron sizes. AFM showed transformation of ZnO NPs from initial rhomboid shapes in water to elongated rods in the aqueous phase of the sand matrix. Solubilization of metals occurred in the sand at similar rates from CuO or ZnO NPs as their bulk equivalents. Amendment of the sand with 500 mg Cu and Zn/kg sand from the NPs significantly (p = 0.05) reduced root growth, but only CuO NPs impaired shoot growth; growth reductions were less with the bulk amendments. Dissolved Cu from CuO NPs contributed to their phytotoxicity but Zn release did not account for the changes in plant growth. Bioaccumula- tion of Cu, mainly as CuO and Cu(I)-sulfur complexes, and Zn as Zn-phosphate was detected in the shoots of NP-challenged plants. Total Cu and Zn levels in shoot were similar whether NP or bulk materials were used. Oxidative stress in the NP-treated plants was evidenced by increased lipid peroxidation and oxidized glutathione in roots and decreased chlorophyll content in shoots; higher peroxidase and catalase activities were present in roots. These findings correlate with the NPs causing increased production of reactive oxygen species. The accumulation of Cu and Zn from NPs into edible plants has relevance to the food chain.

https://www.wpjohnsongroup.utah.edu/pdf/CuOZnOnanoparticles.pdf

CuO and ZnO nanoparticles: phytotoxicity, metal speciation, and induction of oxidative stress in sand-grown wheat Christian O. DimkpaJoan E. McLeanDrew E. LattaEliana Manangon • David W. BrittWilliam P. JohnsonMaxim I. BoyanovAnne J. Anderson

Formation of ternary complexes between arsenic (As) oxyanions and ferric iron (Fe) complexes of humic substances (HS) is often hypothesized to represent a major mechanism for As-HS interactions under oxic conditions. However, direct evidence for this potentially important binding mechanism is still lacking. To investigate the molecular-scale interaction between arsenate, As(V), and HS in the presence of Fe(III), we reacted fulvic and humic acids with Fe(III) (1 wt %) and equilibrated the Fe(III)-HS complexes formed with As(V) at pH 7 (molar Fe/As ∼10). The local (<5 A) coordination environments of As and Fe were subsequently studied by means of X-ray absorption spectroscopy. Our results show that 4.5–12.5 μmol As(V)/g HS (25–70% of total As) was associated with Fe(III). At least 70% of this As pool was bound to Fe(III)-HS complexes via inner-sphere complexation. Results obtained from shell fits of As K-edge extended X-ray absorption fine structure (EXAFS) spectra were consistent with a monodentate binucle...

Spectroscopic evidence for ternary complex formation between arsenate and ferric iron complexes of humic substances.

https://hal.archives-ouvertes.fr/hal-02316307/document

Natural organic matter-cations complexation and its impact on water treatment: A critical review.

https://www.alice.cnptia.embrapa.br/bitstream/doc/1060600/1/AS3977946459545611471853042511content1.pdf

Copper accumulation in vineyard soils: Rhizosphere processes and agronomic practices to limit its toxicity.

The nature of Cu bonding to natural organic matter

Despite the high success of the NICA-Donnan (N-D) model to describe the interaction of protons and metal ions with natural organic matter, the large number of fit parameters is a major hindrance to...

Anthony Matynia

Papers

The nature of Cu bonding to natural organic matter

Convergence-optimized procedure for applying the NICA-Donnan model to potentiometric titrations of humic substances.

Semi-empirical proton binding constants for natural organic matter