A photocatalytic approach was used to synthesize triangular nanoplates in aqueous solution. The synthesis is based on the reduction of a gold salt using a tin(iv) porphyrin as photocatalyst, cetyltrimethylammonium bromide (CTAB) as a stabilizing agent, and triethanolamine (TEA) as the final electron donor. The average edge length of the triangular nanoplates can be easily changed in the range 45-250 nm by varying the concentration of photocatalyst, and fine-tuning of the average edge length is achieved by varying the concentration of CTAB. Study of the mechanism of formation of the nanoplates by UV-vis and by transmission electron microscopy (TEM) shows that there is a first stage where formation of 5 nm seeds takes place, further growth is probably by fusion and by direct reduction of gold onto the preformed nanoparticles. The nanoparticles formed during the photocatalytic reduction of the gold precursor show an irregular shape that evolves to regular triangular nanoplates after ripening in solution for 24 h.

The aim of the study was to estimate the influence of the 2,4-dichlorophenoxy acetic acid and 2-methyl-4-chlorophenoxyacetic acid on the uptake and translocation of Cd, Co, Ni, Cu, Zn, Pb and Mn by wheat (Triticum aestivum L.). Two farmland soils typical for the central Polish rural environment were used. Studies involved soil analyses, contents of bioavailable, exchangeable and total forms for all investigated metals. Atomic absorption spectrometry was used to determine the concentration of the elements. The best correlation between the herbicide rate and the metal concentration was visibly for the underground part of plants. Analysis of variance proved that herbicide treatment of wheat frequently influences the metal transfer from soil and their concentration in roots and shoots. In particular, higher herbicide rates prompted the significant increase of all metals concentration in roots. Additionally, transfer coefficients depended on the type of soil and the herbicide rate applied. Uptake of metals may be also influenced by the formation of sparingly water-soluble metal-herbicide complexes. Its intensity would then depend on the solubility of particular chemical entity with the low solvable Pb, Cu and Cd complexes being the least mobile.

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The effects of 50 and 300 mg L−1 Zn2+ (50 Zn and 300 Zn) were investigated in Triticum aestivum (cv. Żura) grown hydroponically for 7 days. Although wheat treated with 50 Zn took up relatively high amount of the metal (8,943 and 1,503 mg kg−1 DW in roots and shoots, respectively), none of the morphological and cytological parameters were changed. After 300 Zn, the metal concentration increased to 32,205 and 5,553 mg kg−1 DW in roots and shoots, respectively. It was connected with the depletion of shoot and root growth, their fresh and dry weight, water content and mitotic index of root meristematic cells. Microelement contents (Cu, Mn and Fe) after 50 Zn were changed only in roots, while 300 Zn disturbed ion balance in whole plants. The most evident ultrastructural alterations of root meristematic cells caused by both tested Zn2+ doses included increased vacuolization, accumulation of granular deposits inside vacuoles and cell wall thickening. The effect of 300 Zn on root cell ultrastructure was greater that of 50 Zn. The majority of mitochondria had condensed matrix and swollen cristae, plastids contained plastoglobuli, nucleoli were ring-shaped, thinned down cytoplasm with lipid droplets and swollen endoplasmic reticulum cisternae appeared. In mesophyll cells, 50 Zn caused slight reorganization of chloroplast thylakoids and formation of condensed mitochondria. Three hundred Zn triggered more extensive, but not degenerative, changes: plasmolysis of some cells; chloroplasts with protrusions, changed thylakoid organisation and often large starch grains; irregular, condensed mitochondria. The results indicate that T. aestivum cv. Żura is relatively tolerant to Zn stress.

The impact of cerium oxide nanoparticles, bulk cerium oxide and ionic cerium nitrate on the plant development as well as the uptake and further translocation of Cu, Mn, Zn and Fe by sugar pea (Pisum sativum L.) was investigated. Plants were cultivated in the laboratory pot experiments using the modified Hoagland solutions supplemented with cerium compounds at the 200 mg L −1 Ce level. Analysis of variance proved that cerium oxide nanoparticles significantly decreased Cu, Mn, Zn and Fe concentrations in roots and above ground parts of the pea plants. The latter ions are presumably transported via symplastic pathways and may compete with nanoparticles for similar carriers. The lowest impact on the plant growth and the metal uptake was observed under the bulk CeO 2 treatment. On the contrary, strongest interactions were observed for supplementation with ionic cerium nitrate. The highly beneficial effect of cerium oxide nanoparticles on the plant growth was not supported by this study. The latter conclusion is of particular relevance when environmental impact of cerium compounds on the waste management, municipal urban low emissions and food production is to be concerned.

BackgroundImpact of two widely used commercial herbicides, i.e. Aminopielik D 450 SL and Chwastox 300 SL, on the uptake and translocation of selected heavy metals in wheat plants Triticum aestivum L. cultivated in the laboratory pot experiments was investigated. Mineral-humus, loamy sand soil representative for the central part of Poland was applied. Bioavailable, exchangeable and total forms of Cd, Co, Cu, Zn, Pb, and Mn were determined. Transfer coefficients, translocation, and bioaccumulation factors illustrating metal migration in the plant were investigated.ResultsAdministration of commercial herbicides significantly altered heavy metals uptake by wheat in a way distinctively different than that observed for the parent chemically pure synthetic auxins, i.e. 2,4-D and MCPA. In particular, Aminopielik D 450 SL and Chwastox 300 SL prompted heavy metals accumulation in roots as indicated by their high transfer coefficients. Further transport to above ground part of the plant was limited and element dependent.ConclusionsThis work clearly shows that commercial herbicide formulations may act in a distinctively different way than pure active ingredients alone.Electronic supplementary materialThe online version of this article (doi:10.1186/s12302-017-0124-y) contains supplementary material, which is available to authorized users.

Widespread occurrence of ZnO nanoparticles in environment follows the growing number of applications either in technology or agriculture. The impact of five forms of nanoparticulate ZnO on copper, manganese and iron uptake by Pisum sativum L. cultivated in Hoagland solutions was investigated. Plants were collected after twelve days of zinc administration. Effect of bulk ZnO has also been studied. Initial zinc concentration was 100 mg L −1. Nanoparticles were characterized by the transmission electron Microscopy, Dynamic Light Scattering and Zeta potential measurements. Metal contents were analyzed using the Atomic Absorption Spectrometry with flame atomization for samples digested in a microwave closed system. Analysis of variance indicated that zinc species at either molecular or nanoscale levels altered Cu, Mn and Fe uptake and their further transport in pea plants. In particular, significant reduction of Mn and Fe combined with the Cu increase was observed. Additive interactions originated by nanoparticles affect the heavy metals uptake and indicate pollutants migration pathways in plants. Unfortunately, regulations for the plant cultivation were formulated when anthropogenic nanoparticles were not in common use. they underestimate complexity of metals interactions in either plant or habitat. Our results indicate that these additive interactions cannot be neglected and deserve further investigations. Green pea (Pisum sativum L.) is one of the most extensively cultivated grain legumes worldwide. Plants are well adapted to diverse soil zones in either cool or mild climatic regions 1. Their seeds are rich in proteins, carbohydrates, dietary fibers, vitamins as well as minerals and are commonly used as vegetable or important protein source. The latter is of particular relevance when animal feed is concerned 2. The global production of pea is steadily growing as indicated by the projected Compound Annual Growth Rate (CAGR) of 5.9% and has approached 20 million tonnes in 2018 3. Pea genetics was thoroughly studied and in combination with better plant breeding methods has led to variety of improved plant species 4. Nowadays, pea is an important non model plant widely used in applied system biology studies 5. The pea genome has not been completely determined as yet. Nevertheless, it is being frequently applied as a model plant with the almost complete transcript coverage 6. The impact of nanoparticles (NPs) on plants physiology and their nutritional quality is usually assessed using two leading methodologies as presented by Jośko and Oleszczuk 7. Initially, the long-term growth in soils supplemented with representative concentrations of investigated nanoparticles was applied 8,9. Nowadays, the soilless plant cultivation is gaining increasing popularity 10. Hydroponic techniques promote plant growth in nutrient solutions. Their usage by far exceeds the laboratory scale and they have found numerous applications in commercial crop production 11. Several advantages of hydroponic cultures are highly appreciated, i.e. the s...

This work is devoted to the investigation of the effect of alkali and alkaline earth metals addition on Ni/ ZrO 2 catalyst activity in high-temperature cellulose conversion. The catalysts containing 20 % of Ni and 1 % of Ca, Mg, Na and K (calculated per amount of oxide) introduced on ZrO 2 surface by impregnation method were prepared. The surface properties of the investigated samples were characterized by X-ray diffraction, temperatureprogrammed reduction, flame atomic absorption spectrometry, scanning electron microscopy and energy-dispersive X-ray spectroscopy. The composition of the gaseous products was identified using gas chromatography. The performed studies demonstrated that introduction of alkali and alkaline earth metals on the surface of nickel catalyst resulted in the considerable increase in the production of hydrogen in comparison with Ni/ZrO 2 reference sample. The highest hydrogen yield was formed in the presence of the catalyst modified by calcium.