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Nanoparticles (NPs) have been progressively applied in the last decades, which may impact the environment. Synthesis of pigments and nutrient elements uptake by plants can also be affected by NPs. The influence of lanthanum oxide nanoparticles (La2O3 NPs) on growth, pigments synthesis and nutrient elements uptake by Pfaffia glomerata (Spreng.) Pedersen, a medicinal plant native in South America, were evaluated in the present study. P. glomerata plantlets were cultivated for 28 days in the absence (control) and presence of 100, 200 and 400 mg L−1 of La2O3 NPs or bulk-La2O3 (b-La2O3) at the same cultivation conditions. Root development, aerial part growth and pigments concentration in plants were affected by b-La2O3 and La2O3 NPs, mainly by La2O3 NPs. Calcium, Cu, Fe, K, La, Mg, Mn, Mo, P, S and Zn determination in stems and leaves revealed drastically and similar decrease of nutrient elements in plants cultivated in presence of 400 mg L−1 of La2O3 NPs or b-La2O3. Alteration of nutrient elements concentration was also observed for the other treatments. Mapping of elements (using laser ablation inductively coupled plasma mass spectrometry) in leaves of plants submitted to treatment with 400 mg L−1 of b-La2O3 or La2O3 NPs showed differences in the distribution of elements, indicating distinct effects of b-La2O3 and La2O3 NPs on P. glomerata. As such, this study demonstrated that La2O3 NPs may impact plants growth.

The production and use of nanoparticles (NPs) in different fields increased in the last years. However, some NPs have toxicological properties, making these materials potential emerging pollutants. Therefore, it is important to investigate the uptake, transformation, translocation, and deposition of NPs in plants. In this work, laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and micro X-ray fluorescence (μ-XRF) were used to investigate the uptake and translocation of La2O3 NPs to stem and leaves of Pfaffia glomerata (Spreng.) Pedersen after in vitro cultivation of plants in the presence of 400 mg L-1 of La2O3 NPs. By using LA-ICP-MS and μ-XRF, image of the spatial distribution of La in the leaves was obtained, where higher concentration of La was observed in the main veins. Differences in the signal profile of La in leaves of plants cultivated in the presence of bulk La2O3 (b-La2O3) and La2O3 NPs were observed. Sharp peaks of La indicated that NPs were transported to the stems and leaves of plants treated with La2O3 NPs. Both LA-ICP-MS and μ-XRF techniques have shown to be useful for detecting NPs in plants, but LA-ICP-MS is more sensitive than μ-XRF and allowed better detection and visualization of La distribution in the whole leaf.

Rare earth elements (REEs) have several applications but the effects on environment are not well known. Therefore, the aim of this work is to establish a method for direct solid sample analysis by laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) to evaluate the concentration and distribution of REEs in cultivated and non-cultivated soil. Samples were collected in two areas to 40 cm of depth. The LA-ICP-MS method is easy to be implemented and the sample treatment is very fast comprising only its drying, grounding and pressing as a pellet. The accuracy of the method was evaluated by using a certified reference material (BCR 667 – Estuarine Sediment, Institute for Reference Materials and Measurements (IRMM)) where good agreement with the certified values was obtained. Analyte recovery at two levels of concentration (2.5 and 15.0 μg g−1) was also performed and recoveries in the range of 85%–120% were achieved, values that are acceptable for LA-ICP-MS analysis. In general, the concentration of the REEs is higher in the cultivated soil and increased from the surface to deeper layers, which can be a consequence of fertilizer application.

Zinc (Zn) is a micronutrient, but its excessive concentration can impair plant growth and development. Fertilizers, liming materials, pesticides and fungicides containing Zn have contributed to increase its concentration in agricultural soils. The aim of the present study is to evaluate the effect of Zn excess on the non-enzymatic (anthocyanin and β-ecdysone) and enzymatic (superoxide dismutase-SOD and guaiacol peroxidase-GPX) antioxidant system of two P. glomerata accessions (JB and GD) grown in hydroponic system and soil, under short- and long-term exposure times. Three Zn levels (2, 100 and 200 μM) and two short-term exposure times (7 and 14 d) were tested in the hydroponic experiment. Three Zn levels (2, 100 and 200 mg kg−1) and two long-term exposure times (34 and 74 d) were tested in the soil experiment. The effects of Zn excess on P. glomerata accessions depended on the growth system and exposure time. Zinc excess in both tested growth systems resulted in significant change in the tissue oxidative process (MDA concentration) in both accessions, as well as broadened the antioxidant system response, which was based on antioxidant enzymes (SOD and GPX) and secondary metabolites (anthocyanins and β-ecdysone). The highest anthocyanin concentration was observed in accession JB, which was grown in hydroponics, but tissue anthocyanin concentration increased in both accessions, regardless of growth medium and exposure time. The β-ecdysone concentration in the roots increased in both accessions, but accession GD was more responsive to Zn excess. There was significant physiological variation in P.glomerata accessions in response to Zn excess.