Analytical investigation of the influence of micro- and nanoplastic particles in crop plants by electron microscopic imaging and spectroscopyPart of:
The production of human food is inseparably linked with the cycles of life in nature. Entries into the cycles thus enter the human food chain, influencing habitat and health. Polymers are industrial products with use in practically every area of life. The amount of plastic polymers and paper materials is obviously constantly increasing. The resulting plastic waste has become a global problem and is observable from the plastic accumulation in the world's oceans. Polymers in degradation and already granulated microplastics, e.g. in daily care products, contribute to the amount of microplastics. Plastic is therefore found also in freshwaters which are used for water supply of humans, animals and plants. The influence and toxicity of micro- and nano-plastics is not yet sufficiently explored. Depending on the polymer type, plastics stability varies to external influences in respect to action of forces, abrasion, temperature, UV radiation and metabolic conversion by microorganisms. This results in particle fragments with sizes in the micrometer and nanometer range. Crop plants cannot escape the micro- and nano-plastic particles as the particles pass into the soil through contaminated water. Micro- and nanoparticles can be taken up in the food chain by using crop plants as food resource. Therefore, the reliable identification of polymer particles in soil and plant samples is important as in animal organisms. The effect of micro- and nanoparticle on plants is investigated using model plants of Lepidium sativum and Valerianella. Imaging techniques such as scanning electron microscopy (SEM) and focused ion beam (FIB) are used for investigating the microscopic distribution of particles in soil and plant samples. The depicted topographical compositions of micro- and nanoparticles allow conclusions of potential interactions with plant interfaces or the accumulation potential. Energy dispersive X-ray spectroscopy (EDS) and Raman spectroscopy support the microenvironmental differentiation of natural and particle structures based on element- or molecule-specific signatures. The spectroscopic and imaging data can be correlated with the biogenic effects of the micro- and nanoparticles influence on the model plant growth. This allows the methodic evaluation of the chosen spectroscopic SEM/FIB analysis approach for the investigation of the influence and biocompatibility of polymer micro- or nanoparticles on uptake and growth of crop plants.