RESUMO
There are few studies related to the radionuclide remediation options, which comply to the demands of the environmentally non-destructive physical remediation methods. So far, most of the research was conducted on the phytoremediation capacity of different energy crops, as well as the established miscanthus hybrids which involved metal and heavy metal contaminants. Hence, the objective of this research was the radioecological characterization of the examined agroecosystem, including the initial source of the radionuclides (soil) as well as different miscanthus hybrids grown on the same soil. The results have shown that the radioactive content of soil was similar to the global averages. All measurements of the activity concentration of 137Cs in miscanthus samples were below the detection limits. There is also an indication that 210Pb is leaching into the lower layers (or is being taken up by miscanthus plant from the upper layers). Moreover, transfer factors (TFs) for radionuclides, as a more precise parameter for evaluating the phytoremediation potential, were calculated; the TFs were found to be very low for 226Ra (≤0.07), TFs for 40K (≤0.39) and for 232Th (≤0.21) were in the lower limits, whereas the TFs for 238U were found to be the highest (≤0.92). For 210Pb, the TFs were not calculated, since the expectation was that a significant part of the measured quantity came from the air, and not through the soil. Having in mind the sustainability and the circularity aspect of the radionuclide phytoremediation system, the appropriate management method should be applied for the disposal and utilization of the biomass contaminated with radionuclides. This research has shown that the radiological content in miscanthus is high enough and the ash content is low enough that miscanthus ash could be considered as a NORM (Naturally Occurring Radioactive Material), and it can be further used for the construction industry (i.e. concrete, tiles), in mixtures with other materials with certain limitations, similar to the utilization of ash from other sources such as coal or wood.
RESUMO
New biomass crop hybrids for bioeconomic expansion require yield projections to determine their potential for strategic land use planning in the face of global challenges. Our biomass growth simulation incorporates radiation interception and conversion efficiency. Models often use leaf area to predict interception which is demanding to determine accurately, so instead we use low-cost rapid light interception measurements using a simple laboratory-made line ceptometer and relate the dynamics of canopy closure to thermal time, and to measurements of biomass. We apply the model to project the European biomass potentials of new market-ready hybrids for 2020-2030. Field measurements are easier to collect, the calibration is seasonally dynamic and reduces influence of weather variation between field sites. The model obtained is conservative, being calibrated by crops of varying establishment and varying maturity on less productive (marginal) land. This results in conservative projections of miscanthus hybrids for 2020-2030 based on 10% land use conversion of the least (productive) grassland and arable for farm diversification, which show a European potential of 80.7-89.7 Mt year-1 biomass, with potential for 1.2-1.3 EJ year-1 energy and 36.3-40.3 Mt year-1 carbon capture, with seeded Miscanthus sacchariflorus × sinensis displaying highest yield potential. Simulated biomass projections must be viewed in light of the field measurements on less productive land with high soil water deficits. We are attempting to model the results from an ambitious and novel project combining new hybrids across Europe with agronomy which has not been perfected on less productive sites. Nevertheless, at the time of energy sourcing issues, seed-propagated miscanthus hybrids for the upscaled provision of bioenergy offer an alternative source of renewable energy. If European countries provide incentives for growers to invest, seeded hybrids can improve product availability and biomass yields over the current commercial miscanthus variety.