Assessing the Fate, and Environmental Impact of Plastics in Soil and Crop Ecosystems Using Isotopic Techniques
Objectives
- Isolation of deuterated soil bacteria for stable isotope Raman microspectroscopy measurements
- Transferring the stable isotope Raman microspectroscopy approach to monitor biodegradation of (micro)plastics to environmental soil samples
- Measuring the deuterium uptake from deuterated polylactic acid (dPLA) into soil bacteria
Methods of Approach
- Stable isotope Raman microspectroscopy (SIRM)
- Resonance Raman spectroscopy
Description
Because of the ease with which their properties can be tailored, plastics occur in a variety of applications. However, they accumulate in different natural environments. Especially in agriculture, it is impossible to fully retrace the plastics after their end-of-use. Therefore, it is essential to use completely biodegradable polymers for such purposes. While conventional techniques measure microbial activity (i.e., CO2 production) or polymer properties, those methods lack a direct link between the polymer and the biodegrading microbes. Stable isotope approaches can be used to directly trace a label from the plastic into biodegradation products.
In the scope of this IAEA project, the microbial activity of different soil microbiomes is compared, which were either exposed to plastics or not. Therefore, heavy water can be added to the soil and its uptake into microbial biomass can be measured, which is dependent on the microbial activity.
In the next step, the biodegradation of the bio-based polymer polylactic acid (PLA), which is used in agricultural mulch films, should be analyzed in soil samples by tracing deuterium from labeled PLA into microbial biomass with Raman microspectroscopy.
