Almost a quarter of the plastic produced in Europe still ends up in landfills. In addition to the loss of valuable resources, this leads to the generation and accumulation of microplastics in landfills. The microplastics abundance in the refuse and their spatial distribution in the landfill body have not been practically studied. In the current work, changes in the abundance and characteristics of microplastics in landfill refuse from 3 age sections of the Lapės regional landfill, Lithuania, to a depth of 10–20 m were studied. A microplastics abundance of up to 55 particles/g or 52.8 g/kg was found. The lowest microplastics abundance was found in the old section, while the highest in the young (numerical) and the middle-aged (mass) sections. Moreover, microplastics abundance increased with the age of landfilled waste and depth, which may reflect the fragmentation of microplastics and their transport. Polyethylene and polypropylene were the dominant polymer types in all sections, while films were the dominant shape. The carbonyl index of PE microplastics was calculated to monitor microplastics oxidation. The analysis showed an increase of carbonyl index with landfill depth and landfill age, proving the intensive degradation of microplastics. Thus, landfills are large reservoirs of microplastics and their potential sources.

Several isotopologues of the water dimer have been studied in different matrices (Ne, Ar, Kr, and p-H2) at very low temperatures. A fine structure, which is more or less matrix independent and very similar for different intramolecular fundamentals of the same isotopologic dimer, is present on the high wavenumber side of the main component. The bound OD (OH) stretches of the donor have temperature dependent components. The fine structure and temperature dependency is interpreted as evidence for acceptor switching and rotation of the water dimer around its O–O axis in the matrices studied here. The slow nuclear spin equilibration in H2O inhibits the thermal equilibration between the acceptor switching states in H2O–DOH and H2O–DOD. The condensed environment slows down the acceptor switching rate compared to the gas phase. The antisymmetric stretch of the proton acceptor is assigned by combining information from different matrices with the rotation-acceptor switching model.

The photochemistry of the chelated enol form of acetylacetone (AcAc) was investigated by UV excitation of the S₂ state at 266 nm in parahydrogen matrices, complemented by experiments in neon and normal hydrogen matrices. Infrared (IR) spectroscopy, combined with theoretical calculations, was used to identify the photoproducts. Isomerization towards various non-chelated forms (no intramolecular H-bond) of AcAc is the dominant channel whereas fragmentation is very minor. The isomerization kinetics is monitored by IR spectroscopy. Among the seven non-chelated conformers of AcAc, only three are formed in parahydrogen matrices, whereas four are observed in normal hydrogen matrices. This difference suggests that an active tunnelling process between conformers occurs in parahydrogen but is quenched in normal hydrogen where guest–host interactions are stronger. Fragmentation and isomerization of excited AcAc are discussed in the light of these new data. The role of the intermediate triplet state in the S₂ → S₀ relaxation is confirmed, as the importance of phonons in the condensed phase.

The recycling of bio-waste plays an important role in a circular economy as it transforms bio-waste into a valuable resource (organic fertilizer). However, even separately collected bio-waste can contain some plastic waste, which is usually separated after composting and not before it. Primary studies have confirmed the degradation of plastic during composting, but the release of microplastics from them has not been studied. This article presents a quantification and comparison of the release of microplastics from commonly used plastics during green waste composting. Microplastics were identified by Nile red staining and examination under a fluorescent microscope. Plastic degradation was assessed by weight loss calculation, scanning electron microscope (SEM), and Fourier-transform infrared spectroscopy (FTIR) analysis. On average, 17 to 52 microplastics’ are released from 5-by-5 cm pieces of conventional plastics during composting. The control polylactic acid sample showed the smallest amount of released microplastics: four particles on average. The number of released microplastics depended on the polymer type and thickness of the samples. The results of the current article can be further used for the prediction of microplastic generation and setting a limit on the plastic content in bio-waste