A Semi-Parametric Approach to the Detection of Non-Gaussian Gravitational Wave Stochastic Backgrounds

Using a semi-parametric approach based on the fourth-order Edgeworth expansion for the unknown signal distribution, we derive an explicit expression for the likelihood detection statistic in the presence of non-normally distributed gravitational wave stochastic backgrounds. Numerical likelihood maximization exercises based on Monte-Carlo simulations for a set of large tail symmetric non-Gaussian distributions suggest that the fourth cumulant of the signal distribution can be estimated with reasonable precision when the ratio between the signal and the noise variances is larger than 0.01. The estimation of higher-order cumulants of the observed gravitational wave signal distribution is expected to provide additional constraints on astrophysical and cosmological models.Comment: 26 pages, 3 figures, to appear in Phys. Rev.

Editorial for the Special Issue “Microplastics in Aquatic Environments: Occurrence, Distribution and Effects”

The large production and widespread daily consumption of plastic materials—which began in the last century—together with the often-inadequate collection and recycling systems, have made plastics and, consequently, microplastics (MPs) ubiquitous pollutants [...

Hazardous contaminants in plastics contained in compost and agricultural soil

Macro-, meso-and microplastic (MAP, MEP, MP) occurrence in compost is an environmental issue whose extent and effects are not yet understood. Here, we studied the occurrence of MAPs, MEPs and MPs in compost samples, and the transfer of hazardous contaminants from plastics to compost and soil. MAPs/MEPs and MPs concentrations in compost were 6.5 g/kg and 6.6 +/- 1.5 pieces/kg; from common recommendations for compost application, we estimated similar to 4-23 x 10(7) pieces MPs and 4-29 x 10(4) g MAPs/MEPs ha(-1) per year ending into agricultural soils fertilized with such compost. Regarding contaminants, bis(ethylhexyl) phthalate, acetyl tributyl citrate, dodecane and nonanal were extracted in higher concentrations from plastics and plastic-contaminated compost than from compost where MAPs/MEPs had been removed prior to extraction and analysis. However, some contaminants were present even after MAPs/MEPs removal, ascribable to short-and long-term release by MAPs/MEPs, and to the presence of MPs. DEHP concentration was higher in soils where compost was applied than in fields where it was not used. These results, along with estimations of plastic load to soil from the use of compost, show that compost application is a source of plastic pollution into agricultural fields, and that plastic might transfer hazardous contaminants to soil.Peer reviewe

Characterisation of (micro-)plastics in groundwater bodies: insights from Italian aquifers

Nowadays, microplastics (MPs) are considered as contaminants of emerging concern, since they are ubiquitously present in the majority of ecosystems. This research focuses on the chemical characterization of MPs in four Italian groundwater bodies, two karst caves, one in Piedmont and the other in Tuscany, and two saturated alluvial aquifers in Florence (Tuscany). Atmospheric depositions, infiltrations through soil and anthropic contribution, especially in touristic areas, can cause MPs penetration into groundwater bodies, posing a risk not only to groundwaters’ quality but also to biodiversity conservation in these sensitive ecosystems. A single water sample was collected from each sampling site, and, if necessary, an oxidative digestion step was performed to remove any organic matter that could interfere with subsequent analysis. Vacuum filtration was employed on each sample, followed by a preliminary observation using a stereomicroscope to assess colors and shapes. The chemical characterization was done by 2D imaging Fourier Transform Infrared Spectroscopy (FTIR). Every polymer found in each site was classified by shape, color and composition. This study was supported by National Recovery and Resilience Plan (PNRR), Mission 4, Component 2 “From Research to Enterprise”, funded by the European Union NextGenerationEU, CUP B83C22004820002

Occurrence of Natural and Synthetic Micro-Fibers in the Mediterranean Sea: A Review

Among microplastics (MPs), fibers are one of the most abundant shapes encountered in the aquatic environment. Growing attention is being focused on this typology of particles since they are considered an important form of marine contamination. Information about microfibers distribution in the Mediterranean Sea is still limited and the increasing evidence of the high amount of fibers in the aquatic environment should lead to a different classification from MPs which, by definition, are composed only of synthetic materials and not natural. In the past, cellulosic fibers (natural and regenerated) have been likely included in the synthetic realm by hundreds of studies, inflating “micro-plastic” counts in both environmental matrices and organisms. Comparisons are often hampered because many of the available studies have explicitly excluded the micro-fibers (MFs) content due, for example, to methodological problems. Considering the abundance of micro-fibers in the environment, a chemical composition analysis is fundamental for toxicological assessments. Overall, the results of this review work provide the basis to monitor and mitigate the impacts of microfiber pollution on the sea ecosystems in the Mediterranean Sea, which can be used to investigate other basins of the world for future risk assessment