Density variability of COVID-19 face mask litter: A cautionary tale for pandemic PPE waste monitoring.

Despite the requirement for data to be normally distributed with variance being independent of the mean, some studies of plastic litter, including COVID-19 face masks, have not tested for these assumptions before embarking on analyses using parametric statistics. Investigation of new data and secondary analyses of published literature data indicate that face masks are not normally distributed and that variances are not independent of mean densities. In consequence, it is necessary to either use nonparametric analyses or to transform data prior to undertaking parametric approaches. For the new data set, spatial and temporal variance functions indicate that according to Taylor's Power Law, the fourth-root transformation will offer most promise for stabilizing variance about the mean.

First landscape-scale survey of the background level of COVID-19 face mask litter: Exploring the potential for citizen science data collection during a 'pollution pilgrimage' of walking a 250-km roadside transect.

The COVID-19 pandemic has generated a global problem through the cavalier or deliberate disposal of personal protective equipment (PPE) by the general public. This has raised concerns that the billions of discarded face masks pose a threat to wildlife through entanglement or, when broken down, through ingestion of derived microplastics. Previous quantitative surveys of the magnitude of such litter have focused on areas where people congregate, such as tourist beaches and large cities. The present survey is the first to provide data on the background level of face mask litter through a landscape of variable land-use. A 250-km transect along an historic road between Montreal and Quebec City (Canada) was surveyed during a walking pilgrimage, revealing an overall density of 0.0001 ± 0.00006 face masks m-2. Average densities were significantly higher in areas of human occupation compared to agricultural and forested rural land. However, there was no significant correlation between population size of communities and the number of face masks encountered, nor in litter extent and proximity to municipalities. This may be due to the confounding influence of inter-community differences in scheduled street cleaning operations. Seventy-six percent of face masks were of the disposable surgical variety, with the remaining 24% being reusable cloth masks. This, and the fact that only 10% of the former and none of the latter exhibited broken ear straps, insinuates that the litter could be due to accidental loss rather than inappropriate discarding by individuals en route. Scaling-up these findings in relation to the global road network generates a preliminary background estimate for roadside litter of >17 million face masks. The present study endorses the call made by others to engage citizen scientists in surveying PPE litter, in particular, the thousands who each year walk the medieval pilgrimage routes through the landscape of Europe.

Upgrading Marine Ecosystem Restoration Using Ecological-Social Concepts.

Conservation and environmental management are principal countermeasures to the degradation of marine ecosystems and their services. However, in many cases, current practices are insufficient to reverse ecosystem declines. We suggest that restoration ecology, the science underlying the concepts and tools needed to restore ecosystems, must be recognized as an integral element for marine conservation and environmental management. Marine restoration ecology is a young scientific discipline, often with gaps between its application and the supporting science. Bridging these gaps is essential to using restoration as an effective management tool and reversing the decline of marine ecosystems and their services. Ecological restoration should address objectives that include improved ecosystem services, and it therefore should encompass social-ecological elements rather than focusing solely on ecological parameters. We recommend using existing management frameworks to identify clear restoration targets, to apply quantitative tools for assessment, and to make the re-establishment of ecosystem services a criterion for success.

Graphite powder and multiwalled carbon nanotubes chemically modified with 4-nitrobenzylamine.

We demonstrate that graphite powder and multiwalled carbon nanotubes (MWCNTs) can be derivatised by 4-nitrobenzylamine (4-NBA) simply by stirring the graphite powder or MWCNTs in a solution of acetonitrile containing 10 mM 4-NBA. We propose that 4-NBA partially intercalates at localised edge-plane or edge-plane-like defect sites and this hypothesis with a range of experimental data provided by electrochemistry in both aqueous and nonaqueous media, electron microscopy and X-ray powder diffraction.

Selective activation of glycosyl donors utilising electrochemical techniques: a study of the thermodynamic oxidation potentials of a range of chalcoglycosides.

A series of six chalcoglycosides (phenyl-2,3,4,6-tetra-O-benzoyl-1-seleno-beta-D-glucopyranoside, phenyl-2,3,4,6-tetra-O-benzyl-1-seleno-beta-D-glucopyranoside, phenyl-2,3,4,6-tetra-O-benzyl-1-thio-beta-D-glucopyranoside, p-tolyl-2,3,4,6-O-benzoyl-1-thio-beta-D-glucopyranoside, p-tolyl-2,3,4,6-O-benzyl-1-thio-beta-D-glucopyranoside, and phenyl-2,3,4,6-O-benzyl-beta-D-glucopyranoside) are voltammetrically interrogated in dimethyl sulfoxide, so as to determine their formal (i.e. thermodynamic) redox potentials. The electrochemical oxidation of the chalcoglycoside is shown to follow an overall EC-type mechanism, in which the electro-generated cation radical undergoes an irreversible carbon-chalcogen bond rupture to produce the corresponding glycosyl cation, which may react further. The kinetics of the initial heterogeneous electron transfer process and subsequent irreversible homogeneous chemical degradation of the radical cation are reported, with values for the standard electrochemical rate constant k(0) in the order of 10(-2) cm s(-1) and the first order homogeneous rate constant, k(1), of the order of 10(3) s(-1). The formal oxidation potentials were found to vary according to the identity of the chalcogenide, such that OPh > SPh similar to STol > SePh.

Selective electrochemical glycosylation by reactivity tuning.

Electrochemical glycosylation of a selenoglycoside donor proceeds efficiently in an undivided cell in acetonitrile to yield beta-glycosides. Measurement of cyclic voltammograms for a selection of seleno-, thio-, and O-glycosides indicates the dependence of oxidation potential on the anomeric substituent allowing the possibility for the rapid construction of oligosaccharides by selective electrochemical activation utilising variable cell potentials in combination with reactivity tuning of the glycosyl donor. A variety of disaccharides are readily synthesised in high yield, but limitations of the use of selenoglycosides as glycosyl donors for selective glycosylation of thioglycoside acceptors are exposed. The first electrochemical trisaccharide synthesis is described.

Synthesis of fluorescence-labelled disaccharide substrates of glucosidase II.

The fluorescence-labelled disaccharides Glcalpha(1-->3)GlcalphaOR and Glcalpha(1-->3)ManalphaOR, both substrates for the glycoprotein-processing enzyme glucosidase II, were synthesised via the use of a n-pentenyl-derived linker at the anomeric position. This allowed incorporation of a pyrenebutyric acid label, via a sequence of oxidative hydroboration, mesylation, azide displacement, reduction with concomitant global deprotection, and peptide coupling. Selective activation of a fully armed thioglycoside in the presence of n-pentenyl glycosides was readily achieved by the use of methyl triflate as promoter.

Electrocatalytic reactions mediated by N,N,N',N'-Tetraalkyl-1,4-phenylenediamine redox liquid microdroplet-modified electrodes: chemical and photochemical reactions In, and At the surface of, femtoliter droplets.

The electro-oxidation of electrolytically unsupported ensembles of N,N-diethyl-N',N'-dialkyl-para-phenylenediamine (DEDRPD, R = n-butyl, n-hexyl, and n-heptyl) redox liquid femtoliter volume droplets immobilized on a basal plane pyrolytic graphite electrode is reported in the presence of aqueous electrolytes. Electron transfer at these redox liquid modified electrodes is initiated at the microdroplet-electrode-electrolyte three-phase boundary. Dependent on both the lipophilicity of the redox oil and that of the aqueous electrolyte, ion uptake into or expulsion from the organic deposits is induced electrolytically. In the case of hydrophobic electrolytes, redox-active ionic liquids are synthesized, which are shown to catalyze the oxidation of l-ascorbic acid over the surface of the droplets. In contrast, the photoelectrochemical reduction of the anaesthetic reagent halothane proceeds within the droplet deposits and is mediated by the ionic liquid precursor (the DEDRPD oil).

Ontogenetic shift in crayfish δ13C as a measure of land-water ecotonal coupling.

Although ontogenetic changes in the carbon isotope ratios of marine fauna have been well studied those of freshwater organisms have not. As a result, we may have a less than adequate assessment of the incorporation of allochthonous detritus into freshwater foodwebs. This study found a δ13C range of 9‰ for crayfish (Orconectes virilis) from oligotrophic Canadian Shield lakes. Much (60-83%) of this variability was explained by body size. A simple isotopic mixing model suggests that by their third year of life, crayfish in these lakes rely more substantially upon terrestrial detritus than epilithic algae for energy.