Organic matter burial in mangrove forests results in the removal and long-term storage of atmospheric CO₂, so-called “blue carbon.” However, some of this organic matter is metabolized and returned to the atmosphere as CH₄. Because CH₄ has a higher global warming potential than the CO₂ fixed in the organic matter, it can offset the CO₂ removed via carbon burial. We provide the first estimate of the global magnitude of this offset. Our results show that high CH₄ evasion rates have the potential to partially offset blue carbon burial rates in mangrove sediments on average by 20% (sensitivity analysis offset range, 18 to 22%) using the 20-year global warming potential. Hence, mangrove sediment and water CH₄ emissions should be accounted for in future blue carbon assessments.

The Optional Protocol to the United Nations (UN) Convention Against Torture and other Cruel, Inhuman or Degrading Treatment or Punishment (OPCAT) is premised on the concept of prevention: that regular examination by independent national and international bodies of those detained and the institutions detaining them will prevent torture, ill-treatment, and cruel, inhuman or degrading treatment occurring. This paper examines how National Preventive Mechanisms (NPMs) in Europe have interpreted the concept of ‘regular’ visits. By July 2018, 38 NPMs had been designated in Europe, the largest number in any region. Drawing upon desk-based research and a survey among these NPMs, this paper illustrates that their practice varies considerably, with diverging views on how ‘regular’ is interpreted; a number of factors coming into play when one is trying to identify what is regular; and the extent to which, even if one could define regularity, any NPM is fulfilling this requirement. It identifies the need for more research, suggests NPMs may wish to examine their own practice and concludes with a call to the UN Subcommittee on the Prevention of Torture (SPT) to provide and expand upon guidance as to the sorts of factors that NPMs may consider when determining when to visit.

Applying coatings of paraffins and other synthetic waxes is a common approach to impart hydrophobic properties to fibres and thus control their surface characteristics. Replacing these fossil-based products with alternatives derived from renewable resources can contribute to humankind’s transition to a sustainable bioeconomy. This study presents the coating of hemp fibres with waxes extracted from pine bark as an exemplar application. Two bio-based emulsifiers were used to prepare wax emulsions suitable for a dry blending process. The coatings on the fibres were characterised, quantified, and visualised using a combination of spectroscopic and microscopic techniques. Confocal fluorescence microscopy was an excellent tool to investigate the spatial distribution of the pine bark waxes on the fibre surfaces. While successful deposition was demonstrated for all tested formulations, coating homogeneity varied for different emulsifiers. Compounding the hemp fibres with a bio-based polyester resulted in the substantial improvement of the mechanical behaviour. However, the presence of a wax coating on the fibres did not lead to a significant change in mechanical properties compared to the controls with uncoated fibres. Optimising the composite chemistry or adjusting the processing conditions might improve the compatibility of the hemp fibres with the matrix material, resulting in enhanced mechanical performance.