Global modelling of plastic beaching indicates coastlines and coastal waters as significant plastic reservoirs

<p>The distribution of plastic in the ocean is poorly constrained, with the mass of floating plastic at the ocean surface being orders of magnitude smaller than estimated plastic inputs. Coastlines likely contain significant amounts of plastic, but inconsistent methodologies between beached plastic observations prevent determining the mass and distribution of globally beached plastic. We present Lagrangian model sensitivity experiments to estimate the beached fraction of marine plastic and to investigate the global distribution of beached plastic on coastlines.</p><p>We perform simulations where particles, representing masses of floating plastic, are inserted at the ocean coasts. The particles are then advected by surface currents (HYCOM/NCODA global reanalysis and surface Stokes drift from the WaveWatch III global reanalysis) for 5 years. Beaching is parametrized stochastically using exponentional probability. Here, we test the sensitivity to e-folding time scales between 1 and 100 days, applied when plastic is within the coastal zone, within 10km of the nearest coastline. Resuspension of beached plastic is parameterised exponentially with an e-folding timescale between 69 and 273 days. No other loss processes are implemented.</p><p>Between 39-95% of floating plastic mass is beached after 5 years, with the beached fraction depending on the ratio between the beaching and resuspension timescales. In all simulations, at least 77% of floating plastic mass is found either beached or within the coastal zone, indicating coastal regions are a significant reservoir of mismanaged terrestrial plastic. However, plastic entering the ocean from islands or near energetic boundary currents is more likely to reach the open ocean. The distribution of beached plastic is closely related to the input distribution, with the highest concentrations found in Southeast Asia and the Mediterranean.</p><p>Our results highlight coastlines and coastal waters as important reservoirs of marine plastic debris and indicate a need for greater understanding of plastic transport near and at the coastlines. Furthermore, improved representation of plastic beaching can help study marine plastic fragmentation, as mechanical stress during the transitions between coastlines and coastal waters and the increased UV exposure of beached plastic likely contribute to the fragmentation.</p>

Rheology of molding materials for extruding billets to obtain copper-containing alumina-silica catalysts

Using the example of the CAS ‒ C ceramic copper-aluminumsiliceous catalyst for dehydrogenation of cyclohexanol to cyclohexanone in the production of urea, the rheological and mechanical properties of the copper-containing aluminumsiliceous plastic mass depending on its composition are studied. The data on the influence of technological and structural conditions for molding the mass in a screw press on the performance of extrudable ceramic billets are presented. The revealed features in the behavior of the moldable plastic mass are explained by differences in the surface properties of silica particles interacting with the precursor of the active component at the stage of catalyst synthesis. The composition of the molding mass and the extrusion regimes on screw extruders are established, which ensure the output of high-quality and mechanically strong ceramic billets (extrudates).

Slow degradation of compostable plastic carrier bags in a stream and its riparian area

There is no place on Earth where plastic debris could not be found. Impacts of plastics on aesthetics, biota and ecosystems are dependent on how long plastic items last, and what degradation products are released, in recipient environments. As bio-based plastics tend to replace petroleum-based plastics in everyday life, it is important to upgrade knowledge on the degradation of new polymers in natural environments. Single-use plastic carrier bags are nowadays made of bio-plastics certified as biodegradable and compostable. It is unclear, however, whether claims of biodegradability and compostability can be taken as evidence of rapid degradation of plastic bags outside recycling/composting facilities. This study sought to provide quantified information about the degradation of compostable plastic carrier bags in streams and riparian zones. We found that plastic samples enclosed in different types of mesh bags lost weight at extremely slow rates, albeit significant when submerged in a stream. 95% of initial plastic mass remained after 77 days spent in water whereas alder leaf litter allowed to decompose under the same condition had completely disappeared before the end of the study. Determination of respiration rate and invertebrate abundance in plastic samples showed a greater decomposer activity in the stream than in the riparian environment. However, biotically-mediated degradation by decomposers was probably overridden by dissolution processes in mediating plastic mass loss. Our findings suggest that mismanaged plastic carrier bags could impact recipient ecosystems even when they are claimed as biodegradable or compostable.

Research of the plastic strength of alumina mass for molding corundum ceramics by extrusion depending on them humidity

One of the characteristics that makes it possible to evaluate the plasticity and formability of ceramic masses is the plastic strength of structure — the ultimate shear stress that the plastic mass can withstand under static stress. The dependence researches of the plastic strength of alumina masses from alumina MARTOXID and CT 3000 brands on a flour binder on their humidity and keeping time were carried out. The determination of the plastic strength of the masses was carried out on a KP-3 conical plastometer, for which purpose a cone with an apex angle of 30о was used (mass of the cone together with rod is 0.8056 kg). The optimum humidity of alumina masses for the molding of corundum ceramics by extrusion from alumina MARTOXID brand is 19 % and from alumina CT 3000 brand is 20 % were established. In depending on technological needs and capabilities were set that, the keeping time of alumina masses with the optimum humidity can be 1—7 days. The samples of corundum ceramics received by extrusion from the alumina mass of alumina MARTOXID and CT 3000 brands with optimum humidity after firing at 1580 оC are characterized by low open porosity and correspond to high refractories corundum high-density products requirements (open porosity no more 0.8 %).

The Influence of Texture and Firing on Thermal and Elastic Properties of Illite-Based Ceramics

The texture in illite-based ceramics was introduced by spreading a large number of thin layers of a wet plastic mass one on top of the other. The basal planes of the plate-like illite crystals are predominantly oriented parallely with the direction of spreading. The samples were fired at different temperatures ranging from room temperature up to 1100 °C with a heating rate of 5 °C/min, then freely cooled and measured at room temperature. We determined Young modulus (E), thermal diffusivity (a) and relative dimension changes (Δl/l0) in two directions: parallely to the basal planes (a subscript ||) of the illite crystals and perpendicularly to these planes (a subscript ⊥). It was found that the ratio E|| / E⊥ ≈ 2.9 and a|| / a⊥ ≈ 2.0 up to 900 °C. Above 900 °C, the values of E and a increase due to sintering, and the differences between the values measured in the two directions decrease. In the case of the thermal diffusivity these differences do not disappear even after firing at the temperature of 1200 °C.