title: Metabarcoding inventory of an arctic tundra soil ecosystem reveals highly heterogeneous communities at a small scale

authors: Jorna, Jesse

abstract: Biodiversity surveys of Arctic soil ecosystems are limited. Here, we provide a sequence-based inventory of soil fauna from an Arctic tundra ecosystem near the Canadian High Arctic Research Station in Cambridge Bay, Nunavut. Invertebrate communities were extracted at a vegetated and non-vegetated site in three replicates and inventoried using 18S metabarcode sequencing. A total of 361 amplicon sequence variants (ASV) were identified and assigned to the closest matching taxonomic orders, most of which belonged to the Nematoda and Arthropoda. Vegetated soils showed no significantly higher ASV richness relative to non-vegetated soils although they contained a significantly higher diversity of arthropod taxa including insects, mites, and springtails. Most taxa were found only at a single location and even samples from the same site displayed distinct communities, suggesting that belowground species richness in Arctic tundra habitats is highly heterogeneous. Preserving soil biodiversity in a changing Arctic is essential for Inuit communities who rely on intact tundra ecosystems for their health and wellbeing.

text: Metabarcoding inventory of an arctic tundra soil ecosystem reveals highly heterogeneous communities at a small scale Biodiversity surveys of Arctic soil ecosystems are limited. Here, we provide a sequence-based inventory of soil fauna from an Arctic tundra ecosystem near the Canadian High Arctic Research Station in Cambridge Bay, Nunavut. Invertebrate communities were extracted at a vegetated and non-vegetated site in three replicates and inventoried using 18S metabarcode sequencing. A total of 361 amplicon sequence variants (ASV) were identified and assigned to the closest matching taxonomic orders, most of which belonged to the Nematoda and Arthropoda. Vegetated soils showed no significantly higher ASV richness relative to non-vegetated soils although they contained a significantly higher diversity of arthropod taxa including insects, mites, and springtails. Most taxa were found only at a single location and even samples from the same site displayed distinct communities, suggesting that belowground species richness in Arctic tundra habitats is highly heterogeneous. Preserving soil biodiversity in a changing Arctic is essential for Inuit communities who rely on intact tundra ecosystems for their health and wellbeing.

year: 2023-05-01

title: Moisture sorption and plasticization of bloodmeal-based thermoplastics

authors: Verbeek, Casparus Johan R.

subjects: tri-ethylene glycol

abstract: Sorption characteristics, thermo-mechanical and mechanical properties of bloodmeal-based thermoplastics have been investigated between water activities (aw) of 0.2 and 0.8, using water and tri-ethylene glycol (TEG) as plasticizers. Three different mass ratios of TEG to water were used, 1:1, 1:2 and 5:6 with a total plasticizer content of 60 parts per hundred parts bloodmeal. It was found that the equilibrium moisture content and mechanical properties were highly dependent on relative humidity suggesting that material properties may vary during use. The BET and Flory–Huggins equations gave the best fit for desorption and adsorption, respectively, but a significant difference was observed between adsorption and desorption behaviour below a water activity of 0.6, which was thought to be due to changes in intermolecular interactions. The monolayer adsorption capacity (0.05 g/g) was unaffected by the TEG content, using the BET sorption isotherm. The water activity required to form a monolayer (awl) was also independent of the amount of TEG, but was different for adsorption and desorption (about 0.5 and 0.2, respectively). Increasing TEG did not have a strong influence on the equilibrium moisture content, especially at low water activity. Dynamic mechanical analysis revealed that the glass transition temperature decreased almost linearly with increasing water activity, ranging between 3 and 85 ℃, however, above a water activity of 0.6 a second transition was observed, most likely due to phase separation. Depending of TEG content, tensile strength increased from about 10 to 15 MPa at a water activity of 0.4, where after a drastic decrease was observed. A similar trend was observed for elongation at break. At low water activity (below 0.4) elongation was less than 3%, increasing between 30 and 50% at higher water activities. It was concluded that 10–15 wt% represented a critical point above which mechanical properties becomes very sensitive to the relative humidity of the environment.

text: Moisture sorption and plasticization of bloodmeal-based thermoplastics Sorption characteristics, thermo-mechanical and mechanical properties of bloodmeal-based thermoplastics have been investigated between water activities (aw) of 0.2 and 0.8, using water and tri-ethylene glycol (TEG) as plasticizers. Three different mass ratios of TEG to water were used, 1:1, 1:2 and 5:6 with a total plasticizer content of 60 parts per hundred parts bloodmeal. It was found that the equilibrium moisture content and mechanical properties were highly dependent on relative humidity suggesting that material properties may vary during use. The BET and Flory–Huggins equations gave the best fit for desorption and adsorption, respectively, but a significant difference was observed between adsorption and desorption behaviour below a water activity of 0.6, which was thought to be due to changes in intermolecular interactions. The monolayer adsorption capacity (0.05 g/g) was unaffected by the TEG content, using the BET sorption isotherm. The water activity required to form a monolayer (awl) was also independent of the amount of TEG, but was different for adsorption and desorption (about 0.5 and 0.2, respectively). Increasing TEG did not have a strong influence on the equilibrium moisture content, especially at low water activity. Dynamic mechanical analysis revealed that the glass transition temperature decreased almost linearly with increasing water activity, ranging between 3 and 85 ℃, however, above a water activity of 0.6 a second transition was observed, most likely due to phase separation. Depending of TEG content, tensile strength increased from about 10 to 15 MPa at a water activity of 0.4, where after a drastic decrease was observed. A similar trend was observed for elongation at break. At low water activity (below 0.4) elongation was less than 3%, increasing between 30 and 50% at higher water activities. It was concluded that 10–15 wt% represented a critical point above which mechanical properties becomes very sensitive to the relative humidity of the environment.

year: 2011

title: Ka Pū Te Ruha, Ka Hao Te Rangatahi: Maori identities in the twenty-first century

authors: Kukutai, Tahu

abstract: These social divides and problems are at the heart of this text.

text: Ka Pū Te Ruha, Ka Hao Te Rangatahi: Maori identities in the twenty-first century These social divides and problems are at the heart of this text.

year: 2017-02