UC Research Repository
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The UC Research Repository collects, stores and makes available original research from postgraduate students, researchers and academics based at the University of Canterbury.
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Recent Submissions
Temporal dynamics of geothermal microbial communities in Aotearoa-New Zealand
(Frontiers Media SA, 2023) Power , Jean F.; Lowe , Caitlin L.; Carere, Carlo; McDonald , Ian R.; Cary , S. Craig; Stott, Matthew
Microbial biogeography studies, in particular for geothermal-associated habitats, have focused on spatial patterns and/or individual sites, which have limited ability to describe the dynamics of ecosystem behaviour. Here, we report the first comprehensive temporal study of bacterial and archaeal communities from an extensive range of geothermal features in Aotearoa-New Zealand. One hundred and fifteen water column samples from 31 geothermal ecosystems were taken over a 34-month period to ascertain microbial community stability (control sites), community response to both natural and anthropogenic disturbances in the local environment (disturbed sites) and temporal variation in spring diversity across different pH values (pH 3, 5, 7, 9) all at a similar temperature of 60–70°C (pH sites). Identical methodologies were employed to measure microbial diversity via 16S rRNA gene amplicon sequencing, along with 44 physicochemical parameters from each feature, to ensure confidence in comparing samples across timeframes. Our results indicated temperature and associated groundwater physicochemistry were the most likely parameters to vary stochastically in these geothermal features, with community abundances rather than composition more readily affected by a changing environment. However, variation in pH (pH ±1) had a more significant effect on community structure than temperature (±20°C), with alpha diversity failing to adequately measure temporal microbial disparity in geothermal features outside of circumneutral conditions. While a substantial physicochemical disturbance was required to shift community structures at the phylum level, geothermal ecosystems were resilient at this broad taxonomic rank and returned to a pre-disturbed state if environmental conditions re-established. These findings highlight the diverse controls between different microbial communities within the same habitat-type, expanding our understanding of temporal dynamics in extreme ecosystems.
Using Mathematics Curriculum Material when Planning on Practicum: A Case Study of one Primary Year Three Pre-Service Teacher
(MERGA, 2022) Wilson, Susanna; Fitzallen N; Murphy C; Vesife H; Maher N
This paper describes how one third and final year pre-service (PST) used curriculum materials when planning for primary mathematics teaching on practicum. The findings are drawn from a semi-structured focus group interview, where four PSTs recalled how they planned for primary teaching during a previous practicum. This case study shows how one PST used curriculum planning documents from the practicum setting, and a teacher’s guide when planning mathematics lessons. Planning processes are also identified, and implications for associate teachers (ATs), PSTs, and mathematics Initial Teacher Educators are discussed.
Optimising Tree Responses to Root Pruning in Mature Trees: An Introduction to Some New Research
(2023) Benson A; morgenroth, justin
Experimental Validation is Always Required for Molten Oxide Electrolysis Laboratory Crucibles
(Springer Science and Business Media LLC, 2024) Ford K; Marshall, Aaron; Watson, Matthew; Bishop, Catherine
Molten oxide electrolysis (MOE) is a promising electrochemical route to de-carbonize primary and secondary metal production. Developing MOE processes starts with laboratory experiments at temperatures > 1000∘C lasting ~10 hours and requiring long heating/cooling times to protect furnace hardware. Before investigating MOE processes, crucibles must be selected that tolerate the required temperatures while minimizing chemical interactions with the oxide to control melt contamination and contain the melt. Unfortunately no general procedure guiding MOE crucible selection is documented. Here we focus on laboratory crucibles in air for two MOE melts: titania-sodia at 1100∘C and neodymia-boria at 1300∘C . After shortlisting generic crucible materials using Ashby’s method, thermodynamic predictions were made for all-oxide titania-sodia charges using FactSage and cup test experiments were conducted on (i) all-oxide and carbonate charges for titania-sodia and (ii) neodymia-boria charges. While magnesia was predicted to be the best crucible for the titania-sodia melt, alumina was the best choice for both oxide and carbonate charges. The grain boundary networks of both magnesia and YSZ were infiltrated by the oxide and carbonate charges. Platinum was the best crucible for neodymia-boria melts. We show that compositional control during long, high-temperature MOE experiments requires experimental validation for specific chemistries every time.
The role of avalanche deposition on the mass balance of Rolleston Glacier, Arthur’s Pass, New Zealand
(2024) Spera , Alison; Purdie, Heather; Kerr , Tim; Rack , Wolfgang