title: Using undrained cyclic triaxial tests to examine liquefaction resistance of historically liquefied pumiceous volcanic-ash soil materials and back-estimate prehistoric earthquakes.

authors: Chaneva, Jordanka

subjects: Hamilton Basin faults

abstract: Back-analysis of ground motion characteristics, such as earthquake magnitude and peak ground accelerations, in paleoliquefaction studies are most commonly based on empirical CPT- and/or SPT-based correlations that estimate the liquefaction resistance of soil materials of relevance. Laboratory triaxial cyclic tests have not been explored for this purpose to date. Our study investigates the liquefaction resistance of three different beds (with differing grain-size distributions and pumice content) of a single rhyolitic (high-silica) volcanic-ash layer, referred to as Mamaku tephra, that was deposited ~8000 calendar years ago and preserved in lake sediments in multiple extant lakes in the Hamilton lowlands, North Island, New Zealand. 

Paleoliquefaction features observed in the silty and sandy beds of the Mamaku tephra indicate seismic activity in the past. With our main aim being to back-analyse potential prehistoric earthquakes that might have caused the paleoliquefaction features in Mamaku tephra (and other lacustrine tephras), the following steps were taken: 
(1) the liquefaction resistance of the three Mamaku tephra beds with different grain sizes and pumice contents from one site (Lake Areare, northern Hamilton lowlands) was investigated using undrained cyclic triaxial testing;
(2) a framework extending the laboratory liquefaction resistance results of the tested Mamaku beds at Lake Areare to other Mamaku tephra deposits in the lake sediments across the lowlands was proposed; and 
(3) the equivalent peak ground acceleration and earthquake magnitude that would have caused liquefaction of all the lacustrine Mamaku tephra deposits across the lowlands (in 13 lakes) were estimated using available empirical correlation methods. A discussion about the limitations of the proposed framework alongside the qualitative implications on the results is also provided. It was found that the Mamaku tephra deposits are very vulnerable to liquefaction and require very low triggering peak ground acceleration to liquefy, i.e., amax in the range between 0.02 and 0.08 g through the range of magnitudes, M = 5–8.5.

text: Using undrained cyclic triaxial tests to examine liquefaction resistance of historically liquefied pumiceous volcanic-ash soil materials and back-estimate prehistoric earthquakes. Back-analysis of ground motion characteristics, such as earthquake magnitude and peak ground accelerations, in paleoliquefaction studies are most commonly based on empirical CPT- and/or SPT-based correlations that estimate the liquefaction resistance of soil materials of relevance. Laboratory triaxial cyclic tests have not been explored for this purpose to date. Our study investigates the liquefaction resistance of three different beds (with differing grain-size distributions and pumice content) of a single rhyolitic (high-silica) volcanic-ash layer, referred to as Mamaku tephra, that was deposited ~8000 calendar years ago and preserved in lake sediments in multiple extant lakes in the Hamilton lowlands, North Island, New Zealand. 

Paleoliquefaction features observed in the silty and sandy beds of the Mamaku tephra indicate seismic activity in the past. With our main aim being to back-analyse potential prehistoric earthquakes that might have caused the paleoliquefaction features in Mamaku tephra (and other lacustrine tephras), the following steps were taken: 
(1) the liquefaction resistance of the three Mamaku tephra beds with different grain sizes and pumice contents from one site (Lake Areare, northern Hamilton lowlands) was investigated using undrained cyclic triaxial testing;
(2) a framework extending the laboratory liquefaction resistance results of the tested Mamaku beds at Lake Areare to other Mamaku tephra deposits in the lake sediments across the lowlands was proposed; and 
(3) the equivalent peak ground acceleration and earthquake magnitude that would have caused liquefaction of all the lacustrine Mamaku tephra deposits across the lowlands (in 13 lakes) were estimated using available empirical correlation methods. A discussion about the limitations of the proposed framework alongside the qualitative implications on the results is also provided. It was found that the Mamaku tephra deposits are very vulnerable to liquefaction and require very low triggering peak ground acceleration to liquefy, i.e., amax in the range between 0.02 and 0.08 g through the range of magnitudes, M = 5–8.5.

year: 2025

title: ¹⁵N stable isotope probing of pulp and paper wastewaters

authors: Addison, Sarah Louise

subjects: Stable isotope probing

abstract: Stable isotope probing (SIP) is an established technique that can be applied to identify the metabolically active micro-organisms within a microbial population. The SIP method utilises an isotopically-labelled substrate and PCR techniques to discern the members of a microbial community that incorporate the isotope into their DNA or RNA. The current literature gap around using ¹⁵N isotopes with RNA-SIP offers real potential and advantages for targeting and identifying active members from mixed communities involved in global biogeochemical nitrogen cycling.

This study specifically investigated whether nitrogen based compounds ncan be used as substrates in RNA-SIP methodologies and whether they can in turn be used to probe mixed community environments known to be actively fixing nitrogen. The nitrogen-limited systems targeted represented an ideal opportunity to assess the suitability of ¹⁵N-RNA-SIP approaches due to their known high nitrogen fixation rates. Identifying these nitrogen-fixing bacteria could provide a better representation analysis of the community, leading to an improved prediction on how to manage and optimise the treatment performance of target waste systems and to exploit the unique bioconversion properties of these types of organisms.

Initially, the project undertook methodological proof of concept by using a soluble nitrogen source, ¹⁵NH₄Cl, to label the RNA of Novosphingobium nitrogenifigens and a mixed microbial community. Successful separation of the ¹⁴N- (control) and ¹⁵N-RNA was achieved for both pure and mixed communities using isopycnic caesium trifluoroacetate (CsTFA) gradients in an ultracentrifuge. The usefulness of this technique to identify active diazotrophs in real environmental samples was tested using a nitrogen-fixing community from a pulp and paper wastewater treatment system. After growing the mixed culture with ¹⁵N₂ as the sole nitrogen source, the labelled RNA was extracted and fractionated using isopycnic centrifugation in CsTFA gradients.

The community composition of the active nitrogen-fixing community in the ¹⁵N₂ enriched fraction was analysed by establishing a 16S rRNA gene clone library containing over 200 members. These were analysed by comparison with published sequences and by phylogenetic analysis.

It was found that the more isotopic label substrate incorporated, the further the buoyant density (BD) separation between ¹⁵N- and ¹⁴N-RNA. Novosphingobium nitrogenifigens gave an average BD shift of 0.03 + 0.004 g ml⁻¹ (95.0 atom % ¹⁵N) with ¹⁵NH₄Cl. For mixed communities the average BD shift was 0.02 + 0.004 g ml⁻¹ (80.0 atom % ¹⁵N) with 15NH4Cl and 0.013 + 0.002 g ml⁻¹ (32.6 atom % ¹⁵N) when using ¹⁵N₂. Clone library analysis of 16S rRNA genes present in the enriched ¹⁵N-RNA fraction of the mixed community was shown to consist of a diverse population of bacteria as indicated by a Shannon Weaver index value of >2.8. Three dominant genera (Aeromonas, Pseudomonas and Bacillus) were identified by comparison with published sequences and phylogenetic analysis. Many other groups not known as archetypal nitrogen-fixing bacteria were also identified, demonstrating that ¹⁵N₂-RNA-SIP provides a useful tool for the identification of important and previously unknown contributors to nitrogen fixation in a range of environments.

Overall, this project has established that nitrogen based RNA-SIP is a powerful tool that can be used successfully and reproducibly with both pure and complex mixed microbial communities to study active diazotrophs in environmental samples.

text: ¹⁵N stable isotope probing of pulp and paper wastewaters Stable isotope probing (SIP) is an established technique that can be applied to identify the metabolically active micro-organisms within a microbial population. The SIP method utilises an isotopically-labelled substrate and PCR techniques to discern the members of a microbial community that incorporate the isotope into their DNA or RNA. The current literature gap around using ¹⁵N isotopes with RNA-SIP offers real potential and advantages for targeting and identifying active members from mixed communities involved in global biogeochemical nitrogen cycling.

This study specifically investigated whether nitrogen based compounds ncan be used as substrates in RNA-SIP methodologies and whether they can in turn be used to probe mixed community environments known to be actively fixing nitrogen. The nitrogen-limited systems targeted represented an ideal opportunity to assess the suitability of ¹⁵N-RNA-SIP approaches due to their known high nitrogen fixation rates. Identifying these nitrogen-fixing bacteria could provide a better representation analysis of the community, leading to an improved prediction on how to manage and optimise the treatment performance of target waste systems and to exploit the unique bioconversion properties of these types of organisms.

Initially, the project undertook methodological proof of concept by using a soluble nitrogen source, ¹⁵NH₄Cl, to label the RNA of Novosphingobium nitrogenifigens and a mixed microbial community. Successful separation of the ¹⁴N- (control) and ¹⁵N-RNA was achieved for both pure and mixed communities using isopycnic caesium trifluoroacetate (CsTFA) gradients in an ultracentrifuge. The usefulness of this technique to identify active diazotrophs in real environmental samples was tested using a nitrogen-fixing community from a pulp and paper wastewater treatment system. After growing the mixed culture with ¹⁵N₂ as the sole nitrogen source, the labelled RNA was extracted and fractionated using isopycnic centrifugation in CsTFA gradients.

The community composition of the active nitrogen-fixing community in the ¹⁵N₂ enriched fraction was analysed by establishing a 16S rRNA gene clone library containing over 200 members. These were analysed by comparison with published sequences and by phylogenetic analysis.

It was found that the more isotopic label substrate incorporated, the further the buoyant density (BD) separation between ¹⁵N- and ¹⁴N-RNA. Novosphingobium nitrogenifigens gave an average BD shift of 0.03 + 0.004 g ml⁻¹ (95.0 atom % ¹⁵N) with ¹⁵NH₄Cl. For mixed communities the average BD shift was 0.02 + 0.004 g ml⁻¹ (80.0 atom % ¹⁵N) with 15NH4Cl and 0.013 + 0.002 g ml⁻¹ (32.6 atom % ¹⁵N) when using ¹⁵N₂. Clone library analysis of 16S rRNA genes present in the enriched ¹⁵N-RNA fraction of the mixed community was shown to consist of a diverse population of bacteria as indicated by a Shannon Weaver index value of >2.8. Three dominant genera (Aeromonas, Pseudomonas and Bacillus) were identified by comparison with published sequences and phylogenetic analysis. Many other groups not known as archetypal nitrogen-fixing bacteria were also identified, demonstrating that ¹⁵N₂-RNA-SIP provides a useful tool for the identification of important and previously unknown contributors to nitrogen fixation in a range of environments.

Overall, this project has established that nitrogen based RNA-SIP is a powerful tool that can be used successfully and reproducibly with both pure and complex mixed microbial communities to study active diazotrophs in environmental samples.

year: 2008

title: Social deprivation in New Zealand

authors: Harcourt, Brian James

subjects: Deprivation

abstract: The purpose of the thesis was to better understand the phenomenon of social deprivation, world-wide and in particular in New Zealand. Social deprivation has been defined in many ways with multiple surrogates used to ‘measure’ its prevalence. The aim of this research was to provide examples of the lived experiences of social deprivation.

Social constructivist and interpretive lenses were used to portray the voices of those living in deprivation, as well as those people tasked to assist them. A narrative case study approach was employed with participants from Whānau Ora. This social and health initiative offered a holistic approach to assistance in contrast to the usual State agencies operating in a silo fashion, with separate agencies providing for different aspects of social deprivation such as housing, employment, mental health and other services. The approach of Whānau Ora is to support clients’ needs holistically and encourage people to develop their own plans for self- improvement. Navigators help people develop their plans and assist in their interactions with the various State agencies whose services they require. This approach allowed a better understanding of ways to overcome people’s feelings of powerlessness and desperation.

The findings from the study lead to suggestions for the application of evidence-based, complementary, integrated assistance programmes rather than having segregated public service agencies acting independently. The recommendations are simple yet require profound changes in public service operations when attempting to ameliorate or prevent social deprivation among citizens.

text: Social deprivation in New Zealand The purpose of the thesis was to better understand the phenomenon of social deprivation, world-wide and in particular in New Zealand. Social deprivation has been defined in many ways with multiple surrogates used to ‘measure’ its prevalence. The aim of this research was to provide examples of the lived experiences of social deprivation.

Social constructivist and interpretive lenses were used to portray the voices of those living in deprivation, as well as those people tasked to assist them. A narrative case study approach was employed with participants from Whānau Ora. This social and health initiative offered a holistic approach to assistance in contrast to the usual State agencies operating in a silo fashion, with separate agencies providing for different aspects of social deprivation such as housing, employment, mental health and other services. The approach of Whānau Ora is to support clients’ needs holistically and encourage people to develop their own plans for self- improvement. Navigators help people develop their plans and assist in their interactions with the various State agencies whose services they require. This approach allowed a better understanding of ways to overcome people’s feelings of powerlessness and desperation.

The findings from the study lead to suggestions for the application of evidence-based, complementary, integrated assistance programmes rather than having segregated public service agencies acting independently. The recommendations are simple yet require profound changes in public service operations when attempting to ameliorate or prevent social deprivation among citizens.

year: 2019