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Characterising the decay of organic metal complexes in speleothem-forming cave waters
No full textOrganic metal complexes (OMCs) transport trace metals (e.g., Co, Ni, Cu) from surface soils, via the unsaturated zone, to sites of cave carbonate (speleothem) formation. OMCs clearly imprint on speleothem trace element chemistry, but the role of kinetic factors in the signal transfer process has yet to be elucidated. We investigated whether OMCs may viably link metal concentrations in stalagmites and local hydrology (i.e., drip rate), via their time-sensitive dissociation (or ‘decay’) in the speleothem water thin-film. We performed competitive ligand exchange experiments using water and soil samples from eight geographically diverse Aotearoa New Zealand caves, providing a first comparative characterisation of speleothem-specific OMC kinetics. Critically, this approach corroborated that NOM ligands limit transition metal availability at the dripwater-speleothem interface, exhibiting stabilities on the order Cu ≈ Co > Ni, whereas organic complexation of the alkaline earth metals Mg and Sr was virtually absent. Systematic variations of OMC stability with natural organic matter characteristics were not observed amongst water samples, whilst enhanced complexation was clearly evident in the comparably organic-rich soil extracts. Our results imply that the supply of transition metals to speleothems is inversely related to drip rate, increasing with drip interval via the decay of OMCs. This process appears most sensitive on time-scales relevant to typical speleothem-forming settings (<0 to ca. 40 drips min‾¹, corresponding to ca. <5.6 mL min‾¹), and therefore provides a general, mechanistic link to a quantitative proxy of palaeoclimatic cave drip rates
Model simplification to simulate groundwater recharge from a perched gravel-bed river
No full textGravel-bed rivers are an important source of groundwater recharge in some regions of the world. Their interactions with groundwater are complex and highly variable in space and time, with considerable water storage in the riverbed sediments. In losing river sections, where most of the groundwater recharge occurs, the river can be separated from the regional groundwater system by an unsaturated zone (i.e., perched). The complexity of groundwater–surface water interactions in these environments calls for the use of 3D fully integrated hydrological models to represent them, but their computational intensity limits their practicality for parameter inference, uncertainty quantification and regional scale problems. On the other hand, the simple groundwater–surface water exchange functions currently implemented in regional scale groundwater models are not suited to represent complex gravel-bed river systems such as braided rivers. There is therefore a need for developing groundwater–surface water exchange functions tailored to gravel-bed rivers that can be used in regional scale models. To address this issue, we developed a model simplification framework that combines a 3D integrated surface and subsurface hydrological model, a 2D cross-sectional river-aquifer model and a 1D conductance-based analytical model. We aim at broadly simplifying the 3D model while ensuring the appropriate simulation of groundwater recharge. We demonstrate our modelling approach on the Selwyn River (New Zealand) using piezometric data and groundwater recharge estimates derived from field observations and satellite imagery. Our results indicates that groundwater recharge from this river can be simulated using a simple 1D analytical model, which can easily be implemented in regional groundwater models (e.g., MODFLOW models). However, to represent properly the time variability of groundwater recharge, it is essential to use the groundwater level in the shallow aquifer associated with the river as input to the regional groundwater model. Our approach is generally transferable to other gravel-bed rivers but requires some observations of river losses for proper calibration
A gastrointestinal parasite infection model for chronic stress in livestock and its impact on meat quality
No full textLivestock stressors are known to have an impact on both animal welfare and meat quality. As a model of acute stress, we have previously demonstrated the impact of pre-slaughter simulated mustering on several important meat quality markers in lamb, including high pH [1, 2]. To examine a chronic stressor in livestock, we have adapted a model of a sub-clinical infection with gastrointestinal nematode(GIN) parasite infection in sheep. Six month old ram lambs were challenged with a mixed infection of Trichostrongylus colubriformis and Teladorsagia circumcincta (Treatment group, n=6), which are common gastrointestinal parasites frequently encountered in pasture, and compared with those without parasites (Control, n=6) (AEC2023-71). The goal is to understand how parasite infection can impact on inflammatory response as a proxy for animal welfare, along with determining if parasite infection has an impact on meat quality markers. We will also use an emerging metabolomics method, rapid evaporative ionisation mass spectrometry, to provide complementary analytical information on changes to organ and meat metabolite and lipid composition. This data will contribute towards defining and designing further investigations on chronic stressors in livestock. In future, characterised biomarkers of stressors could be used for enhancing animal welfare and confirm the relationship between minimising pre-slaughter stressors and improving the consistency of meat quality
Pasture formulation for optimised yield and weed suppression under sheep grazing and irrigation in Canterbury
No full textFarmers need evidence to make decisions about what forage species and how much of each species to use in their pastures. This paper provides data from a study that aimed to formulate a sheep pasture from a diverse pool of six species. At Lincoln University, 69 monocultures and mixtures varying widely in sown number and proportions of perennial ryegrass, cocksfoot, plantain, white clover, red clover and subterranean clover were examined under sheep grazing for 4 years. Measured pasture functions were annual total herbage and weed yields. On average total yield increased and weed yield decreased with increases in number of species, but species’ proportions determined the optimal pasture. For example, on average six-species mixtures had 1.6 t/ha more total yield and 1.8 t/ha less weed yield than two-species mixtures (12.1 and 3.1 t/ha) at year 1. However, several pastures of equal number of species had above-average total and below-average weed yields. The pasture that maximised yield and weed suppression (14.1 and 0.3 t/ha per annum) had sown proportions of 0.5 ryegrass and 0.25 each of white and red clovers based on seed count; equivalent to 9.7, 1.3 and 9.0 kg/ha for a total sowing rate of 20 kg/ha
Can additives or controlled release coating improve the nitrogen use efficiency of urea fertiliser?
No full textA plot trial was undertaken to determine whether tactical use of nitrogen (N) fertiliser, applied with or without coating or additive, improved herbage yield and N use efficiency. A randomised complete block design was used to compare no fertiliser (CON), frequent low rates of urea (FL), infrequent moderate rates of urea (IM), IM with controlled release (IM+CR), IM with Progibb (IM+PG), IM with AgriSea (IM+AS), or IM with N-Boost (IM+NB) on irrigated, grazed perennial ryegrass and white clover dairy pastures in Canterbury. The total annual N applied in all fertilised treatments was 190 kg N/ha. The use of fertiliser increased annual herbage yield (16.9 vs 14.5±0.44 t DM/ha/y; P<0.05). Combining urea with a coating or additive altered the distribution of pasture growth but did not affect net annual production or herbage quality. Due to the lack of response and greater application costs with liquid versus granule products, these results highlight the need to consider expected responses to different fertiliser regimes when adopting practices to achieve economic benefits and N efficiency
Elucidating phosphorus removal dynamics in a denitrifying woodchip bioreactor
No full textDenitrifying woodchip bioreactors (DBRs) are an established nitrate mitigation technology, but uncertainty remains on their viability for phosphorus (P) removal due to inconsistent source-sink behaviour in field trials. We investigated whether iron (Fe) redox cycling could be the missing link needed to explain P dynamics in these systems. A pilot-scale DBR (Aotearoa New Zealand) was monitored for the first two drainage seasons (2017–2018), with supplemental in−field measurements of reduced solutes (Fe²⁺, HS⁻/H₂S) and their conjugate oxidised species (Fe³⁺/SO₄²⁻) made in 2021 to constrain within-reactor redox gradients. Consistent with thermodynamics, the dissolution of Fe³⁺(s) to Fe²⁺(aq) within the DBR sequentially followed O₂, NO₃− and MnO₂(s) reduction, but occurred before SO²‾₄ reduction. Monitoring of inlet and outlet chemistry revealed tight coupling between Fe and P (inlet R² 0.94, outlet R² 0.85), but distinct dynamics between drainage seasons. In season one, outlet P exceeded inlet P (net P source), and coincided with elevated outlet Fe²⁺, but at ⁓50 % lower P concentrations relative to inlet Fe:P ratios. In season 2 the reactor became a net P sink, coinciding with declining outlet Fe²⁺ concentrations (indicating exhaustion of Fe³⁺(s) hydroxides and associated P). In order to characterize P removal under varying source dynamics (i.e. inflows vs in-situ P releases), we used the inlet Fe vs P relationship to estimate P binding to colloidal Fe (hydr)oxide surfaces under oxic conditions, and the outlet Fe²⁺ concentration to estimate in-situ P releases associated with Fe (hydr)oxide reduction. Inferred P-removal rates were highest early in season 1 (k = 0.60 g P m³ d⁻¹; 75–100 % removal), declining significantly thereafter (k = 0.01 ± 0.02 g P m³ d⁻¹; ca. 3–67 % removal). These calculations suggest that microbiological P removal in DBRs can occur at comparable magnitudes to nitrate removal by denitrification, depending mainly on P availability and hydraulic retention efficiency
Living in two worlds: Sir Hēnare Ngata, the first Māori Public Accountant in Aotearoa New Zealand (1917-2011)
No full textSir Hēnare Ngata was the first Māori Public Accountant in New Zealand in 1949. Using a biographical approach, we explore his accounting career and the use of his knowledge of the Indigenous and Anglocentric worlds to empower his wider community. The research utilises a career-crafting theoretical framework, archival sources and unstructured, in-depth conversations and meetings conducted with family and work associates to examine his role in the Māori community and impact as an accountant.
Career crafting analysis reveals how Sir Hēnare Ngata combined Māori culture, Māori practices and beliefs with the tools of Anglocentric accounting and knowledge of Māori land law to support Māori in navigating land development, business financial requirements and policies and programmes. He made a significant contribution to mana Māori, bicultural management practices and Māori economic development. His bicultural approach combining the holistic Māori worldview and Anglocentric accounting provides rich insights for those involved in social and environmental accounting and governance reporting
Compound-specific isotope analysis as a potential approach for investigation of cerebral accumulation of docosahexaenoic acid: Previous milestones and recent trends
No full textDocosahexaenoic acid (DHA, C22:6 n-3), a predominant omega-3 polyunsaturated fatty acid in brain, plays a vital role in cerebral development and exhibits functions with potential therapeutic efects (synaptic function, neurogenesis, brain infammation regulation) in neurodegenerative diseases. The most common approaches of studying the cerebral accretion and metabolism of DHA involve the use of stable or radiolabeled tracers. Although these methods approved kinetic modeling of ratios and turnovers for fatty acids, they are associated with excessive costs, restrictive studies, and singular dosing efects. Compound-specifc isotope analysis (CSIA) is recognized as a cost-efective alternative approach for investigating DHA metabolism in vitro and in vivo. This method involves determining variations in ¹³C content to identify the sources of specific compounds. This review comprehensively discusses a summary of diferent methods and recent advancements in CSIA application in studying DHA turnover in brain. Following, the ability and applications of CSIA by using gas-chromatography combined with isotope ratio mass-spectrometry to diferentiate between natural endogenous DHA in brain and exogenous DHA are also highlighted. In general, the efciency of CSIA has been demonstrated in utilizing natural ¹³C enrichment to distinguish between the incorporation of newly synthesized or pre-existing DHA into the brain and other body tissues, eliminating the need of tracers. This review provides comprehensive knowledge, which will have potential applications in both academia and industry for advancing the understanding in neurobiology and enhancing the development of nutritional strategies and pharmaceutical interventions targeting brain health
Young people and future generations in environmental policy and planning in Aotearoa New Zealand : A dissertation submitted in partial fulfilment of the requirements for the Degree of Master of Planning
No full textThis dissertation examines how young people and future generations are taken into account in environmental policy and planning in Aotearoa New Zealand. Decisions made today will profoundly impact the lives of present young people and future generations, for instance with irreversible biodiversity loss and climate change. This raises questions of how young people and future generations are taken into account, or given voice, within environmental governance.
In this context, this research sought to examine how young people and future generations are included or represented in environmental policy and planning in Aotearoa, including identification of the institutions and mechanisms for intergenerational environmental justice. To do this, it draws on documentary analysis of 40 key pieces of environmental legislation, including the Environment Act 1986, Resource Management Act 1991, Climate Change Response Act 2002, and Local Government Act 2002, as well as national policy statements and a sampling of case law. Document analysis was supplemented with six in-depth key informant interviews to explore the strengths, challenges, and possibilities of existing practices for intergenerational environmental justice in Aotearoa.
This dissertation argues that the current system for environmental policy and planning in Aotearoa New Zealand is not sufficient to achieve intergenerational environmental justice. The research reveals an inconsistent and narrow framing of intergenerational environmental justice in key environmental legislation and policy and suggests that young people and future generations are not effectively engaged in decision-making. The analysis suggests: (1) the importance of clarifying key definitions and goals of intergenerational environmental justice and sustainable development; (2) establishing mechanisms for representation of future generations and strengthening legislation to demonstrably take them into account; and (3) explicitly recognising young people in environmental legislation, as well as improving practices to meaningfully engage with them in environmental decision-making. It also recognises the need for wider societal shifts to facilitate meaningful and enduring change
Living in two worlds: Sir Hēnare Ngata, the first Māori Public Accountant in Aotearoa New Zealand (1917-2011)
No full textSir Hēnare Ngata was the first Māori Public Accountant in New Zealand in 1949. Using a biographical approach, we explore his accounting career and the use of his knowledge of the Indigenous and Anglocentric worlds to empower his wider community. The research utilises a career-crafting theoretical framework, archival sources and unstructured, in-depth conversations and meetings conducted with family and work associates to examine his role in the Māori community and impact as an accountant.
Career crafting analysis reveals how Sir Hēnare Ngata combined Māori culture, Māori practices and beliefs with the tools of Anglocentric accounting and knowledge of Māori land law to support Māori in navigating land development, business financial requirements and policies and programmes. He made a significant contribution to mana Māori, bicultural management practices and Māori economic development. His bicultural approach combining the holistic Māori worldview and Anglocentric accounting provides rich insights for those involved in social and environmental accounting and governance reporting