title: In situ measurement of metal-ligand complex dissociation rates in cave dripwaters

authors: Guo, Xiaoli

abstract: The purpose of this study was to develop a new method for determining the trace metal binding properties of natural organic matter (NOM) in cave dripwaters. The methodology is based on the diffusive gradients in the thin-films (DGT) technique, but differs from DGT by using advective gradients along hydrogel to resolve temporal trends in dissociation. For this reason, it is referred to as advective gradients in thin-films (AGT). 
NOM is a ubiquitous component in natural waters. The complexation capacities of NOM ligands for metal ions in cave waters has a great impact on the transport of trace metals to, and their incorporation in, calcium carbonate cave deposits (speleothems). The relationship between the kinetics of metal-NOM complexes and the concentration of the metal-carbonate solid solution in actively forming cave precipitates, is the major focus in this study. The primary goal of this research is the determination of the mean kinetics of compositionally-unknown metal-NOM complexes in situ with the application of AGT.
The first part of this study was to calibrate the self-assembled AGT device containing a resin gel (for the binding of metal ions). A range of drip rates was tested to establish the relationship between drip rates and flow velocity within the gel with the aim of establishing a calibration function between drip discharge and flow rate within the gel. The second part of this study was to validate the method using metal-ligand complexes of known character. Synthetic solutions containing organic ligands at known concentrations were measured. The experimental data showed acceptable reproducibility, and the modelling results agreed well with the literature. 
After the laboratory-based study of the AGT method, the device was deployed in Aranui Cave, which is a natural cave located in the Waitomo District, New Zealand. Four transition metals were found in both resin gel samples and the water sample. The accumulation behaviour of the metals in the Chelex-100 resin gel demonstrated the capability of the AGT method to measure trace metals bound to unknown NOM ligands in cave dripwaters. The dynamics of the dissociation of metal-NOM complexes can be reflected by the distinct dissociation patterns of the metals.
This newly developed method can semi-qualitatively determine the dissociation rates of labile and partially labile metal-NOM complexes in natural waters. However, further optimisation of the method will be required to improve the precision and accuracy of measurements. In summary, this study provides the basic framework for further research of a new palaeoclimate proxy utilising trace meta-content in speleothems.

text: In situ measurement of metal-ligand complex dissociation rates in cave dripwaters The purpose of this study was to develop a new method for determining the trace metal binding properties of natural organic matter (NOM) in cave dripwaters. The methodology is based on the diffusive gradients in the thin-films (DGT) technique, but differs from DGT by using advective gradients along hydrogel to resolve temporal trends in dissociation. For this reason, it is referred to as advective gradients in thin-films (AGT). 
NOM is a ubiquitous component in natural waters. The complexation capacities of NOM ligands for metal ions in cave waters has a great impact on the transport of trace metals to, and their incorporation in, calcium carbonate cave deposits (speleothems). The relationship between the kinetics of metal-NOM complexes and the concentration of the metal-carbonate solid solution in actively forming cave precipitates, is the major focus in this study. The primary goal of this research is the determination of the mean kinetics of compositionally-unknown metal-NOM complexes in situ with the application of AGT.
The first part of this study was to calibrate the self-assembled AGT device containing a resin gel (for the binding of metal ions). A range of drip rates was tested to establish the relationship between drip rates and flow velocity within the gel with the aim of establishing a calibration function between drip discharge and flow rate within the gel. The second part of this study was to validate the method using metal-ligand complexes of known character. Synthetic solutions containing organic ligands at known concentrations were measured. The experimental data showed acceptable reproducibility, and the modelling results agreed well with the literature. 
After the laboratory-based study of the AGT method, the device was deployed in Aranui Cave, which is a natural cave located in the Waitomo District, New Zealand. Four transition metals were found in both resin gel samples and the water sample. The accumulation behaviour of the metals in the Chelex-100 resin gel demonstrated the capability of the AGT method to measure trace metals bound to unknown NOM ligands in cave dripwaters. The dynamics of the dissociation of metal-NOM complexes can be reflected by the distinct dissociation patterns of the metals.
This newly developed method can semi-qualitatively determine the dissociation rates of labile and partially labile metal-NOM complexes in natural waters. However, further optimisation of the method will be required to improve the precision and accuracy of measurements. In summary, this study provides the basic framework for further research of a new palaeoclimate proxy utilising trace meta-content in speleothems.

year: 2019

title: From rhetoric to reality: which resilience, why resilience, and whose resilience in spatial planning?

authors: White, Iain

subjects: Science & Technology

abstract: This paper analyses contrasting academic understandings of ‘equilibrium resilience’ and ‘evolutionary resilience’ and investigates how these nuances are reflected within both policy and practice. We reveal that there is a lack of clarity in policy, where these differences are not acknowledged with resilience mainly discussed as a singular, vague, but optimistic aim. This opaque political treatment of the term and the lack of guidance has affected practice by privileging an equilibrist interpretation over more transformative, evolutionary measures. In short, resilience within spatial planning is characterised by a simple return to normality that is more analogous with planning norms, engineered responses, dominant interests, and technomanagerial trends. The paper argues that, although presented as a possible paradigm shift, resilience policy and practice underpin existing behaviour and normalise risk. It leaves unaddressed wider sociocultural concerns and instead emerges as a narrow, regressive, technorational frame centred on reactive measures at the building scale.

text: From rhetoric to reality: which resilience, why resilience, and whose resilience in spatial planning? This paper analyses contrasting academic understandings of ‘equilibrium resilience’ and ‘evolutionary resilience’ and investigates how these nuances are reflected within both policy and practice. We reveal that there is a lack of clarity in policy, where these differences are not acknowledged with resilience mainly discussed as a singular, vague, but optimistic aim. This opaque political treatment of the term and the lack of guidance has affected practice by privileging an equilibrist interpretation over more transformative, evolutionary measures. In short, resilience within spatial planning is characterised by a simple return to normality that is more analogous with planning norms, engineered responses, dominant interests, and technomanagerial trends. The paper argues that, although presented as a possible paradigm shift, resilience policy and practice underpin existing behaviour and normalise risk. It leaves unaddressed wider sociocultural concerns and instead emerges as a narrow, regressive, technorational frame centred on reactive measures at the building scale.

year: 2014

title: Intersecting knowledge worlds: Describing the cultural interfaces within a socioscientific issue

authors: Wagner, Brent

subjects: cultural interface

abstract: Increasing numbers of science teachers in Aotearoa New Zealand are exploring ways to incorporate indigenous mātauranga Māori (Māori knowledge and ways of knowing) into their science programmes. This article presents findings from a study that examined how senior biology students in two English-medium secondary schools incorporated mātauranga Māori alongside biological science knowledge in their discussions about the use of 1080 poison to control mammalian predators. From a social constructivist ontology and interpretivist mode of inquiry using qualitative methodology, a triadic epistemic agency conceptual framework was developed inductively and used to analyse students’ written scripts for their national school leaving qualification (NCEA), and transcriptions of individual interviews. The study took place prior to the introduction of equal status to mātauranga Māori within the New Zealand Curriculum. Deductive analysis using the Triadic identified a group of ten students who drew from both knowledge systems, with varying degrees of knowledge integration. In addition to detailed representations of the theoretical space of the locale of the learner, the findings also identified three distinctive cultural interfaces occupied by the students: conflicted, parallel, and, connected. The findings underscore the importance of enabling diverse knowledge systems in biology classes to converge. Specifically, the incorporation of mātauranga Māori alongside biological science knowledge encourages a critical stance towards knowledge claims, supports pluralist knowledge use among culturally and linguistically diverse learners and promotes critical engagement with socioscientific issues (SSI) in senior secondary school biology.

text: Intersecting knowledge worlds: Describing the cultural interfaces within a socioscientific issue Increasing numbers of science teachers in Aotearoa New Zealand are exploring ways to incorporate indigenous mātauranga Māori (Māori knowledge and ways of knowing) into their science programmes. This article presents findings from a study that examined how senior biology students in two English-medium secondary schools incorporated mātauranga Māori alongside biological science knowledge in their discussions about the use of 1080 poison to control mammalian predators. From a social constructivist ontology and interpretivist mode of inquiry using qualitative methodology, a triadic epistemic agency conceptual framework was developed inductively and used to analyse students’ written scripts for their national school leaving qualification (NCEA), and transcriptions of individual interviews. The study took place prior to the introduction of equal status to mātauranga Māori within the New Zealand Curriculum. Deductive analysis using the Triadic identified a group of ten students who drew from both knowledge systems, with varying degrees of knowledge integration. In addition to detailed representations of the theoretical space of the locale of the learner, the findings also identified three distinctive cultural interfaces occupied by the students: conflicted, parallel, and, connected. The findings underscore the importance of enabling diverse knowledge systems in biology classes to converge. Specifically, the incorporation of mātauranga Māori alongside biological science knowledge encourages a critical stance towards knowledge claims, supports pluralist knowledge use among culturally and linguistically diverse learners and promotes critical engagement with socioscientific issues (SSI) in senior secondary school biology.

year: 2026