Massey Documents by Type

Permanent URI for this communityhttps://mro.massey.ac.nz/handle/10179/294

Browse

Has files: YesSubject: search.filters.subject.Mercury

Search Results

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    Multidimensional trace metals and nutritional niche differ between sexually immature and mature common dolphins (Delphinus delphis)
    (Elsevier Ltd., 2023-06-26) Stockin KA; Machovsky-Capuska GE; Palmer EI; Amiot C
    There is a need to understand the links between metals and nutrition for apex marine predators, which may be subject to different ecotoxicological effects at different life stages. We combined stomach content analyses (SCA), prey composition analysis (PCA), the Multidimensional Niche Framework (MNNF) with Bayesian multivariate ellipses, trace metal analysis and nicheROVER to investigate nutrition and trace metals across sex, age, and sexual maturity status in common dolphins (Delphinus delphis) from New Zealand. A broader prey composition niche breadth (SEAc) was estimated for immature compared to mature conspecifics, showing a higher degree of prey and nutrient generalism driven by protein (P) intake. Cd and Zn niche similarities suggests these metals were incorporated through similar prey in both immature and mature dolphins, whereas Hg and Se niche divergence indicates uptake occurred via different prey. Our multidisciplinary assessment demonstrated how nutrients and metal interactions differ in common dolphins depending upon sexual maturity. This approach has relevance when considering how marine pollution, environmental fluctuations and climate change may affect nutritional and trace metal interactions during different reproductive stages within marine predators.
  • Thumbnail Image
    Item
    Mercury elimination in artisanal and small scale gold mining : progress and barriers in implementing national action plan to eliminate mercury in Indonesia (case study : Banyumas regency) : a thesis presented in partial fulfilment of the requirements for the degree of Master in Environmental Management at Massey University, Manawatū, New Zealand
    (Massey University, 2017) Octaviano, Hernandi Albeto
    The artisanal and small-scale gold mining (ASGM) sector is one of the main contributors of mercury emissions Indonesia. As a result of the participation of Indonesia in the Minamata Convention on Mercury, Indonesia established the national action plan (NAP) to eliminate mercury in ASGM that started in 2014 and ends in 2018. To date, there is no report or study that discusses the implementation progress of the NAP. The aim of this research is to investigate the progress of the NAP to eliminate mercury in ASGM in Indonesia. In addition, the study aims to identify barriers for implementation of the NAP. The research in this thesis is a qualitative research that utilises a case study method, in order to gain a deep insight into how stakeholders implement the NAP. Banyumas regency is taken as the case study, since the area has extensive ASGM activities, which emit a high level of mercury into the environment. The primary data for this research is gathered through semi-structured interviews, while secondary data is obtained from institution reports, newspaper articles and government websites. The findings of this research have identified several action plans, for example: the establishment of a stakeholder’s forum at national level; a study on alternative technology; health effects and environmental tests; and training for the miners, which were all undertaken according to the NAP. However, other action plans, for example, regulations regarding formalisation of ASGM; a mercury database; alternative livelihood training; and mercury awareness included in the education curriculum are progressing slowly. In addition, there are four barriers that hinder the implementation of the NAP: institutional barriers (lack of resources, political will and poor coordination); policy barriers (lack of legal formalisation framework and policy support); technical barriers (lack of supporting tools, lack of information on ASGM and miners’ involvement, low level of trust in alternative technology and location difficulties) and socio-economic barriers (miners’ beliefs and social conditions). This research proposes several recommendations to improve the progress of the NAP and to reduce barriers toward implementation, such as improvement in financial availability by cooperating with other actors such as Bappenas, to secure the funding for the implementation of NAP and regulations improvement; strengthening the implementation of NAP by appointing leading ministries such as Coordinating Ministries of Maritime affairs to coordinate the implementation of NAP and adding participation of other actor such as academics to participate in the NAP; and developing approaches and tools to disseminate information. Keywords: artisanal and small-scale gold mining, ASGM, mercury, national action plan, implementation, barriers, Indonesia.
  • Thumbnail Image
    Item
    The electrochemical deposition of mercury on glassy carbon electrodes : a thesis in partial fulfilment of the requirements for the degree of Masters in Science in Chemistry at Massey University, Palmerston North, New Zealand
    (Massey University, 2000) Moretto, Giovanna Lucia
    The mechanism for the reduction of Hg2+ on glassy carbon in aqueous acetate and nitrate electrolyte was studied. This deposition process is of interest due to the wide electroanalytical applications of mercury thin film electrodes. It was found in the early stages of this work that even though the use of these electrodes is wide spread, there has been little investigation into how the deposition stage occurs. The electrochemical techniques used were cyclic voltammetry and chronoamperometry. A range of experiments were undertaken including concentration dependence, rotation dependence, scan rate dependence, electrochemical-cleaning, and the dependence of the length of time left at open potential. The acetate experiments were carried out at a constant pH of 5.0 and all experiments were carried out at a constant temperature of 20°C. Significant dependence was established in the cyclic voltammetry work for all the experimental conditions. In acetate electrolyte the development of peaks C1 and C2 were seen after cycling of the electrode without mechanical-cleaning. A shift in the reduction potential from a mechanically-cleaned electrode cycle to the next cycle without intervening cleaning was also observed. Two new anodic peaks, A2 and A3, were also seen in acetate electrolyte. At high concentrations cathodic current spikes were observed at the extreme cathodic limits of the voltammograms. The response that was observed in nitrate electrolyte was dissimilar to that in acetate. The shift in reduction potential, current spikes, peaks C1, C2, A2, and A3, were never observed for the deposition of Hg2+ in nitrate electrolyte. The chronoamperometry work on microelectrodes led to a number of new phenomena. Transients that were obtained from these experiments lead to the development of a quantitative nucleation and growth model for the growth of hemispherical mercury droplets. At the onset of reduction the transients follow a t2 function which is in accordance with surface area dependence growth of the droplet. However, after a short length of time, the transients start to follow a function of t 1/2, which is suggestive of perimeter growth control. This is assumed to be due to the formation of a semi-passivating Hg2(OAc)2 film over the mercury droplet where Hg2+2 forms as a result of a disproportionation reaction. A qualitative model was also developed to account for the observations of both the microelectrode results and most of the features seen in the cyclic voltammetry work.
  • Thumbnail Image
    Item
    Entanglements and disentanglements : a posthuman approach to mercury use in artisanal and small-scale gold mining in Antioquia, Colombia : a thesis presented in partial fulfilment of the requirements for the degree of Master of Arts in Social Anthropology at Massey University, Palmerston North, New Zealand
    (Massey University, 2016) Robertson, Thomas Jonathan
    This research uses qualitative research techniques and posthuman theories to investigate the dynamic relationship between artisanal and small-scale gold miners and mercury in the context of Antioquia, Colombia. This is done to contribute to understandings of, and inform potential solutions for, the global environmental problem that is mercury pollution from artisanal and small-scale gold mining (ASGM). Miners come to know mercury through practices, and through these practices, mercury comes to be co-constitutive of an informal ASGM industry. Mercury provides an easy yet profitable mode of gold extraction with limited capital expenditure. Eliminating the use of mercury means a re-constitution of ASGM as a formal industry with higher levels of capital investment, new actors and a shift to a more representational approach to knowing materials. The use of toxic mercury and an increase in the enforcement of mining legislation are framing miners as illegal. Formal, responsible mining is becoming a dominant reality, and informal miners who resent being labelled illegal are working to transition to this reality. Miners’ experiences of this transition vary greatly, and this variation can be explored through the lens of ecological habitus. Many miners are using mercury elimination to perform good citizenship by mining responsibly, introducing a performative aspect to formalisation. Nevertheless, miners still face significant challenges to formalisation. As a result, many miners have had to become subcontractors for large-scale mining companies, entering exploitative relationships with which mercury, through its absence, is complicit. Taking this approach towards understanding the relationship between miners and mercury has helped to resolve the conflict between material and social deterministic views of the practice of mercury use, and linked mercury to a wider political context, which is a necessary consideration for a collaborative approach with miners to eliminate mercury. Keywords: Artisanal and small-scale gold mining; ASGM; mercury; Colombia; anthropology; posthumanism; entanglements; politics of materiality; performativity; informality.
  • Thumbnail Image
    Item
    Mercury clusters from van der Waals to the metallic solid : a thesis presented in partial fulfillment of the requirements of the degree of Doctor of Philosophy in Theoretical Chemistry at Massey University, Albany, New Zealand
    (Massey University, 2003) Gaston, Nicola
    The nature of mercury clusters is studied in an attempt to reconcile the behaviour of the solid with that of the smallest molecules. Related systems such as Zn, Cd, and Ba are investigated for comparison. A range of ab initio methods are employed, and their accuracy assessed. Density functional theory (DFT) based methods are shown to be unreliable. Different functionals vary widely in their description of a particular system, such as the dimer, while individual functionals vary in accuracy when applied across a range of system sizes. This is related to the neglect of van der Waals forces by DFT for the smaller systems, but raises interesting questions about the solid. Wavefunction-based methods are seen to be much more reliable than DFT, although a high-level description of correlation is required. Hartree-Fock (HF) calculations are shown to be consistent in their description of systems of all sizes, and therefore although inadequate on its own the addition of a correlation potential derived from the many-body perturbational (MP2) calculation for the dimer corrects HF to produce exactly the correct bond lengths (when compared to the best known data) for all sizes up to the bulk lattice. The use of higher order many-body potentials is investigated and compared to the situation observed for the noble gases, since for small sizes these are the closest analogues of the neutral mercury clusters. The question of how to simulate transitions in large clusters is addressed. Transitions of interest in clusters are the liquid to solid phase transition, the metal to non-metal transition, or a structural transition from one isomeric motif to another. Therefore the ability to calculate the properties of these clusters accurately is as important as the question of structure. Four-component DFT calculations for the mercury dimer polarisability agree well with the anisotropy derived from Raman spectroscopy. Various isomers proposed in the literature are compared for the smaller mercury clusters. The structures of cationic clusters are also optimised, and their electronic excitation spectra are investigated through CIS(D) and TD-DFT calculations and compared to experimental results. The structures of anionic zinc clusters are obtained and the density of states compared with experiment. The structures and spectra of these clusters are related to those seen for the magnesium analogues, and the effect of the d-electrons in perturbing the jellium model description of these clusters is considered.