title: Ecotoxicological review of alum applications to the Rotorua Lakes

authors: Tempero, Grant Wayne

abstract: The use of alum (aluminium sulphate) has become a recognised technique for the restoration of freshwater systems. When added to water, alum dissociates and dissolved aluminium undergoes a series of hydrolysis reactions resulting in the formation of aluminium hydroxide (Al(OH)₃) which adsorbs dissolved phosphorus and coagulates suspended solids. The resulting flocculent sequesters dissolved and particulate phosphorus, reducing primary production, thereby improving water clarity.
Aluminium hydroxide is a relatively benign substance with peak abundance occurring at pH 6.3; above and below this point, soluble, more toxic aluminium species predominate. For example, under alkaline conditions (>pH 8.5) toxic Al(OH4)⁻ forms, while below pH 4.5 free monomeric aluminium (Al³⁺) becomes prevalent. The hydrolysis reaction of aluminium (Al) causes the release of H⁺, lowering pH and potentially causing the formation of toxic aluminium species. It is therefore critical that application rates do not exceed the buffering capacity of the treated system. In addition, eutrophic systems often experience photosynthetic driven alkaline pH shifts, resulting in Al solubilisation and the formation of the toxic Al species (Al(OH)₄⁻).
The Bay of Plenty Regional Council has initiated several alum dosing programmes in the Rotorua lakes district in an effort to reduce lake trophic levels. Currently, continuous alum dosing is undertaken on the Puarenga and Utuhina Streams discharging to Lake Rotorua and the Waitangi Soda Stream discharging to Lake Rotoehu. In addition, seven discrete alum applications have been conducted on Lake Okaro since 2003. This has resulted in the total applications of 444.2, 55.2, and 2.8 tonnes of Al to lakes Rotorua, Rotoehu and Okaro respectively. Current estimated continuous lake water dose rates for Lake Rotoehu 6.72 µg Al l-1 and Lake Rotorua 2.62 µg Al l⁻¹ are low by international standards and the estimated maximum dose applied to Lake Okaro of 0.22 mg Al l⁻¹ lake water was also conservative.
A literature review was undertaken to provide guidance on a number of concerns associated with alum dosing of the Rotorua lakes. This includes; (1) the likely concentration thresholds for acute toxicological effects from Al dosing and whether current dosing programmes are likely to exceed them; (2) the fate of flocculated Al in lake sediments and whether they pose an ecological hazard; (3) the risk of the buffering capacity of water in the Rotorua lakes being exceeded leading to release of toxic Al species; and (4) the risk to biota of burial by Alfloc and its potential to disrupt lake processes.
The toxicity of Al is closely associated with pH, and acute toxic effects are likely to be a combination of physiological responses to both acidic pH and Al. Fish appear to be the most susceptible group to Al toxicity with respiratory disruption initially occurring at pH 6.0 due to gill irritation by colloidal Al. This is followed by increasing levels of osmoregulatory disruption peaking at pH 3.0 where Al³⁺ is the predominant species. Toxic effects may also manifest under alkaline conditions (pH >8.5), and although the precise mechanism is unknown it is theorised that the gills may be the primary site of action. As well as pH, susceptibility to Al toxicity is dependent on a number of factors including species, life stage, and even whether the organism has had previously exposure to Al. In addition, a number of chemical components have an ameliorating influence; foremost amongst these are dissolved organic matter (DOM), silica and calcium concentrations.

text: Ecotoxicological review of alum applications to the Rotorua Lakes The use of alum (aluminium sulphate) has become a recognised technique for the restoration of freshwater systems. When added to water, alum dissociates and dissolved aluminium undergoes a series of hydrolysis reactions resulting in the formation of aluminium hydroxide (Al(OH)₃) which adsorbs dissolved phosphorus and coagulates suspended solids. The resulting flocculent sequesters dissolved and particulate phosphorus, reducing primary production, thereby improving water clarity.
Aluminium hydroxide is a relatively benign substance with peak abundance occurring at pH 6.3; above and below this point, soluble, more toxic aluminium species predominate. For example, under alkaline conditions (>pH 8.5) toxic Al(OH4)⁻ forms, while below pH 4.5 free monomeric aluminium (Al³⁺) becomes prevalent. The hydrolysis reaction of aluminium (Al) causes the release of H⁺, lowering pH and potentially causing the formation of toxic aluminium species. It is therefore critical that application rates do not exceed the buffering capacity of the treated system. In addition, eutrophic systems often experience photosynthetic driven alkaline pH shifts, resulting in Al solubilisation and the formation of the toxic Al species (Al(OH)₄⁻).
The Bay of Plenty Regional Council has initiated several alum dosing programmes in the Rotorua lakes district in an effort to reduce lake trophic levels. Currently, continuous alum dosing is undertaken on the Puarenga and Utuhina Streams discharging to Lake Rotorua and the Waitangi Soda Stream discharging to Lake Rotoehu. In addition, seven discrete alum applications have been conducted on Lake Okaro since 2003. This has resulted in the total applications of 444.2, 55.2, and 2.8 tonnes of Al to lakes Rotorua, Rotoehu and Okaro respectively. Current estimated continuous lake water dose rates for Lake Rotoehu 6.72 µg Al l-1 and Lake Rotorua 2.62 µg Al l⁻¹ are low by international standards and the estimated maximum dose applied to Lake Okaro of 0.22 mg Al l⁻¹ lake water was also conservative.
A literature review was undertaken to provide guidance on a number of concerns associated with alum dosing of the Rotorua lakes. This includes; (1) the likely concentration thresholds for acute toxicological effects from Al dosing and whether current dosing programmes are likely to exceed them; (2) the fate of flocculated Al in lake sediments and whether they pose an ecological hazard; (3) the risk of the buffering capacity of water in the Rotorua lakes being exceeded leading to release of toxic Al species; and (4) the risk to biota of burial by Alfloc and its potential to disrupt lake processes.
The toxicity of Al is closely associated with pH, and acute toxic effects are likely to be a combination of physiological responses to both acidic pH and Al. Fish appear to be the most susceptible group to Al toxicity with respiratory disruption initially occurring at pH 6.0 due to gill irritation by colloidal Al. This is followed by increasing levels of osmoregulatory disruption peaking at pH 3.0 where Al³⁺ is the predominant species. Toxic effects may also manifest under alkaline conditions (pH >8.5), and although the precise mechanism is unknown it is theorised that the gills may be the primary site of action. As well as pH, susceptibility to Al toxicity is dependent on a number of factors including species, life stage, and even whether the organism has had previously exposure to Al. In addition, a number of chemical components have an ameliorating influence; foremost amongst these are dissolved organic matter (DOM), silica and calcium concentrations.

year: 2015

title: The impact of work experience on subsequent career outcomes of New Zealand university graduates

authors: Tutbury, Alicia Anne

subjects: Student work experience impact on subsequent career outcomes

abstract: The principal objective of this study was to ascertain whether career outcome differences exist between recent university graduates who have had differing types of work experience while completing their studies. Specifically, comparisons were made between graduates who had no work experience at all while studying (the ‘None’ group), those who had work experience unrelated to their degree (the ‘Unrelated’ group) and those who gained work experience that was related to what they were studying at university (the ‘Related’ group).
   Participants were drawn from alumni organisations and various websites including social media. Participants completed an online questionnaire which measured five distinct constructs: job satisfaction, career satisfaction, life satisfaction, affective organisational commitment and person organisation fit. Participants were also asked to report on their university and employment history, their current employment and their demographics. The final sample consisted of 130 participants, an overall response rate of 48.5%. Following a factor analysis, a series of one way ANOVA’s were conducted on the three groups and the above
variables.
   The most notable finding was that graduates who had related work experience were more likely to have both applied for fewer jobs and started on a higher salary after entering the employment market than those who had no work
experience at all. These graduates also felt significantly more prepared for employment, felt that their current employment was appropriate to their level of education and were more likely to report that the work experience they gained while studying was an important factor in successfully acquiring their first job as well as being useful in finding a ‘satisfying job’. These graduates were more likely to be employed full time and have a job requiring a qualification or some form of formal training than both those graduates who had unrelated work experience or no work experience. Finally, the results indicate that graduates who felt their current employment was appropriate to their level of education, regardless of the type of work experience they gained, were more likely to have higher scores on the five constructs.
   The results presented in this study revealed a number of significant differences between the three groups, thereby supporting the research rationale, and indicating that working while completing a university degree does have certain benefits for recent university graduates. This study has provided new evidence in an area lacking in research and becoming increasingly important as rising numbers of young people in New Zealand are achieving qualifications at universities. Students who did not work while at university had fewer opportunities available to them when entering the labour market. Therefore, the practical implications for future university graduates are far reaching as students can see, post graduation, the benefits for combining work and study.
   Longitudinal research into the relationship between student work experience and graduate career outcomes is recommended in order to examine the continued influence that work experience could have on areas such as wage raises and career progression. Investigation into employer’s thoughts and perceptions of university graduates with no, unrelated or related work experiences would be valuable to gauge exactly what employers look for when hiring university
graduates, how they rate students who have no work experience in comparison to those who do and the extent that these differing work experiences could impact a job applicant’s employment possibilities.

text: The impact of work experience on subsequent career outcomes of New Zealand university graduates The principal objective of this study was to ascertain whether career outcome differences exist between recent university graduates who have had differing types of work experience while completing their studies. Specifically, comparisons were made between graduates who had no work experience at all while studying (the ‘None’ group), those who had work experience unrelated to their degree (the ‘Unrelated’ group) and those who gained work experience that was related to what they were studying at university (the ‘Related’ group).
   Participants were drawn from alumni organisations and various websites including social media. Participants completed an online questionnaire which measured five distinct constructs: job satisfaction, career satisfaction, life satisfaction, affective organisational commitment and person organisation fit. Participants were also asked to report on their university and employment history, their current employment and their demographics. The final sample consisted of 130 participants, an overall response rate of 48.5%. Following a factor analysis, a series of one way ANOVA’s were conducted on the three groups and the above
variables.
   The most notable finding was that graduates who had related work experience were more likely to have both applied for fewer jobs and started on a higher salary after entering the employment market than those who had no work
experience at all. These graduates also felt significantly more prepared for employment, felt that their current employment was appropriate to their level of education and were more likely to report that the work experience they gained while studying was an important factor in successfully acquiring their first job as well as being useful in finding a ‘satisfying job’. These graduates were more likely to be employed full time and have a job requiring a qualification or some form of formal training than both those graduates who had unrelated work experience or no work experience. Finally, the results indicate that graduates who felt their current employment was appropriate to their level of education, regardless of the type of work experience they gained, were more likely to have higher scores on the five constructs.
   The results presented in this study revealed a number of significant differences between the three groups, thereby supporting the research rationale, and indicating that working while completing a university degree does have certain benefits for recent university graduates. This study has provided new evidence in an area lacking in research and becoming increasingly important as rising numbers of young people in New Zealand are achieving qualifications at universities. Students who did not work while at university had fewer opportunities available to them when entering the labour market. Therefore, the practical implications for future university graduates are far reaching as students can see, post graduation, the benefits for combining work and study.
   Longitudinal research into the relationship between student work experience and graduate career outcomes is recommended in order to examine the continued influence that work experience could have on areas such as wage raises and career progression. Investigation into employer’s thoughts and perceptions of university graduates with no, unrelated or related work experiences would be valuable to gauge exactly what employers look for when hiring university
graduates, how they rate students who have no work experience in comparison to those who do and the extent that these differing work experiences could impact a job applicant’s employment possibilities.

year: 2013

title: Safety hubs and partnership policing: Coordination, collaboration and partnership working in Auckland city centre

authors: Tompson, Lisa

subjects: Community Safety

abstract: This report presents key insights from an exploratory study of the Safety Hub initiative that first appeared in the run up to the 2023 Women’s World Cup in Auckland. It highlights the potential and the pitfalls of partnership-based approaches to community safety in Aotearoa New Zealand. The study was based on a series of in-person focus group discussions and semi-structured interviews with key partners and stakeholders including Community Patrols New Zealand (CPNZ) volunteers, NZ Police (Auckland city Beat officers and Liaison staff), Auckland council staff and Ngā Watene Māori (Māori Wardens). Data collection for this study took place over a four-month period from November 2024 through to February 2025, structured around the availability of participants. The study employed a thematic analysis methodology to systematically identify and organise key themes and issues within the qualitative data gathered from interviews and focus groups.
In summary, the operational reality of the Safety Hub was rather less structured and more ‘organic’ than some participants had hoped, but it still delivered meaningful outcomes. The Safety Hub made its own valuable contribution to community safety while the difficulties it faced helped identify the need for a wider, linked-up ecosystem of community safety in Auckland city. The Hub has proved itself to be a viable concept, that diverse partners can work together in a shared space, and that the presence of volunteers does offer reassurance and can make people feel safer. However, those involved in the Hub also identified a range of challenges that need to be overcome if the Hub is to be more than just a base for increasing the visibility and presence of capable guardians.

text: Safety hubs and partnership policing: Coordination, collaboration and partnership working in Auckland city centre This report presents key insights from an exploratory study of the Safety Hub initiative that first appeared in the run up to the 2023 Women’s World Cup in Auckland. It highlights the potential and the pitfalls of partnership-based approaches to community safety in Aotearoa New Zealand. The study was based on a series of in-person focus group discussions and semi-structured interviews with key partners and stakeholders including Community Patrols New Zealand (CPNZ) volunteers, NZ Police (Auckland city Beat officers and Liaison staff), Auckland council staff and Ngā Watene Māori (Māori Wardens). Data collection for this study took place over a four-month period from November 2024 through to February 2025, structured around the availability of participants. The study employed a thematic analysis methodology to systematically identify and organise key themes and issues within the qualitative data gathered from interviews and focus groups.
In summary, the operational reality of the Safety Hub was rather less structured and more ‘organic’ than some participants had hoped, but it still delivered meaningful outcomes. The Safety Hub made its own valuable contribution to community safety while the difficulties it faced helped identify the need for a wider, linked-up ecosystem of community safety in Auckland city. The Hub has proved itself to be a viable concept, that diverse partners can work together in a shared space, and that the presence of volunteers does offer reassurance and can make people feel safer. However, those involved in the Hub also identified a range of challenges that need to be overcome if the Hub is to be more than just a base for increasing the visibility and presence of capable guardians.

year: 2025