title: What’s that bug? Community participation in biosecurity in Mount Maunganui, New Zealand

authors: Payne, Penny R.

abstract: Biosecurity is essential to protect against the negative effects of non-native invasive species. As part of the government’s ‘Biosecurity 2025’ Initiative to enlist all New Zealanders as biosecurity risk managers, Tauranga Moana has been named the ‘biosecurity capital’ of New Zealand. The initiative will involve large-scale citizen science, for reporting and management of pest and disease threats. In this context we measured baseline awareness, perceptions and behaviour around biosecurity among two key groups of respondents, the local community at Mount Maunganui (surrounding Tauranga’s port) and school children. An online survey was completed by 324 members of the local community, while 120 school children completed a survey about their biosecurity knowledge and behaviours after using a biosecurity education kit. Results indicate that while both groups report a relatively high level of understanding about the concept of biosecurity, and acknowledge it as extremely important, knowledge of current pest threats and correct biosecurity behaviours could be improved. Mount Maunganui community members rate their understanding of biosecurity as better than the average New Zealander, but are less likely to have taken regular biosecurity action in the past year. For school children, improved biosecurity efforts could be evidenced by more active pest monitoring, and greater discussion about biosecurity outside of school (e.g. with their family at home). Key enablers for achieving more impactful citizen science for biosecurity among these groups are targeted education, and practical advice about what they can do to help.

text: What’s that bug? Community participation in biosecurity in Mount Maunganui, New Zealand Biosecurity is essential to protect against the negative effects of non-native invasive species. As part of the government’s ‘Biosecurity 2025’ Initiative to enlist all New Zealanders as biosecurity risk managers, Tauranga Moana has been named the ‘biosecurity capital’ of New Zealand. The initiative will involve large-scale citizen science, for reporting and management of pest and disease threats. In this context we measured baseline awareness, perceptions and behaviour around biosecurity among two key groups of respondents, the local community at Mount Maunganui (surrounding Tauranga’s port) and school children. An online survey was completed by 324 members of the local community, while 120 school children completed a survey about their biosecurity knowledge and behaviours after using a biosecurity education kit. Results indicate that while both groups report a relatively high level of understanding about the concept of biosecurity, and acknowledge it as extremely important, knowledge of current pest threats and correct biosecurity behaviours could be improved. Mount Maunganui community members rate their understanding of biosecurity as better than the average New Zealander, but are less likely to have taken regular biosecurity action in the past year. For school children, improved biosecurity efforts could be evidenced by more active pest monitoring, and greater discussion about biosecurity outside of school (e.g. with their family at home). Key enablers for achieving more impactful citizen science for biosecurity among these groups are targeted education, and practical advice about what they can do to help.

year: 2023-02

title: Influence of ageing heating rates on the microstructure and mechanical properties of Ti-5553 alloy

authors: Jia, Mengqi

subjects: fatigue

abstract: The Ti-5553 alloy, a high-strength β-titanium alloy, is increasingly recognised for its exceptional mechanical properties, making it a preferred material for critical aerospace applications. This thesis examines the effects of varying ageing heating rates on the microstructure and mechanical properties of the forged Ti-5553 alloy, focusing on hardness, tensile properties, and fatigue performance. Following solution treatment at 810°C, the alloy was aged at 610°C with heating rates of 1°C/min, 5°C/min, 10°C/min, and 15°C/min. Detailed microstructural analysis was conducted using Scanning Electron Microscopy (SEM) and Energy Dispersive X ray Spectroscopy (EDX). The microstructural examination revealed that different ageing heating rates caused only minor variations in the alloy's bimodal microstructure. Slower ageing heating rates produced a relatively fine, homogeneously distributed primary α phase within the β grains, while faster rates resulted in a slightly coarser bimodal microstructure. Chemical homogeneity analysis confirmed a consistent distribution of critical elements, with α stabilisers concentrated in the primary α phase and β stabilisers in the β phase, ensuring stable phase compositions across all samples. The observed slight microstructural changes were reflected in the alloy's mechanical properties. Hardness across different ageing heating rates varied between 357.4 HV and 372.6 HV. The ultimate tensile strength (UTS) declined from 1307.2 MPa at 1°C/min to 1264.5 MPa at 15°C/min, while ductility improved from 15.6% to 17.1% over the same range. The alloy demonstrated good fatigue resistance at lower stress amplitudes and ageing heating rates, enduring over 10 million cycles at 337.5 MPa under the 1°C/min condition. However, fatigue life decreased with higher stress amplitudes and ageing heating rates, highlighting the alloy's sensitivity to more extreme conditions. In summary, while the varying ageing heating rates resulted in only minor changes to the microstructure, these alterations had some impact on the mechanical properties of the Ti-5553 alloy. These findings highlight the importance of precise microstructural control in optimising the alloy's performance, especially in applications where achieving a balance between strength, ductility, and fatigue resistance is crucial.

text: Influence of ageing heating rates on the microstructure and mechanical properties of Ti-5553 alloy The Ti-5553 alloy, a high-strength β-titanium alloy, is increasingly recognised for its exceptional mechanical properties, making it a preferred material for critical aerospace applications. This thesis examines the effects of varying ageing heating rates on the microstructure and mechanical properties of the forged Ti-5553 alloy, focusing on hardness, tensile properties, and fatigue performance. Following solution treatment at 810°C, the alloy was aged at 610°C with heating rates of 1°C/min, 5°C/min, 10°C/min, and 15°C/min. Detailed microstructural analysis was conducted using Scanning Electron Microscopy (SEM) and Energy Dispersive X ray Spectroscopy (EDX). The microstructural examination revealed that different ageing heating rates caused only minor variations in the alloy's bimodal microstructure. Slower ageing heating rates produced a relatively fine, homogeneously distributed primary α phase within the β grains, while faster rates resulted in a slightly coarser bimodal microstructure. Chemical homogeneity analysis confirmed a consistent distribution of critical elements, with α stabilisers concentrated in the primary α phase and β stabilisers in the β phase, ensuring stable phase compositions across all samples. The observed slight microstructural changes were reflected in the alloy's mechanical properties. Hardness across different ageing heating rates varied between 357.4 HV and 372.6 HV. The ultimate tensile strength (UTS) declined from 1307.2 MPa at 1°C/min to 1264.5 MPa at 15°C/min, while ductility improved from 15.6% to 17.1% over the same range. The alloy demonstrated good fatigue resistance at lower stress amplitudes and ageing heating rates, enduring over 10 million cycles at 337.5 MPa under the 1°C/min condition. However, fatigue life decreased with higher stress amplitudes and ageing heating rates, highlighting the alloy's sensitivity to more extreme conditions. In summary, while the varying ageing heating rates resulted in only minor changes to the microstructure, these alterations had some impact on the mechanical properties of the Ti-5553 alloy. These findings highlight the importance of precise microstructural control in optimising the alloy's performance, especially in applications where achieving a balance between strength, ductility, and fatigue resistance is crucial.

year: 2024-09-15

title: Assessment of effects of proposed treated wastewater discharge to the Te Arikiroa Thermal Channel and Sulphur Bay (Lake Rotorua)

authors: Dada, Ayokunle Christopher

abstract: After 2019, irrigation operations at the Land Treatment System (LTS) in the Whakarewarewa Forest are scheduled to cease. A number of options and locations have been considered for the discharge of the treated wastewater when the current discharge consent ceases. Following consultations and technical assessments, the preferred option of Rotorua Lakes Council is to upgrade the existing plant to a full Membrane Bioreactor Plant with the addition of an Ultraviolet Disinfection System (or alternative treatment to achieve an equivalent performance in terms of treated wastewater quality). Under this arrangement, wastewater would be subjected to biological, chemical and physical treatment processes, and the treated wastewater discharged through Te Arikiroa Thermal Channel to Sulphur Bay. Rotorua Lakes Council is thus undertaking an environmental impact assessment study to determine the effects of discharging treated wastewater to the thermal channel and Puarenga Bay (Lake Rotorua), with particular reference to aesthetic, water quality and ecological considerations. These considerations include potential effects related to faecal indicator bacteria, nutrient concentrations, metals, dissolved oxygen, and taonga species (native species of cultural significance).
The assessment focused on:
(i)	The projected treated wastewater characteristics;

(ii)	Existing conditions of the receiving water;

(iii)	The sensitivity of the receiving water and the impact of the proposed discharge on water quality and taonga species (native species of cultural significance) in Te Arikiroa Thermal Channel and Sulphur Bay.

The main techniques used to inform the assessment in this study were:
1) Analysis of historical water quality data, 2011-2014;
2) Collection of additional water quality data at Te Arikiroa Thermal Channel and Sulphur Bay and along a transect to quantify spatial variability (sampling in 2016 and 2017);
3) Mass balance dilution modelling to predict water quality in the Te Arikiroa Thermal Channel and Sulphur Bay (Lake Rotorua), at a site outside of the assumed mixing zone;
4) Lake ecosystem modelling conducted by Abell et al. (2015) to assess effects related to eutrophication;
5) Background review of biological information and field investigations for taonga species at Sulphur Bay and Te Arikiroa Thermal Channel (2017).

text: Assessment of effects of proposed treated wastewater discharge to the Te Arikiroa Thermal Channel and Sulphur Bay (Lake Rotorua) After 2019, irrigation operations at the Land Treatment System (LTS) in the Whakarewarewa Forest are scheduled to cease. A number of options and locations have been considered for the discharge of the treated wastewater when the current discharge consent ceases. Following consultations and technical assessments, the preferred option of Rotorua Lakes Council is to upgrade the existing plant to a full Membrane Bioreactor Plant with the addition of an Ultraviolet Disinfection System (or alternative treatment to achieve an equivalent performance in terms of treated wastewater quality). Under this arrangement, wastewater would be subjected to biological, chemical and physical treatment processes, and the treated wastewater discharged through Te Arikiroa Thermal Channel to Sulphur Bay. Rotorua Lakes Council is thus undertaking an environmental impact assessment study to determine the effects of discharging treated wastewater to the thermal channel and Puarenga Bay (Lake Rotorua), with particular reference to aesthetic, water quality and ecological considerations. These considerations include potential effects related to faecal indicator bacteria, nutrient concentrations, metals, dissolved oxygen, and taonga species (native species of cultural significance).
The assessment focused on:
(i)	The projected treated wastewater characteristics;

(ii)	Existing conditions of the receiving water;

(iii)	The sensitivity of the receiving water and the impact of the proposed discharge on water quality and taonga species (native species of cultural significance) in Te Arikiroa Thermal Channel and Sulphur Bay.

The main techniques used to inform the assessment in this study were:
1) Analysis of historical water quality data, 2011-2014;
2) Collection of additional water quality data at Te Arikiroa Thermal Channel and Sulphur Bay and along a transect to quantify spatial variability (sampling in 2016 and 2017);
3) Mass balance dilution modelling to predict water quality in the Te Arikiroa Thermal Channel and Sulphur Bay (Lake Rotorua), at a site outside of the assumed mixing zone;
4) Lake ecosystem modelling conducted by Abell et al. (2015) to assess effects related to eutrophication;
5) Background review of biological information and field investigations for taonga species at Sulphur Bay and Te Arikiroa Thermal Channel (2017).

year: 2018