title: Investigating groundwater derived nutrient fluxes within Tauranga harbour, New Zealand

authors: Stewart, Benjamin Thomas

subjects: Submarine groundwater discharge (SGD)

abstract: Submarine groundwater discharge (SGD) is one of the key pathways that connects land and ocean, delivering freshwater, nutrients, carbon, metals, and other chemical constituents to coastal waters. In New Zealand, local Māori have had a strong cultural connection to this natural process for centuries. Recently, it has been recognised that this process is important in global hydrological and biogeochemical cycles. Due to the large coastline to land area ratio, steep topography, permeable sediments and high rainfall, oceanic islands, may have the potential for disproportionally large SGD fluxes into the ocean compared to river inputs. Since SGD is driven under different timescales and processes (saline porewater through sediments and fresh groundwater from aquifers), it can provide a continual source of nutrients to coastal water bodies. This has previously received very little attention in New Zealand despite its potential importance, mainly due to the difficulty in measuring this diffuse process. 
Regional system scale studies among oceanic islands are poorly quantified and understood, especially in the South Pacific region.  Population increases have placed added stresses on hydrological cycles and subsequent land use changes, particularly agriculture, have resulted in excess nutrient loading and nitrogen pollution in coastal systems. Radium isotopes were used to quantify SGD and related nutrient fluxes into Tauranga Harbour, a coastal lagoon system, on the largely volcanic North Island of New Zealand. A ²²⁶Ra mass balance quantified SGD fluxes at the harbour scale, resulting in a range of SGD flux rates between 0.53 cm d⁻¹ and 3.09 x10⁶ m³ d⁻¹. When compared to other freshwater discharges (rivers and streams) into the harbour this was between ~1 – 2.8 times greater in flow. SGD inputs were also calculated to be ~5 times (for nitrogen) and ~8 times (for phosphorus) greater than the input from surrounding rivers and streams. Over the past decades the harbour has suffered reduced water quality and has inter-annual macro-algal blooms of Ulva spp. (sea lettuce). Harbour waters had a N:P ratio of ~17:1 with a positive relationship between radium isotopes (assumed groundwater related) and N:P ratios. This demonstrated that SGD has major implications for primary production, including recurrent algal bloom events which commonly occur in the harbour.
While higher loads of inorganic and organic nitrogen from surrounding water catchments are important for water quality, the physical processes that control estuarine flushing, such as tides, wind, rainfall, and freshwater discharge are equally as important. To better understand how future changes in climate over the coming century will impact coastal systems a numerical model was developed and combined with machine learning techniques to ‘emulate’ dilution rates based on time series of historical hydro-metrological data. A 22-year hind cast revealed the spatial variability of flushing times over short term ‘event’ and long range inter annual timescales. A significant relationship (r² 0.43 p =<0.001) between flushing rates and the southern oscillation index (SOI) was also established, highlighting direct and indirect implications of climate on water quality by altering flushing rates, nutrient availability, storage and transport across different regions. Using these data driven tools will be important into the future for monitoring water movement and ‘estuarine forecasting’. 
Finally, I present a study that assessed the effects of spring-neap tidal variations on estuarine connectivity over multiple spatial scales. Being a tidally dominated system, variations in tidal amplitudes can alter the movement of water and associated chemical exchanges between the harbours sub estuaries and coastal shelf. A combination of numerical modelling and artificial tracer experiments were used together with field-based measurements of naturally occurring radioactive tracers (radium). The modelled flushing times across all harbour regions (~4 – 20 days) agreed well with calculated apparent Ra ages. The average apparent radium water ages were revealed to be younger on spring tide at the harbour scale, suggesting tidal pumping of radium rich water from sub regions. Waters at the harbour scale were also well mixed from other sub regions. Nutrients and other chemical constituents varied substantially with the tide and were up to 4 times greater at the sub estuary scale on ebb tides. This demonstrated the important role of spring-neap tidal cycles in water transport, mixing and biogeochemical behaviour within sensitive coastal lagoon systems.

text: Investigating groundwater derived nutrient fluxes within Tauranga harbour, New Zealand Submarine groundwater discharge (SGD) is one of the key pathways that connects land and ocean, delivering freshwater, nutrients, carbon, metals, and other chemical constituents to coastal waters. In New Zealand, local Māori have had a strong cultural connection to this natural process for centuries. Recently, it has been recognised that this process is important in global hydrological and biogeochemical cycles. Due to the large coastline to land area ratio, steep topography, permeable sediments and high rainfall, oceanic islands, may have the potential for disproportionally large SGD fluxes into the ocean compared to river inputs. Since SGD is driven under different timescales and processes (saline porewater through sediments and fresh groundwater from aquifers), it can provide a continual source of nutrients to coastal water bodies. This has previously received very little attention in New Zealand despite its potential importance, mainly due to the difficulty in measuring this diffuse process. 
Regional system scale studies among oceanic islands are poorly quantified and understood, especially in the South Pacific region.  Population increases have placed added stresses on hydrological cycles and subsequent land use changes, particularly agriculture, have resulted in excess nutrient loading and nitrogen pollution in coastal systems. Radium isotopes were used to quantify SGD and related nutrient fluxes into Tauranga Harbour, a coastal lagoon system, on the largely volcanic North Island of New Zealand. A ²²⁶Ra mass balance quantified SGD fluxes at the harbour scale, resulting in a range of SGD flux rates between 0.53 cm d⁻¹ and 3.09 x10⁶ m³ d⁻¹. When compared to other freshwater discharges (rivers and streams) into the harbour this was between ~1 – 2.8 times greater in flow. SGD inputs were also calculated to be ~5 times (for nitrogen) and ~8 times (for phosphorus) greater than the input from surrounding rivers and streams. Over the past decades the harbour has suffered reduced water quality and has inter-annual macro-algal blooms of Ulva spp. (sea lettuce). Harbour waters had a N:P ratio of ~17:1 with a positive relationship between radium isotopes (assumed groundwater related) and N:P ratios. This demonstrated that SGD has major implications for primary production, including recurrent algal bloom events which commonly occur in the harbour.
While higher loads of inorganic and organic nitrogen from surrounding water catchments are important for water quality, the physical processes that control estuarine flushing, such as tides, wind, rainfall, and freshwater discharge are equally as important. To better understand how future changes in climate over the coming century will impact coastal systems a numerical model was developed and combined with machine learning techniques to ‘emulate’ dilution rates based on time series of historical hydro-metrological data. A 22-year hind cast revealed the spatial variability of flushing times over short term ‘event’ and long range inter annual timescales. A significant relationship (r² 0.43 p =<0.001) between flushing rates and the southern oscillation index (SOI) was also established, highlighting direct and indirect implications of climate on water quality by altering flushing rates, nutrient availability, storage and transport across different regions. Using these data driven tools will be important into the future for monitoring water movement and ‘estuarine forecasting’. 
Finally, I present a study that assessed the effects of spring-neap tidal variations on estuarine connectivity over multiple spatial scales. Being a tidally dominated system, variations in tidal amplitudes can alter the movement of water and associated chemical exchanges between the harbours sub estuaries and coastal shelf. A combination of numerical modelling and artificial tracer experiments were used together with field-based measurements of naturally occurring radioactive tracers (radium). The modelled flushing times across all harbour regions (~4 – 20 days) agreed well with calculated apparent Ra ages. The average apparent radium water ages were revealed to be younger on spring tide at the harbour scale, suggesting tidal pumping of radium rich water from sub regions. Waters at the harbour scale were also well mixed from other sub regions. Nutrients and other chemical constituents varied substantially with the tide and were up to 4 times greater at the sub estuary scale on ebb tides. This demonstrated the important role of spring-neap tidal cycles in water transport, mixing and biogeochemical behaviour within sensitive coastal lagoon systems.

year: 2021

title: Introduction

authors: Middleton, Sue

abstract: The editors of this book met and became friends in Wellington in the late 1970s, when we were in our early thirties. We had a lot in common. We were taking time out from school-teaching, had preschool children in the Victoria University Crèche and, having gained our BA degrees in “other” subjects, were completing “bridging” courses required for entry to an MA by thesis in Education.1 We bonded in a student-centred course facilitated by Jack Shallcrass, who encouraged us to work independently on philosophical questions that would inform our theses. In 1979 we each—albeit in different contexts—got to know Geraldine McDonald. And for the next 50 years, our lives, research, publishing, and political activities—sometimes individually and sometimes together—would, from time to time, intertwine with hers.

text: Introduction The editors of this book met and became friends in Wellington in the late 1970s, when we were in our early thirties. We had a lot in common. We were taking time out from school-teaching, had preschool children in the Victoria University Crèche and, having gained our BA degrees in “other” subjects, were completing “bridging” courses required for entry to an MA by thesis in Education.1 We bonded in a student-centred course facilitated by Jack Shallcrass, who encouraged us to work independently on philosophical questions that would inform our theses. In 1979 we each—albeit in different contexts—got to know Geraldine McDonald. And for the next 50 years, our lives, research, publishing, and political activities—sometimes individually and sometimes together—would, from time to time, intertwine with hers.

year: 2019

title: Violation of te whare tangata - the maternal body: Young women's journeys through pregnancy and partner terrorism

authors: Marsh, Tuihana M.

subjects: Partner Terrorism

abstract: Partner terrorism is a leading social issue in Aotearoa. It occurs with such frequency and ferocity that it is often considered an epidemic. This has placed us in the shameful position of being the highest ranked nation in the western world for the prevalence of intimate partner violence. This research explored young women’s experiences of intimate partner violence during pregnancy. Eleven women aged 14 - 17 years when pregnant were interviewed. A mana wāhine theoretical perspective was employed, guided by a kaupapa Māori research methodology. Pūrākau was used as a method to present and validate the women’s voices.
The key findings identified that these relationships began with the potential of any other relationship. However, they typically followed a pattern of co-habituation and entrapment through pregnancy and financial dependence. It was evident the partner terrorism was brought into these relationships by the terrorist partners, and was the first experience of this violence for many of the women. The terrorism continued to escalate. Separating from their terrorist partners did not result in the women being any safer, with some continuing to experience life-threatening acts of terrorism post separation. Pregnancy did not serve as a protective factor: the violation of te whare tangata generally occurred before, during and after pregnancy. Often, the acts of terrorism escalated following the birth of their pēpī, with their partner’s terrorism being a direct assault on ūkaipō, disrupting bonding and mothering practices. Many of the women were able to recognise the terrorism to which they were subjected only in hindsight. Despite this, they showed ingenuity and resilience in the ways they resisted the terrorism in efforts to keep themselves and their pēpī safe. Breaking free of these relationships demanded intervention and support from outsiders. The women remain strongly committed to the welfare of their pēpī.

text: Violation of te whare tangata - the maternal body: Young women's journeys through pregnancy and partner terrorism Partner terrorism is a leading social issue in Aotearoa. It occurs with such frequency and ferocity that it is often considered an epidemic. This has placed us in the shameful position of being the highest ranked nation in the western world for the prevalence of intimate partner violence. This research explored young women’s experiences of intimate partner violence during pregnancy. Eleven women aged 14 - 17 years when pregnant were interviewed. A mana wāhine theoretical perspective was employed, guided by a kaupapa Māori research methodology. Pūrākau was used as a method to present and validate the women’s voices.
The key findings identified that these relationships began with the potential of any other relationship. However, they typically followed a pattern of co-habituation and entrapment through pregnancy and financial dependence. It was evident the partner terrorism was brought into these relationships by the terrorist partners, and was the first experience of this violence for many of the women. The terrorism continued to escalate. Separating from their terrorist partners did not result in the women being any safer, with some continuing to experience life-threatening acts of terrorism post separation. Pregnancy did not serve as a protective factor: the violation of te whare tangata generally occurred before, during and after pregnancy. Often, the acts of terrorism escalated following the birth of their pēpī, with their partner’s terrorism being a direct assault on ūkaipō, disrupting bonding and mothering practices. Many of the women were able to recognise the terrorism to which they were subjected only in hindsight. Despite this, they showed ingenuity and resilience in the ways they resisted the terrorism in efforts to keep themselves and their pēpī safe. Breaking free of these relationships demanded intervention and support from outsiders. The women remain strongly committed to the welfare of their pēpī.

year: 2019