title: Constructed treatment wetlands: Tools to attenuate diffuse agricultural pollution and enhance the biodiversity of eutrophic peat lake ecosystems

authors: Eivers, Rebecca Sylvia

subjects: biodiversity

abstract: Agricultural land use is a major source of nitrogen (N), phosphorus (P) and suspended sediment (SS) to aquatic ecosystems.  Elevated inputs of N, P and SS associated with agricultural expansion and intensification have led to widespread degradation of surface waters throughout the world, causing eutrophication and excessive sedimentation of many rivers, lakes, wetlands, and estuaries.  In excess, these contaminants cause diverse negative impacts on lake ecosystems such as prolific growth of phytoplankton and aquatic plants, toxic algal blooms and collapse of macrophyte beds, high turbidity and in-filling, as well as reduced biodiversity, health and resilience.  Shallow peat lakes in the Waikato region of New Zealand have catchment soils that are highly erodible and readily leach nutrients, with low capacity to assimilate elevated loads of N, P and SS. These lakes have some of the poorest water quality amongst lakes in New Zealand.  
Constructed treatment wetlands (CTWs) are used internationally as technologies to improve the quality of stormwater and wastewater from municipal, industrial and agricultural point sources.  Further, CTWs are becoming increasingly prevalent as mitigation tools to manage diffuse pollution from agricultural runoff. However, discrepancies among studies of the performance of CTWs treating diffuse sources of N, P and SS have created uncertainty for end-users.  As such, more field-based research is required to establish the suitability of CTWs as management tools for diffuse agricultural runoff where flow rates are unregulated and pollutant concentrations can be highly variable.  Improving our knowledge of the efficacy of CTWs within intensive agricultural landscapes will increase confidence and encourage more widespread implementation of these mitigation tools by those involved with water quality management.
Actions are underway to restore several highly eutrophic Waikato peat lakes that have catchments used for intensive dairy production.  Local land-care groups, landowners and lake managers are working collaboratively to improve water quality and enhance biodiversity.  CTWs have been implemented as mitigation tools to manage diffuse sources of N, P and SS and reduce loads to the receiving lakes. Restoration group members additionally anticipate that CTWs will improve biodiversity through provision of supplementary habitat within the highly modified, homogeneous agricultural landscape.  The primary objective of my research was to evaluate the dual benefits of CTWs as tools for nutrient and sediment attenuation, and restoration of biodiversity within peat lake ecosystems.
The efficacy of CTWs treating diffuse agricultural pollution is influenced by three key elements: CTW morphology, internal contaminant cycling, and the composition of influent constituents.  I quantified the magnitude, composition and variability of constituent inputs in surface waters draining small subcatchments of five shallow peat lakes.  Up to 26 channelised streams were sampled seasonally over 18 months from 2010 to 2011.  Subcatchments had predominantly peat, peaty loam or clay loam soil types and ranged in area from c. 1 to 195 ha (mean 23 ha; median 6 ha).  Extensive spatial and temporal variation in nutrient and sediment loads was evident, driven by seasonality and differences between subcatchment soil types and farm-scale management practices. Total N concentrations were highly variable (0.24 - 13.55 mg L-1; median 2.13 mg L-1), attributable to varying concentrations of nitrate-N and particulate organic-N, which ranged from 0.01 to 10.28 mg L-1 and 0.01 to 4.63 mg L-1, respectively.  Total P concentrations ranged widely (0.01 - 3.02 mg L-1; median 0.13), with exceptionally high concentrations of dissolved P in watercourses draining subcatchments with deep (≥7 m) peat soils and very low surface-water pH (< 4) (mean 1.29 mg PO4-P L-1; n=15).  These results stress the importance of considering soil type when deriving appropriate environmental targets and controls for diffuse pollution from intensive agricultural peat lake catchments.  Lake-catchment nutrient loads calculated from subcatchment daily loads were greater than many of those reported elsewhere in New Zealand, indicating the significance of the nutrient problem faced by water quality managers of Waikato’s shallow peat lakes.  
The efficacy of CTWs as management tools to attenuate diffuse sources of N, P, and SS from agricultural subcatchments of the five peat lakes was investigated concurrently.  Different potential predictors of CTW performance were evaluated for up to 26 CTWs and the effect of morphological and environmental variables on internal nutrient cycling and treatment performance were elucidated.  All CTWs were comprised of a sedimentation pond 'module', with around half including shallow wetland modules planted with native plant species, and three with additional sedimentation pond modules. Inflows were surface-flow watercourses diverted from modified or artificial drainage networks, and outflows were either surface-flow (through drainage channels or culverts) or filtration (through vegetated riparian margins). Morphological predictors of CTW performance included area (range 7 – 1950 m²), depth (0.2 – 2.1 m), volume (12 – 2030 m³), wetland to catchment area ratio (0.01 – 1.18), hydraulic retention time (0.2 – 37.2 h), and hydraulic loading rate (0.4 – 130 m d-1). The presence/absence of macrophytes, the outlet type and the number of CTW modules were included in analyses as categorical variables. Reductions in N, P and SS differed considerably among CTWs, driven by varying influent concentrations and dominant forms of N, P, and SS, as well as CTW morphologies and internal nutrient cycling. Generally, CTWs with larger areas and volumes had higher removal rates of nitrate, total N and coarse sediments, while deeper CTWs more effectively reduced particulate N and volatile SS. Macrophytes improved removal of nitrate and P, whereas filtration outlets frequently increased ammonium. Greater accumulated sediment depths were associated with reduced P removal efficiency, signifying the importance of CTW maintenance such as periodic removal of accumulated sediment. Increasing the number of CTW modules generally improved pollutant removal performance; thus, implementing individualised CTW treatment-train concepts is recommended.  
Zooplankton communities were studied to investigate the value of CTWs as tools to improve the biodiversity of peat lake ecosystems through provision of supplementary habitat.  Zooplankton are an essential component of healthy functioning lake and wetland ecosystems. Despite this, zooplankton communities within CTWs in agricultural landscapes remain unstudied.  Zooplankton taxa richness, total abundance and community composition were compared among three habitat types (lakes, CTWs and drainage ditches) within the five study catchments.  CTWs supported zooplankton species otherwise absent from lake and drain habitats, increasing the biodiversity of the highly-modified peat lake catchments. Taxa richness of CTWs was higher than that of drains, and a few CTWs had greater diversity than some of the lakes.  Zooplankton communities were significantly influenced by habitat area, depth and pH, as well as ammonium and phosphate concentrations, water temperature, dissolved oxygen, and macrophyte cover.  This thesis explored opportunities for refining CTW designs, to enhance habitat diversity and support zooplankton species that improve ecosystem function and may increase CTW performance in agricultural landscapes.
The results of my research present key design considerations for surface flow CTWs treating diffuse agricultural pollution from peat lake catchments used for intensive dairy production.  Collectively, the findings of this thesis provide a scientific basis for more comprehensive, holistic CTW designs to mitigate inputs of N, P and SS, and quantitative evidence of the value of agricultural CTWs as water quality and restoration management tools for peat lake ecosystems.  This thesis also provides recommendations for future research to improve our understanding of the complex hydrological and biogeochemical processes driving nutrient losses from peat lake catchments used for intensive dairy production, to inform restoration and rehabilitation of shallow peat lake ecosystems in New Zealand.

text: Constructed treatment wetlands: Tools to attenuate diffuse agricultural pollution and enhance the biodiversity of eutrophic peat lake ecosystems Agricultural land use is a major source of nitrogen (N), phosphorus (P) and suspended sediment (SS) to aquatic ecosystems.  Elevated inputs of N, P and SS associated with agricultural expansion and intensification have led to widespread degradation of surface waters throughout the world, causing eutrophication and excessive sedimentation of many rivers, lakes, wetlands, and estuaries.  In excess, these contaminants cause diverse negative impacts on lake ecosystems such as prolific growth of phytoplankton and aquatic plants, toxic algal blooms and collapse of macrophyte beds, high turbidity and in-filling, as well as reduced biodiversity, health and resilience.  Shallow peat lakes in the Waikato region of New Zealand have catchment soils that are highly erodible and readily leach nutrients, with low capacity to assimilate elevated loads of N, P and SS. These lakes have some of the poorest water quality amongst lakes in New Zealand.  
Constructed treatment wetlands (CTWs) are used internationally as technologies to improve the quality of stormwater and wastewater from municipal, industrial and agricultural point sources.  Further, CTWs are becoming increasingly prevalent as mitigation tools to manage diffuse pollution from agricultural runoff. However, discrepancies among studies of the performance of CTWs treating diffuse sources of N, P and SS have created uncertainty for end-users.  As such, more field-based research is required to establish the suitability of CTWs as management tools for diffuse agricultural runoff where flow rates are unregulated and pollutant concentrations can be highly variable.  Improving our knowledge of the efficacy of CTWs within intensive agricultural landscapes will increase confidence and encourage more widespread implementation of these mitigation tools by those involved with water quality management.
Actions are underway to restore several highly eutrophic Waikato peat lakes that have catchments used for intensive dairy production.  Local land-care groups, landowners and lake managers are working collaboratively to improve water quality and enhance biodiversity.  CTWs have been implemented as mitigation tools to manage diffuse sources of N, P and SS and reduce loads to the receiving lakes. Restoration group members additionally anticipate that CTWs will improve biodiversity through provision of supplementary habitat within the highly modified, homogeneous agricultural landscape.  The primary objective of my research was to evaluate the dual benefits of CTWs as tools for nutrient and sediment attenuation, and restoration of biodiversity within peat lake ecosystems.
The efficacy of CTWs treating diffuse agricultural pollution is influenced by three key elements: CTW morphology, internal contaminant cycling, and the composition of influent constituents.  I quantified the magnitude, composition and variability of constituent inputs in surface waters draining small subcatchments of five shallow peat lakes.  Up to 26 channelised streams were sampled seasonally over 18 months from 2010 to 2011.  Subcatchments had predominantly peat, peaty loam or clay loam soil types and ranged in area from c. 1 to 195 ha (mean 23 ha; median 6 ha).  Extensive spatial and temporal variation in nutrient and sediment loads was evident, driven by seasonality and differences between subcatchment soil types and farm-scale management practices. Total N concentrations were highly variable (0.24 - 13.55 mg L-1; median 2.13 mg L-1), attributable to varying concentrations of nitrate-N and particulate organic-N, which ranged from 0.01 to 10.28 mg L-1 and 0.01 to 4.63 mg L-1, respectively.  Total P concentrations ranged widely (0.01 - 3.02 mg L-1; median 0.13), with exceptionally high concentrations of dissolved P in watercourses draining subcatchments with deep (≥7 m) peat soils and very low surface-water pH (< 4) (mean 1.29 mg PO4-P L-1; n=15).  These results stress the importance of considering soil type when deriving appropriate environmental targets and controls for diffuse pollution from intensive agricultural peat lake catchments.  Lake-catchment nutrient loads calculated from subcatchment daily loads were greater than many of those reported elsewhere in New Zealand, indicating the significance of the nutrient problem faced by water quality managers of Waikato’s shallow peat lakes.  
The efficacy of CTWs as management tools to attenuate diffuse sources of N, P, and SS from agricultural subcatchments of the five peat lakes was investigated concurrently.  Different potential predictors of CTW performance were evaluated for up to 26 CTWs and the effect of morphological and environmental variables on internal nutrient cycling and treatment performance were elucidated.  All CTWs were comprised of a sedimentation pond 'module', with around half including shallow wetland modules planted with native plant species, and three with additional sedimentation pond modules. Inflows were surface-flow watercourses diverted from modified or artificial drainage networks, and outflows were either surface-flow (through drainage channels or culverts) or filtration (through vegetated riparian margins). Morphological predictors of CTW performance included area (range 7 – 1950 m²), depth (0.2 – 2.1 m), volume (12 – 2030 m³), wetland to catchment area ratio (0.01 – 1.18), hydraulic retention time (0.2 – 37.2 h), and hydraulic loading rate (0.4 – 130 m d-1). The presence/absence of macrophytes, the outlet type and the number of CTW modules were included in analyses as categorical variables. Reductions in N, P and SS differed considerably among CTWs, driven by varying influent concentrations and dominant forms of N, P, and SS, as well as CTW morphologies and internal nutrient cycling. Generally, CTWs with larger areas and volumes had higher removal rates of nitrate, total N and coarse sediments, while deeper CTWs more effectively reduced particulate N and volatile SS. Macrophytes improved removal of nitrate and P, whereas filtration outlets frequently increased ammonium. Greater accumulated sediment depths were associated with reduced P removal efficiency, signifying the importance of CTW maintenance such as periodic removal of accumulated sediment. Increasing the number of CTW modules generally improved pollutant removal performance; thus, implementing individualised CTW treatment-train concepts is recommended.  
Zooplankton communities were studied to investigate the value of CTWs as tools to improve the biodiversity of peat lake ecosystems through provision of supplementary habitat.  Zooplankton are an essential component of healthy functioning lake and wetland ecosystems. Despite this, zooplankton communities within CTWs in agricultural landscapes remain unstudied.  Zooplankton taxa richness, total abundance and community composition were compared among three habitat types (lakes, CTWs and drainage ditches) within the five study catchments.  CTWs supported zooplankton species otherwise absent from lake and drain habitats, increasing the biodiversity of the highly-modified peat lake catchments. Taxa richness of CTWs was higher than that of drains, and a few CTWs had greater diversity than some of the lakes.  Zooplankton communities were significantly influenced by habitat area, depth and pH, as well as ammonium and phosphate concentrations, water temperature, dissolved oxygen, and macrophyte cover.  This thesis explored opportunities for refining CTW designs, to enhance habitat diversity and support zooplankton species that improve ecosystem function and may increase CTW performance in agricultural landscapes.
The results of my research present key design considerations for surface flow CTWs treating diffuse agricultural pollution from peat lake catchments used for intensive dairy production.  Collectively, the findings of this thesis provide a scientific basis for more comprehensive, holistic CTW designs to mitigate inputs of N, P and SS, and quantitative evidence of the value of agricultural CTWs as water quality and restoration management tools for peat lake ecosystems.  This thesis also provides recommendations for future research to improve our understanding of the complex hydrological and biogeochemical processes driving nutrient losses from peat lake catchments used for intensive dairy production, to inform restoration and rehabilitation of shallow peat lake ecosystems in New Zealand.

year: 2018

title: Interactive group activity: a socially mediated tool for opening an interpretive space in classroom research

authors: Whyte, Barbara

subjects: children’s meaning making

abstract: An ongoing challenge in classroom research is to understand children’s perspectives on their learning. While learning is highly individual, it is also significantly social and this raises methodological challenges. An Interactive Group Activity (IGA) is one of several data collection strategies used during the action research phase of the Connecting Curriculum, Connecting Learningproject (2010–2011) focusing on arts-based curriculum integration. This article concentrates on the IGA tool as a means of uncovering children’s meaning making following an extended period of learning. Of particular note is the use of an arts pedagogical device to introduce the IGA to children, a device that frames the purpose of the task. In effect, the IGA acts as a group assessment device underlining the socially mediated nature of children’s learning. This article describes how the IGA tool evolved, gives its form and structure, argues for its affordances and suggests possibilities for its wider use.

text: Interactive group activity: a socially mediated tool for opening an interpretive space in classroom research An ongoing challenge in classroom research is to understand children’s perspectives on their learning. While learning is highly individual, it is also significantly social and this raises methodological challenges. An Interactive Group Activity (IGA) is one of several data collection strategies used during the action research phase of the Connecting Curriculum, Connecting Learningproject (2010–2011) focusing on arts-based curriculum integration. This article concentrates on the IGA tool as a means of uncovering children’s meaning making following an extended period of learning. Of particular note is the use of an arts pedagogical device to introduce the IGA to children, a device that frames the purpose of the task. In effect, the IGA acts as a group assessment device underlining the socially mediated nature of children’s learning. This article describes how the IGA tool evolved, gives its form and structure, argues for its affordances and suggests possibilities for its wider use.

year: 2012

title: Understanding the construction of belonging in a for-profit ECE centre: An ethnographic study

authors: Westerbeke, Lynley Ann

subjects: Belonging

abstract: Participation in high quality early childhood education [ECE] is recognised as having long ranging academic and social benefits for children, especially those from disadvantaged backgrounds (Mitchell, Wylie & Carr, 2008).   In 2010 the ECE Participation Programme was successfully introduced to increase enrolment in ECE for targeted groups, such as Māori, Pasifika, and low income families.  I argue that focusing on increased participation alone is limiting and participation requires being viewed alongside the notion of belonging.  With the majority of children participating in for-profit ECE centres in Aotearoa New Zealand (Ministry of Education, 2015) I suggest that what children are participating in merits greater investigation.    
In this thesis belonging is positioned as not simply obtaining membership, but utilising Rogoff’s (2003) understanding of participation, it is viewed as something which is highly influential, where core values are transmitted and transformed.
The research questions guiding this thesis are:
1.	What affordances and challenges to belonging are identified by stakeholders participating in a privately owned, for-profit, ECE centre?
2.	How is the ethical stewardship of Te Whāriki reflected in the leadership’s decision making?
This thesis used a critical ethnographic methodology, and was conducted over a nine month period in a for-profit ECE centre, with the researcher in the role of participant observer.  The centre is located in a lower socio-economic area of an inner city suburb and is accessed by families who at the time of the study had only 30% of its parents in paid employment.  The majority of children identified as Māori and lived in close proximity to the centre, and all teachers at the centre identified as Pākehā.  The stakeholders identified for this study were the children, their parents and the teachers.  Three teachers participated in the study and four children were selected for case study, aged between two and four and a half years.  Data was generated primarily through semi-structured interviews with the children, their parents and the teachers, and observation of the setting.  The data was viewed utilising Rogoff’s (2003) three foci of analysis, with three contributing factors to belonging identified by participants; values, relationships and leadership.
The thesis argues that belonging is complex and participation in for-profit ECE services is an ethical concern, not only for the children and their families but also for teachers.  To make sense of the aligned yet often contradicting perspectives of the stakeholders I propose a belonging framework, conceptualised to bring understanding to the construction of belonging within the centre.  It suggests that belonging to the centre can be viewed from three distinct viewpoints; it can be observed, lived, and framed.   The study evidenced that the day-to-day lived experiences of the children are not fully known by parents and, while also lived, belonging is primarily observed for this cohort.  Within the context of lived belonging the teachers’ and leadership’s philosophical and pedagogical approaches meet, and often collide.  The child is placed at the heart of the framework where belonging is lived and it is here that meaning for this group is primarily created, and cultural values are transmitted and transformed.  The third perspective is how belonging is framed, with the leaders’ operational decision making setting the parameters for the stakeholders’ participation.  It is in this space that the actual values guiding the setting are revealed.
My thesis aims to explain the impact on the stakeholders’ sense of belonging when a government funded centre is driven by agendas not fully aligned with the intentions of the democratic and bicultural curriculum, Te Whāriki.  This study adds to the literature on for-profit ECE services, participation in ECE in Aotearoa New Zealand, and leadership in ECE.

text: Understanding the construction of belonging in a for-profit ECE centre: An ethnographic study Participation in high quality early childhood education [ECE] is recognised as having long ranging academic and social benefits for children, especially those from disadvantaged backgrounds (Mitchell, Wylie & Carr, 2008).   In 2010 the ECE Participation Programme was successfully introduced to increase enrolment in ECE for targeted groups, such as Māori, Pasifika, and low income families.  I argue that focusing on increased participation alone is limiting and participation requires being viewed alongside the notion of belonging.  With the majority of children participating in for-profit ECE centres in Aotearoa New Zealand (Ministry of Education, 2015) I suggest that what children are participating in merits greater investigation.    
In this thesis belonging is positioned as not simply obtaining membership, but utilising Rogoff’s (2003) understanding of participation, it is viewed as something which is highly influential, where core values are transmitted and transformed.
The research questions guiding this thesis are:
1.	What affordances and challenges to belonging are identified by stakeholders participating in a privately owned, for-profit, ECE centre?
2.	How is the ethical stewardship of Te Whāriki reflected in the leadership’s decision making?
This thesis used a critical ethnographic methodology, and was conducted over a nine month period in a for-profit ECE centre, with the researcher in the role of participant observer.  The centre is located in a lower socio-economic area of an inner city suburb and is accessed by families who at the time of the study had only 30% of its parents in paid employment.  The majority of children identified as Māori and lived in close proximity to the centre, and all teachers at the centre identified as Pākehā.  The stakeholders identified for this study were the children, their parents and the teachers.  Three teachers participated in the study and four children were selected for case study, aged between two and four and a half years.  Data was generated primarily through semi-structured interviews with the children, their parents and the teachers, and observation of the setting.  The data was viewed utilising Rogoff’s (2003) three foci of analysis, with three contributing factors to belonging identified by participants; values, relationships and leadership.
The thesis argues that belonging is complex and participation in for-profit ECE services is an ethical concern, not only for the children and their families but also for teachers.  To make sense of the aligned yet often contradicting perspectives of the stakeholders I propose a belonging framework, conceptualised to bring understanding to the construction of belonging within the centre.  It suggests that belonging to the centre can be viewed from three distinct viewpoints; it can be observed, lived, and framed.   The study evidenced that the day-to-day lived experiences of the children are not fully known by parents and, while also lived, belonging is primarily observed for this cohort.  Within the context of lived belonging the teachers’ and leadership’s philosophical and pedagogical approaches meet, and often collide.  The child is placed at the heart of the framework where belonging is lived and it is here that meaning for this group is primarily created, and cultural values are transmitted and transformed.  The third perspective is how belonging is framed, with the leaders’ operational decision making setting the parameters for the stakeholders’ participation.  It is in this space that the actual values guiding the setting are revealed.
My thesis aims to explain the impact on the stakeholders’ sense of belonging when a government funded centre is driven by agendas not fully aligned with the intentions of the democratic and bicultural curriculum, Te Whāriki.  This study adds to the literature on for-profit ECE services, participation in ECE in Aotearoa New Zealand, and leadership in ECE.

year: 2016