title: Lake Rotorua sediment survey

authors: Özkundakci, Deniz

abstract: Water quality in Lake Rotorua has improved over recent years, with reductions of nitrogen, phosphorus and chloropyll a concentrations, and increased water clarity. These changes coincide with alum dosing of the Utuhina and Puarenga inflows, commenced in 2007 and 2010 respectively. The aim of inflow alum dosing is to reduce external phosphorus load by binding (inactivation of) phosphorus flowing into the lake, however, it has been hypothesised that dosing these streams has had subsidiary beneficial effects on the water quality in the lake itself. Namely, the hypothesised effects relate to adsorption of P in the water column and the settling of alum flocs onto bottom sediments, which in turn could reduce sediment release of phosphorus into the overlying water column (internal loading). This report was commissioned by Bay of Plenty Regional Council to investigate the possibility of stream-dosed alum improving water quality in Lake Rotorua. The objective of this study was to assess how much of the dosed alum, if any, could have been deposited onto the bottom sediments of Lake Rotorua where it could reduce internal phosphorus loading. This objective was achieved by two approaches: (i) a field survey of Lake Rotorua bottom sediments in order to observe any changes in sediment aluminium and phosphorus concentrations following the alum dosing of Utuhina and Puarenga streams and (ii) an aluminium mass balance for the inflows and lake, to explore the potential amount of alum settling out of the water column and onto the bottom sediment, taking into account the potential phosphorus uptake rate of alum.
In comparison with sediment samples collected in 2006, sediment Al concentrations in 2012 were lower in the main basin of the lake. Phosphorus concentrations in the sediments were reduced at four sites located near to the discharges of the Utuhina and Puarenga Streams, but sites further from the stream (i.e. deep basin and close to the Ohau Channel outlet) showed increased concentrations of phosphorus in the sediment. 
The aluminium mass balance for Lake Rotorua provided insights into the potential amount of alum reaching the lake and sediments after some proportion of the aluminium had bound phosphorus in the preceding ‘reactor’, including the inflows. There was a low probability that a large proportion of the dosed Al would have reached the sediments in Lake Rotorua. Only in the years 2010 and 2011, when alum dose rate to the streams was comparably high, some of the dosed alum was likely to have reached the lake sediments. There was a high probability that a large fraction of the Al reached the lake water column with the potential to reduce in-lake water column P concentrations.
Scenarios in the aluminium mass balance were developed to ascertain the conditions needed to achieve a given target for percentage uptake of lake water column P, with respect to the parameters for the fraction of TP available for uptake by alum and the effective Al: P ratio. Only when simulating a 90% reduction of water column P concentrations was the range of possible parameter values for achieving such a reduction relatively constrained. In simulated scenarios where a substantial reduction of internal P loading was the target, parameter values in both the inflows and water column were considerably constrained, indicating that phosphorus uptake by aluminium was likely to be considerable in the inflow and water column. Even with constraint of the parameter values in the inflows and water column, it appeared unlikely that an amount of alum could reach the sediment sufficient to significantly reduce internal P loading.
Changes in sediment P concentrations observed in this study are suggested to have occurred through the synergistic effects of changes in external nutrient loading, sediment focusing and changes in duration and severity of anoxic events in the hypolimnion of the lake driven by unusual climatic events during that time which may have reduced water column stability. The alum mass balance results suggest that although it is possible that some alum reached the bottom sediments in Lake Rotorua, any effect on internal loading was likely to be minor, even in the years 2010 and 2011 when the alum dose rates were comparably high. The conditions under which a substantial reduction of internal P loading would have been possible (with respect to the fraction of the P pool available for uptake and the effective Al:P ratio), are considered highly optimistic (i.e. Al:P ratio ~ 3.5) when compared to literature values of Al:P ratios in other alum-dosed eutrophic lakes.
This study suggests that the amount of Al dosed to the streams is unlikely to explain completely the recent improvement of water quality in Lake Rotorua. Any claim otherwise, should be viewed with caution and can be regarded as optimistic.

text: Lake Rotorua sediment survey Water quality in Lake Rotorua has improved over recent years, with reductions of nitrogen, phosphorus and chloropyll a concentrations, and increased water clarity. These changes coincide with alum dosing of the Utuhina and Puarenga inflows, commenced in 2007 and 2010 respectively. The aim of inflow alum dosing is to reduce external phosphorus load by binding (inactivation of) phosphorus flowing into the lake, however, it has been hypothesised that dosing these streams has had subsidiary beneficial effects on the water quality in the lake itself. Namely, the hypothesised effects relate to adsorption of P in the water column and the settling of alum flocs onto bottom sediments, which in turn could reduce sediment release of phosphorus into the overlying water column (internal loading). This report was commissioned by Bay of Plenty Regional Council to investigate the possibility of stream-dosed alum improving water quality in Lake Rotorua. The objective of this study was to assess how much of the dosed alum, if any, could have been deposited onto the bottom sediments of Lake Rotorua where it could reduce internal phosphorus loading. This objective was achieved by two approaches: (i) a field survey of Lake Rotorua bottom sediments in order to observe any changes in sediment aluminium and phosphorus concentrations following the alum dosing of Utuhina and Puarenga streams and (ii) an aluminium mass balance for the inflows and lake, to explore the potential amount of alum settling out of the water column and onto the bottom sediment, taking into account the potential phosphorus uptake rate of alum.
In comparison with sediment samples collected in 2006, sediment Al concentrations in 2012 were lower in the main basin of the lake. Phosphorus concentrations in the sediments were reduced at four sites located near to the discharges of the Utuhina and Puarenga Streams, but sites further from the stream (i.e. deep basin and close to the Ohau Channel outlet) showed increased concentrations of phosphorus in the sediment. 
The aluminium mass balance for Lake Rotorua provided insights into the potential amount of alum reaching the lake and sediments after some proportion of the aluminium had bound phosphorus in the preceding ‘reactor’, including the inflows. There was a low probability that a large proportion of the dosed Al would have reached the sediments in Lake Rotorua. Only in the years 2010 and 2011, when alum dose rate to the streams was comparably high, some of the dosed alum was likely to have reached the lake sediments. There was a high probability that a large fraction of the Al reached the lake water column with the potential to reduce in-lake water column P concentrations.
Scenarios in the aluminium mass balance were developed to ascertain the conditions needed to achieve a given target for percentage uptake of lake water column P, with respect to the parameters for the fraction of TP available for uptake by alum and the effective Al: P ratio. Only when simulating a 90% reduction of water column P concentrations was the range of possible parameter values for achieving such a reduction relatively constrained. In simulated scenarios where a substantial reduction of internal P loading was the target, parameter values in both the inflows and water column were considerably constrained, indicating that phosphorus uptake by aluminium was likely to be considerable in the inflow and water column. Even with constraint of the parameter values in the inflows and water column, it appeared unlikely that an amount of alum could reach the sediment sufficient to significantly reduce internal P loading.
Changes in sediment P concentrations observed in this study are suggested to have occurred through the synergistic effects of changes in external nutrient loading, sediment focusing and changes in duration and severity of anoxic events in the hypolimnion of the lake driven by unusual climatic events during that time which may have reduced water column stability. The alum mass balance results suggest that although it is possible that some alum reached the bottom sediments in Lake Rotorua, any effect on internal loading was likely to be minor, even in the years 2010 and 2011 when the alum dose rates were comparably high. The conditions under which a substantial reduction of internal P loading would have been possible (with respect to the fraction of the P pool available for uptake and the effective Al:P ratio), are considered highly optimistic (i.e. Al:P ratio ~ 3.5) when compared to literature values of Al:P ratios in other alum-dosed eutrophic lakes.
This study suggests that the amount of Al dosed to the streams is unlikely to explain completely the recent improvement of water quality in Lake Rotorua. Any claim otherwise, should be viewed with caution and can be regarded as optimistic.

year: 2014

title: Student disengagement: Why they say they don’t come

authors: Weijers, Dan M.

abstract: Nearing the end of the academic year for most students, attendance at lectures is dropping to 25% and below. Why are students at the University of Waikato skipping lectures? I combine student attendance rates with data from several student evaluations (that include specific questions about engagement and attendance) to investigate what might be causing student disengagement and non-attendance. The data are drawn from evaluations of a few first and second year philosophy classes over the last two years. The results imply a pedagogical crisis in which “learning” has been relegated so far down students’ list of priorities that it doesn’t feature at all in their educational decision-making! I recommend stop-gap measures and the need for a more thorough investigation.

text: Student disengagement: Why they say they don’t come Nearing the end of the academic year for most students, attendance at lectures is dropping to 25% and below. Why are students at the University of Waikato skipping lectures? I combine student attendance rates with data from several student evaluations (that include specific questions about engagement and attendance) to investigate what might be causing student disengagement and non-attendance. The data are drawn from evaluations of a few first and second year philosophy classes over the last two years. The results imply a pedagogical crisis in which “learning” has been relegated so far down students’ list of priorities that it doesn’t feature at all in their educational decision-making! I recommend stop-gap measures and the need for a more thorough investigation.

year: 2018

title: Alternative anthropologies: Kete aronui from the Waikato

authors: McCormack, Fiona

abstract: As three anthropologists working at the University of Waikato in Hamilton, Aotearoa (New Zealand), we experience anthropology in our daily work in the context of our local histories, communities and politics. While many anthropologists are familiar with the critiques of anthropology that play out in the USA or Europe, the narratives and practices of anthropology from places such as New Zealand are less well known. We argue that these local, diverse experiences of anthropology can enlarge our international understandings and imaginations of what anthropology can be, as well as the challenges it may face.

Anthropologists working in New Zealand today face the same plethora of academic pressures as those found in their counterparts in North America, Britain and Europe; pressures instigated by decades of neoliberal reform, managerialism, and the impact of new entrepreneurial and corporate models of universities that shape everyday identities and social relationships (Shore 2010). Similarly, the critique of anthropology as a discipline rooted in colonial imperatives and practices, resounds in a society whose imperial history and settler colonial present continues to imprint on educational institutions, pedagogy and research. In New Zealand, no neat historical trajectory marks a path from extractive research, wherein Indigenous knowledge and ways of life are pottled for export to the empire’s core, to one based on mutuality, co-creation and the indigenisation of anthropological knowledge.

text: Alternative anthropologies: Kete aronui from the Waikato As three anthropologists working at the University of Waikato in Hamilton, Aotearoa (New Zealand), we experience anthropology in our daily work in the context of our local histories, communities and politics. While many anthropologists are familiar with the critiques of anthropology that play out in the USA or Europe, the narratives and practices of anthropology from places such as New Zealand are less well known. We argue that these local, diverse experiences of anthropology can enlarge our international understandings and imaginations of what anthropology can be, as well as the challenges it may face.

Anthropologists working in New Zealand today face the same plethora of academic pressures as those found in their counterparts in North America, Britain and Europe; pressures instigated by decades of neoliberal reform, managerialism, and the impact of new entrepreneurial and corporate models of universities that shape everyday identities and social relationships (Shore 2010). Similarly, the critique of anthropology as a discipline rooted in colonial imperatives and practices, resounds in a society whose imperial history and settler colonial present continues to imprint on educational institutions, pedagogy and research. In New Zealand, no neat historical trajectory marks a path from extractive research, wherein Indigenous knowledge and ways of life are pottled for export to the empire’s core, to one based on mutuality, co-creation and the indigenisation of anthropological knowledge.

year: 2025