title: Place-responsive choreography and activism

authors: Barbour, Karen

abstract: Sensory encounters with place, site and landscape have the potential to stimulate new and deeply felt engagements with local places, and to prompt discussion about the relationships between place, culture and identity. Such sensory encounters may also offer opportunities for critical, reflexive theorising and practice (Pink, 2008, 2009; Stevenson, 2014; Warren, 2012). Within the myriad of potentialities offered in research, a focus on sensory and embodied encounters with local places prompts me to articulate intersections between local issues of social justice and environmental activism and feminist choreography. As a dance artist and researcher, ethnographic research has led me to autoethnographic performance as a specific means to articulate my encounters with place through embodied expression and textual representation.

text: Place-responsive choreography and activism Sensory encounters with place, site and landscape have the potential to stimulate new and deeply felt engagements with local places, and to prompt discussion about the relationships between place, culture and identity. Such sensory encounters may also offer opportunities for critical, reflexive theorising and practice (Pink, 2008, 2009; Stevenson, 2014; Warren, 2012). Within the myriad of potentialities offered in research, a focus on sensory and embodied encounters with local places prompts me to articulate intersections between local issues of social justice and environmental activism and feminist choreography. As a dance artist and researcher, ethnographic research has led me to autoethnographic performance as a specific means to articulate my encounters with place through embodied expression and textual representation.

year: 2016

title: Sulphate partitioning into calcite: Experimental verification of pH control and application to seasonality in speleothems

authors: Wynn, Peter M.

subjects: Science & Technology

abstract: Carbonate-associated sulphate (CAS) is a useful carrier of palaeoenvironmental information throughout the geologic record, particularly through its stable isotope composition. However, a paucity of experimental data restricts quantitative understanding of sulphate incorporation into carbonates, and consequently CAS concentrations and their diagenetic modifications are rarely interpreted. However, in the case of calcite speleothems, the remarkably high-resolution CAS records which are obtainable via modern microanalytical techniques represent a potentially invaluable source of palaeoenvironmental information. Here, we describe the results of controlled experiments of sulphate co-precipitation with calcite in freshwater solutions where pH, saturation state, and sulphate concentration were varied independently of each other. Solution pH is confirmed as the principal control on sulphate incorporation into calcite. The relative efficiency of incorporation was calculated as a partition coefficient Dₛₒ₄=(mSO₄/mCO₃)solid/(mSO₄/mCO₃)solution. High crystal growth rates (driven by either pH or saturation state) encouraged higher values of Dₛₒ₄ because of an increasing concentration of defect sites on crystal surfaces. At low growth rates, Dₛₒ₄ was reduced due to an inferred competition between sulphate and bicarbonate at the calcite surface. These experimental results are applied to understand the incorporation of sulphate into speleothem calcite. The experimentally determined pH-dependence suggests that strong seasonal variations in cave air PCO₂ could account for annual cycles in sulphate concentration observed in stalagmites. Our new experimentally determined values of Dₛₒ₄ were compared with Dₛₒ₄ values calculated from speleothem-drip water monitoring from two caves within the Austrian and Italian Alps. At Obir cave, Austria, Dₛₒ₄ (×10⁵) varies between 11.1 (winter) and 9.0 (summer) and the corresponding figures for Ernesto cave, Italy, are 15.4 (winter) and 14.9 (summer). These values approximate predicted Dₛₒ₄ values based on our chamber experiments containing both low (2 ppm) and high (20 ppm) sulphate concentrations. Our experimental values of Dₛₒ₄ obtained at crystal growth rates typical of stalagmites, closely match those observed in other cave sites from around the world. This validates the universality of the controls behind Dₛₒ₄ and will enhance the use of speleothem CAS as a palaeoenvironmental proxy.

text: Sulphate partitioning into calcite: Experimental verification of pH control and application to seasonality in speleothems Carbonate-associated sulphate (CAS) is a useful carrier of palaeoenvironmental information throughout the geologic record, particularly through its stable isotope composition. However, a paucity of experimental data restricts quantitative understanding of sulphate incorporation into carbonates, and consequently CAS concentrations and their diagenetic modifications are rarely interpreted. However, in the case of calcite speleothems, the remarkably high-resolution CAS records which are obtainable via modern microanalytical techniques represent a potentially invaluable source of palaeoenvironmental information. Here, we describe the results of controlled experiments of sulphate co-precipitation with calcite in freshwater solutions where pH, saturation state, and sulphate concentration were varied independently of each other. Solution pH is confirmed as the principal control on sulphate incorporation into calcite. The relative efficiency of incorporation was calculated as a partition coefficient Dₛₒ₄=(mSO₄/mCO₃)solid/(mSO₄/mCO₃)solution. High crystal growth rates (driven by either pH or saturation state) encouraged higher values of Dₛₒ₄ because of an increasing concentration of defect sites on crystal surfaces. At low growth rates, Dₛₒ₄ was reduced due to an inferred competition between sulphate and bicarbonate at the calcite surface. These experimental results are applied to understand the incorporation of sulphate into speleothem calcite. The experimentally determined pH-dependence suggests that strong seasonal variations in cave air PCO₂ could account for annual cycles in sulphate concentration observed in stalagmites. Our new experimentally determined values of Dₛₒ₄ were compared with Dₛₒ₄ values calculated from speleothem-drip water monitoring from two caves within the Austrian and Italian Alps. At Obir cave, Austria, Dₛₒ₄ (×10⁵) varies between 11.1 (winter) and 9.0 (summer) and the corresponding figures for Ernesto cave, Italy, are 15.4 (winter) and 14.9 (summer). These values approximate predicted Dₛₒ₄ values based on our chamber experiments containing both low (2 ppm) and high (20 ppm) sulphate concentrations. Our experimental values of Dₛₒ₄ obtained at crystal growth rates typical of stalagmites, closely match those observed in other cave sites from around the world. This validates the universality of the controls behind Dₛₒ₄ and will enhance the use of speleothem CAS as a palaeoenvironmental proxy.

year: 2018

title: Recognising the negative impacts of aquatic weed management: Okawa Bay, Lake Rotoiti case study

authors: Scholes, Paul

abstract: The Te Arawa Rotorua Lakes Programme continues to implement measures to maintain and restore lake water quality in line with trophic level indices (TLI’s) for respective lakes. In Lakes Rotorua and Rotoiti this has also meant not only reducing nutrients to and in the lakes but also managing periodic cyano-bacterial (blue-green) algal blooms.
Restoration measures in the Rotorua and Rotoiti catchments have included land use management efforts to arrest nutrient inputs; diversion of Lake Rotorua waters from entering Rotoiti; sewage reticulation of lakeside communities; and treatment of inflows
with aluminium sulphate (alum). While restoration efforts have produced water quality gains in both lakes, in recent years, cyano-bacterial blooms have occurred in the shallow embayment of Lake Rotoiti, known as Okawa Bay.
These water quality gains have not come without a cost. Submerged aquatic weeds such as Hornwort are an increasing problem in the Rotorua Te Arawa Lakes and significant resources are needed to manage infestations primarily for aesthetic and recreational
amenity. Control of exotic aquatic weed is mostly with application of herbicide. Herbicide treatment leaves a decomposing biomass in the waterbody, potentially increasing the nutrient status.
We examine the impact aquatic weed decomposition has had on Okawa Bay’s nutrient status and the cyano-bacterial blooms over recent summers, and Bay of Plenty Regional Council’s response to reduce localised bloom development.

text: Recognising the negative impacts of aquatic weed management: Okawa Bay, Lake Rotoiti case study The Te Arawa Rotorua Lakes Programme continues to implement measures to maintain and restore lake water quality in line with trophic level indices (TLI’s) for respective lakes. In Lakes Rotorua and Rotoiti this has also meant not only reducing nutrients to and in the lakes but also managing periodic cyano-bacterial (blue-green) algal blooms.
Restoration measures in the Rotorua and Rotoiti catchments have included land use management efforts to arrest nutrient inputs; diversion of Lake Rotorua waters from entering Rotoiti; sewage reticulation of lakeside communities; and treatment of inflows
with aluminium sulphate (alum). While restoration efforts have produced water quality gains in both lakes, in recent years, cyano-bacterial blooms have occurred in the shallow embayment of Lake Rotoiti, known as Okawa Bay.
These water quality gains have not come without a cost. Submerged aquatic weeds such as Hornwort are an increasing problem in the Rotorua Te Arawa Lakes and significant resources are needed to manage infestations primarily for aesthetic and recreational
amenity. Control of exotic aquatic weed is mostly with application of herbicide. Herbicide treatment leaves a decomposing biomass in the waterbody, potentially increasing the nutrient status.
We examine the impact aquatic weed decomposition has had on Okawa Bay’s nutrient status and the cyano-bacterial blooms over recent summers, and Bay of Plenty Regional Council’s response to reduce localised bloom development.

year: 2015