title: Modelling the response of a highly eutrophic lake to reductions in external and internal nutrient loading

authors: Özkundakci, Deniz

subjects: Lake Okaro

abstract: The reduction of macronutrients to levels that limit primary production is often a critical element of mitigating eutrophication and reducing the potential for algal blooms. Lake Okaro has remained highly eutrophic despite an intensive catchment and in-lake restoration programme, including implementation of a constructed wetland, riparian protection, an alum application and application of a modified zeolite mineral (Z2G1) to reduce internal nutrient loading. A one-dimensional process-based ecosystem model (DYRESM-CAEDYM) was used in this study to investigate the need for further nutrient loading reductions of both nitrogen (N) and phosphorus (P). The model was calibrated against field data for a 2-year period and validated over two separate 1-year periods. Model simulations suggest that the trophic status of the lake, measured quantitatively with the Trophic Level Index (TLI), could shift from highly eutrophic to mesotrophic with external and internal loads of both N and P reduced by 75-90%. The magnitude of the nutrient load reductions is indicative of a major challenge in being able to effect transitions across trophic state categories for eutrophic lakes.

text: Modelling the response of a highly eutrophic lake to reductions in external and internal nutrient loading The reduction of macronutrients to levels that limit primary production is often a critical element of mitigating eutrophication and reducing the potential for algal blooms. Lake Okaro has remained highly eutrophic despite an intensive catchment and in-lake restoration programme, including implementation of a constructed wetland, riparian protection, an alum application and application of a modified zeolite mineral (Z2G1) to reduce internal nutrient loading. A one-dimensional process-based ecosystem model (DYRESM-CAEDYM) was used in this study to investigate the need for further nutrient loading reductions of both nitrogen (N) and phosphorus (P). The model was calibrated against field data for a 2-year period and validated over two separate 1-year periods. Model simulations suggest that the trophic status of the lake, measured quantitatively with the Trophic Level Index (TLI), could shift from highly eutrophic to mesotrophic with external and internal loads of both N and P reduced by 75-90%. The magnitude of the nutrient load reductions is indicative of a major challenge in being able to effect transitions across trophic state categories for eutrophic lakes.

year: 2011-06

title: Measurement of internal stress in Radiata pine sapwood during drying using an improved online sensor

authors: Ferrari, Silvia

subjects: piezoresistive pressure sensor

abstract: Internal stress in wood as a result of kiln drying is an important factor that affects the quality of the final product. Internal stress is inherently difficult to measure and it is usually either assessed through destructive sample evaluation after drying, or is predictively modelled using extensive material property relations which require much effort to obtain. This study describes improvements of the design, accuracy, and precision of a previously constructed stress sensor for the direct measurement of internal stress in wood during drying. The sensor is designed to be placed directly into a wood block and it records online internal uniaxial stress. Lurethane® was found to be the best material for transmitting internal stress to the sensor because reduced creep was observed, compared with Teflon® which was originally used. Stress modelling showed that a linear relation could be theoretically obtained between the stress from the sensor and the actual primary axis stress that is likely to occur in an intact wood block. Accordingly, the response of a sensor placed in a certain area could be successfully calibrated. However, rotation of the sensor away from the primary stress axis caused a decrease in recorded stress but did not affect stress trends during drying, provided the angle remained constant. Finally, stress results from drying Pinus radiata D. Don at 70°C are also described and discussed.

text: Measurement of internal stress in Radiata pine sapwood during drying using an improved online sensor Internal stress in wood as a result of kiln drying is an important factor that affects the quality of the final product. Internal stress is inherently difficult to measure and it is usually either assessed through destructive sample evaluation after drying, or is predictively modelled using extensive material property relations which require much effort to obtain. This study describes improvements of the design, accuracy, and precision of a previously constructed stress sensor for the direct measurement of internal stress in wood during drying. The sensor is designed to be placed directly into a wood block and it records online internal uniaxial stress. Lurethane® was found to be the best material for transmitting internal stress to the sensor because reduced creep was observed, compared with Teflon® which was originally used. Stress modelling showed that a linear relation could be theoretically obtained between the stress from the sensor and the actual primary axis stress that is likely to occur in an intact wood block. Accordingly, the response of a sensor placed in a certain area could be successfully calibrated. However, rotation of the sensor away from the primary stress axis caused a decrease in recorded stress but did not affect stress trends during drying, provided the angle remained constant. Finally, stress results from drying Pinus radiata D. Don at 70°C are also described and discussed.

year: 2010

title: “BODY-SNATCHING”: Changes to coroners legislation and possible Māori responses

authors: Mika, Carl Te Hira

subjects: body-snatcher

abstract: The term body-snatcher has enjoyed a renaissance in the media recently, as various Māori have moved to reclaim their deceased relations. From a Māori perspective, the claiming of bodies has nothing to do with body-snatching, a term that referred to episodes in the West. Indeed, Māori may see some laws themselves as instruments that snatch the body, in contravention of Māori customs. One of these laws, the Coroners Act 2006, may have made some progress by quietly acknowledging these customs in many ways, but that is merely the start of a greater dialogue between Māori and the Crown in relation to proper Māori respect of the dead body.

text: “BODY-SNATCHING”: Changes to coroners legislation and possible Māori responses The term body-snatcher has enjoyed a renaissance in the media recently, as various Māori have moved to reclaim their deceased relations. From a Māori perspective, the claiming of bodies has nothing to do with body-snatching, a term that referred to episodes in the West. Indeed, Māori may see some laws themselves as instruments that snatch the body, in contravention of Māori customs. One of these laws, the Coroners Act 2006, may have made some progress by quietly acknowledging these customs in many ways, but that is merely the start of a greater dialogue between Māori and the Crown in relation to proper Māori respect of the dead body.

year: 2009