title: Denitrification potential in lake sediment increases across a gradient of catchment agriculture

authors: Bruesewitz, Denise A.

subjects: nitrogen

abstract: Intensification of catchment agriculture has increased nutrient loads and accelerated eutrophication in some lakes, often resulting in episodic harmful algal blooms or prolonged periods of anoxia. The influence of catchment agriculture on lake sediment denitrification capacity as a nitrogen (N) removal mechanism in lakes is largely unknown, particularly in contrast to research on denitrification in agricultural streams and rivers. We measured denitrification enzyme activity (DEA) to assess sediment denitrification potential in seven monomictic and three polymictic lakes that range in the proportion of agriculture in the catchment from 3 to 96% to determine if there is a link between agricultural land use in the lake catchment and sediment denitrification potential. We collected sediment cores for DEA measurements over 3 weeks in austral spring 2008 (October– November). Lake Okaro, with 96% catchment agriculture, had approximately 15 times higher DEA than Lake Tikitapu, with 3% catchment agriculture (232.2 ± 55.9 vs. 15.9 ± 4.5 lg N gAFDM -1 h-1, respectively). Additionally, sediment denitrification potential increased with the proportion of catchment in agriculture (R2 = 0.85, P < 0.001). Our data suggest that lakes retain a high capacity to remove excessNvia denitrification under increasing N loads from higher proportions of catchment agriculture. However, evidence from the literature suggests that despite a high capacity for denitrification and longer water residence times, lakes with high N loads will still remove a smaller proportion of their N load. Lakes have a denitrification potential that reflects the condition of the lake catchment, but more measurements of in situ denitrification rates across lake catchments is necessary to determine if this capacity translates to high N removal rates.

text: Denitrification potential in lake sediment increases across a gradient of catchment agriculture Intensification of catchment agriculture has increased nutrient loads and accelerated eutrophication in some lakes, often resulting in episodic harmful algal blooms or prolonged periods of anoxia. The influence of catchment agriculture on lake sediment denitrification capacity as a nitrogen (N) removal mechanism in lakes is largely unknown, particularly in contrast to research on denitrification in agricultural streams and rivers. We measured denitrification enzyme activity (DEA) to assess sediment denitrification potential in seven monomictic and three polymictic lakes that range in the proportion of agriculture in the catchment from 3 to 96% to determine if there is a link between agricultural land use in the lake catchment and sediment denitrification potential. We collected sediment cores for DEA measurements over 3 weeks in austral spring 2008 (October– November). Lake Okaro, with 96% catchment agriculture, had approximately 15 times higher DEA than Lake Tikitapu, with 3% catchment agriculture (232.2 ± 55.9 vs. 15.9 ± 4.5 lg N gAFDM -1 h-1, respectively). Additionally, sediment denitrification potential increased with the proportion of catchment in agriculture (R2 = 0.85, P < 0.001). Our data suggest that lakes retain a high capacity to remove excessNvia denitrification under increasing N loads from higher proportions of catchment agriculture. However, evidence from the literature suggests that despite a high capacity for denitrification and longer water residence times, lakes with high N loads will still remove a smaller proportion of their N load. Lakes have a denitrification potential that reflects the condition of the lake catchment, but more measurements of in situ denitrification rates across lake catchments is necessary to determine if this capacity translates to high N removal rates.

year: 2011

title: Use of motion sensors for autonomous monitoring of hydraulic environments

authors: Kularatna, Nihal

subjects: commercial-off-the-shelf motion sensors

abstract: Low cost, miniaturized, commercial-off-the-shelf (COTS) motion sensors, collectively with processors, an energy source and other electronic circuitry can be packaged into very small volumes for autonomous operation. If such a system operates over short periods of time, or data acquisitions occur at a very low frequency, processor resources should be sufficient to manage offsets and errors. The paper analyzes a typical set of COTS accelerometers and gyroscopes, to indicate how best these can be used in hydraulic environments. Application examples such as river bed sediment monitoring, milk vat monitoring etc. are briefly discussed, with application oriented design approaches. Minimizing the power consumption to introduce a novel, rechargeable power supply design is briefly outlined.

text: Use of motion sensors for autonomous monitoring of hydraulic environments Low cost, miniaturized, commercial-off-the-shelf (COTS) motion sensors, collectively with processors, an energy source and other electronic circuitry can be packaged into very small volumes for autonomous operation. If such a system operates over short periods of time, or data acquisitions occur at a very low frequency, processor resources should be sufficient to manage offsets and errors. The paper analyzes a typical set of COTS accelerometers and gyroscopes, to indicate how best these can be used in hydraulic environments. Application examples such as river bed sediment monitoring, milk vat monitoring etc. are briefly discussed, with application oriented design approaches. Minimizing the power consumption to introduce a novel, rechargeable power supply design is briefly outlined.

year: 2008

title: Adolescent Māori mothers experiences with social support during pregnancy, birth and motherhood and their participation in education

authors: Rawiri, Casey

subjects: social support

abstract: The purpose of this research was to investigate the role of social support in helping
adolescent Māori mothers cope with pregnancy, birth and motherhood, with a
particular emphasis on its role in enabling them to continue at school. The aim of this
research is to understand and make sense of these experiences and to perhaps identify
gaps within an individual's social network. The analysis and methodology of the
research was underpinned by a community psychology framework.
Nine interviews were conducted with young Māori women who had become pregnant
and continued with their pregnancy, all before the age of 20. The in depth interviews
included questions focusing on the young women learning of pregnancy, the
pregnancy, birth, caring for their child and their experiences with education and future
plans.
Negative experiences were usually those which involved unsupportive people.
Positive interactions were those where support, of all types, was offered and useful to
my participants and their children. Education was highlighted as the most effective
way of providing a better life for adolescent mothers and their children.
The research highlights the importance of social support and the continuation of
education. Combining the efforts of positive social networks and social support
services can improve the lives of adolescent Māori mothers and their children.

text: Adolescent Māori mothers experiences with social support during pregnancy, birth and motherhood and their participation in education The purpose of this research was to investigate the role of social support in helping
adolescent Māori mothers cope with pregnancy, birth and motherhood, with a
particular emphasis on its role in enabling them to continue at school. The aim of this
research is to understand and make sense of these experiences and to perhaps identify
gaps within an individual's social network. The analysis and methodology of the
research was underpinned by a community psychology framework.
Nine interviews were conducted with young Māori women who had become pregnant
and continued with their pregnancy, all before the age of 20. The in depth interviews
included questions focusing on the young women learning of pregnancy, the
pregnancy, birth, caring for their child and their experiences with education and future
plans.
Negative experiences were usually those which involved unsupportive people.
Positive interactions were those where support, of all types, was offered and useful to
my participants and their children. Education was highlighted as the most effective
way of providing a better life for adolescent mothers and their children.
The research highlights the importance of social support and the continuation of
education. Combining the efforts of positive social networks and social support
services can improve the lives of adolescent Māori mothers and their children.

year: 2007