title: Palaeolimnology of Adelaide Tarn, a ~14,000-year-old low-alpine glacial lake, northwestern South Island, New Zealand

authors: Foster, Courtney Renee

subjects: Palaeolimnology

abstract: A palaeolimnology study has been carried out on a ~14,000 calendar [cal]-year-old low-alpine glacial lake, Adelaide Tarn. The lake is located in a cirque basin at ~1260 m elevation in the Tasman Mountains, just below present-day treeline, within Kahurangi National Park, northern South Island, New Zealand. A 5.6-m long sediment core was retrieved from the lake by staff of GNS Science. The chronology of the core was constructed from 15 ¹⁴C dates obtained via AMS on 14 samples of in-situ plant macrofossils and one sample of bulk organic sediment. The core was divided into lithozones 1, 2, and 3 from the base through to the top of the core. Lithozone 1 (5.6–4.8 m) comprises inorganic (carbon content 0.3 to 4%) grey silts with gravel (Munsell colour 5Y 6/1) and these sediments, primarily composed of angular particles identifed by scanning electron microscopy (SEM), date to a little earlier than ~13,932 cal yr BP. Lithozone 2 consists of organic (carbon content up to 15%) brownish black (10YR 2/3) silt and clay and extends from ~13,932 to ~7709 cal yr BP. In lithozone 2, diatoms appear, as identified by SEM. Lithozone 3 is made up of dark brown (10YR 3/4) organic silt (carbon content 5 to 10%) and extends from ~7709 cal yr BP through to the top of the core which has an age estimated to be a little older than ~700 cal yr BP on the basis of a ¹⁴C date (~926 cal yr BP) at 13 cm depth and a pollen record that shows neither a Polynesian deforestation signal (i.e. the sediments likely pre-date ~700 cal yr BP) nor European adventives (i.e. the sediments pre-date ~1840 AD). Lithozone 3 is diatom-rich with subordinate angular particles. Intermittent yellow/brown (10YR 6/8) laminae occur throughout lithozones 2 and 3; one lamination occurs near the top of lithozone 1. These yellow/brown laminae comprise mainly angular clastic particles (evident in SEM micrographs) and show a slight increase in sand compared with non-laminated sediments, and the laminae are inferred to reflect terrigenous input to the lake as a consequence of storms or during intense rainfall events. These possible storm events may correspond with ENSO events as described/identified in Lake Tutira in Hawke’s Bay. 
Multiple components of the sediment archive were analysed to reconstruct the history of the lake and its catchment. Properties included were X-radiography, grey-scale, magnetic susceptibility, grain size, plant macrofossil assemblages, organic carbon content, and isotopes δ¹⁵N and δ¹³C. 
The results show four phases of climate variability (Adelaide Tarn climate events, AT-CEs) from the onset of lake formation ~14,000 cal yr BP. AT-CE1: early sediments ~14,000 cal yr BP show enhanced terrigenous input (fine-grained grey silts, with gravel layers, of lithozone 1), consistent with fluvio-glacial in-wash during retreat from the Adelaide Tarn basin of a local cirque glacier. AT-CE2: from ~13,932 to ~10,000 cal yr BP, erosion of the catchment is much diminished, indicated by decreases in modal grain size and magnetic susceptibility, and lake productivity concomitantly commences as shown by the δ¹³C and δ¹⁵N isotope records. Poaceae species dominate the macrofossil plant assemblages with no tree-species found. AT-CE2 (~13,932 to ~10,000 cal yr BP) is inferred to be one of warming but the catchment was not yet stable and little or no soil formation occurred that would allow habitation by tree species. AT-CE3: the third palaeoenvironmental phase, from ~10,000 to ~2400 cal yr BP, is marked by an expansion of Nothofagus (Nothofagus menziesii and Nothofagus fusca) forest with minor constituents of Libocedrus biwillii and Phyllocladus alpinus. This phase is inferred to be one of sustained warm conditions and a stable catchment. Adelaide Tarn is situated 250 m higher than the present-day altitudinal limit of N. fusca and the presence of macrofossils of this species in the sediment record suggests that between ~6400 and ~2400 cal yr BP the mean annual temperature was possibly ~1.2˚C warmer than present based on an observed environmental lapse rate of 0.47˚C/100 m. There was slight increase in denitrification from ~8000 through to ~3000 cal yr BP, suggesting that primary productivity increased in the lake. AT-CE4: from ~2400 cal yr BP, the fourth phase, the plant assemblage shifted to Poaceae-dominated; cold-sensitive taxa were forced to descend, marked by disappearance of forest species from the plant macrofossil assemblage. The climate is inferred to have deteriorated and the tree-line descended to near the present-day position. 
The Adelaide Tarn record is one of only a few spanning the last ~14,000 years in central New Zealand, and is especially useful in adding to the plant macrofossil records, which are rare. The Adelaide Tarn record was compared with the newly-published New Zealand climate event stratigraphy (NZ-CES), with the proposed tripartite subdivision of the Holocene, and with a number of records across New Zealand that are based on various proxies including speleothems and pollen assemblages. None of the NZ-CES events were clearly evident in the Adelaide Tarn record (apart from NZce-1), and the proposed boundaries of the subdivided Holocene (at ~8.2 ka and 4.2 ka) were not evident. A palynological record spanning the last ~12,000 years from Cropp Valley, western South Island, showed close consistency with the Adelaide Tarn record.

text: Palaeolimnology of Adelaide Tarn, a ~14,000-year-old low-alpine glacial lake, northwestern South Island, New Zealand A palaeolimnology study has been carried out on a ~14,000 calendar [cal]-year-old low-alpine glacial lake, Adelaide Tarn. The lake is located in a cirque basin at ~1260 m elevation in the Tasman Mountains, just below present-day treeline, within Kahurangi National Park, northern South Island, New Zealand. A 5.6-m long sediment core was retrieved from the lake by staff of GNS Science. The chronology of the core was constructed from 15 ¹⁴C dates obtained via AMS on 14 samples of in-situ plant macrofossils and one sample of bulk organic sediment. The core was divided into lithozones 1, 2, and 3 from the base through to the top of the core. Lithozone 1 (5.6–4.8 m) comprises inorganic (carbon content 0.3 to 4%) grey silts with gravel (Munsell colour 5Y 6/1) and these sediments, primarily composed of angular particles identifed by scanning electron microscopy (SEM), date to a little earlier than ~13,932 cal yr BP. Lithozone 2 consists of organic (carbon content up to 15%) brownish black (10YR 2/3) silt and clay and extends from ~13,932 to ~7709 cal yr BP. In lithozone 2, diatoms appear, as identified by SEM. Lithozone 3 is made up of dark brown (10YR 3/4) organic silt (carbon content 5 to 10%) and extends from ~7709 cal yr BP through to the top of the core which has an age estimated to be a little older than ~700 cal yr BP on the basis of a ¹⁴C date (~926 cal yr BP) at 13 cm depth and a pollen record that shows neither a Polynesian deforestation signal (i.e. the sediments likely pre-date ~700 cal yr BP) nor European adventives (i.e. the sediments pre-date ~1840 AD). Lithozone 3 is diatom-rich with subordinate angular particles. Intermittent yellow/brown (10YR 6/8) laminae occur throughout lithozones 2 and 3; one lamination occurs near the top of lithozone 1. These yellow/brown laminae comprise mainly angular clastic particles (evident in SEM micrographs) and show a slight increase in sand compared with non-laminated sediments, and the laminae are inferred to reflect terrigenous input to the lake as a consequence of storms or during intense rainfall events. These possible storm events may correspond with ENSO events as described/identified in Lake Tutira in Hawke’s Bay. 
Multiple components of the sediment archive were analysed to reconstruct the history of the lake and its catchment. Properties included were X-radiography, grey-scale, magnetic susceptibility, grain size, plant macrofossil assemblages, organic carbon content, and isotopes δ¹⁵N and δ¹³C. 
The results show four phases of climate variability (Adelaide Tarn climate events, AT-CEs) from the onset of lake formation ~14,000 cal yr BP. AT-CE1: early sediments ~14,000 cal yr BP show enhanced terrigenous input (fine-grained grey silts, with gravel layers, of lithozone 1), consistent with fluvio-glacial in-wash during retreat from the Adelaide Tarn basin of a local cirque glacier. AT-CE2: from ~13,932 to ~10,000 cal yr BP, erosion of the catchment is much diminished, indicated by decreases in modal grain size and magnetic susceptibility, and lake productivity concomitantly commences as shown by the δ¹³C and δ¹⁵N isotope records. Poaceae species dominate the macrofossil plant assemblages with no tree-species found. AT-CE2 (~13,932 to ~10,000 cal yr BP) is inferred to be one of warming but the catchment was not yet stable and little or no soil formation occurred that would allow habitation by tree species. AT-CE3: the third palaeoenvironmental phase, from ~10,000 to ~2400 cal yr BP, is marked by an expansion of Nothofagus (Nothofagus menziesii and Nothofagus fusca) forest with minor constituents of Libocedrus biwillii and Phyllocladus alpinus. This phase is inferred to be one of sustained warm conditions and a stable catchment. Adelaide Tarn is situated 250 m higher than the present-day altitudinal limit of N. fusca and the presence of macrofossils of this species in the sediment record suggests that between ~6400 and ~2400 cal yr BP the mean annual temperature was possibly ~1.2˚C warmer than present based on an observed environmental lapse rate of 0.47˚C/100 m. There was slight increase in denitrification from ~8000 through to ~3000 cal yr BP, suggesting that primary productivity increased in the lake. AT-CE4: from ~2400 cal yr BP, the fourth phase, the plant assemblage shifted to Poaceae-dominated; cold-sensitive taxa were forced to descend, marked by disappearance of forest species from the plant macrofossil assemblage. The climate is inferred to have deteriorated and the tree-line descended to near the present-day position. 
The Adelaide Tarn record is one of only a few spanning the last ~14,000 years in central New Zealand, and is especially useful in adding to the plant macrofossil records, which are rare. The Adelaide Tarn record was compared with the newly-published New Zealand climate event stratigraphy (NZ-CES), with the proposed tripartite subdivision of the Holocene, and with a number of records across New Zealand that are based on various proxies including speleothems and pollen assemblages. None of the NZ-CES events were clearly evident in the Adelaide Tarn record (apart from NZce-1), and the proposed boundaries of the subdivided Holocene (at ~8.2 ka and 4.2 ka) were not evident. A palynological record spanning the last ~12,000 years from Cropp Valley, western South Island, showed close consistency with the Adelaide Tarn record.

year: 2013

title: Energy losses by anisotropic viscous dissipation in transient magnetic reconnection

authors: Craig, Ian J.D.

subjects: magnetic reconnection

abstract: Global energy losses associated with transient magnetic reconnection in a viscous resistive plasma are examined. The Braginskii stress tensor is used to model the plasma viscosity for conditions typical of the solar corona. Analytic arguments are used to show that the large-scale advective flows associated with magnetic merging are likely to generate significant viscous losses. It is pointed out that the development of a visco-resistive reconnection scale, predicted for the classical shear viscosity, is not expected in the more realistic case of the Braginskii viscosity. Numerical simulations of planar coalescence merging show that viscous losses should easily dominate resistive losses for physically plausible parameters in flaring regions. Our computations imply that flare-like rates exceeding 10²⁹ erg s⁻¹ can be achieved under plausible coronal conditions.

text: Energy losses by anisotropic viscous dissipation in transient magnetic reconnection Global energy losses associated with transient magnetic reconnection in a viscous resistive plasma are examined. The Braginskii stress tensor is used to model the plasma viscosity for conditions typical of the solar corona. Analytic arguments are used to show that the large-scale advective flows associated with magnetic merging are likely to generate significant viscous losses. It is pointed out that the development of a visco-resistive reconnection scale, predicted for the classical shear viscosity, is not expected in the more realistic case of the Braginskii viscosity. Numerical simulations of planar coalescence merging show that viscous losses should easily dominate resistive losses for physically plausible parameters in flaring regions. Our computations imply that flare-like rates exceeding 10²⁹ erg s⁻¹ can be achieved under plausible coronal conditions.

year: 2010

title: Mai ngā reo pou tangata

authors: Nathan, Lisa Kiriwai

subjects: Maori

abstract: Globally the prevalence rate of dementia is estimated to be 50 million.  In 2016, Aotearoa New Zealand prevalence projections reported 62,287 people were affected by dementia.  Māori represented 5.1 per cent, which is expected to rise to 8 per cent by 2038.  Māori people prefer to care for ill kaumātua (older people) at home and are experiencing greater stress and increased caregiver burden due to the cultural expectations of caring for kaumātua at home.  The two aims of this study were first, to explore the perspectives of Māori whānau carers caring for kaumātua with dementia, and the second aim was to explore the perspectives of staff who work for dementia service providers, addressing areas such as staff’s experiences with Māori whānau carers and cultural competency in service delivery.
	Semi-structured interviews were conducted with eight whānau (11 whānau carers) within the Waikato region of New Zealand and seven service provider staff participants. Whānau carers were interviewed first.  They were asked to share information about their kaumātua.  The topics explored the diagnosis process; the behavioural changes of the kaumātua living with dementia and the whānau caring experience.  Thematic analysis was conducted on the resulting transcripts to identify themes and to identify potential service providers to approach for interviews.  Five service provider organisations were selected, of which four service providers were able to commit to an interview.  One service provider could not commit to an interview due to thesis time constraints. Seven staff participants across the four service providers were recruited and invited to share their perspectives of working with Māori whānau.  Again, thematic analysis was conducted on the verbatim transcripts to identify salient themes.
	Two major findings amidst the perspectives of whānau carers was identified.  First, the systemic lack of support across three dimensions, and second the negative impact of caregiver burden. The first deficiency was the lack of support from whānau members, second, the lack of support from community services and third, the lack of support from the government.  Whānau experienced poor health as a result of caregiver burden. Staff participants findings were firstly staff believed they were culturally inclusive and responsive, second they reported going beyond their roles and the system to support Māori and third staff identified barriers which exist for Māori in terms of accessing services.
	Whānau carers are struggling to find support from other whānau members.  Some whānau members are critical of caring methods, while others place additional burden on the carers.  Whānau are often described as an interconnected unit, however findings show that Māori whānau carers are feeling isolated and alone, and as a result are experiencing poor health. 
	Whānau carers perceive a services in their community as not being culturally inclusive or appropriate.  Staff participants said that they incorporate respect and compassion into their service delivery.  Staff recognise that the numbers of Māori represented at services are low, compared to non-Māori clients.  Services need to be integrate cultural training on a regular basis to ensure Māori are comfortable with being Māori in service settings.

text: Mai ngā reo pou tangata Globally the prevalence rate of dementia is estimated to be 50 million.  In 2016, Aotearoa New Zealand prevalence projections reported 62,287 people were affected by dementia.  Māori represented 5.1 per cent, which is expected to rise to 8 per cent by 2038.  Māori people prefer to care for ill kaumātua (older people) at home and are experiencing greater stress and increased caregiver burden due to the cultural expectations of caring for kaumātua at home.  The two aims of this study were first, to explore the perspectives of Māori whānau carers caring for kaumātua with dementia, and the second aim was to explore the perspectives of staff who work for dementia service providers, addressing areas such as staff’s experiences with Māori whānau carers and cultural competency in service delivery.
	Semi-structured interviews were conducted with eight whānau (11 whānau carers) within the Waikato region of New Zealand and seven service provider staff participants. Whānau carers were interviewed first.  They were asked to share information about their kaumātua.  The topics explored the diagnosis process; the behavioural changes of the kaumātua living with dementia and the whānau caring experience.  Thematic analysis was conducted on the resulting transcripts to identify themes and to identify potential service providers to approach for interviews.  Five service provider organisations were selected, of which four service providers were able to commit to an interview.  One service provider could not commit to an interview due to thesis time constraints. Seven staff participants across the four service providers were recruited and invited to share their perspectives of working with Māori whānau.  Again, thematic analysis was conducted on the verbatim transcripts to identify salient themes.
	Two major findings amidst the perspectives of whānau carers was identified.  First, the systemic lack of support across three dimensions, and second the negative impact of caregiver burden. The first deficiency was the lack of support from whānau members, second, the lack of support from community services and third, the lack of support from the government.  Whānau experienced poor health as a result of caregiver burden. Staff participants findings were firstly staff believed they were culturally inclusive and responsive, second they reported going beyond their roles and the system to support Māori and third staff identified barriers which exist for Māori in terms of accessing services.
	Whānau carers are struggling to find support from other whānau members.  Some whānau members are critical of caring methods, while others place additional burden on the carers.  Whānau are often described as an interconnected unit, however findings show that Māori whānau carers are feeling isolated and alone, and as a result are experiencing poor health. 
	Whānau carers perceive a services in their community as not being culturally inclusive or appropriate.  Staff participants said that they incorporate respect and compassion into their service delivery.  Staff recognise that the numbers of Māori represented at services are low, compared to non-Māori clients.  Services need to be integrate cultural training on a regular basis to ensure Māori are comfortable with being Māori in service settings.

year: 2019