title: Image data fusion for the remote sensing of freshwater environments

authors: Ashraf, Muhammad Salman

subjects: freshwater environment

abstract: Remote sensing based mapping of diverse and heterogeneous freshwater environments requires high-resolution images. Data fusion is a useful technique for producing a high-resolution multispectral image from the merging of a high-resolution panchromatic image with a low-resolution multispectral image. Given the increasing availability of images from different satellite sensors that have different spectral and spatial resolutions, data fusion techniques that combine the strengths of different images will be increasingly important to Geography for land-cover mapping. Different data fusion methods however, add spectral and spatial distortions to the resultant data depending on the geographical context; therefore a careful selection of the fusion method is required. This paper compares a technique called subtractive resolution merge, which has not previously been formally tested, with conventional techniques such as Brovey transformation, principal component substitution, local mean and variance matching, and optimised high pass filter addition. Data fusion techniques are grouped into spectral and spatial centric methods. Subtractive resolution merge belongs to a new class of data fusion techniques that uses a mix of both spatial and spectral centric approaches. The different data fusion techniques were applied to a QuickBird image of a semi-aquatic freshwater environment in New Zealand. The results were compared both qualitatively and quantitatively using spectral and spatial error metrics. This research concludes that subtractive resolution merge performed better than all the other techniques and will be a valuable technique for enhancing images for freshwater land-cover mapping.

text: Image data fusion for the remote sensing of freshwater environments Remote sensing based mapping of diverse and heterogeneous freshwater environments requires high-resolution images. Data fusion is a useful technique for producing a high-resolution multispectral image from the merging of a high-resolution panchromatic image with a low-resolution multispectral image. Given the increasing availability of images from different satellite sensors that have different spectral and spatial resolutions, data fusion techniques that combine the strengths of different images will be increasingly important to Geography for land-cover mapping. Different data fusion methods however, add spectral and spatial distortions to the resultant data depending on the geographical context; therefore a careful selection of the fusion method is required. This paper compares a technique called subtractive resolution merge, which has not previously been formally tested, with conventional techniques such as Brovey transformation, principal component substitution, local mean and variance matching, and optimised high pass filter addition. Data fusion techniques are grouped into spectral and spatial centric methods. Subtractive resolution merge belongs to a new class of data fusion techniques that uses a mix of both spatial and spectral centric approaches. The different data fusion techniques were applied to a QuickBird image of a semi-aquatic freshwater environment in New Zealand. The results were compared both qualitatively and quantitatively using spectral and spatial error metrics. This research concludes that subtractive resolution merge performed better than all the other techniques and will be a valuable technique for enhancing images for freshwater land-cover mapping.

year: 2011

title: Development and application of a method for U-Th dating of the Bonney Drift, Taylor Valley, Antarctica

authors: Smith, David W.

abstract: The lacustrine carbonates of the Bonney Drift, Taylor Valley, Antarctica were deposited in lakes proglacial to glaciers advancing through the valley, and now occur as lag and clasts in the glacial drift formed by the glacier. They commonly contain 8 to 25% detritus, including high levels of silica, titanium, iron, manganese, and other elements; making the extraction and purification of uranium and thorium problematic.

A standard U-Th dating process was adapted to deal with the technical problems peculiar to the samples dated. Silica often formed a gel at the head of the U-Th separation column, and was removed using HF. Titanium frequently precipitated out during the conversion of the thorium fraction from a HCl matrix to HNO₃ form (used for further ion exchange purification) causing very low thorium recovery. This was overcome by using much higher volumes during conversion. 

The uranium eluate from the separation column often contained high levels of iron and manganese. These were removed on a small ion exchange column in HNO₃. The resin and wash volumes were adjusted to allow iron and manganese to wash off, but allowing the uranium to be held and eluted subsequently. 

An electrodeposition method was developed to achieve the thin plates necessary for alpha spectroscopy. Silver cathode discs were used in a teflon plating cell, with a stirrer rotating on the spiral planar platinum anode. An NH₄Cl/HCl electrolyte was used, adjusted in pH after sample uptake. 

Of the 62 samples successfully dated, 13 were eliminated for such reasons as low resolution and spectral shift; leaving 17 duplicates, one triplicate and 12 single analyses for further consideration. Samples with low ²³²Th/TIFFS
Th levels were corrected for detrital ²³²Th addition. 

The dates obtained were considered in terms of age, geographic distribution, and uranium isotope ratios and concentrations. δ180 suggested that samples were derived from either Taylor Glacier meltwaters, or possibly Ross Ice Sheet Stage 6 meltwaters, and showed that δ180 values in the meltwaters increased towards the middle of each event. 

Three major events were identified. 
(i) an extensive period of deposition around 240 to 300kA (Stage 9?), This may possibly represent two events, in a lake(s) most likely formed proglacial to an expanded Taylor Glacier. 
(ii) a short period of lacustrine conditions around 175 to 190 kA ago, correlated with either Taylor Glacier expansion at the end of Stage 7, or Ross Ice Sheet thickening at the start of Stage 6. 
(iii) a period of carbonate deposition from 130 to 80 kA( Stage 5), more extensive than that at 175-190 kA. The expanding glacier (Taylor II) then advanced through the carbonates, and those of the earlier events, and redeposited. 

The events interpreted appear to correlate with global interglacials, as suggested by Hendy et al (1979). It seems that during interglacials, the East Antarctic Ice Sheet expands (the absence of a sea ice apron allows increased precipitation). As a result, expansion of the East Antarctic Ice Sheet would be expected as a consequence of greenhouse gas warming, offsetting sea level rises caused by melting of temperate glaciers and ice sheets.

text: Development and application of a method for U-Th dating of the Bonney Drift, Taylor Valley, Antarctica The lacustrine carbonates of the Bonney Drift, Taylor Valley, Antarctica were deposited in lakes proglacial to glaciers advancing through the valley, and now occur as lag and clasts in the glacial drift formed by the glacier. They commonly contain 8 to 25% detritus, including high levels of silica, titanium, iron, manganese, and other elements; making the extraction and purification of uranium and thorium problematic.

A standard U-Th dating process was adapted to deal with the technical problems peculiar to the samples dated. Silica often formed a gel at the head of the U-Th separation column, and was removed using HF. Titanium frequently precipitated out during the conversion of the thorium fraction from a HCl matrix to HNO₃ form (used for further ion exchange purification) causing very low thorium recovery. This was overcome by using much higher volumes during conversion. 

The uranium eluate from the separation column often contained high levels of iron and manganese. These were removed on a small ion exchange column in HNO₃. The resin and wash volumes were adjusted to allow iron and manganese to wash off, but allowing the uranium to be held and eluted subsequently. 

An electrodeposition method was developed to achieve the thin plates necessary for alpha spectroscopy. Silver cathode discs were used in a teflon plating cell, with a stirrer rotating on the spiral planar platinum anode. An NH₄Cl/HCl electrolyte was used, adjusted in pH after sample uptake. 

Of the 62 samples successfully dated, 13 were eliminated for such reasons as low resolution and spectral shift; leaving 17 duplicates, one triplicate and 12 single analyses for further consideration. Samples with low ²³²Th/TIFFS
Th levels were corrected for detrital ²³²Th addition. 

The dates obtained were considered in terms of age, geographic distribution, and uranium isotope ratios and concentrations. δ180 suggested that samples were derived from either Taylor Glacier meltwaters, or possibly Ross Ice Sheet Stage 6 meltwaters, and showed that δ180 values in the meltwaters increased towards the middle of each event. 

Three major events were identified. 
(i) an extensive period of deposition around 240 to 300kA (Stage 9?), This may possibly represent two events, in a lake(s) most likely formed proglacial to an expanded Taylor Glacier. 
(ii) a short period of lacustrine conditions around 175 to 190 kA ago, correlated with either Taylor Glacier expansion at the end of Stage 7, or Ross Ice Sheet thickening at the start of Stage 6. 
(iii) a period of carbonate deposition from 130 to 80 kA( Stage 5), more extensive than that at 175-190 kA. The expanding glacier (Taylor II) then advanced through the carbonates, and those of the earlier events, and redeposited. 

The events interpreted appear to correlate with global interglacials, as suggested by Hendy et al (1979). It seems that during interglacials, the East Antarctic Ice Sheet expands (the absence of a sea ice apron allows increased precipitation). As a result, expansion of the East Antarctic Ice Sheet would be expected as a consequence of greenhouse gas warming, offsetting sea level rises caused by melting of temperate glaciers and ice sheets.

year: 1991

title: Genealogical Violence: Mormon (Mis)Appropriation of Māori Cultural Memory through Falsification of Whakapapa

authors: Simon, Hemopereki

subjects: whakapapa

abstract: The study examines how members of the historically white possessive and supremacist Church of Jesus Christ of Latter-day Saints in the United States (mis)appropriated Māori genealogy, known as whakapapa. The Mormon use of whakapapa to promote Mormon cultural memory and narratives perpetuates settler/invader colonialism and white supremacy, as this paper shows. The research discusses Church racism against Native Americans and Pacific Peoples. This paper uses Anthropologist Thomas Murphy’s scholarship to demonstrate how problematic the Book of Mormon’s religio-colonial identity of Lamanites is for these groups. Application of Aileen Moreton-Robinson’s white possessive doctrine and Hemopereki Simon’s adaptation to cover Church-Indigenous relations and the salvation contract is discussed. We explore collective and cultural memory and discuss key Māori concepts like Mana, Taonga, Tapu, and Whakapapa. A brief review of LDS scholar Louis C. Midgley’s views on Church culture, including Herewini Jones’s whakapapa wānanga, is followed by a discussion of Māori cultural considerations and issues. The paper concludes that the alteration perpetuates settler/invader colonialism and Pacific peoples’ racialization and white supremacy. Genetics science and human migration studies contradict Mormon identity narratives and suggest the BOM is spiritual rather than historical. Finally, the paper suggests promoting intercultural engagement on Mormon (mis)appropriation of taonga Māori.

text: Genealogical Violence: Mormon (Mis)Appropriation of Māori Cultural Memory through Falsification of Whakapapa The study examines how members of the historically white possessive and supremacist Church of Jesus Christ of Latter-day Saints in the United States (mis)appropriated Māori genealogy, known as whakapapa. The Mormon use of whakapapa to promote Mormon cultural memory and narratives perpetuates settler/invader colonialism and white supremacy, as this paper shows. The research discusses Church racism against Native Americans and Pacific Peoples. This paper uses Anthropologist Thomas Murphy’s scholarship to demonstrate how problematic the Book of Mormon’s religio-colonial identity of Lamanites is for these groups. Application of Aileen Moreton-Robinson’s white possessive doctrine and Hemopereki Simon’s adaptation to cover Church-Indigenous relations and the salvation contract is discussed. We explore collective and cultural memory and discuss key Māori concepts like Mana, Taonga, Tapu, and Whakapapa. A brief review of LDS scholar Louis C. Midgley’s views on Church culture, including Herewini Jones’s whakapapa wānanga, is followed by a discussion of Māori cultural considerations and issues. The paper concludes that the alteration perpetuates settler/invader colonialism and Pacific peoples’ racialization and white supremacy. Genetics science and human migration studies contradict Mormon identity narratives and suggest the BOM is spiritual rather than historical. Finally, the paper suggests promoting intercultural engagement on Mormon (mis)appropriation of taonga Māori.

year: 2024