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31.
Much research in human geography has been, often inadvertently, sexist. We first propose some reasons for this and then review the feminist contributions in other disciplines. The bulk of the paper examines some examples of sexist bias in the content, methods, and purposes of geographic research, suggests the nature of the damage that such bias inflicts on geographic knowledge, and identifies ways in which nonsexist geography might emerge. 相似文献
32.
Spectroscopic studies of Mars analog materials combining multiple spectral ranges and techniques are necessary in order to obtain ground truth information for interpretation of rocks and soils on Mars. Two hydrothermal rocks from Yellowstone National Park, Wyoming, were characterized here because they contain minerals requiring water for formation and they provide a possible niche for some of the earliest organisms on Earth. If related rocks formed in hydrothermal sites on Mars, identification of these would be important for understanding the geology of the planet and potential habitability for life. XRD, thermal properties, VNIR, mid-IR, and Raman spectroscopy were employed to identify the mineralogy of the samples in this study. The rocks studied here include a travertine from Mammoth Formation that contains primarily calcite with some aragonite and gypsum and a siliceous sinter from Octopus Spring that contains a variety of poorly crystalline to amorphous silicate minerals. Calcite was detected readily in the travertine rock using any one of the techniques studied. The small amount of gypsum was uniquely identified using XRD, VNIR, and mid-IR, while the aragonite was uniquely identified using XRD and Raman. The siliceous sinter sample was more difficult to characterize using each of these techniques and a combination of all techniques was more useful than any single technique. Although XRD is the historical standard for mineral identification, it presents some challenges for remote investigations. Thermal properties are most useful for minerals with discrete thermal transitions. Raman spectroscopy is most effective for detecting polarized species such as CO3, OH, and CH, and exhibits sharp bands for most highly crystalline minerals when abundant. Mid-IR spectroscopy is most useful in characterizing Si-O (and metal-O) bonds and also has the advantage that remote information about sample texture (e.g., particle size) can be determined. Mid-IR spectroscopy is also sensitive to structural OH, CO3, and SO4 bonds when abundant. VNIR spectroscopy is best for characterizing metal excitational bands and water, and is also a good technique for identification of structural OH, CO3, SO4, or CH bonds. Combining multiple techniques provides the most comprehensive information about mineralogy because of the different selection rules and particle size sensitivities, in addition to maximum coverage of excitational and vibrational bands at all wavelengths. This study of hydrothermal rocks from Yellowstone provides insights on how to combine information from multiple instruments to identify mineralogy and hence evidence of water on Mars. 相似文献
33.
34.
Janice Monk 《The Professional geographer》2013,65(3):464-465
Conceptual advances for understanding the organization of family farms have not yet initiated parallel debates about how they might be aligned with the methods used to understand them. Customization of a novel research approach—farm life history—for an investigation of the socioeconomic organization of forty Australian farms responds to this literature gap. Individual farm life histories were initiated using farm tours (truck journeys) in which changes to the composition of land parcels prompted research conversations. The researcher and participants benefited from using motorized transport and traveling while talking, but the benefits were experienced unevenly across research encounters. 相似文献
35.
Tara R. Clark Jian-xin Zhao Yue-xing Feng Terry J. Done Stacy Jupiter Janice Lough John M. Pandolfi 《Geochimica et cosmochimica acta》2012
The main limiting factor in obtaining precise and accurate uranium-series (U-series) ages of corals that lived during the last few hundred years is the ability to constrain and correct for initial thorium-230 (230Th0), which is proportionally much higher in younger samples. This is becoming particularly important in palaeoecological research where accurate chronologies, based on the 230Th chronometer, are required to pinpoint changes in coral community structure and the timing of mortality events in recent time (e.g. since European settlement of northern Australia in the 1850s). In this study, thermal ionisation mass spectrometry (TIMS) U-series dating of 43 samples of known ages collected from living Porites spp. from the far northern, central and southern inshore regions of the Great Barrier Reef (GBR) was performed to spatially constrain initial 230Th/232Th (230Th/232Th0) variability. In these living Porites corals, the majority of 230Th/232Th0 values fell within error of the conservative bulk Earth 230Th/232Th atomic value of 4.3 ± 4.3 × 10?6 (2σ) generally assumed for 230Th0 corrections where the primary source is terrestrially derived. However, the results of this study demonstrate that the accuracy of 230Th ages can be further improved by using locally determined 230Th/232Th0 values for correction, supporting the conclusion made by Shen et al. (2008) for the Western Pacific. Despite samples being taken from regions adjacent to contrasting levels of land modification, no significant differences were found in 230Th/232Th0 between regions exposed to varying levels of sediment during river runoff events. Overall, 39 of the total 43 230Th/232Th0 atomic values measured in samples from inshore reefs across the entire region show a normal distribution ranging from 3.5 ± 1.1 to 8.1 ± 1.1 × 10?6, with a weighted mean of 5.76 ± 0.34 × 10?6 (2σ, MSWD = 8.1). Considering the scatter of the data, the weighted mean value with a more conservative assigned error of 25% (i.e. 5.8 ± 1.4 × 10?6) that encompasses the full variation of the 39 230Th/232Th0 measurements is recommended as a more appropriate value for initial 230Th corrections for U-series dating of most Porites samples from inshore regions of the GBR. This will result in significant improvement in both the precision and accuracy of the corrected 230Th ages related to those based on the assumed bulk Earth 230Th/232Th0 value of 4.3 ± 4.3 × 10?6. However, several anomalously high 230Th/232Th0 values reaching up to 28.0 ± 1.6 × 10?6 occasionally found in some coral annual bands coinciding with El Niño years imply high 230Th/232Th0 sources and highlight the complexities of understanding 230Th/232Th0 variability. For U-series dating of young coral samples from such sites where anomalous 230Th/232Th0 values occur, we suggest replicate dating of multiple growth bands with known age difference to verify age accuracy. 相似文献
36.
Dawn J. Wright Elizabeth O'Dea Judith B. Cushing Janice E. Cuny Douglas R. Toomey 《Marine Geodesy》2013,36(1-2):73-86
During several decades of investigation, the East Pacific Rise seafloor-spreading center at 9°-10°N has been explored by marine geologists, geophysicists, chemists, and biologists, and has emerged as one of the best studied sections of the global midocean ridge. It is an example of a region for which there is now a great wealth of observational data, results, and data-driven theoretical studies. However, these have yet to be fully utilized, either by research scientists or educators. While the situation is improving, a large amount of data, results, and related theoretical models still exist either in an inert, noninteractive form (e.g., journal publications) or as unlinked and currently incompatible computer data or algorithms. Presented here is the prototype of a computational environment and toolset, called the Virtual Research Vessel, to improve the situation by providing marine scientists and educators with simultaneous access to data, maps, and numerical models. While infrastructure is desired and needed for ready access to data and the resulting maps via web GIS in order to link disparate data sets (data to data), it is argued that data must also be linked to models for better exploration of new relations between observables, refinement of numerical simulations, and the quantitative evaluation of scientific hypotheses. For widespread data access, web GIS is therefore only a preliminary step rather than a final solution, and the ongoing implementation of the Virtual Research Vessel (scheduled for final completion in 2004-2005) is a case study for the midocean ridge community to test the effectiveness of moving beyond the data-to-data mode towards data-to-models and data-to-interpretation. 相似文献
37.
AbstractEcological flow needs (EFN) frameworks incorporate a range of ecologically-relevant hydrological variables based on prior knowledge of river regime characteristics. However, when applied in cold regions, these approaches have largely ignored the influence of winter ice cover and the spring freshet on hydrological regimes: key components of river systems in cold regions with important direct effects on water quality, aquatic habitat and ecology. Here, we combine a review of the published literature on cold-regions hydrology and hydro-ecology with available hydrometric information for sites across Canada, a major cold-region country, to explore phenomena unique to these systems. We identify several ecologically-relevant hydrological measures (i.e. annual ice on/off dates, ice-cover duration, spring freshet initiation, peak water level during river ice break-up), pairing these with established metrics for incorporation into an enhanced suite of indicators specifically designed for cold regions. This paper presents the Cold-regions Hydrological Indicators of Change (CHIC), which can provide the basis for the assessment of EFN and climate change assessments in cold-region river ecosystems.
Editor Z.W. Kundzewicz; Guest editor M. AcremanCitation Peters, D.L., Monk, W.A., and Baird, D.J., 2014. Cold-regions Hydrological Indicators of Change (CHIC) for ecological flow needs assessment. Hydrological Sciences Journal, 59 (3–4), 502–516. 相似文献
38.
The transport of woody debris from urban surfaces,through local urban waterways,to constriction and blockage risk locations is not well understood.Flume trials have identified debris and watercourse dimensions as influential factors on debris movement,and large woody debris movement has been traced in the natural rural environment using time series photography,active transponders,and field surveys.Using novel passive transponder technology,small woody debris has been traced through an urban case study watercourse to establish key influential factors on urban debris transport.Through incorporating urban debris transport detail into the source and deposition process,a complete picture of urban debris transport can be created,supporting effective culvert and trash screen design,watercourse maintenance and blockage risk assessment.This case study highlights that factors beyond watercourse depth and velocity are influential in debris movement within an urban watercourse.Debris dimension and source location upstream are shown to significantly affect the potential for debris to reach a downstream constriction,illustrating a possible distance limitation in nuisance flow debris blockage risk. 相似文献
39.
Janice Stonebridge Rachel Baldwin Neil R. Thomson Carol Ptacek 《Ground Water Monitoring & Remediation》2020,40(2):73-80
Fluoride (F−) concentration in groundwater can be used as an independent measure of the degradation of per- and polyfluoroalkyl substances (PFAS) at contaminated sites. This study assessed the impact of the groundwater matrix, oxidizing reagents, quenching agent, and sample handling procedures (filtration) on determinations of F−. F− was quantified using a fluoride-selective electrode (FSE) using matrix spike recovery (acceptable range 75 to 125%) and electrode slope performance (ideal range −54 to −60 mV). For the unaltered aqueous matrices considered (ultrapure water, ultrapure water with sodium chloride, and simulated groundwater), matrix spike recoveries were greater than 93% and acceptable electrode slopes (−59.5 ± 0.2 mV) were obtained. Matrix spike recoveries and electrode slopes when persulfate or permanganate was added were 87 and 93%, and −58.4 ± 1.3 and −47.3 ± 2.2 mV, respectively. Therefore, quantifying F− in matrices containing permanganate should involve use of either a matrix-matched calibration curve or the method of standard additions due to the low electrode slope. The addition of ascorbic acid as a quenching agent resulted in a decrease in matrix spike recoveries to <74% and suggests alternate quenching procedures should be used if an FSE is employed to measure F−. Removal of sediments by filtration prior to the addition of the fluoride spike led to improved matrix spike recoveries (>96%), which were otherwise underestimated using the FSE in the presence of sediments. While the FSE may be a quick and portable tool, its significant limitations need to be fully understood before it can be used to quantify the production of F− resulting from the potential degradation of PFAS at field sites. 相似文献
40.
Mario Parente Heather D. Makarewicz Janice L. Bishop 《Planetary and Space Science》2011,59(5-6):423-442
This study advances curve-fitting modeling of absorption bands of reflectance spectra and applies this new model to spectra of Martian meteorites ALH 84001 and EETA 79001 and data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). This study also details a recently introduced automated parameter initialization technique. We assess the performance of this automated procedure by comparing it to the currently available initialization method and perform a sensitivity analysis of the fit results to variation in initial guesses. We explore the issues related to the removal of the continuum, offer guidelines for continuum removal when modeling the absorptions and explore different continuum-removal techniques. We further evaluate the suitability of curve fitting techniques using Gaussians/Modified Gaussians to decompose spectra into individual end-member bands. We show that nonlinear least squares techniques such as the Levenberg–Marquardt algorithm achieve comparable results to the MGM model (Sunshine and Pieters, 1993, Sunshine et al., 1990) for meteorite spectra. Finally we use Gaussian modeling to fit CRISM spectra of pyroxene and olivine-rich terrains on Mars. Analysis of CRISM spectra of two regions show that the pyroxene-dominated rock spectra measured at Juventae Chasma were modeled well with low Ca pyroxene, while the pyroxene-rich spectra acquired at Libya Montes required both low-Ca and high-Ca pyroxene for a good fit. 相似文献