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首页> 外文学位 >The role of water in the development of surface roughness and mineralogical variability on playa surface sediments: Implications for aeolian erodibility and dust emission.
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The role of water in the development of surface roughness and mineralogical variability on playa surface sediments: Implications for aeolian erodibility and dust emission.

机译：水在普拉亚表面沉积物表面粗糙度和矿物学变异性发展中的作用：对风蚀性和粉尘排放的影响。

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摘要

Playas are significant sources for atmospheric mineral dust, but the evolution of their surface erodibility through time is not well established, leading to difficulties in modeling dust emission. Investigation of the spatial and temporal variability of surfaces within dust source regions has the potential to elucidate the processes that control erodibility and to improve model predictions of dust emission. In this dissertation the variability in time and space of surface mineralogical composition, particle size distribution, and surface roughness is measured in a playa (the Black Rock Desert, NV, USA). Water is found to be critical to the development of playa surfaces. Analysis of samples from the Black Rock playa demonstrates that the playa is mainly composed of quartz (∼30 wt%), clay (∼45 wt%), plagioclase (∼10 wt%), calcite (2-15 wt%), and halite (0-40 wt%). Composition varies between the center of the playa (more frequently inundated) and edge, with smaller particles, more clay, less plagioclase, and less calcite in the central areas. The surface roughness of the Black Rock playa is observed through time (2004-2010) using synthetic aperture radar (SAR) remote sensing data. Surface roughness is relatively constant during the dry summer months, but changes significantly from year to year, suggesting that water and inundation have more control on playa surfaces than anthropogenic activity or saltation abrasion. Roughness is low in years with heavy precipitation, but late drying areas of the playa are rough. Small scale lab experiments on a playa analog surface demonstrate that cycles of wetting/drying increase roughness, particularly for surfaces with added CaCO 3; a surface with added CaCO3 produced aggregates of a size appropriate for saltation (<100 microm) through wetting/drying cycles, while a surface with added NaCl remained relatively smooth. These observations suggest a conceptual framework for the development of surfaces in a playa: inundation smooths the playa surface while cycles of wetting/drying roughen it. The surface is particularly susceptible to roughening when it is rich in calcite.
机译：普拉亚斯是大气矿物粉尘的重要来源，但其表面可蚀性随时间的变化尚不完全清楚，从而导致了粉尘排放模型的困难。对尘埃源区域内表面的时空变化的研究可能阐明控制可蚀性的过程，并改善粉尘排放的模型预测。在本文中，在普拉亚海滩（美国内华达州黑岩沙漠）中测量了表面矿物组成，颗粒分布和表面粗糙度随时间和空间的变化。人们发现水对海滩表面的形成至关重要。对黑岩普拉亚岩样品的分析表明，普拉亚岩主要由石英（〜30 wt％），粘土（〜45 wt％），斜长石（〜10 wt％），方解石（2-15 wt％）和盐（0-40重量％）。成分在Playa的中心（经常被淹没）和边缘之间变化，中心区域的颗粒更小，粘土更多，斜长石和方解石更少。使用合成孔径雷达（SAR）遥感数据，可以观察到整个时间（2004-2010年）黑岩海滩的表面粗糙度。在干燥的夏季月份中，表面粗糙度相对恒定，但逐年变化很大，这表明水和淹没比人为活动或盐蚀磨损对普拉亚表面的控制更大。降水量大的年份，粗糙度较低，但普拉亚的后期干燥区域较粗糙。在海滩模拟表面上进行的小型实验室实验表明，润湿/干燥的循环会增加粗糙度，尤其是对于添加了CaCO 3的表面；添加了CaCO3的表面通过润湿/干燥循环产生了适合于盐化（<100微米）大小的聚集体，而添加了NaCl的表面保持相对光滑。这些观察结果提出了在普拉亚海滩表面发展的概念框架：淹没使普拉亚海滩表面变光滑，而润湿/干燥的周期则使其变得粗糙。当其富含方解石时，表面特别容易变粗糙。

著录项

  • 作者

    Tollerud, Heather J.;

  • 作者单位

    The Pennsylvania State University.;

  • 授予单位 The Pennsylvania State University.;
  • 学科 Geochemistry.;Remote Sensing.;Mineralogy.;Atmospheric Chemistry.
  • 学位 Ph.D.
  • 年度 2014
  • 页码 213 p.
  • 总页数 213
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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