<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>32</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Khan, Alia L.</style></author><author><style face="normal" font="default" size="100%">Diane M. McKnight</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Quantifying sources, distribution, and processing of light absorbing aerosols in the cryosphere: A comparison of dissolved and refractory black carbon in polar and high mountain regions</style></title><secondary-title><style face="normal" font="default" size="100%">Department of Civil and Environmental Engineering</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">applied sciences</style></keyword><keyword><style  face="normal" font="default" size="100%">black carbon</style></keyword><keyword><style  face="normal" font="default" size="100%">cryosphere</style></keyword><keyword><style  face="normal" font="default" size="100%">earth sciences</style></keyword><keyword><style  face="normal" font="default" size="100%">glacial melt</style></keyword><keyword><style  face="normal" font="default" size="100%">health and environmental sciences</style></keyword><keyword><style  face="normal" font="default" size="100%">light absorbing aerosols</style></keyword><keyword><style  face="normal" font="default" size="100%">polar regions</style></keyword><keyword><style  face="normal" font="default" size="100%">snow</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2016</style></year></dates><urls><web-urls><url><style face="normal" font="default" size="100%">https://search.proquest.com/docview/1834518541?accountid=14503</style></url></web-urls></urls><publisher><style face="normal" font="default" size="100%">University of Colorado</style></publisher><pub-location><style face="normal" font="default" size="100%">Boulder, CO</style></pub-location><volume><style face="normal" font="default" size="100%">Ph.D.</style></volume><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;div title=&quot;Page 4&quot;&gt;&lt;div&gt;&lt;div&gt;&lt;p&gt;Light absorbing aerosols (LAAs) in snow and ice are one of the least understood parameters in global climate models due to complicated physical processes within the cryosphere and too few&amp;nbsp;in situ&amp;nbsp;observations. Ground observations are limited due to the difficulty of collecting and preserving samples for analysis from remote environments.&lt;br /&gt;In order to help build a larger repository of ground observations, this dissertation explores the concentration and composition of black carbon (BC) in snow and glacial melt-water across the polar regions in the Arctic and Antarctic, as well as major mountain regions such as the Himalayas, Rockies, and Andes Mountains.&lt;/p&gt;&lt;p&gt;Three state-of-the-art methods for BC detection are applied in this dissertation. The first chapter identifies chemical signatures of past and present sources of dissolved black carbon (DBC) in Antarctic lakes, utilizing a DBC molecular marker method. Here we find that DBC with a woody signature is preserved in the deep, ancient brines of Antarctic lake bottom waters. In contrast, the surface waters are enriched in BC from fossil fuels. The second chapter, which also utilizes the DBC molecular marker&lt;/p&gt;&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;div&gt;&lt;p&gt;iii&amp;nbsp;&lt;/p&gt;&lt;/div&gt;&lt;/div&gt;&lt;/div&gt;&lt;p&gt;&amp;nbsp;&lt;/p&gt;&lt;div title=&quot;Page 5&quot;&gt;&lt;div&gt;&lt;div&gt;&lt;p&gt;technique, explores DBC across the cryosphere. We show that DBC concentrations are surprisingly high in the bottom waters of Antarctic lakes compared to other remote regions of the cryosphere, even those located near point sources. Aged snow also contains higher DBC concentrations than fresh snow suggesting that dry deposition brings the majority of BC to the cryosphere. Additionally, the DBC composition across samples from the cryosphere are similar due to high amounts of solar exposure leading to photodegradation, except in fresh snow with a wildfire signature. The third and fourth chapters utilize the Single Particle Soot Photometer to measure refractory black carbon (rBC). The third chapter also applies spectral albedo measurements and the light absorption heating method to find that&amp;nbsp;coal dust from an active mine in Svalbard, Norway significantly reduces the spectral reflectance of the surrounding Arctic surface snow.&amp;nbsp;The fourth chapter reports aerosol rBC concentrations in the boundary layer of the McMurdo Dry Valleys, as well as in snow from the accumulation area of the Commonwealth Glacier. Here we determine that aerosol concentrations increase during high wind events, but there is no significant trend in deposition in the snow pit. This could be due to sporadic deposition during katabatic wind events.&lt;/p&gt;&lt;p&gt;These findings support the importance of real&amp;nbsp;in-situ&amp;nbsp;observations in order to fully understand the role of BC in the global carbon cycle. It is also evident that local environmental processes can control the concentrations and composition of BC in the cryosphere. These ground-based measurements will likely serve as ground validation for future remote sensing of snow/ice impurities and LAAs deposition models.&lt;/p&gt;&lt;/div&gt;&lt;/div&gt;&lt;/div&gt;&lt;p&gt;&amp;nbsp;&lt;/p&gt;</style></abstract><work-type><style face="normal" font="default" size="100%">doctoral</style></work-type></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>32</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Weaver, Mitchell R.</style></author><author><style face="normal" font="default" size="100%">Michael N. Gooseff</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Hydrologic controls of nutrient fluxes in glacial meltwater streams at inter-annual, seasonal, and daily timescales in the McMurdo Dry Valleys, Antarctica</style></title><secondary-title><style face="normal" font="default" size="100%">Department of Civil &amp; Environmental Engineering</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Antarctica</style></keyword><keyword><style  face="normal" font="default" size="100%">biogeochemistry</style></keyword><keyword><style  face="normal" font="default" size="100%">chemical weathering</style></keyword><keyword><style  face="normal" font="default" size="100%">discharge</style></keyword><keyword><style  face="normal" font="default" size="100%">electrical conductivity</style></keyword><keyword><style  face="normal" font="default" size="100%">glacial melt</style></keyword><keyword><style  face="normal" font="default" size="100%">glaciers</style></keyword><keyword><style  face="normal" font="default" size="100%">hydrology</style></keyword><keyword><style  face="normal" font="default" size="100%">hyporheic</style></keyword><keyword><style  face="normal" font="default" size="100%">MCM LTER</style></keyword><keyword><style  face="normal" font="default" size="100%">McMurdo Dry Valleys</style></keyword><keyword><style  face="normal" font="default" size="100%">nutrient fluxes</style></keyword><keyword><style  face="normal" font="default" size="100%">nutrients</style></keyword><keyword><style  face="normal" font="default" size="100%">polar desert</style></keyword><keyword><style  face="normal" font="default" size="100%">solute chemistry</style></keyword><keyword><style  face="normal" font="default" size="100%">stream chemistry</style></keyword><keyword><style  face="normal" font="default" size="100%">streamflow</style></keyword><keyword><style  face="normal" font="default" size="100%">water chemistry</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2011</style></year></dates><urls><web-urls><url><style face="normal" font="default" size="100%">https://etda.libraries.psu.edu/catalog/11568</style></url></web-urls></urls><publisher><style face="normal" font="default" size="100%">Pennsylvania State University</style></publisher><volume><style face="normal" font="default" size="100%">M.S.</style></volume><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;In the McMurdo Dry Valleys of Antarctica, glaciers are hydrologically linked to closed-basin lakes at the valley floor by glacial meltwater streams. Streams flow through porous, well-defined channels with extensive chemically active hyporheic zones. Temporally varying dynamics of meltwater generation and sub-stream thaw depth are thought to control the potential for the hyporheic zone and benthic communities to influence transport of nutrients and dissolved ions downstream. Using the McMurdo LTER database, patterns in stream discharge, electrical conductivity (both with 15-minute sampling intervals), and solute chemistry (weekly sampling intervals) were examined on eight MDV streams from 1990-2008. Discharge and electrical conductivity values were highly variable among streams. Discharge values were highly dependent upon glacial source area, but meteorological and topographical complexities create large variability at all time scales. The longer streams were found to have much higher electrical conductivity values than the shorter streams, suggesting that there are more opportunities for hyporheic weathering reactions along longer stream reaches. Weekly sampled water solutes from each stream&amp;#39;s entire record were plotted against the discharge recorded at the time when the sample was taken. Silicate concentrations displayed a decreasing logarithmic relationship, while nutrient concentrations had no apparent relationship. This suggests that with the exception to bioreactive solutes, the majority of hyporheic interactions could possibly be characterized by electrical conductivity and discharge. To attain information on in-stream nutrient dynamics and nutrient fluxes, glacial source water at the upper reach of Green Creek and stream outlet water at the lower reach of Green Creek were sampled hourly for two separate diel periods during the 2008-09 austral summer. Both dates were in late January under two distinct flow conditions (~0.5 L/s and ~10 L/s). Under low flow conditions, nutrient cycling was found to be uptake dominated. High flow conditions showed both uptake and regeneration with much higher nutrient loads, but as in the low flow conditions, no apparent temporal trends were found. Nutrient concentrations could not be predicted using the two parameters of discharge and electrical conductivity with in-stream nutrient dynamics likely too complicated at the sub-daily scale.&lt;/p&gt;</style></abstract><work-type><style face="normal" font="default" size="100%">masters</style></work-type></record></records></xml>