Digital Commons Network^™

A Synthesis Program: Reducing Uncertainties Of The Terrestrial Biosphere Carbon Cycle At Various Spatio Temporal Scales, Xinyuan Wei

Electronic Theses and Dissertations

The terrestrial biosphere plays an important role in the global carbon cycle, and disturbance fire and climate extreme drought have strong direct and indirect impacts on the carbon fluxes. In addition, the lateral dissolved organic carbon (DOC) flux from soils to inland waters represents an important component of the terrestrial biosphere carbon cycle.

Fires play an important role in the terrestrial biosphere carbon cycle, not only through direct carbon release but also contributing to a potential long-term storage as pyrogenic carbon (PyC). PyC is formed through fires, and because it may resist further biological and chemical degradation, is more stable …

Sulfur And Trace Metal Cycling At Convergent Margins, Jesse B. Walters

Electronic Theses and Dissertations

Subduction zones are the site of long-term chemical exchange between Earth’s surface and interior geochemical reservoirs. Subducting slabs are progressively depleted in volatiles and other mobile elements through dehydration and melting reactions. These elements are then introduced to the mantle wedge and volcanic arc. One consequence of this cycle is that volcanic arcs produce the most oxidized magmas on Earth. Sulfur, which exhibits a range in valence states from S^2- to S⁶⁺, is one of the few elements in the subducting slab capable of oxidizing the arc and mantle wedge. Sulfides in the slab may also act …

Variations In The Southern Hemisphere Westerlies Over The Last 23,000 Years From Lake Records In The Falkland Islands, Meghan M. Spoth

Electronic Theses and Dissertations

The Southern Hemisphere Westerlies (SHW) are an important driver of climate in the mid-latitudes of the Southern Hemisphere. Abrupt latitudinal migration of this coupled atmospheric-oceanic system is thought to be linked to the onset of the Termination at the end of the last ice age and to subsequent climatic variation through the late-glacial period and Holocene. However, the timing and spatial extent of these shifts, as well as variations in wind intensity, are poorly constrained, hindering our understanding of abrupt climate change in the Southern Hemisphere. In addition, future changes in the position and intensity of the SHW are a …

Fostering Climate Change Resilience: A Socio-Ecological Forest Systems Approach, Alyssa R. Soucy

Electronic Theses and Dissertations

As climate change continues to impact socio-ecological systems, those that rely on natural resources are highly sensitive to climatic changes. Maine’s forest industry provides for the economic and social well-being of many residents and is especially vulnerable to climate change impacts. Changes in growing season length and timing, forest health threats imposed by insects and pathogens, extreme weather events, shifting forest composition, and changes in natural disturbance severity and frequency have already begun, and are projected to continue, to impact forest systems in the Northeastern U.S. While climate change presents a threat to forest systems, opportunities also arise due to …

A Groundwater Flow Model To Aid In Water Resource Management For The Carraipia Basin In The Coastal Semi-Arid Region Of La Guajira State (Colombia), Efren D. Gomez Arevalo

Electronic Theses and Dissertations

About 160,000 inhabitants live in the 1,600 square kilometers Carraipia River Basin located in northeastern Colombia and northwestern Venezuela. Historically, water has been supplied to the inhabitants in this arid coastal region by shallow dug wells. Water supplied by these wells is frequently of poor quality due to high concentrations of total dissolved solids (TDS). Recently, due to the increasing demand for water, numerous deep wells have been drilled in the region to supply water to rural and urban areas from deep aquifers. Colombian agencies seek more quantitative information on groundwater resources, driven by increasingly severe water shortages over the …

An Algorithm To Estimate Suspended Particulate Matter Concentrations And Associated Uncertainties From Remote Sensing Reflectance In Coastal Environments, Juliana Tavora

Electronic Theses and Dissertations

Suspended Particulate Matter (SPM) is a major constituent in coastal waters, involved in processes such as light attenuation, pollutant propagation, and waterways blockage. The spatial distribution of SPM is an indicator of deposition and erosion patterns in estuaries and coastal zones and a necessary input to estimate the material fluxes from the land through rivers to the sea. In-situ methods to estimate SPM provide limited spatial data in comparison to the coverage that can be obtained remotely. Ocean color remote sensing complements field measurements by providing estimates of the spatial distributions of surface SPM concentration in natural waters, with high …