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Full-Text Articles in Physical Sciences and Mathematics
The Spectral Variability Of Astronomical Pahs, Matthew Shannon
The Spectral Variability Of Astronomical Pahs, Matthew Shannon
Electronic Thesis and Dissertation Repository
Polycyclic aromatic hydrocarbons (PAHs) are highly abundant molecules found throughout the universe. Illuminated by ultraviolet photons, they can emit up to 10% of the total power output of star-forming galaxies and are involved in many important physical and chemical processes (e.g., gas heating). They produce prominent emission bands between 3-20 μm which vary strongly in intensity and spectral profile. The origins of these variations are not fully understood, which limits the use of PAHs as (ubiquitous) diagnostic tracers of physical conditions. To characterize their variability, we studied the relative intensities and profiles of the 10-20 μm PAH bands in a …
Dissolved Organic Matter In Subarctic Streams And Rivers: Direct And Proxy Measures Of Quantity, Quality, And Mercury, Tara M. Despault
Dissolved Organic Matter In Subarctic Streams And Rivers: Direct And Proxy Measures Of Quantity, Quality, And Mercury, Tara M. Despault
Electronic Thesis and Dissertation Repository
The drainage network of the Hudson Bay Lowlands (HBL) peatland complex regulates the transport of freshwater and solutes, including dissolved organic matter (DOM) and mercury, to Hudson Bay. Due to the remoteness and areal extent of the HBL, traditional, campaign-based sampling programs are unable to fully elucidate the region’s hydrology and biogeochemistry. This study investigated seasonal variability of DOM quantity and quality in two distinct stream orders to explore DOM sources to surface waters in the region, and assessed optical measurements as proxies for riverine DOM and mercury. In-stream primary production and enhanced microbial processing influenced DOM characteristics during base …