Physical Sciences and Mathematics Commons^™

Stable Carbon And Nitrogen Isotopes Of Shell Bound Organic Matter, Implications For Modern And Ancient Food Web Dynamics, Shibajyoti Das

Dissertations - ALL

Stable isotopes are an important tool for solving biogeochemical problems and have been increasingly applied in ecosystem studies because of their utility as source-to-sink tracers and for ecological information. Elements like C and N have more than one stable isotope, and their isotopic compositions (δ15N and δ13C) vary in a foreseeable way and are specifically useful in studying global elemental cycles and energy flow through ecosystems. δ15N and δ13C of organic matter (OM) are diagnostic of an organism's diet and have been used as a proxy for trophic level reconstructions. However, because of several analytical constraints, the use of stable …

The Impact Of Stream-Groundwater Exchange On Seasonal Nitrate Loads In An Urban Stream, Julio I. Beltran

Theses - ALL

Urbanization negatively impacts water quality in streams by reducing stream-groundwater interactions, which reduces the stream’s ability to naturally attenuate nitrate. Meadowbrook Creek, a first order urban stream in Syracuse, New York, has a negative urbanization gradient that results in urbanized headwaters that are disconnected from the floodplain, and downstream reaches that have intact riparian floodplains and connection to riparian aquifers. This system allows us to assess how stream-aquifer interactions in urban streams impact the net sources and sinks of nitrate at the reach scale. We used continuous (15-minute) streamflow measurements, along with weekly grab samples at three gauging stations positioned …

Characterizing Ancient Chemoclines Through The Use Of Pigment Biomarkers And Sedimentary Stable Isotope Signatures, Benjamin T. Uveges

Dissertations - ALL

This dissertation focuses on identifying and qualifying chemocline dynamics, namely depth and stability, in stratified aquatic systems through the use of sedimentary pigments and the stable carbon and nitrogen isotopes of organic matter. The central aim of the research comprising this volume is to identify how chemocline fluctuations are expressed in the pigment and stable isotope signatures of aquatic sediments, and how those fluctuations may have impacted nutrient cycling in past intervals of marine anoxia and mass extinction.

In order to help gauge how the depth of the chemocline may affect specific pigment signatures and concentrations in sediments, I first …