|Tuesday, April 11th|
Devon Yee, Whitman College
2:00 PM - 2:15 PM
Oysters, nitrates and filtration, oh my! As part of an NSF-funded mathematical modeling group at St. Mary's College (Maryland), I explored the following research prompt: Determine strategic locations for oyster reefs in Chesapeake Bay such that they mediate nitrate and nitrite pollution. We developed a simplified tank model to approximate fluid flow and describe salinity, nitrates and nitrites in the bay. Additionally, we created a second model describing nitrate and nitrite pollution as point sources using an exponential decay function. In my presentation, I discuss mathematical modeling, describe and analyze our two models of the Chesapeake, and share ongoing research.
Connor Welty, Whitman College
2:15 PM - 2:30 PM
The pollution of heavy metals into the ocean from many different sources is bio-accumulating into the marine food chain and is consequently spreading into deeper ocean zones. While there are studies analyzing heavy metal and other element concentrations in fish in various locations, none have specifically investigated how the isotopic ratios of these elements in fish differ through ocean depth zones. Our study used an FAAS and an ICP-MS to determine the concentrations of arsenic, barium, cadmium, chromium, cobalt, copper, lead, mercury, nickel, selenium, zinc and their respective isotopes in fish ranging from the epipelagic (<2,000 m) to the hadalpelagic (7,000-11,000 m) zones of the ocean.
Isabel Christy, Whitman College
2:30 PM - 2:45 PM
The concentration of gadopentetic acid (Gd-DTPA), an MRI contrasting agent, has increased in urban waterways over the past three decades. While Gd-DTPA is so stable in freshwater that toxic Gd3+ is unlikely to be released, little is known about the stability of this complex in marine environments. At high salinity, Mg and Ca may reduce the concentration of free DTPA and release Gd3+ into the environment. In my study, the stability constants for complexes of DTPA with Ca and Mg were measured at seawater ionic strength by potentiometric titration to better understand the behavior of Gd-DTPA in marine environments. A side-reaction coefficient for DTPA in seawater was calculated from these constants to predict the speciation and complexation of DTPA in marine environments. I conclude that Gd-DTPA largely dissociates in seawater, releasing toxic Gd3+ to marine ecosystems.
Alex Waheed, Whitman College
2:45 PM - 3:00 PM
The environmental history of lake ecosystems in the United States is broadly defined by a slow increase in contamination triggered by the Industrial Revolution and urbanization beginning around 1850, a sharper increase around 1950 and a general decrease following environmental legislation in the 1970s. This collaborative study examines sediment cores taken from three Wisconsin lakes spanning a range of human influence: Lake Monona (impacted), Sparkling Lake (relatively pristine) and Shadow Lake (remediated). I and several other students collected and analyzed data from these lakes to create a comprehensive picture of environmental quality, using radiometric dating, sediment analysis, geochemistry and live/dead records of subfossil assemblages. Sediment cores were analyzed for heavy metal concentrations using X-ray fluorescence. Our data will be correlated to other students’ biologic and geochemical data, which together can be used to assess the consequences of both pollution and remediation on lake ecosystems.