Summer 2008 Undergraduate Research Experience (URE) Program [website]
Younger Dryas Impact Study
Mentor: Dr. Malcolm LeCompte
Abstract
The events precipitating the dramatic, millennial long climatic cooling known as the Younger Dryas, that occurred approximately 13,000 years ago remain a mystery. Recent evidence suggests an extraterrestrial impact on the Laurentide ice sheet may have provided the trigger for a massive influx of fresh glacial melt water theorized to have flooded the North Atlantic and shut down the Thermohaline circulation that moderates climate in the northern hemisphere.The apparent absence of an easily identified impact crater has focused the search for evidence of an impact on a search for extraterrestrial markers embedded in the Earth’s sedimentary record.
Association of an impact with coincident reduction in the numbers of megafauna species and human population of North America has suggested a strategy for the search for evidence of the impact. If an impact is responsible for initiating the onset of the Younger Dryas, the ultimate disappearance of megafauna species and the decline in human population, then the evidence should lie at the sedimentary boundary (YDB) separating the Younger Dryas from the preceding Bolling-Allerod at a depth corresponding to 12,900 years before present.
Some of these evidential markers (magnetic grains and spherules, charcoal, and glass-like carbon) was relatively easy to extract and identify while others (nanodiamonds and fullerenes) required great care, expensive instrumentation and considerable training. Fortunately, the vessels (carbon spherules) containing the more challenging markers were identified and extracted during the soil processing for magnetic spherules and charcoal. The research project also included an investigation of local paleo-lake depressions known to harbor impact markers and whose stratigraphy could have revealed a clearer understanding of the processes that shaped the coastal topography during the Younger Dryas. The research was carried out using a combination of Ground Penetrating RADAR (GPR) and sample coring to probe the subsurface deposits of selected depressions.
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2007-2008 Undergraduate Research Team [website]
A Multiple Linear Regression of pCO2 against Sea Surface Temperature, Salinity, and Chlorophyll a at Station BATS and its Potential for Estimate pCO2 from Satellite Data.
Mentor: Dr. Jinchun Yuan
Abstract
A Multiple Linear Regression of pCO2 against Sea SurfaceTemperature, Salinity, and Chlorophyll a at Station BATS and its Potential for Estimate pCO2 from Satellite Data Abstract Ocean is one of the major reservoirs of carbon and can be a major sink of anthropogenic carbon dioxide. Together with pH, alkalinity, and total dissolved inorganic carbon (DIC), partial pressure of carbon dioxide (pCO2) is one of the four essential parameters for determining aquatic CO2 system. These four CO2 parameters are interrelated through chemical equilibrium and the determination of any two is sufficient for calculating the other two parameters. Ship-based oceanographic research cruise, that is expensive to operate and inefficient to provide global coverage, has long been the main source of data for characterizing oceanic CO2 system. Recently, Lohrenz and Cai (2006) conducted a field study of partial pressure of carbon dioxide, temperature, salinity, and Chlorophill a in surface waters of the Northern Gulf of Mexico and developed a correlation method for estimating carbon dioxide distribution from the Moderate Resolution Imaging Spectroradiometer (MODIS) remote sensing data. Although it showed great potential, the correlation is based on field data with a small temperature variation and atypical salinity for open ocean waters, and it is not clear whether it can be applied elsewhere in the ocean. Here, we proposed to extend the applicability of the method by conducting a data analysis study of field observations conducted at station BATS (Bermuda Atlantic Time-Series) Specifically, we have: (1) Obtain field data of alkalinity, DIC, temperature, salinity, and Chlorophill a determined at BATS station in the last two decades; (2) Calculate pCO2 from alkalinity and DIC; (3) Apply the correlation method to test the applicability of the method in the central Atlantic Ocean.
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