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Publication Date

2024-05-13

First Advisor

Greg de Wet

Second Advisor

Amy Rhodes

Document Type

Honors Project

Degree Name

Bachelor of Arts

Department

Environmental Science and Policy

Abstract

This project utilizes FTIR Spectroscopy, an emerging method for generating BSi and TOC predictions to reconstruct past climate at Lacawac Lake in Lake Ariel, Pennsylvania. BSi and TOC are broad environmental proxies, where relatively higher percentages correlate with warmer temperatures and relatively lower percentages correlate with colder temperatures. Prior methods exist for producing BSi and TOC values but consume large amounts of sediment and are time-consuming and expensive. BSi has been especially difficult to quantify via traditional methods due to the margin of error associated with different lab techniques. FTIR Spectroscopy presents a unique opportunity to improve BSi predictions and quickly generate high-resolution climate reconstructions. Raw FTIR absorbance is converted to weight percentages of BSi and TOC based on a calibration data set of traditional values. This project thickens FTIR methodology by addressing uncertainties about the calibration data set. Based on preliminary FTIR predictions with four calibrations, a localized calibration most accurately captures past climate trends at Lacawac Lake. FTIR predictions generated with the 50% calibration had an AAD of 1.25% for BSi and 4.48% for TOC; predictions generated via the 100% calibration had an AAD of 1.13% for BSi and 4.06% for TOC. While the 100% calibration produced the most accurate results, the 50% calibration is ideal for maximizing efficiency when generating FTIR data sets. The similar trends in the traditional and FTIR data demonstrate that interpretation of FTIR data is possible with a well-calibrated data set. The results from this study still need to be constrained by an accurate age model, however, the BSi and TOC curves appear to suggest LIS meltwater influence from ~1,300cm to 1,100cm, and diverging proxy trends from 900-5cm. Following the initial climate response, Lacawac BSi likely indicates temperature and insolation changes, and TOC likely indicates changes in surrounding landscape vegetation. The significance of Lacawac paleoclimate reconstruction over the past ~15,000 years could be thickened with additional climate proxies and knowledge about historical human activity in northeastern Pennsylvania.

Rights

©2024 M. A. Fischer. Access limited to the Smith College community and other researchers while on campus. Smith College community members also may access from off-campus using a Smith College log-in. Other off-campus researchers may request a copy through Interlibrary Loan for personal use.

Language

English

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