Title

Holocene changes in algal abundance and dissolved oxygen discovered in Sluice Pond, MA through spectroscopy and analysis of a sediment core

First Author's Department

Department Of Geology

Second Author's Department

Department of Geological Sciences

Third Author's Department

Department of Geological Sciences

Fourth Author's Department

Department of Geology

Date

3-21-2019

Document Type

Poster

Abstract

Throughout the Holocene, Sluice Pond (Lynn, MA, USA), has experienced fluctuations in algal communities and dissolved oxygen (DO) content based on measurements from a sediment core raised from its anoxic central basin. The variability in the core’s composition can be mapped with Visible Derivative Spectroscopy based on varimax-rotated, principal component analysis (VPCA) through wavelet analysis and by plotting this information against an AMS 14C constrained age model. The temporal history yields a better understanding of the lake’s changing environment and provides insight into the extent of preserved natural and human events. Thirteen separate constituents were present in the core, as mixtures of six different orthogonal (or independent) VPCA components that account for 97.1% of the variance in the data set. Six components were extracted overall, but a detailed look at two is presented in this project. Through the data collected in 6VPCA1 and in 6VPCA6, algal blooms and lake turbidity can be mapped out and referenced against the age model to show changes in relative concentration. The data shows anoxic conditions through the increase or decrease of DO indicators. The first component oscillates on a period of 4 ka, and the second has a 6 ka oscillation. Major climate events such as the Younger Dryas and the 8.2-kiloyear event are represented in the data by a large drop in algal concentrations and an increase in DO during both extreme cold events. Within the last 200 years, fluctuations in algal blooms, turbidity, and DO have increased dramatically in both frequency and extent. Through the data and methods used in this project, we are given a representation of the natural variance over the Holocene and can start to understand how humans may have impacted Sluice Pond. This new information allows for a better understanding of the conditions Sluice Pond has experienced in the past and can inform us on steps that need to be taken for the overall health of the lake. ​

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