Date of Award

12-31-2013

Document Type

Campus Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry/Green Chemistry

First Advisor

Robyn Hannigan

Second Advisor

Jason Evans

Third Advisor

Deyang Qu

Abstract

Global change drivers, such as land-use change and global climate change, are altering environmental systems (e.g., lakes). Closed-basin lakes are sensitive to global change because they act as sinks for allochthonous matter via precipitation, runoff, and groundwater, while output is almost exclusively limited to evaporation. This dissertation studies the impacts of land-use change and global climate change on one such closed-basin lake, Étang Saumâtre, Haiti (a.k.a. Lac Azuéi, Lago del Fondo, and Yainagua). The three dissertation studies reconstruct the lake's paleoenvironment by analyzing radioactive isotopes, stable isotopes, gastropod shells, nutrients, satellite imagery, rare earth elements, and trace metals in lake sediment and groundwater. Four groundwater samples were collected from hand pumped wells in May 2010, and in May 2011 sediment cores were collected from different stations in the lake. In the first study, depleted δ13CTOC signatures accompanied by enriched δ15NTN signatures and higher TP concentrations indicate that human and livestock wastewater effluent has caused an increase in nutrient loading in the lake after 1960. In the second study, an increase in precipitation around Étang Saumâtre is shown to have expanded the lake's shoreline and altered the lake sediment geochemistry by depleting bulk sediment carbonate content and δ18Ocarb signatures over time. In the third study, we show that targeted trace metal (As, Cr, Cu, and Zn) concentrations have been increasing since 1984-1987, and in particular Cr concentrations are greater than both US and international guideline values. Taken as a whole, this dissertation elucidates several impacts of global change on Étang Saumâtre over the past 74-108 years by assessing the lake's geochemistry. More research is required to better characterize Étang Saumâtre and interdisciplinary collaborations are needed to explore the implications of the lake's geochemistry, productivity, and response to land-use and global climate change impacts.

Comments

Free and open access to this Campus Access Dissertation is made available to the UMass Boston community by ScholarWorks at UMass Boston. Those not on campus and those without a UMass Boston campus username and password may gain access to this dissertation through resources like Proquest Dissertations & Theses Global or through Interlibrary Loan. If you have a UMass Boston campus username and password and would like to download this work from off-campus, click on the "Off-Campus UMass Boston Users" link above.

Download
Off-Campus UMass Boston Users

Share

COinS