A biogeochemical investigation of Trunk River Lagoon, Falmouth, Massachusetts

Abstract

This thesis delves into the intricate dynamics of lipid biomarker creation, deposition and preservation within Trunk River Lagoon, encompassing sediments, microbial blooms, and mats. Through a multi-faceted approach, the research uncovers the interplay between natural processes and anthropogenic influences, shedding light on the evolutionary trajectory of this aquatic ecosystem. From ancient sediment records to contemporary microbial communities, each aspect offers unique insights into environmental changes and the implications for interpreting biomarker signals

In chapter 2 we employ radiocarbon dating, stable isotope geochemistry, and lipid biomarker analyses on a 2-meter sediment core spanning 3000 years, revealing shifts from a freshwater to a brackish environment with evidence of anthropogenic contamination. In Chapter 3, biomarker analyses on active blooms unveil a diverse microbial community receiving organic inputs from various sources, including sewage. Moreover, lipid analyses reveals rapid sulfurization of organic matter in the water column. In Chapter 4, attention turns to the preservation of biolipids within modern microbial mats. Through detailed analysis, the study reveals primary diagenetic processes such as hydrogenation and sulfurization, highlighting the complexities involved in interpreting biomarker distributions accurately.

Overall, this research underscores the necessity of comprehensive lipid analysis in modern environments to accurately interpret biomarker distribution and abundance. These findings not only advance our understanding of sedimentary records and biomarker signals but also emphasize the complex interplay between natural processes and anthropogenic influences in shaping contemporary aquatic ecosystems.