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Date of Award
Summer 2025
Document Type
Masters Thesis
Department or Program Affiliation
Chemistry
Degree Name
Master of Science (MS)
Department
Chemistry
First Advisor
Clark, Catherine D.
Second Advisor
Lemkau, Karin
Third Advisor
Montaño, Manuel D.
Abstract
Padilla Bay, located in the Puget Sound estuarine system of Washington state, is a biologically diverse area with extensive eelgrass beds that play a key role in the ecological balance of the region. This study investigated the complex dynamics of dissolved organic matter (DOM) by examining its sources, transformations, and export patterns in salt marsh and eelgrass environments. Using optical techniques and advanced Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), we obtained a detailed molecular understanding of how environmental processes shaped DOM. Sampling was conducted over the course of a year at the Little Indian Slough salt marsh to capture tidal and seasonal variations in DOM. In the salt marsh, we quantified dissolved organic carbon (DOC) and characterized the optical properties of water across tidal phases, leveraging the absorbance and fluorescence characteristics of chromophoric dissolved organic matter (CDOM). This enabled us to analyze DOM composition and transformations using spectroscopic techniques. We also analyzed marsh plant leachates, particularly from saltgrass, to assess their integration into the broader DOM pool. We examined whether DOM export from the marsh peaked during ebb tides in the warmer months due to heightened vegetation productivity. We also explored whether eelgrass-derived material introduced distinct molecular signatures. Additionally, we conducted biological and photochemical degradation experiments to assess DOM lability and its transformations over time. By comparing molecular compositions across different sources and conditions, including high and low tides, eelgrass, salt grass, and degradation products, we aimed to understand the dynamic interplay of biogeochemical processes in Padilla Bay. The integration of mass spectrometry data with environmental monitoring enhanced our understanding of DOM cycling and its ecological implications, supporting informed strategies for the conservation and management of coastal ecosystems.
Type
Text
Keywords
Dissolved Organic Matter (DOM), Chromophoric Dissolved Organic Matter (CDOM), Estuarine Carbon Cycling, Padilla Bay, Optical Spectroscopy, Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS), Eelgrass, Salt Marsh, Photodegradation, Biodegradation
Publisher
Western Washington University
OCLC Number
1534560132
Subject – LCSH
Water--Organic compound content--Washington (State)--Padilla Bay; Optical spectroscopy--Washington (State)--Padilla Bay; Estuarine ecology--Washington (State)--Padilla Bay; Eelgrass--Washington (State)--Padilla Bay; Salt marsh ecology--Washington (State)--Padilla Bay; Ion cyclotron resonance spectrometry; Fourier transform spectroscopy; Photodegradation--Washington (State)--Padilla Bay
Geographic Coverage
Padilla Bay (Wash.)
Format
application/pdf
Genre/Form
masters theses
Language
English
Rights
Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.
Recommended Citation
Karp, Lauren, "Exploring the Complex Dynamics of Dissolved Organic Matter Across Diverse Ecosystems in Padilla Bay" (2025). WWU Graduate School Collection. 1438.
https://cedar.wwu.edu/wwuet/1438