Document Type

Honors Thesis

Major

Marine Science

Advisor(s)

Margaret Estapa

Committee Members

Damian Brady, Mark Wells

Graduation Year

May 2024

Publication Date

Spring 5-2024

Abstract

Colored dissolved organic matter (CDOM) contributes largely to ocean color, and therefore, influences processes and applications that interact with light in the ocean such as remote sensing and biogeochemistry. It is a component part of dissolved organic carbon (DOC) and there is a strong relationship in coastal waters between CDOM absorption and DOC concentration. CDOM optical properties also vary with salinity and source. These important aspects of CDOM absorption led us to collect CDOM samples across the salinity gradients of 3 estuaries in Maine: the Penobscot, Damariscotta, and Sheepscot. We sampled stations along the salinity gradient in each estuary from June 2023 to August 2023 and measured the absorption spectra of the samples from each of the stations. The CDOM absorption was used to find spectral slope and to estimate DOC concentration in the Penobscot, Damariscotta, and Sheepscot estuaries using models from other studies. The spectral slope increased across the 3 estuaries respectively and ranged from 0.0146 nm-1 to 0.0184 nm-1. The Penobscot DOC concentration was estimated to be between 8.2 mg/L and 5.1 mg/L, the Damariscotta, between 2 mg/L and 5 mg/L, and the Sheepscot, between around 2.2 mg/L. The optical properties of CDOM were found to be increasingly similar between the Damariscotta and Sheepscot with proximity to the ocean. The absorption and spectral slope of the CDOM in the Penobscot was relatively uniform compared to that of the Damariscotta and Sheepscot. This study uses the optical properties of CDOM to further our knowledge of its source and distribution and DOC concentration estimations in Maine estuaries.

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