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Date of Award

Summer 2024

Document Type

Masters Thesis

Department or Program Affiliation

Environmental Science (Marine & Estuarine Science)

Degree Name

Master of Science (MS)

Department

Environmental Sciences

First Advisor

Sofield, Ruth M.

Second Advisor

Van Alstyne, Kathryn Lyn, 1962-

Third Advisor

Burnaford, Jennifer

Abstract

Seaweed are cultivated and harvested around the world for many uses including food, pharmaceuticals, cosmetics, and fuel. Seaweed aquaculture has been on the rise globally, and interest has been expressed in the United States in furthering the development of the industry. Because seaweed can absorb contaminants into their tissues, an understanding of the risks to consumers is important for informing those consumers and maintaining public support for the industry. Seven species of seaweed that are either wild-harvested or of interest to aquaculture were collected from the Washington State Salish Sea and analyzed for differences in contaminants by season, site, algal taxon, and year. Water samples and blades of sugar kelp, Saccharina latissima, were collected from Blue Dot Sea Farm (US) during the growing season and post-harvest for analyses of metal content, PFAS, and PCBs. Common green ulvoid seaweed was collected monthly to measure seasonal variation and from 12 distinct locations simultaneously around the Salish Sea to measure spatial variation. Concentrations of legacy (PCBs, arsenic, cadmium, and lead) and emerging (per-and polyfluoroalkyl substances (PFAS)) contaminants were measured in the seaweeds. Concentrations of contaminants were compared to human health-based screening levels calculated from the USEPA and reported international limits. Legacy contaminants (metals, PCBs) differed between seaweed type (rhodophytes, phaeophytes, and chlorophytes) as well as by season, year, and location. PFAS compounds were detected in all seaweed samples, dominated by short-chain PFAS 6:2 FTS. The ratio of inorganic arsenic to total arsenic within seaweed tissue varied by seaweed taxon but remained less than 1% of total arsenic content and were below screening levels or international limits. Reference dose-based screening levels (SLRfD) were exceeded for three samples of Nereocystis luetkeana for Cd, but all other samples fell below SLRfD for Cd, Cr, Ni, Pb, V, Zn, and total PCBs. These measurements serve as an important baseline for directing current and future environmental monitoring, management, and aquaculture practices.

Type

Text

Keywords

seaweed, kelp, edible seaweed, metals, arsenic, contaminants of concern, PFAS

Publisher

Western Washington University

OCLC Number

1453236257

Subject – LCSH

Marine algae as food--Salish Sea (B.C. and Wash.); Marine algae--Effect of heavy metals on--Salish Sea (B.C. and Wash.); Kelps--Effect of heavy metals on--Salish Sea (B.C. and Wash.); Perfluorinated chemicals--Environmental aspects--Salish Sea (B.C. and Wash.); Polychlorinated biphenyls--Environmental aspects--Salish Sea (B.C. and Wash.); Persistent pollutants--Salish Sea (B.C. and Wash.); Aquaculture--Salish Sea (B.C. and Wash.)

Geographic Coverage

Salish Sea (B.C. and 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.

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