Graduation Date

Spring 2021

Document Type



Master of Science degree with a major in Natural Resources, option Forestry, Watershed, & Wildland Sciences

Committee Chair Name

Andrew Stubblefield

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Matthew Hurst

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

David Baston

Third Committee Member Affiliation

HSU Faculty or Staff

Subject Categories

Natural Resources


Pharmaceuticals are found in water systems and are classified as contaminants due to their adverse effects on numerous types of aquatic organisms. Estradiol, a natural occurring estrogen and ethinylestradiol, a common synthetic estrogen found in birth control, are a class of pharmaceuticals called endocrine-disruptive contaminants (EDC). These contaminants have been shown to cause developmental delays in fish as well as feminizing male fish in concentrations as low as 1 ng/L for both estradiol and ethinylestradiol, and bioaccumulating in mollusks and oysters. There are many natural and human-assisted methods for removing pharmaceuticals in water, and they are dependent on both the properties of the contaminant and the type of treatment applied. Ten different wastewater treatment processes at two different wastewater treatment plants were studied to compare the removal of estrogen out of the wastewater. The first facility, the Arcata Wastewater Treatment Plant and Wildlife Sanctuary, utilizes oxidation ponds and constructed wetlands for the final treatment processes. The second facility, in Ferndale, CA is an active sludge wastewater treatment plant. The samples were analyzed by both HPLC and ELISA, however, the data measured on the HPLC was not used due to discrepancies in the results. The concentration of estradiol was found to be from 131 ng/L to 212 ng/L in Arcata influent and from 46 ng/L to 113 ng/L in the effluent. The concentration of ethinylestradiol was found to be from 0.49 ng/L to 0.63 ng/L in the Arcata influent and from 0.36 ng/L to 0.46 ng/L in the effluent. In Ferndale, the concentration of estradiol was found to be from 123 ng/L to 143 ng/L in the influent and 18 ng/L to 131 ng/L in the effluent while the concentration of ethinylestradiol was found to be 0.47 ng/L to 0.56 ng/L in the influent and 0.33 ng/L to 0.41 ng/L in the effluent. The concentration of estrogen increased in numerous treatments, while the oxidation pond and aeration basin were the only treatments that showed consistent decrease of concentration at either site. The oxidation pond had the highest removal efficiency with 80% of the incoming estradiol removed and 25% of the incoming ethinylestradiol removed. The concentration of estradiol at both locations was greater than 1 ng/L which is greater than levels that are safe for fish. Additional studies are recommended to determine how far from the discharge point the concentration of estrogen drops below 1 ng/L and whether the oysters in the Humboldt Bay are bioaccumulating estrogen to an unsafe concentration.

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