Date of Award
Master of Science (MS)
The Yupik people of St. Lawrence Island, Alaska have a traditional subsistence lifestyle with the majority of their diet consisting of local birds, fish, seal, walrus, and whale. Diets based on fish and marine mammals, such as the Yupik diet, are potential pathways for exposure to mercury and other toxic metals. At St. Lawrence Island, metal contaminants may come from local sources such as weathered rock or two abandoned U.S. military bases or remote sources through atmospheric deposition or seasonal migration of animals to the island.
The main goals of this study are to determine the total concentrations of copper (Cu), arsenic (As), selenium (Se), cadmium (Cd), mercury (Hg), and lead (Pb) and the Se:Hg ratios in foodstuffs of the traditional Yupik diet. A secondary goal is to use C stable isotope ratios to quantify trophic levels and biomagnification within the ecosystem. For this study, 216 samples from 28 different species and 14 different types of tissue were collected by Yupik hunters at the time of kill or shortly thereafter during the years of 2005, 2006, and 2007. . The majority of samples represent fat, kidney, liver, and muscle tissues of bearded seal, polar bear, reindeer, and walrus. The data show no significant differences among muscle tissues of the walrus, seal, polar bear, or reindeer for any of the metals analyzed. Among the different tissues sampled, however, walrus, seal, and polar bear liver and reindeer liver and kidney have significantly higher concentrations of Cu, Cd, Hg, and Pb compared to all other tissue types. In contrast, Se is more concentrated in muscle tissue than in liver. Arsenic in walrus is concentrated in blubber, oil, and skin relative to other tissues. In most animals and tissues, the Se:Hg ratio is significantly greater than 10:1 with only polar bear, seal, reindeer, and some sea bird tissues less than 10:1 and approaching 1:1.
The Se:Hg ratio is believed to affect the bioavailablity of both elements with higher Se:Hg ratios considered advantageous to both mitigating the negative effects of Hg and promoting the effects of Se, a vial nutrient.
The results, together with dietary surveys, can be used to determine how much of the Yupik’s exposure to environmental contaminants is from traditional foods, and to provide a basis for the members of the Yupik community to make informed decisions about dietary choices.
Kricheff, Judith, "Metal concentrations in native Yupik foodstuffs from St. Lawrence Island, Alaska" (2009). Geology Theses and Dissertations. 48.