Date Awarded

2013

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Virginia Institute of Marine Science

Advisor

Michale Newman

Abstract

Mercury concentrations and determinants of mercury accumulation were examined for ten finfish species from the lower Chesapeake Bay and its tributaries. None of the sampled fish had total mercury concentrations approaching the U.S. EPA human health screening value. Mercury concentrations in different fish species generally increased with increasing delta 15N, but not delta 13C, suggesting that trophic position, but not dietary carbon source was a dominant determinant. A methylmercury biomagnification model was built to estimate a food web magnification factor of approximately 10-fold increase per trophic level in Chesapeake Bay. Based on otolith strontium-calcium ratios, Atlantic croaker inhabiting less saline waters might accumulate more mercury than those inhabiting more saline waters. Positive intraspecies relationships between methylmercury concentration and delta 13C were identified for summer flounder, weakfish, American eel, Atlantic croaker, and spot. Fish consumption and associated mercury exposure were explored for two ethnic (Chinese and Vietnamese) church communities along coastal Virginia, as well as two general population (non-Asian) churches in this region. Individual seafood consumption rates for the ethnic communities were higher than the general U.S. fish consumption rate of 12.8 g/person/day. People from the general population churches and Chinese church took in most of their mercury from market fish (distributed and sold nationally) whereas people from the Vietnamese church took in mercury from both the market and local fish as they tended to eat a large amount of diverse local species. Hair mercury concentrations in the Chinese and the Vietnamese church were higher than the overall level for U.S. women (0.20 mug/g), but lower than the published WHO exposure threshold of 14 mug/g. Regression between seafood consumption rates and hair mercury concentrations suggested that dietary mercury ingestion through seafood was positively related to mercury exposure. Mercury exposure of the Vietnamese community was higher compared to the Chinese community, which itself was higher than the general church communities. Regardless, the daily methylmercury intake rates for all studied communities were lower than the U.S. EPA Reference Dose of 0.1 mug/kg BW-day. Keywords: Mercury, methylmercury, trophic ecology, biomagnification, fish, Chesapeake Bay, exposure assessment, seafood consumption, Chinese, Vietnamese.

DOI

https://dx.doi.org/doi:10.25773/v5-28gf-a156

Rights

© The Author

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