by Margaret Pizer
This is part two of a two part series on Xiaoyu Xu’s research on mercury in seafood. Click here to read part one.
Following the Mercury
Much of the mercury that gets deposited in the U.S. comes from burning fossil fuels. About half comes from U.S. emissions, but the other half comes from Asia—mostly from China. The significance of this is not lost on Xiaoyu Xu, who grew up in Northeastern China and completed her Masters degree at Central China Normal University. Recently, she finished her Ph.D. as a Virginia Sea Grant Research Fellow studying seafood consumption and mercury exposure in the Chesapeake Bay.
Mercury used to be thought of as a local problem, the result, for example, of a company or industry dumping contaminants in a particular river or watershed. But, says Xu’s Ph.D. advisor Mike Newman at Virginia Institute of Marine Science, “mercury transcends that local context in that it can be dispersed very very widely in the atmosphere.”
The recent economic boom in China has resulted in an increase in mercury-containing emissions. The mercury level in the fumes is not that high, but mercury biomagnifies in food web. Because animals cannot get rid of some types of mercury, animals accumulate more and more mercury over the course of their lifetimes. Predatory animals can have very high mercury levels because when they eat, they take in the mercury from their prey as well as the mercury from their prey’s prey.
For humans, too much mercury consumption can affect the nervous system in adults and can lead to developmental problems and birth defects in children and babies.
To China and Back
While those in Tidewater Virginia may not have too much to worry about when it comes to mercury exposure, the picture in parts of China and throughout Asia may be very different.
“What somebody in this country consumes each day of seafood is nothing compared to many Asian cultures,” says Newman. Cultural practices, like eating fish heads and organs, which tend to be higher in mercury than the muscles, can also increase exposure. Newman says that colleagues who have estimated mercury exposure from fish consumption in Hong Kong have found much more worrisome exposure rates.
To follow up on these regional and global differences, Xu is currently doing post-doctoral research with one of those collaborators—Wen-Xiong Wang of Hong Kong University of Science and Technology. Research on metal contamination in the ocean there will allow Xu to bring her travels and her studies of this global issue full-circle.
“This is not my problem or their problem; this is our problem, and we need to interact and engage,” says Newman.
