Study shows coastal water, not sediment, predicts mercury contamination

Feb 18, 2014

A Dartmouth-University of Connecticut study of the northeast United States shows that methylmercury concentrations in estuary waters—not in sediment as commonly thought—are the best way to predict mercury contamination in the marine food chain.

The findings raise questions about current mercury cleanup practices, and shed new light on the different ways in which the toxic metal bioaccumulates in aquatic species, from bottom-dwelling worms to to larger fish consumed by humans. Results of the study will appear Feb. 18 in the journal PLOS ONE. A PDF of the study is available on request.

"Our paper shows 's impact on food webs is not simply based on sediment contamination but is far more complex and appears based on the flux of methylmercury from sediments to the or even methylmercury transported via water from other parts of the watershed," says Professor Celia Chen, principal investigator and a project leader of Dartmouth's Toxic Metals Superfund Research Program.

Mercury released into the air through industrial pollution is turned into its most toxic form, methylmercury, in coastal sediment, streams and oceans. The Dartmouth-UConn team studied 10 estuaries from New Jersey's Hackensack Meadowlands to the Gulf of Maine. They found that methylmercury concentrations in the water, not the sediment, predicted methylmercury concentrations in killifish and Atlantic silversides, and that concentrations were higher in these forage fish than in bottom-feeding worms. Concentrations in sediment only predicted contamination levels in the worms.

The findings suggest that mercury assessment and remediation, which currently focus on sediment contamination, should instead focus on measuring methylmercury in water column particles, which may be contaminated by the local pollution source or reflect sources outside of the specific estuary. "Our results across a broad range of sites demonstrate that the pathways of methylmercury to lower level estuarine organisms are distinctly different between organisms in the and forage fish," Chen says. "Thus, even in systems with contaminated sediments, transfer of methylmercury into estuarine food webs may be driven more by the amount of methylmercury available in the water column."

Explore further: Weird weather lingers in Alaska's largest city

add to favorites email to friend print save as pdf

Related Stories

Warmer oceans could raise mercury levels in fish

Oct 03, 2013

Rising ocean surface temperatures caused by climate change could make fish accumulate more mercury, increasing the health risk to people who eat seafood, Dartmouth researchers and their colleagues report ...

Research reveals new challenges for mercury cleanup

Aug 06, 2013

More forms of mercury can be converted to deadly methylmercury than previously thought, according to a study published Sunday in Nature Geoscience. The discovery provides scientists with another piece of the ...

Dangerous methylmercury levels in sushi

Nov 25, 2013

Eating sushi can increase risk of cardiovascular disease. A recent study showed that tuna sashimi contains the highest levels of methylmercury in fish-sushi, based on samples taken from across the USA.

Recommended for you

New challenges for ocean acidification research

11 hours ago

Over the past decade, ocean acidification has received growing recognition not only in the scientific area. Decision-makers, stakeholders, and the general public are becoming increasingly aware of "the other carbon dioxide ...

Compromises lead to climate change deal

11 hours ago

Earlier this month, delegates from the various states that make up the UN met in Lima, Peru, to agree on a framework for the Climate Change Conference that is scheduled to take place in Paris next year. For ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.