<http://schema.org/alternativeHeadline>
"While mercury levels are dropping slightly, the metal can build up to toxic levels in animals over time. This can have effects on the food chain, including the seafood humans eat."^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.mnn.com/earth-matters/wilderness-resources/stories/the-deep-ocean-traps-mercury>