Every year, yellowfin tuna get a little more poisonous to eat. Since 2008, the amount of mercury found in the fish has gone up 3.8% a year, and that trend will probably continue–the amount of the toxic heavy metal in the ocean may double by 2050. But now there may be a good way to start taking it out.
The solution: Fake coral. Taking inspiration from the fact that coral is very good at sucking mercury out of ocean water, researchers at Anhui Jianzhu University in China created a synthetic coral that can do the same thing. While mercury is one of the many reasons that real coral are dying, the fake coral can safely suck it up.
The key is the curving, lumpy, fold-filled shape of coral, which gives the mercury more places to stick. “In general, adsorbents can remove more pollutants if they have more exposed surface area,” says Xianbiao Wang, one of the researchers that led the new design. The branches of the coral make the surface area larger than something flat or round, while tiny pores draw in pollution.
The design is made from nano-sized aluminum oxide, something that has been used for mercury cleanup in the past. But the new structure is 2.7 times better at removing the metal. In the researcher’s experiment in the lab, the structure was able to collect about 49 milligrams of mercury for every gram of fake coral.
After it fills up with mercury, the coral-like device could be taken out of the water and the mercury safely removed. So far, the scientists haven’t tested this step; they say the design will probably evolve before it’s actually in use.
“We just present a good example for biomimetic coral-like adsorbents for enhanced adsorption performance,” Wang says. “These results could inspire other biomimetic adsorbents…It probably needs more research for the real application in the ocean.”
In the meantime, some countries, like the U.S., are slowly starting to cut down on mercury pollution from sources like coal power plants. But even if all mercury pollution stopped–something that’s unlikely to happen soon–we’d still have quite a bit of the metal to clean up: Since the industrial revolution, humans have pumped out tens of thousands of tons of mercury that ended up in the ocean.