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4 | NewScientist | 9 August 2014 OF ALL the things to lose. New data suggests that we still don’t know where our emissions of toxic mercury end up. Somewhere out there are tens of thousands of tonnes of missing mercury. Mercury is released by several industries and accumulates as methyl mercury in aquatic organisms. It causes brain damage and birth deformities. Last year, governments agreed the Minamata Convention to control emissions. It was named for Minamata Bay in Japan, the site of a major mercury poisoning in the mid-20th century. Carl Lamborg of the Woods Hole Oceanographic Institution in Massachusetts has found that, since industrialisation, mercury levels near the ocean surface have tripled in many places (Nature, DOI: 10.1038/nature13563). The highest rates are in cold waters FUTURE Mars explorers can breathe easy. The next NASA rover to land on the Red Planet will bring equipment that can take carbon dioxide out of the atmosphere and break it apart to make pure oxygen. The gear is part of a package of seven instruments that will be fitted on the Mars 2020 rover, NASA announced on 31 July. The rover will also carry a weather station, a pair of spectrometers to determine REX/APA Rogue mercury Oxygen on Mars UpfrOnT “Mercury levels have tripled in many parts of the ocean, and are highest around Iceland and Antarctica” around Iceland and Antarctica, where they are enough to damage marine life and threaten humans. But the levels are much lower than expected, Lamborg says, given known emissions from coal burning, cement production, waste incineration and small- scale gold mining. He estimates the oceans contain between 60,000 and 80,000 tonnes of mercury, less than a quarter of the 350,000 tonnes expected (Environmental Science & Technology, doi.org/ckm949). Where is the rest? Small-scale gold mining may be a big source, so the lost mercury could be in soils near mines, Lamborg says. Alternatively, the lost mercury could be in sediments of estuaries and coastal waters, particularly in Asia. Last month, Helen Amos of Harvard University estimated that up to 90 per cent of the mercury flowing down rivers from mining areas ends up in these sediments (Environmental Science & Technology, doi.org/t2h). If those sediments get stirred up, local mercury levels could reach those seen at Minamata, which affected thousands of people. the composition of the Martian soil, and a ground-penetrating radar to examine the subsurface. Two instruments on the rover’s head will be souped-up versions of what its older sibling, Curiosity, carries: a laser that can vaporise rocks and scan them for their compositions, and a panoramic, zoomable camera that will take short movies as the rover drives. Despite the payload, Mars 2020 will have room to stow away soil and rock samples, which NASA hopes will be returned to Earth on a future mission. Gaza counts cost of crisis THE Israeli military had withdrawn from Gaza as New Scientist went to press, but Gazan troubles are far from over. On Saturday, UN officials said that Gaza’s medical services and facilities were ”on the verge of collapse”. By the time Israeli forces withdrew, more than 1800 Palestinians had died – most of them civilians and almost 400 of them children – and 67 Israelis, 64 of whom were soldiers. The damage to Gaza’s health system is extensive. During the conflict, a third of Gaza’s hospitals were hit, as were 14 of its 33 primary healthcare clinics and 29 ambulances operating in the zone. At least five medical staff died on duty, with tens injured. A report released on Monday by the UN Office for the Coordination of Humanitarian Affairs estimates that at least 373,000 Palestinian children need psychological support and counselling. It says one-quarter of Gaza’s population of 1.8 million has been displaced, with 270,000 in shelters run by the UN Relief and Works Agency (UNRWA). “With 270,000 in 90 shelters, averaging 3000 in each, shelters are very crowded,” says UNRWA’s Akihiro Seita. “Medicines for hygiene are badly needed, such as lice shampoo, scabies cream and skin rash creams,” he says. “The worst-case scenario is an outbreak of infectious disease.” Some help is getting through. A shipment of $1.4 million in medical supplies arrived last week, as did 130 tonnes of medical aid. –Struggling to cope– Don’t feed the microbes THIS is not a health drink. The waters of North America’s Lake Erie turned lurid green this week, thanks to a bloom of toxic bacteria. The bloom has now receded and the water is drinkable again, but the challenge is to stop it happening again. The blue-green cyanobacteria Microcystis aeruginosa built up at the western end of the lake, which is the main source of drinking water for Toledo, Ohio. The bacterium produces a toxin called microcystin, forcing Toledo to turn off the water supply. Such blooms are increasingly common in Lake Erie, as phosphorus from fertilisers runs into the water and feeds the cyanobacteria. To prevent blooms, Ohio must stem the flow of phosphorus, says Jeffrey Reutter of Ohio State University in Columbus. Farmers should test soil to help them only use as much fertiliser as is necessary, and apply it when planting so unused phosphorus isn’t left lying around.
