Newscripts
initial theory, it seemed, now held water. But not everyone is buying it, and many suspect an alternative cupric culprit. An article in Forbes posited that an excessive amount of copper sulfate, a blue salt used to kill algae in pools, turned the water green. Once in the water, the metal would readily form emerald-colored copper chloride complexes and the sulfate could react to form hydrogen sulfide, which is the source of stinky fart smell. The article also argued that algae grow too slowly to cloud and discolor an entire Olympic-sized pool in a matter of hours. “I think I have to agree with the Forbes writer,” says Stephen Miller, whose group studies green algae at the University of Maryland, Baltimore County. “We would be thrilled to get that kind of growth, at that scale, in my lab. If that green color really is due to algal he diving pool at the Rio Olympic Games growth, I want to isolate those species.” made waves earlier this month by going from “Any color change that happens that quickly does a healthy blue to a muddled and befuddling point to a chemical reaction rather than anything shade of green in a matter of hours. biological,” agrees Philip Larese-Casanova, an enviThe adjacent water polo pool soon followed suit. ronmental engineer who studies water pollutants at Olympic officials first blamed algae. Then the InterNortheastern University. national Swimming Federation said that the pools had Still, it’s a little more difficult to explain away the run out of the chemicals needed to maintain a proper pools’ murk with chemistry than with an algal explanation. But perhaps we should allow ourselves some wiggle room. After Green with envy. Or all, as Rio spokesperson Mario algae. Or copper: Andrada told the media during the You can’t prove it pool cleanup efforts: “Chemistry is isn’t envy … not an exact science.” Copper could precipitate and form colloidal particles to cloud the water under the right conditions, Larese-Casanova says. Or copper particles could have come from deteriorating piping in the pools’ plumbing, he says. He’s not the first to float this theory, but neither he nor the Newscripts sleuths could track down what the plumbing is made of. So the copper hypothesis is not without its own insufficiencies. And at least one researcher familiar with algae gives the microorganisms a fighting chance in the pool. In the absence of chlorine and predators, algae could thrive in Rio’s warmth and sunshine, says Ferdi L. Hellweger, a colleague of pH, resulting in the sickly hue. Athletes complained of Larese-Casanova’s who studies microbial ecology at fart smells and poor visibility in the water as the aquatNortheastern. “And if the water is clear otherwise, the ics center tried unsuccessfully to clear up the water. color of the algae can come out strongly,” he says. Finally, after days of public scrutiny, Olympic offiHe adds that it’s unlikely that the bloom blossomed cials held a press conference to offer the following final from a single cell but a larger population could have explanation: A well-meaning worker dumped 160 L of been seeded in the outdoor pool, perhaps dropped off hydrogen peroxide into the water the day of the openby a bird. Stranger things than algae have turned up in ing ceremony, but the intended disinfecRio’s waters. tant instead disarmed the pools’ biocidal Matt Davenport The real cause may remain forever unknown. It would chlorine, as reported by the New York Times. wrote this week’s have been easy to find answers with standard tests, our This stripped the pools of their best decolumn. Please sources say, but the pools were drained and refilled fense against microorganisms. send comments ahead of the synchronized swimming events. Like a Although the officials stopped short of and suggestions to bunch of silver medalists, the Newscripts gang is left to naming algae at the press conference, their
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Green chemistry at the Rio Olympics
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C&EN | CEN.ACS.ORG | AUGUST 29, 2016
CREDIT: CAO C/ZUMA PRESS/SPLASH NEWS/NEWSCOM
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