英语访谈节目:如何解决洪水后的水污染问题

JUDY WOODRUFF: As hurricanes become more intense and wetter due to climate change, massive flooding events from hurricanes like Florence and Harvey may become even more severe and occur more frequently. Yet surprisingly little is known about the contaminants lurking in storm waters afterward and their impacts on human health. Special correspondent Cat Wise reports now from North Carolina, where there's an effort under way to change that. It's part of our weekly look at the Leading Edge of science, technology and health.

CAT WISE: Eight trillion gallons, that's the estimated amount of rain that fell across North Carolina from Hurricane Florence. During the catastrophic flooding that followed, hog lagoon waste, raw sewage, and coal ash were among the toxic substances that flowed into waterways and communities. University of North Carolina scientist Rachel Noble spent a lot of time in those floodwaters. She collects samples after extreme storms, more than 1,000 since Florence, and brings them back to her lab. Noble and her students are studying the pathogens in floodwaters, drinking water, and shellfish. Two months after the storm, they continue to see problems.

RACHEL NOBLE, University of North Carolina: It's gone on longer than we might have expected, and we're also seeing contamination that is popping up in locations that we might not have expected it.

CAT WISE: Contact with floodwaters can cause skin infections and diarrheal illnesses, but in rare instances, exposure can be deadly. Wounds infected with certain strains of vibrio, a bacteria which likes warm brackish waters, an kill within 24 hours if not treated.

DR. VICKI MORRIS, Carteret Health Care: The main thing that I think we have noticed is an increase in the number of salmonella cases.

CAT WISE: Vicki Morris is a local infectious disease doctor who has seen an uptick in flood-associated illnesses. She says it's often hard to know to what her patients have been exposed to.

DR. VICKI MORRIS: Right now, if a patient comes in, we have to do a culture, and it can take 48 to 72 hours for the germs to grow. If I knew what were in the floodwater or the drinking water of my patients, it would help me choose the initial antibiotics with more info to go on.

CAT WISE: Noble agrees there is a big need for more water quality testing during floods and faster results.

RACHEL NOBLE: The way the system works is that we often tell people about the results of contaminated water after they have already had them to drink or after they have already been exposed to them. We're telling them in the newspaper and on the Internet after the fact.

CAT WISE: Part of that lag time, she says, is due to water testing agencies often being overwhelmed and out of power during flooding events. But it's also because current tests, which look for signs of E. coli, a telltale bacteria for other pathogens, are slow. She's developed a way to speed things up.

RACHEL NOBLE: This is the existing test that we use for bacteria in water. It relies on growing the bacteria from the water, and it will take about 24 hours for a result. The new test we have developed actually determines the amount of DNA of a certain type of bacteria, so, in this case, E. coli, and we can get a result from this test in about an hour.

CAT WISE: Noble's new test, which is undergoing regulatory review by the EPA, is currently processed in her lab using a DNA sensing machine. But in the future, she hopes to be able to go mobile. While progress is being made on rapid water tests, another challenge for researchers after big storms is tracking where contaminated waters are flowing. But a unique collaboration is now under way to tackle that problem with some sophisticated new tools. On a recent morning, Duke University scientists Dave Johnston and Rett Newton joined Noble for a scenic boat ride with an important scientific goal: to test two devices they hope will one day transform the way floodwaters and sources of contamination are tracked.

DAVE JOHNSTON, Duke University: Once we have the autonomous boat on station, then we can get the drone ready to go.

CAT WISE: Johnston and Newton are in the early stages of using autonomous boats and drones with highly sensitive cameras to survey and sample waters difficult for researchers like noble to reach. Back on shore at Duke's Marine lab, which was hit hard by Hurricane Florence, Johnston explained why the new tools are helpful

DAVE JOHNSTON: There are a lot of places where you don't want people to actually expose themselves to those places. Think about doing water quality testing at a mine tailing pond, right? So programming a little boat to travel up into a tidal creek, or to have program a drone to go over to a certain spot and take a sample, those are revolutionary technologies that allow us to sample in places that people just can't get to.

CAT WISE: The team is also outfitting drones with thermal cameras, which can provide a clear picture of where sources of water are flowing, a tool that could be helpful when trying to pinpoint sources of contamination.

DAVE JOHNSTON: In this case, we see water that's coming from a warm area, and we're able to actually see where that water is going. It's pretty cool. It takes a pretty sharp left-hand. We'd be able to say, hey, there's a potential for exposure in these locations.

CAT WISE: Rett Newton is a Ph.D. student at Duke who knows his way around high-tech equipment. He also happens to be a retired Air Force colonel who flew F-15s, and he's the current mayor of Beaufort, a picturesque coastal town which experienced flooding after Florence. When he's not tending to the needs of his community, he is often out flying drones over the local waterways. Is this an exciting time to be in this field?

RETT NEWTON, Duke University Ph.D. Student: It's really exciting, yes, even for a crusty old guy like me watching the young folks, the young students, and they're really fired up. Every single day, we're seeing new platforms, new sensors, new applications. And a lot of the power is in the processing right now, trying to get the processing quicker for us to get some of this data in near real time.

CAT WISE: UNC's Rachel Noble is hoping all that new data and other rapid water tests she's developing, including one for vibrio, will help to keep the public better informed during future storms. For the PBS NewsHour, I'm Cat Wise in Morehead City, North Carolina.