"No swimming" signs have already popped up this summer along coastlines where fecal bacteria have invaded otherwise inviting¹ waters. Some vacationers ignore the signs while others resign themselves to tanning and playing on the beach. But should those avoiding the water be wary² of the sand, too? New research in the ACS journal Environmental Science & Technology investigates reasons why the answer could be "yes." Sewage-contaminated coastal³ waters can lead to stomach aches, diarrhea and rashes for those who accidentally swallow harmful microbes or come into contact with them. But over the past decade, scientists have been finding fecal bacteria in beach sand at levels 10 to 100 times higher than in nearby seawater. Tao Yan and colleagues wanted to find out why. 

 

In the lab, the researchers created microcosms of beach sand and seawater contaminated with sewage to see how the overall bacterial⁴ populations, including fecal dwellers⁵ responsible for causing illness, would change over time. They found that microbial communities tended to decay much slower in the simulated beach sand environment than in the water, which could help explain why more fecal bacteria are found on sandy beaches affected⁶ by wastewater pollution than in the waves. 

 

The authors acknowledge funding from the Hawaii Department of Health.

 

The American Chemical Society is a nonprofit organization chartered by the U.S. Congress. With more than 158,000 members, ACS is the world's largest scientific society and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio.

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