How does your dip in a local watering hole affect the stream’s chemistry? Researchers who previously analyzed the impact of people swimming and tubing on a Colorado creek report updated observations in ACS ES&T Water. 

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They find that these recreational activities over a busy Labor Day weekend have a short-term effect, increasing the levels of metals, human gut-associated microbes and substances from personal care products.

READ MORE: Swimming with superbugs: the hidden threat in freshwater environments

READ MORE: Tubing and swimming change the chemistry and microbiome of streams

Researchers James Ranville, Carsten Prasse, John Spear, Noor Hamden, Carmen Villarruel and colleagues studied how recreational activities, such as float tubing, around the 2022 Labor Day weekend affected a natural stream’s chemistry and microbiome. They presented a preliminary assessment of chemical and microbial constituents at ACS Fall 2023, a meeting of the American Chemical Society.

Now, the researchers have expanded the analyses in Colorado’s Clear Creek to include additional organic contaminants. They sampled water downstream of a busy area with people tubing and swimming and compared the results to an undisturbed location upstream and a day with no one at the two sites.

Human activities

Their observations indicate changes in:

  • Metals: People in the stream stirred up sediment, resuspending particles containing copper, lead and zinc into the water.
  • Microbial community: The abundance of microorganisms associated with the human gut microbiome increased when people were present, but the stream returned to an undisturbed, background microbiome within 48 hours.
  • Organic compounds: Analyses detected a broad spectrum of compounds such as ones from personal care products, including makeup and hair styling products, as well as insect repellants. Some, such as the pain killer acetaminophen, suggest human excretion in the stream as well.

While high levels of tubing and swimming impacted the stream, the results from the study suggest that these types of human activities didn’t have long-term effects. However, the researchers say that native creek organisms could react negatively to prolonged or repeated exposure to metals, microbes associated with humans, or organic compounds of concern.

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